Java tutorial
/* * Copyright (C) 2013 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.telegram.android.support.widget; import android.content.Context; import android.database.Observable; import android.graphics.Canvas; import android.graphics.PointF; import android.graphics.Rect; import android.os.Build; import android.os.Bundle; import android.os.Parcel; import android.os.Parcelable; import android.support.annotation.Nullable; import android.support.v4.util.ArrayMap; import android.support.v4.view.InputDeviceCompat; import android.support.v4.view.MotionEventCompat; import android.support.v4.view.ScrollingView; import android.support.v4.view.VelocityTrackerCompat; import android.support.v4.view.ViewCompat; import android.support.v4.view.ViewConfigurationCompat; import android.support.v4.view.accessibility.AccessibilityEventCompat; import android.support.v4.view.accessibility.AccessibilityNodeInfoCompat; import android.support.v4.view.accessibility.AccessibilityRecordCompat; import android.support.v4.widget.EdgeEffectCompat; import android.support.v4.widget.ScrollerCompat; import static org.telegram.android.support.widget.AdapterHelper.UpdateOp; import static org.telegram.android.support.widget.AdapterHelper.Callback; import android.util.AttributeSet; import android.util.Log; import android.util.SparseArray; import android.util.SparseIntArray; import android.util.TypedValue; import android.view.FocusFinder; import android.view.MotionEvent; import android.view.VelocityTracker; import android.view.View; import android.view.ViewConfiguration; import android.view.ViewGroup; import android.view.ViewParent; import android.view.accessibility.AccessibilityEvent; import android.view.accessibility.AccessibilityManager; import android.view.animation.Interpolator; import org.telegram.android.AndroidUtilities; import java.util.ArrayList; import java.util.Collections; import java.util.List; /** * A flexible view for providing a limited window into a large data set. * * <h3>Glossary of terms:</h3> * * <ul> * <li><em>Adapter:</em> A subclass of {@link Adapter} responsible for providing views * that represent items in a data set.</li> * <li><em>Position:</em> The position of a data item within an <em>Adapter</em>.</li> * <li><em>Index:</em> The index of an attached child view as used in a call to * {@link ViewGroup#getChildAt}. Contrast with <em>Position.</em></li> * <li><em>Binding:</em> The process of preparing a child view to display data corresponding * to a <em>position</em> within the adapter.</li> * <li><em>Recycle (view):</em> A view previously used to display data for a specific adapter * position may be placed in a cache for later reuse to display the same type of data again * later. This can drastically improve performance by skipping initial layout inflation * or construction.</li> * <li><em>Scrap (view):</em> A child view that has entered into a temporarily detached * state during layout. Scrap views may be reused without becoming fully detached * from the parent RecyclerView, either unmodified if no rebinding is required or modified * by the adapter if the view was considered <em>dirty</em>.</li> * <li><em>Dirty (view):</em> A child view that must be rebound by the adapter before * being displayed.</li> * </ul> * * <h4>Positions in RecyclerView:</h4> * <p> * RecyclerView introduces an additional level of abstraction between the {@link Adapter} and * {@link LayoutManager} to be able to detect data set changes in batches during a layout * calculation. This saves LayoutManager from tracking adapter changes to calculate animations. * It also helps with performance because all view bindings happen at the same time and unnecessary * bindings are avoided. * <p> * For this reason, there are two types of <code>position</code> related methods in RecyclerView: * <ul> * <li>layout position: Position of an item in the latest layout calculation. This is the * position from the LayoutManager's perspective.</li> * <li>adapter position: Position of an item in the adapter. This is the position from * the Adapter's perspective.</li> * </ul> * <p> * These two positions are the same except the time between dispatching <code>adapter.notify* * </code> events and calculating the updated layout. * <p> * Methods that return or receive <code>*LayoutPosition*</code> use position as of the latest * layout calculation (e.g. {@link ViewHolder#getLayoutPosition()}, * {@link #findViewHolderForLayoutPosition(int)}). These positions include all changes until the * last layout calculation. You can rely on these positions to be consistent with what user is * currently seeing on the screen. For example, if you have a list of items on the screen and user * asks for the 5<sup>th</sup> element, you should use these methods as they'll match what user * is seeing. * <p> * The other set of position related methods are in the form of * <code>*AdapterPosition*</code>. (e.g. {@link ViewHolder#getAdapterPosition()}, * {@link #findViewHolderForAdapterPosition(int)}) You should use these methods when you need to * work with up-to-date adapter positions even if they may not have been reflected to layout yet. * For example, if you want to access the item in the adapter on a ViewHolder click, you should use * {@link ViewHolder#getAdapterPosition()}. Beware that these methods may not be able to calculate * adapter positions if {@link Adapter#notifyDataSetChanged()} has been called and new layout has * not yet been calculated. For this reasons, you should carefully handle {@link #NO_POSITION} or * <code>null</code> results from these methods. * <p> * When writing a {@link LayoutManager} you almost always want to use layout positions whereas when * writing an {@link Adapter}, you probably want to use adapter positions. */ public class RecyclerView extends ViewGroup implements ScrollingView { private static final String TAG = "RecyclerView"; private static final boolean DEBUG = false; /** * On Kitkat and JB MR2, there is a bug which prevents DisplayList from being invalidated if * a View is two levels deep(wrt to ViewHolder.itemView). DisplayList can be invalidated by * setting View's visibility to INVISIBLE when View is detached. On Kitkat and JB MR2, Recycler * recursively traverses itemView and invalidates display list for each ViewGroup that matches * this criteria. */ private static final boolean FORCE_INVALIDATE_DISPLAY_LIST = Build.VERSION.SDK_INT == 18 || Build.VERSION.SDK_INT == 19 || Build.VERSION.SDK_INT == 20; private static final boolean DISPATCH_TEMP_DETACH = false; public static final int HORIZONTAL = 0; public static final int VERTICAL = 1; public static final int NO_POSITION = -1; public static final long NO_ID = -1; public static final int INVALID_TYPE = -1; /** * Constant for use with {@link #setScrollingTouchSlop(int)}. Indicates * that the RecyclerView should use the standard touch slop for smooth, * continuous scrolling. */ public static final int TOUCH_SLOP_DEFAULT = 0; /** * Constant for use with {@link #setScrollingTouchSlop(int)}. Indicates * that the RecyclerView should use the standard touch slop for scrolling * widgets that snap to a page or other coarse-grained barrier. */ public static final int TOUCH_SLOP_PAGING = 1; private static final int MAX_SCROLL_DURATION = 2000; /** * RecyclerView is calculating a scroll. * If there are too many of these in Systrace, some Views inside RecyclerView might be causing * it. Try to avoid using EditText, focusable views or handle them with care. */ private static final String TRACE_SCROLL_TAG = "RV Scroll"; /** * OnLayout has been called by the View system. * If this shows up too many times in Systrace, make sure the children of RecyclerView do not * update themselves directly. This will cause a full re-layout but when it happens via the * Adapter notifyItemChanged, RecyclerView can avoid full layout calculation. */ private static final String TRACE_ON_LAYOUT_TAG = "RV OnLayout"; /** * NotifyDataSetChanged or equal has been called. * If this is taking a long time, try sending granular notify adapter changes instead of just * calling notifyDataSetChanged or setAdapter / swapAdapter. Adding stable ids to your adapter * might help. */ private static final String TRACE_ON_DATA_SET_CHANGE_LAYOUT_TAG = "RV FullInvalidate"; /** * RecyclerView is doing a layout for partial adapter updates (we know what has changed) * If this is taking a long time, you may have dispatched too many Adapter updates causing too * many Views being rebind. Make sure all are necessary and also prefer using notify*Range * methods. */ private static final String TRACE_HANDLE_ADAPTER_UPDATES_TAG = "RV PartialInvalidate"; /** * RecyclerView is rebinding a View. * If this is taking a lot of time, consider optimizing your layout or make sure you are not * doing extra operations in onBindViewHolder call. */ private static final String TRACE_BIND_VIEW_TAG = "RV OnBindView"; /** * RecyclerView is creating a new View. * If too many of these present in Systrace: * - There might be a problem in Recycling (e.g. custom Animations that set transient state and * prevent recycling or ItemAnimator not implementing the contract properly. ({@link * > Adapter#onFailedToRecycleView(ViewHolder)}) * * - There might be too many item view types. * > Try merging them * * - There might be too many itemChange animations and not enough space in RecyclerPool. * >Try increasing your pool size and item cache size. */ private static final String TRACE_CREATE_VIEW_TAG = "RV CreateView"; private final RecyclerViewDataObserver mObserver = new RecyclerViewDataObserver(); final Recycler mRecycler = new Recycler(); private SavedState mPendingSavedState; AdapterHelper mAdapterHelper; ChildHelper mChildHelper; /** * Prior to L, there is no way to query this variable which is why we override the setter and * track it here. */ private boolean mClipToPadding; /** * Note: this Runnable is only ever posted if: * 1) We've been through first layout * 2) We know we have a fixed size (mHasFixedSize) * 3) We're attached */ private final Runnable mUpdateChildViewsRunnable = new Runnable() { public void run() { if (!mFirstLayoutComplete) { // a layout request will happen, we should not do layout here. return; } if (mDataSetHasChangedAfterLayout) { dispatchLayout(); } else if (mAdapterHelper.hasPendingUpdates()) { eatRequestLayout(); mAdapterHelper.preProcess(); if (!mLayoutRequestEaten) { // We run this after pre-processing is complete so that ViewHolders have their // final adapter positions. No need to run it if a layout is already requested. rebindUpdatedViewHolders(); } resumeRequestLayout(true); } } }; private final Rect mTempRect = new Rect(); private Adapter mAdapter; private LayoutManager mLayout; private RecyclerListener mRecyclerListener; private final ArrayList<ItemDecoration> mItemDecorations = new ArrayList<ItemDecoration>(); private final ArrayList<OnItemTouchListener> mOnItemTouchListeners = new ArrayList<OnItemTouchListener>(); private OnItemTouchListener mActiveOnItemTouchListener; private boolean mIsAttached; private boolean mHasFixedSize; private boolean mFirstLayoutComplete; private boolean mEatRequestLayout; private boolean mLayoutRequestEaten; // binary OR of change events that were eaten during a layout or scroll. private int mEatenAccessibilityChangeFlags; private boolean mAdapterUpdateDuringMeasure; private final boolean mPostUpdatesOnAnimation; private final AccessibilityManager mAccessibilityManager; /** * Set to true when an adapter data set changed notification is received. * In that case, we cannot run any animations since we don't know what happened. */ private boolean mDataSetHasChangedAfterLayout = false; /** * This variable is incremented during a dispatchLayout and/or scroll. * Some methods should not be called during these periods (e.g. adapter data change). * Doing so will create hard to find bugs so we better check it and throw an exception. * * @see #assertInLayoutOrScroll(String) * @see #assertNotInLayoutOrScroll(String) */ private int mLayoutOrScrollCounter = 0; private EdgeEffectCompat mLeftGlow, mTopGlow, mRightGlow, mBottomGlow; ItemAnimator mItemAnimator = new DefaultItemAnimator(); private static final int INVALID_POINTER = -1; /** * The RecyclerView is not currently scrolling. * @see #getScrollState() */ public static final int SCROLL_STATE_IDLE = 0; /** * The RecyclerView is currently being dragged by outside input such as user touch input. * @see #getScrollState() */ public static final int SCROLL_STATE_DRAGGING = 1; /** * The RecyclerView is currently animating to a final position while not under * outside control. * @see #getScrollState() */ public static final int SCROLL_STATE_SETTLING = 2; // Touch/scrolling handling private int mScrollState = SCROLL_STATE_IDLE; private int mScrollPointerId = INVALID_POINTER; private VelocityTracker mVelocityTracker; private int mInitialTouchX; private int mInitialTouchY; private int mLastTouchX; private int mLastTouchY; private int mTouchSlop; private final int mMinFlingVelocity; private final int mMaxFlingVelocity; // This value is used when handling generic motion events. private float mScrollFactor = Float.MIN_VALUE; private final ViewFlinger mViewFlinger = new ViewFlinger(); final State mState = new State(); private OnScrollListener mScrollListener; private List<OnScrollListener> mScrollListeners; // For use in item animations boolean mItemsAddedOrRemoved = false; boolean mItemsChanged = false; private ItemAnimator.ItemAnimatorListener mItemAnimatorListener = new ItemAnimatorRestoreListener(); private boolean mPostedAnimatorRunner = false; private RecyclerViewAccessibilityDelegate mAccessibilityDelegate; // simple array to keep min and max child position during a layout calculation // preserved not to create a new one in each layout pass private final int[] mMinMaxLayoutPositions = new int[2]; private Runnable mItemAnimatorRunner = new Runnable() { @Override public void run() { if (mItemAnimator != null) { mItemAnimator.runPendingAnimations(); } mPostedAnimatorRunner = false; } }; private static final Interpolator sQuinticInterpolator = new Interpolator() { public float getInterpolation(float t) { t -= 1.0f; return t * t * t * t * t + 1.0f; } }; public RecyclerView(Context context) { this(context, null); } public RecyclerView(Context context, @Nullable AttributeSet attrs) { this(context, attrs, 0); } public RecyclerView(Context context, @Nullable AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); setFocusableInTouchMode(true); final int version = Build.VERSION.SDK_INT; mPostUpdatesOnAnimation = version >= 16; final ViewConfiguration vc = ViewConfiguration.get(context); mTouchSlop = vc.getScaledTouchSlop(); mMinFlingVelocity = vc.getScaledMinimumFlingVelocity(); mMaxFlingVelocity = vc.getScaledMaximumFlingVelocity(); setWillNotDraw(ViewCompat.getOverScrollMode(this) == ViewCompat.OVER_SCROLL_NEVER); mItemAnimator.setListener(mItemAnimatorListener); initAdapterManager(); initChildrenHelper(); // If not explicitly specified this view is important for accessibility. if (ViewCompat.getImportantForAccessibility(this) == ViewCompat.IMPORTANT_FOR_ACCESSIBILITY_AUTO) { ViewCompat.setImportantForAccessibility(this, ViewCompat.IMPORTANT_FOR_ACCESSIBILITY_YES); } mAccessibilityManager = (AccessibilityManager) getContext().getSystemService(Context.ACCESSIBILITY_SERVICE); setAccessibilityDelegateCompat(new RecyclerViewAccessibilityDelegate(this)); } /** * Returns the accessibility delegate compatibility implementation used by the RecyclerView. * @return An instance of AccessibilityDelegateCompat used by RecyclerView */ public RecyclerViewAccessibilityDelegate getCompatAccessibilityDelegate() { return mAccessibilityDelegate; } /** * Sets the accessibility delegate compatibility implementation used by RecyclerView. * @param accessibilityDelegate The accessibility delegate to be used by RecyclerView. */ public void setAccessibilityDelegateCompat(RecyclerViewAccessibilityDelegate accessibilityDelegate) { mAccessibilityDelegate = accessibilityDelegate; ViewCompat.setAccessibilityDelegate(this, mAccessibilityDelegate); } private void initChildrenHelper() { mChildHelper = new ChildHelper(new ChildHelper.Callback() { @Override public int getChildCount() { return RecyclerView.this.getChildCount(); } @Override public void addView(View child, int index) { RecyclerView.this.addView(child, index); dispatchChildAttached(child); } @Override public int indexOfChild(View view) { return RecyclerView.this.indexOfChild(view); } @Override public void removeViewAt(int index) { final View child = RecyclerView.this.getChildAt(index); if (child != null) { dispatchChildDetached(child); } RecyclerView.this.removeViewAt(index); } @Override public View getChildAt(int offset) { return RecyclerView.this.getChildAt(offset); } @Override public void removeAllViews() { final int count = getChildCount(); for (int i = 0; i < count; i++) { dispatchChildDetached(getChildAt(i)); } RecyclerView.this.removeAllViews(); } @Override public ViewHolder getChildViewHolder(View view) { return getChildViewHolderInt(view); } @Override public void attachViewToParent(View child, int index, ViewGroup.LayoutParams layoutParams) { final ViewHolder vh = getChildViewHolderInt(child); if (vh != null) { if (!vh.isTmpDetached() && !vh.shouldIgnore()) { throw new IllegalArgumentException( "Called attach on a child which is not" + " detached: " + vh); } if (DEBUG) { Log.d(TAG, "reAttach " + vh); } vh.clearTmpDetachFlag(); } RecyclerView.this.attachViewToParent(child, index, layoutParams); } @Override public void detachViewFromParent(int offset) { final View view = getChildAt(offset); if (view != null) { final ViewHolder vh = getChildViewHolderInt(view); if (vh != null) { if (vh.isTmpDetached() && !vh.shouldIgnore()) { throw new IllegalArgumentException( "called detach on an already" + " detached child " + vh); } if (DEBUG) { Log.d(TAG, "tmpDetach " + vh); } vh.addFlags(ViewHolder.FLAG_TMP_DETACHED); } } RecyclerView.this.detachViewFromParent(offset); } }); } void initAdapterManager() { mAdapterHelper = new AdapterHelper(new Callback() { @Override public ViewHolder findViewHolder(int position) { final ViewHolder vh = findViewHolderForPosition(position, true); if (vh == null) { return null; } // ensure it is not hidden because for adapter helper, the only thing matter is that // LM thinks view is a child. if (mChildHelper.isHidden(vh.itemView)) { if (DEBUG) { Log.d(TAG, "assuming view holder cannot be find because it is hidden"); } return null; } return vh; } @Override public void offsetPositionsForRemovingInvisible(int start, int count) { offsetPositionRecordsForRemove(start, count, true); mItemsAddedOrRemoved = true; mState.mDeletedInvisibleItemCountSincePreviousLayout += count; } @Override public void offsetPositionsForRemovingLaidOutOrNewView(int positionStart, int itemCount) { offsetPositionRecordsForRemove(positionStart, itemCount, false); mItemsAddedOrRemoved = true; } @Override public void markViewHoldersUpdated(int positionStart, int itemCount) { viewRangeUpdate(positionStart, itemCount); mItemsChanged = true; } @Override public void onDispatchFirstPass(UpdateOp op) { dispatchUpdate(op); } void dispatchUpdate(UpdateOp op) { switch (op.cmd) { case UpdateOp.ADD: mLayout.onItemsAdded(RecyclerView.this, op.positionStart, op.itemCount); break; case UpdateOp.REMOVE: mLayout.onItemsRemoved(RecyclerView.this, op.positionStart, op.itemCount); break; case UpdateOp.UPDATE: mLayout.onItemsUpdated(RecyclerView.this, op.positionStart, op.itemCount); break; case UpdateOp.MOVE: mLayout.onItemsMoved(RecyclerView.this, op.positionStart, op.itemCount, 1); break; } } @Override public void onDispatchSecondPass(UpdateOp op) { dispatchUpdate(op); } @Override public void offsetPositionsForAdd(int positionStart, int itemCount) { offsetPositionRecordsForInsert(positionStart, itemCount); mItemsAddedOrRemoved = true; } @Override public void offsetPositionsForMove(int from, int to) { offsetPositionRecordsForMove(from, to); // should we create mItemsMoved ? mItemsAddedOrRemoved = true; } }); } /** * RecyclerView can perform several optimizations if it can know in advance that changes in * adapter content cannot change the size of the RecyclerView itself. * If your use of RecyclerView falls into this category, set this to true. * * @param hasFixedSize true if adapter changes cannot affect the size of the RecyclerView. */ public void setHasFixedSize(boolean hasFixedSize) { mHasFixedSize = hasFixedSize; } /** * @return true if the app has specified that changes in adapter content cannot change * the size of the RecyclerView itself. */ public boolean hasFixedSize() { return mHasFixedSize; } @Override public void setClipToPadding(boolean clipToPadding) { if (clipToPadding != mClipToPadding) { invalidateGlows(); } mClipToPadding = clipToPadding; super.setClipToPadding(clipToPadding); if (mFirstLayoutComplete) { requestLayout(); } } /** * Configure the scrolling touch slop for a specific use case. * * Set up the RecyclerView's scrolling motion threshold based on common usages. * Valid arguments are {@link #TOUCH_SLOP_DEFAULT} and {@link #TOUCH_SLOP_PAGING}. * * @param slopConstant One of the <code>TOUCH_SLOP_</code> constants representing * the intended usage of this RecyclerView */ public void setScrollingTouchSlop(int slopConstant) { final ViewConfiguration vc = ViewConfiguration.get(getContext()); switch (slopConstant) { default: Log.w(TAG, "setScrollingTouchSlop(): bad argument constant " + slopConstant + "; using default value"); // fall-through case TOUCH_SLOP_DEFAULT: mTouchSlop = vc.getScaledTouchSlop(); break; case TOUCH_SLOP_PAGING: mTouchSlop = ViewConfigurationCompat.getScaledPagingTouchSlop(vc); break; } } /** * Swaps the current adapter with the provided one. It is similar to * {@link #setAdapter(Adapter)} but assumes existing adapter and the new adapter uses the same * {@link ViewHolder} and does not clear the RecycledViewPool. * <p> * Note that it still calls onAdapterChanged callbacks. * * @param adapter The new adapter to set, or null to set no adapter. * @param removeAndRecycleExistingViews If set to true, RecyclerView will recycle all existing * Views. If adapters have stable ids and/or you want to * animate the disappearing views, you may prefer to set * this to false. * @see #setAdapter(Adapter) */ public void swapAdapter(Adapter adapter, boolean removeAndRecycleExistingViews) { setAdapterInternal(adapter, true, removeAndRecycleExistingViews); setDataSetChangedAfterLayout(); requestLayout(); } /** * Set a new adapter to provide child views on demand. * <p> * When adapter is changed, all existing views are recycled back to the pool. If the pool has * only one adapter, it will be cleared. * * @param adapter The new adapter to set, or null to set no adapter. * @see #swapAdapter(Adapter, boolean) */ public void setAdapter(Adapter adapter) { setAdapterInternal(adapter, false, true); requestLayout(); } /** * Replaces the current adapter with the new one and triggers listeners. * @param adapter The new adapter * @param compatibleWithPrevious If true, the new adapter is using the same View Holders and * item types with the current adapter (helps us avoid cache * invalidation). * @param removeAndRecycleViews If true, we'll remove and recycle all existing views. If * compatibleWithPrevious is false, this parameter is ignored. */ private void setAdapterInternal(Adapter adapter, boolean compatibleWithPrevious, boolean removeAndRecycleViews) { if (mAdapter != null) { mAdapter.unregisterAdapterDataObserver(mObserver); mAdapter.onDetachedFromRecyclerView(this); } if (!compatibleWithPrevious || removeAndRecycleViews) { // end all running animations if (mItemAnimator != null) { mItemAnimator.endAnimations(); } // Since animations are ended, mLayout.children should be equal to // recyclerView.children. This may not be true if item animator's end does not work as // expected. (e.g. not release children instantly). It is safer to use mLayout's child // count. if (mLayout != null) { mLayout.removeAndRecycleAllViews(mRecycler); mLayout.removeAndRecycleScrapInt(mRecycler); } // we should clear it here before adapters are swapped to ensure correct callbacks. mRecycler.clear(); } mAdapterHelper.reset(); final Adapter oldAdapter = mAdapter; mAdapter = adapter; if (adapter != null) { adapter.registerAdapterDataObserver(mObserver); adapter.onAttachedToRecyclerView(this); } if (mLayout != null) { mLayout.onAdapterChanged(oldAdapter, mAdapter); } mRecycler.onAdapterChanged(oldAdapter, mAdapter, compatibleWithPrevious); mState.mStructureChanged = true; markKnownViewsInvalid(); } /** * Retrieves the previously set adapter or null if no adapter is set. * * @return The previously set adapter * @see #setAdapter(Adapter) */ public Adapter getAdapter() { return mAdapter; } /** * Register a listener that will be notified whenever a child view is recycled. * * <p>This listener will be called when a LayoutManager or the RecyclerView decides * that a child view is no longer needed. If an application associates expensive * or heavyweight data with item views, this may be a good place to release * or free those resources.</p> * * @param listener Listener to register, or null to clear */ public void setRecyclerListener(RecyclerListener listener) { mRecyclerListener = listener; } /** * <p>Return the offset of the RecyclerView's text baseline from the its top * boundary. If the LayoutManager of this RecyclerView does not support baseline alignment, * this method returns -1.</p> * * @return the offset of the baseline within the RecyclerView's bounds or -1 * if baseline alignment is not supported */ @Override public int getBaseline() { if (mLayout != null) { return mLayout.getBaseline(); } else { return super.getBaseline(); } } /** * Set the {@link LayoutManager} that this RecyclerView will use. * * <p>In contrast to other adapter-backed views such as {@link android.widget.ListView} * or {@link android.widget.GridView}, RecyclerView allows client code to provide custom * layout arrangements for child views. These arrangements are controlled by the * {@link LayoutManager}. A LayoutManager must be provided for RecyclerView to function.</p> * * <p>Several default strategies are provided for common uses such as lists and grids.</p> * * @param layout LayoutManager to use */ public void setLayoutManager(LayoutManager layout) { if (layout == mLayout) { return; } // TODO We should do this switch a dispachLayout pass and animate children. There is a good // chance that LayoutManagers will re-use views. if (mLayout != null) { if (mIsAttached) { mLayout.dispatchDetachedFromWindow(this, mRecycler); } mLayout.setRecyclerView(null); } mRecycler.clear(); mChildHelper.removeAllViewsUnfiltered(); mLayout = layout; if (layout != null) { if (layout.mRecyclerView != null) { throw new IllegalArgumentException("LayoutManager " + layout + " is already attached to a RecyclerView: " + layout.mRecyclerView); } mLayout.setRecyclerView(this); if (mIsAttached) { mLayout.dispatchAttachedToWindow(this); } } requestLayout(); } @Override protected Parcelable onSaveInstanceState() { SavedState state = new SavedState(super.onSaveInstanceState()); if (mPendingSavedState != null) { state.copyFrom(mPendingSavedState); } else if (mLayout != null) { state.mLayoutState = mLayout.onSaveInstanceState(); } else { state.mLayoutState = null; } return state; } @Override protected void onRestoreInstanceState(Parcelable state) { mPendingSavedState = (SavedState) state; super.onRestoreInstanceState(mPendingSavedState.getSuperState()); if (mLayout != null && mPendingSavedState.mLayoutState != null) { mLayout.onRestoreInstanceState(mPendingSavedState.mLayoutState); } } /** * Override to prevent freezing of any views created by the adapter. */ @Override protected void dispatchSaveInstanceState(SparseArray<Parcelable> container) { dispatchFreezeSelfOnly(container); } /** * Override to prevent thawing of any views created by the adapter. */ @Override protected void dispatchRestoreInstanceState(SparseArray<Parcelable> container) { dispatchThawSelfOnly(container); } /** * Adds a view to the animatingViews list. * mAnimatingViews holds the child views that are currently being kept around * purely for the purpose of being animated out of view. They are drawn as a regular * part of the child list of the RecyclerView, but they are invisible to the LayoutManager * as they are managed separately from the regular child views. * @param viewHolder The ViewHolder to be removed */ private void addAnimatingView(ViewHolder viewHolder) { final View view = viewHolder.itemView; final boolean alreadyParented = view.getParent() == this; mRecycler.unscrapView(getChildViewHolder(view)); if (viewHolder.isTmpDetached()) { // re-attach mChildHelper.attachViewToParent(view, -1, view.getLayoutParams(), true); } else if (!alreadyParented) { mChildHelper.addView(view, true); } else { mChildHelper.hide(view); } } /** * Removes a view from the animatingViews list. * @param view The view to be removed * @see #addAnimatingView(RecyclerView.ViewHolder) * @return true if an animating view is removed */ private boolean removeAnimatingView(View view) { eatRequestLayout(); final boolean removed = mChildHelper.removeViewIfHidden(view); if (removed) { final ViewHolder viewHolder = getChildViewHolderInt(view); mRecycler.unscrapView(viewHolder); mRecycler.recycleViewHolderInternal(viewHolder); if (DEBUG) { Log.d(TAG, "after removing animated view: " + view + ", " + this); } } resumeRequestLayout(false); return removed; } /** * Return the {@link LayoutManager} currently responsible for * layout policy for this RecyclerView. * * @return The currently bound LayoutManager */ public LayoutManager getLayoutManager() { return mLayout; } /** * Retrieve this RecyclerView's {@link RecycledViewPool}. This method will never return null; * if no pool is set for this view a new one will be created. See * {@link #setRecycledViewPool(RecycledViewPool) setRecycledViewPool} for more information. * * @return The pool used to store recycled item views for reuse. * @see #setRecycledViewPool(RecycledViewPool) */ public RecycledViewPool getRecycledViewPool() { return mRecycler.getRecycledViewPool(); } /** * Recycled view pools allow multiple RecyclerViews to share a common pool of scrap views. * This can be useful if you have multiple RecyclerViews with adapters that use the same * view types, for example if you have several data sets with the same kinds of item views * displayed by a {@link android.support.v4.view.ViewPager ViewPager}. * * @param pool Pool to set. If this parameter is null a new pool will be created and used. */ public void setRecycledViewPool(RecycledViewPool pool) { mRecycler.setRecycledViewPool(pool); } /** * Sets a new {@link ViewCacheExtension} to be used by the Recycler. * * @param extension ViewCacheExtension to be used or null if you want to clear the existing one. * * @see {@link ViewCacheExtension#getViewForPositionAndType(Recycler, int, int)} */ public void setViewCacheExtension(ViewCacheExtension extension) { mRecycler.setViewCacheExtension(extension); } /** * Set the number of offscreen views to retain before adding them to the potentially shared * {@link #getRecycledViewPool() recycled view pool}. * * <p>The offscreen view cache stays aware of changes in the attached adapter, allowing * a LayoutManager to reuse those views unmodified without needing to return to the adapter * to rebind them.</p> * * @param size Number of views to cache offscreen before returning them to the general * recycled view pool */ public void setItemViewCacheSize(int size) { mRecycler.setViewCacheSize(size); } /** * Return the current scrolling state of the RecyclerView. * * @return {@link #SCROLL_STATE_IDLE}, {@link #SCROLL_STATE_DRAGGING} or * {@link #SCROLL_STATE_SETTLING} */ public int getScrollState() { return mScrollState; } private void setScrollState(int state) { if (state == mScrollState) { return; } if (DEBUG) { Log.d(TAG, "setting scroll state to " + state + " from " + mScrollState, new Exception()); } mScrollState = state; if (state != SCROLL_STATE_SETTLING) { stopScrollersInternal(); } dispatchOnScrollStateChanged(state); } /** * Add an {@link ItemDecoration} to this RecyclerView. Item decorations can * affect both measurement and drawing of individual item views. * * <p>Item decorations are ordered. Decorations placed earlier in the list will * be run/queried/drawn first for their effects on item views. Padding added to views * will be nested; a padding added by an earlier decoration will mean further * item decorations in the list will be asked to draw/pad within the previous decoration's * given area.</p> * * @param decor Decoration to add * @param index Position in the decoration chain to insert this decoration at. If this value * is negative the decoration will be added at the end. */ public void addItemDecoration(ItemDecoration decor, int index) { if (mLayout != null) { mLayout.assertNotInLayoutOrScroll("Cannot add item decoration during a scroll or" + " layout"); } if (mItemDecorations.isEmpty()) { setWillNotDraw(false); } if (index < 0) { mItemDecorations.add(decor); } else { mItemDecorations.add(index, decor); } markItemDecorInsetsDirty(); requestLayout(); } /** * Add an {@link ItemDecoration} to this RecyclerView. Item decorations can * affect both measurement and drawing of individual item views. * * <p>Item decorations are ordered. Decorations placed earlier in the list will * be run/queried/drawn first for their effects on item views. Padding added to views * will be nested; a padding added by an earlier decoration will mean further * item decorations in the list will be asked to draw/pad within the previous decoration's * given area.</p> * * @param decor Decoration to add */ public void addItemDecoration(ItemDecoration decor) { addItemDecoration(decor, -1); } /** * Remove an {@link ItemDecoration} from this RecyclerView. * * <p>The given decoration will no longer impact the measurement and drawing of * item views.</p> * * @param decor Decoration to remove * @see #addItemDecoration(ItemDecoration) */ public void removeItemDecoration(ItemDecoration decor) { if (mLayout != null) { mLayout.assertNotInLayoutOrScroll("Cannot remove item decoration during a scroll or" + " layout"); } mItemDecorations.remove(decor); if (mItemDecorations.isEmpty()) { setWillNotDraw(ViewCompat.getOverScrollMode(this) == ViewCompat.OVER_SCROLL_NEVER); } markItemDecorInsetsDirty(); requestLayout(); } /** * Set a listener that will be notified of any changes in scroll state or position. * * @param listener Listener to set or null to clear * * @deprecated Use {@link #addOnScrollListener(OnScrollListener)} and * {@link #removeOnScrollListener(OnScrollListener)} */ @Deprecated public void setOnScrollListener(OnScrollListener listener) { mScrollListener = listener; } /** * Add a listener that will be notified of any changes in scroll state or position. * * <p>Components that add a listener should take care to remove it when finished. * Other components that take ownership of a view may call {@link #clearOnScrollListeners()} * to remove all attached listeners.</p> * * @param listener listener to set or null to clear */ public void addOnScrollListener(OnScrollListener listener) { if (mScrollListeners == null) { mScrollListeners = new ArrayList<OnScrollListener>(); } mScrollListeners.add(listener); } /** * Remove a listener that was notified of any changes in scroll state or position. * * @param listener listener to set or null to clear */ public void removeOnScrollListener(OnScrollListener listener) { if (mScrollListeners != null) { mScrollListeners.remove(listener); } } /** * Remove all secondary listener that were notified of any changes in scroll state or position. */ public void clearOnScrollListeners() { if (mScrollListeners != null) { mScrollListeners.clear(); } } /** * Convenience method to scroll to a certain position. * * RecyclerView does not implement scrolling logic, rather forwards the call to * {@link android.support.v7.widget.RecyclerView.LayoutManager#scrollToPosition(int)} * @param position Scroll to this adapter position * @see android.support.v7.widget.RecyclerView.LayoutManager#scrollToPosition(int) */ public void scrollToPosition(int position) { stopScroll(); if (mLayout == null) { Log.e(TAG, "Cannot scroll to position a LayoutManager set. " + "Call setLayoutManager with a non-null argument."); return; } mLayout.scrollToPosition(position); awakenScrollBars(); } /** * Starts a smooth scroll to an adapter position. * <p> * To support smooth scrolling, you must override * {@link LayoutManager#smoothScrollToPosition(RecyclerView, State, int)} and create a * {@link SmoothScroller}. * <p> * {@link LayoutManager} is responsible for creating the actual scroll action. If you want to * provide a custom smooth scroll logic, override * {@link LayoutManager#smoothScrollToPosition(RecyclerView, State, int)} in your * LayoutManager. * * @param position The adapter position to scroll to * @see LayoutManager#smoothScrollToPosition(RecyclerView, State, int) */ public void smoothScrollToPosition(int position) { if (mLayout == null) { Log.e(TAG, "Cannot smooth scroll without a LayoutManager set. " + "Call setLayoutManager with a non-null argument."); return; } mLayout.smoothScrollToPosition(this, mState, position); } @Override public void scrollTo(int x, int y) { throw new UnsupportedOperationException("RecyclerView does not support scrolling to an absolute position."); } @Override public void scrollBy(int x, int y) { if (mLayout == null) { Log.e(TAG, "Cannot scroll without a LayoutManager set. " + "Call setLayoutManager with a non-null argument."); return; } final boolean canScrollHorizontal = mLayout.canScrollHorizontally(); final boolean canScrollVertical = mLayout.canScrollVertically(); if (canScrollHorizontal || canScrollVertical) { scrollByInternal(canScrollHorizontal ? x : 0, canScrollVertical ? y : 0, false, 0, 0); } } /** * Helper method reflect data changes to the state. * <p> * Adapter changes during a scroll may trigger a crash because scroll assumes no data change * but data actually changed. * <p> * This method consumes all deferred changes to avoid that case. */ private void consumePendingUpdateOperations() { mUpdateChildViewsRunnable.run(); } /** * Does not perform bounds checking. Used by internal methods that have already validated input. * <p> * It also reports any unused scroll request to the related EdgeEffect. * * @param x The amount of horizontal scroll request * @param y The amount of vertical scroll request * @param fromMotionEvent If request is originated from a MotionEvent, this should be set to * true and motionX/motionY should be provided, false otherwise. * @param motionX The x coordinate of the MotionEvent which triggered this scroll. Unused if * fromMotionEvent is false. * @param motionY The y coordinate of the MotionEvent which triggered this scroll. Unused if * fromMotionEvent is false. * * @return Whether any scroll was consumed in either direction. */ boolean scrollByInternal(int x, int y, boolean fromMotionEvent, int motionX, int motionY) { int overscrollX = 0, overscrollY = 0; int hresult = 0, vresult = 0; consumePendingUpdateOperations(); if (mAdapter != null) { eatRequestLayout(); onEnterLayoutOrScroll(); if (x != 0) { hresult = mLayout.scrollHorizontallyBy(x, mRecycler, mState); overscrollX = x - hresult; } if (y != 0) { vresult = mLayout.scrollVerticallyBy(y, mRecycler, mState); overscrollY = y - vresult; } if (supportsChangeAnimations()) { // Fix up shadow views used by changing animations int count = mChildHelper.getChildCount(); for (int i = 0; i < count; i++) { View view = mChildHelper.getChildAt(i); ViewHolder holder = getChildViewHolder(view); if (holder != null && holder.mShadowingHolder != null) { ViewHolder shadowingHolder = holder.mShadowingHolder; View shadowingView = shadowingHolder != null ? shadowingHolder.itemView : null; if (shadowingView != null) { int left = view.getLeft(); int top = view.getTop(); if (left != shadowingView.getLeft() || top != shadowingView.getTop()) { shadowingView.layout(left, top, left + shadowingView.getWidth(), top + shadowingView.getHeight()); } } } } } onExitLayoutOrScroll(); resumeRequestLayout(false); } if (!mItemDecorations.isEmpty()) { invalidate(); } if (ViewCompat.getOverScrollMode(this) != ViewCompat.OVER_SCROLL_NEVER) { if (fromMotionEvent) { pullGlows(motionX, overscrollX, motionY, overscrollY); } considerReleasingGlowsOnScroll(x, y); } if (hresult != 0 || vresult != 0) { dispatchOnScrolled(hresult, vresult); } if (!awakenScrollBars()) { invalidate(); } return hresult != 0 || vresult != 0; } /** * <p>Compute the horizontal offset of the horizontal scrollbar's thumb within the horizontal * range. This value is used to compute the length of the thumb within the scrollbar's track. * </p> * * <p>The range is expressed in arbitrary units that must be the same as the units used by * {@link #computeHorizontalScrollRange()} and {@link #computeHorizontalScrollExtent()}.</p> * * <p>Default implementation returns 0.</p> * * <p>If you want to support scroll bars, override * {@link RecyclerView.LayoutManager#computeHorizontalScrollOffset(RecyclerView.State)} in your * LayoutManager. </p> * * @return The horizontal offset of the scrollbar's thumb * @see android.support.v7.widget.RecyclerView.LayoutManager#computeHorizontalScrollOffset * (RecyclerView.Adapter) */ @Override public int computeHorizontalScrollOffset() { return mLayout.canScrollHorizontally() ? mLayout.computeHorizontalScrollOffset(mState) : 0; } /** * <p>Compute the horizontal extent of the horizontal scrollbar's thumb within the * horizontal range. This value is used to compute the length of the thumb within the * scrollbar's track.</p> * * <p>The range is expressed in arbitrary units that must be the same as the units used by * {@link #computeHorizontalScrollRange()} and {@link #computeHorizontalScrollOffset()}.</p> * * <p>Default implementation returns 0.</p> * * <p>If you want to support scroll bars, override * {@link RecyclerView.LayoutManager#computeHorizontalScrollExtent(RecyclerView.State)} in your * LayoutManager.</p> * * @return The horizontal extent of the scrollbar's thumb * @see RecyclerView.LayoutManager#computeHorizontalScrollExtent(RecyclerView.State) */ @Override public int computeHorizontalScrollExtent() { return mLayout.canScrollHorizontally() ? mLayout.computeHorizontalScrollExtent(mState) : 0; } /** * <p>Compute the horizontal range that the horizontal scrollbar represents.</p> * * <p>The range is expressed in arbitrary units that must be the same as the units used by * {@link #computeHorizontalScrollExtent()} and {@link #computeHorizontalScrollOffset()}.</p> * * <p>Default implementation returns 0.</p> * * <p>If you want to support scroll bars, override * {@link RecyclerView.LayoutManager#computeHorizontalScrollRange(RecyclerView.State)} in your * LayoutManager.</p> * * @return The total horizontal range represented by the vertical scrollbar * @see RecyclerView.LayoutManager#computeHorizontalScrollRange(RecyclerView.State) */ @Override public int computeHorizontalScrollRange() { return mLayout.canScrollHorizontally() ? mLayout.computeHorizontalScrollRange(mState) : 0; } /** * <p>Compute the vertical offset of the vertical scrollbar's thumb within the vertical range. * This value is used to compute the length of the thumb within the scrollbar's track. </p> * * <p>The range is expressed in arbitrary units that must be the same as the units used by * {@link #computeVerticalScrollRange()} and {@link #computeVerticalScrollExtent()}.</p> * * <p>Default implementation returns 0.</p> * * <p>If you want to support scroll bars, override * {@link RecyclerView.LayoutManager#computeVerticalScrollOffset(RecyclerView.State)} in your * LayoutManager.</p> * * @return The vertical offset of the scrollbar's thumb * @see android.support.v7.widget.RecyclerView.LayoutManager#computeVerticalScrollOffset * (RecyclerView.Adapter) */ @Override public int computeVerticalScrollOffset() { return mLayout.canScrollVertically() ? mLayout.computeVerticalScrollOffset(mState) : 0; } /** * <p>Compute the vertical extent of the vertical scrollbar's thumb within the vertical range. * This value is used to compute the length of the thumb within the scrollbar's track.</p> * * <p>The range is expressed in arbitrary units that must be the same as the units used by * {@link #computeVerticalScrollRange()} and {@link #computeVerticalScrollOffset()}.</p> * * <p>Default implementation returns 0.</p> * * <p>If you want to support scroll bars, override * {@link RecyclerView.LayoutManager#computeVerticalScrollExtent(RecyclerView.State)} in your * LayoutManager.</p> * * @return The vertical extent of the scrollbar's thumb * @see RecyclerView.LayoutManager#computeVerticalScrollExtent(RecyclerView.State) */ @Override public int computeVerticalScrollExtent() { return mLayout.canScrollVertically() ? mLayout.computeVerticalScrollExtent(mState) : 0; } /** * <p>Compute the vertical range that the vertical scrollbar represents.</p> * * <p>The range is expressed in arbitrary units that must be the same as the units used by * {@link #computeVerticalScrollExtent()} and {@link #computeVerticalScrollOffset()}.</p> * * <p>Default implementation returns 0.</p> * * <p>If you want to support scroll bars, override * {@link RecyclerView.LayoutManager#computeVerticalScrollRange(RecyclerView.State)} in your * LayoutManager.</p> * * @return The total vertical range represented by the vertical scrollbar * @see RecyclerView.LayoutManager#computeVerticalScrollRange(RecyclerView.State) */ @Override public int computeVerticalScrollRange() { return mLayout.canScrollVertically() ? mLayout.computeVerticalScrollRange(mState) : 0; } void eatRequestLayout() { if (!mEatRequestLayout) { mEatRequestLayout = true; mLayoutRequestEaten = false; } } void resumeRequestLayout(boolean performLayoutChildren) { if (mEatRequestLayout) { if (performLayoutChildren && mLayoutRequestEaten && mLayout != null && mAdapter != null) { dispatchLayout(); } mEatRequestLayout = false; mLayoutRequestEaten = false; } } /** * Animate a scroll by the given amount of pixels along either axis. * * @param dx Pixels to scroll horizontally * @param dy Pixels to scroll vertically */ public void smoothScrollBy(int dx, int dy) { if (mLayout == null) { Log.e(TAG, "Cannot smooth scroll without a LayoutManager set. " + "Call setLayoutManager with a non-null argument."); return; } if (!mLayout.canScrollHorizontally()) { dx = 0; } if (!mLayout.canScrollVertically()) { dy = 0; } if (dx != 0 || dy != 0) { mViewFlinger.smoothScrollBy(dx, dy); } } /** * Begin a standard fling with an initial velocity along each axis in pixels per second. * If the velocity given is below the system-defined minimum this method will return false * and no fling will occur. * * @param velocityX Initial horizontal velocity in pixels per second * @param velocityY Initial vertical velocity in pixels per second * @return true if the fling was started, false if the velocity was too low to fling or * LayoutManager does not support scrolling in the axis fling is issued. * * @see LayoutManager#canScrollVertically() * @see LayoutManager#canScrollHorizontally() */ public boolean fling(int velocityX, int velocityY) { if (mLayout == null) { Log.e(TAG, "Cannot fling without a LayoutManager set. " + "Call setLayoutManager with a non-null argument."); return false; } final boolean canScrollHorizontal = mLayout.canScrollHorizontally(); final boolean canScrollVertical = mLayout.canScrollVertically(); if (!canScrollHorizontal || Math.abs(velocityX) < mMinFlingVelocity) { velocityX = 0; } if (!canScrollVertical || Math.abs(velocityY) < mMinFlingVelocity) { velocityY = 0; } velocityX = Math.max(-mMaxFlingVelocity, Math.min(velocityX, mMaxFlingVelocity)); velocityY = Math.max(-mMaxFlingVelocity, Math.min(velocityY, mMaxFlingVelocity)); if (velocityX != 0 || velocityY != 0) { mViewFlinger.fling(velocityX, velocityY); return true; } return false; } /** * Stop any current scroll in progress, such as one started by * {@link #smoothScrollBy(int, int)}, {@link #fling(int, int)} or a touch-initiated fling. */ public void stopScroll() { setScrollState(SCROLL_STATE_IDLE); stopScrollersInternal(); } /** * Similar to {@link #stopScroll()} but does not set the state. */ private void stopScrollersInternal() { mViewFlinger.stop(); if (mLayout != null) { mLayout.stopSmoothScroller(); } } /** * Apply a pull to relevant overscroll glow effects */ private void pullGlows(int x, int overscrollX, int y, int overscrollY) { boolean invalidate = false; if (overscrollX < 0) { ensureLeftGlow(); invalidate = mLeftGlow.onPull(-overscrollX / (float) getWidth(), 1f - y / (float) getHeight()) || invalidate; } else if (overscrollX > 0) { ensureRightGlow(); invalidate = mRightGlow.onPull(overscrollX / (float) getWidth(), y / (float) getHeight()) || invalidate; } if (overscrollY < 0) { ensureTopGlow(); invalidate = mTopGlow.onPull(-overscrollY / (float) getHeight(), x / (float) getWidth()) || invalidate; } else if (overscrollY > 0) { ensureBottomGlow(); invalidate = mBottomGlow.onPull(overscrollY / (float) getHeight(), 1f - x / (float) getWidth()) || invalidate; } if (invalidate || overscrollX != 0 || overscrollY != 0) { ViewCompat.postInvalidateOnAnimation(this); } } private void releaseGlows() { boolean needsInvalidate = false; if (mLeftGlow != null) needsInvalidate = mLeftGlow.onRelease(); if (mTopGlow != null) needsInvalidate |= mTopGlow.onRelease(); if (mRightGlow != null) needsInvalidate |= mRightGlow.onRelease(); if (mBottomGlow != null) needsInvalidate |= mBottomGlow.onRelease(); if (needsInvalidate) { ViewCompat.postInvalidateOnAnimation(this); } } private void considerReleasingGlowsOnScroll(int dx, int dy) { boolean needsInvalidate = false; if (mLeftGlow != null && !mLeftGlow.isFinished() && dx > 0) { needsInvalidate = mLeftGlow.onRelease(); } if (mRightGlow != null && !mRightGlow.isFinished() && dx < 0) { needsInvalidate |= mRightGlow.onRelease(); } if (mTopGlow != null && !mTopGlow.isFinished() && dy > 0) { needsInvalidate |= mTopGlow.onRelease(); } if (mBottomGlow != null && !mBottomGlow.isFinished() && dy < 0) { needsInvalidate |= mBottomGlow.onRelease(); } if (needsInvalidate) { ViewCompat.postInvalidateOnAnimation(this); } } void absorbGlows(int velocityX, int velocityY) { if (velocityX < 0) { ensureLeftGlow(); mLeftGlow.onAbsorb(-velocityX); } else if (velocityX > 0) { ensureRightGlow(); mRightGlow.onAbsorb(velocityX); } if (velocityY < 0) { ensureTopGlow(); mTopGlow.onAbsorb(-velocityY); } else if (velocityY > 0) { ensureBottomGlow(); mBottomGlow.onAbsorb(velocityY); } if (velocityX != 0 || velocityY != 0) { ViewCompat.postInvalidateOnAnimation(this); } } void ensureLeftGlow() { if (mLeftGlow != null) { return; } mLeftGlow = new EdgeEffectCompat(getContext()); if (mClipToPadding) { mLeftGlow.setSize(getMeasuredHeight() - getPaddingTop() - getPaddingBottom(), getMeasuredWidth() - getPaddingLeft() - getPaddingRight()); } else { mLeftGlow.setSize(getMeasuredHeight(), getMeasuredWidth()); } } void ensureRightGlow() { if (mRightGlow != null) { return; } mRightGlow = new EdgeEffectCompat(getContext()); if (mClipToPadding) { mRightGlow.setSize(getMeasuredHeight() - getPaddingTop() - getPaddingBottom(), getMeasuredWidth() - getPaddingLeft() - getPaddingRight()); } else { mRightGlow.setSize(getMeasuredHeight(), getMeasuredWidth()); } } void ensureTopGlow() { if (mTopGlow != null) { return; } mTopGlow = new EdgeEffectCompat(getContext()); if (mClipToPadding) { mTopGlow.setSize(getMeasuredWidth() - getPaddingLeft() - getPaddingRight(), getMeasuredHeight() - getPaddingTop() - getPaddingBottom()); } else { mTopGlow.setSize(getMeasuredWidth(), getMeasuredHeight()); } } void ensureBottomGlow() { if (mBottomGlow != null) { return; } mBottomGlow = new EdgeEffectCompat(getContext()); if (mClipToPadding) { mBottomGlow.setSize(getMeasuredWidth() - getPaddingLeft() - getPaddingRight(), getMeasuredHeight() - getPaddingTop() - getPaddingBottom()); } else { mBottomGlow.setSize(getMeasuredWidth(), getMeasuredHeight()); } } void invalidateGlows() { mLeftGlow = mRightGlow = mTopGlow = mBottomGlow = null; } // Focus handling @Override public View focusSearch(View focused, int direction) { View result = mLayout.onInterceptFocusSearch(focused, direction); if (result != null) { return result; } final FocusFinder ff = FocusFinder.getInstance(); result = ff.findNextFocus(this, focused, direction); if (result == null && mAdapter != null && mLayout != null) { eatRequestLayout(); result = mLayout.onFocusSearchFailed(focused, direction, mRecycler, mState); resumeRequestLayout(false); } return result != null ? result : super.focusSearch(focused, direction); } @Override public void requestChildFocus(View child, View focused) { if (!mLayout.onRequestChildFocus(this, mState, child, focused) && focused != null) { mTempRect.set(0, 0, focused.getWidth(), focused.getHeight()); // get item decor offsets w/o refreshing. If they are invalid, there will be another // layout pass to fix them, then it is LayoutManager's responsibility to keep focused // View in viewport. final ViewGroup.LayoutParams focusedLayoutParams = focused.getLayoutParams(); if (focusedLayoutParams instanceof LayoutParams) { // if focused child has item decors, use them. Otherwise, ignore. final LayoutParams lp = (LayoutParams) focusedLayoutParams; if (!lp.mInsetsDirty) { final Rect insets = lp.mDecorInsets; mTempRect.left -= insets.left; mTempRect.right += insets.right; mTempRect.top -= insets.top; mTempRect.bottom += insets.bottom; } } offsetDescendantRectToMyCoords(focused, mTempRect); offsetRectIntoDescendantCoords(child, mTempRect); requestChildRectangleOnScreen(child, mTempRect, !mFirstLayoutComplete); } super.requestChildFocus(child, focused); } @Override public boolean requestChildRectangleOnScreen(View child, Rect rect, boolean immediate) { return mLayout.requestChildRectangleOnScreen(this, child, rect, immediate); } @Override public void addFocusables(ArrayList<View> views, int direction, int focusableMode) { if (mLayout == null || !mLayout.onAddFocusables(this, views, direction, focusableMode)) { super.addFocusables(views, direction, focusableMode); } } @Override protected void onAttachedToWindow() { super.onAttachedToWindow(); mLayoutOrScrollCounter = 0; mIsAttached = true; mFirstLayoutComplete = false; if (mLayout != null) { mLayout.dispatchAttachedToWindow(this); } mPostedAnimatorRunner = false; } @Override protected void onDetachedFromWindow() { super.onDetachedFromWindow(); if (mItemAnimator != null) { mItemAnimator.endAnimations(); } mFirstLayoutComplete = false; stopScroll(); mIsAttached = false; if (mLayout != null) { mLayout.dispatchDetachedFromWindow(this, mRecycler); } removeCallbacks(mItemAnimatorRunner); } /** * Checks if RecyclerView is in the middle of a layout or scroll and throws an * {@link IllegalStateException} if it <b>is not</b>. * * @param message The message for the exception. Can be null. * @see #assertNotInLayoutOrScroll(String) */ void assertInLayoutOrScroll(String message) { if (!isRunningLayoutOrScroll()) { if (message == null) { throw new IllegalStateException( "Cannot call this method unless RecyclerView is " + "computing a layout or scrolling"); } throw new IllegalStateException(message); } } /** * Checks if RecyclerView is in the middle of a layout or scroll and throws an * {@link IllegalStateException} if it <b>is</b>. * * @param message The message for the exception. Can be null. * @see #assertInLayoutOrScroll(String) */ void assertNotInLayoutOrScroll(String message) { if (isRunningLayoutOrScroll()) { if (message == null) { throw new IllegalStateException( "Cannot call this method while RecyclerView is " + "computing a layout or scrolling"); } throw new IllegalStateException(message); } } /** * Add an {@link OnItemTouchListener} to intercept touch events before they are dispatched * to child views or this view's standard scrolling behavior. * * <p>Client code may use listeners to implement item manipulation behavior. Once a listener * returns true from * {@link OnItemTouchListener#onInterceptTouchEvent(RecyclerView, MotionEvent)} its * {@link OnItemTouchListener#onTouchEvent(RecyclerView, MotionEvent)} method will be called * for each incoming MotionEvent until the end of the gesture.</p> * * @param listener Listener to add */ public void addOnItemTouchListener(OnItemTouchListener listener) { mOnItemTouchListeners.add(listener); } /** * Remove an {@link OnItemTouchListener}. It will no longer be able to intercept touch events. * * @param listener Listener to remove */ public void removeOnItemTouchListener(OnItemTouchListener listener) { mOnItemTouchListeners.remove(listener); if (mActiveOnItemTouchListener == listener) { mActiveOnItemTouchListener = null; } } private boolean dispatchOnItemTouchIntercept(MotionEvent e) { final int action = e.getAction(); if (action == MotionEvent.ACTION_CANCEL || action == MotionEvent.ACTION_DOWN) { mActiveOnItemTouchListener = null; } final int listenerCount = mOnItemTouchListeners.size(); for (int i = 0; i < listenerCount; i++) { final OnItemTouchListener listener = mOnItemTouchListeners.get(i); if (listener.onInterceptTouchEvent(this, e) && action != MotionEvent.ACTION_CANCEL) { mActiveOnItemTouchListener = listener; return true; } } return false; } private boolean dispatchOnItemTouch(MotionEvent e) { final int action = e.getAction(); if (mActiveOnItemTouchListener != null) { if (action == MotionEvent.ACTION_DOWN) { // Stale state from a previous gesture, we're starting a new one. Clear it. mActiveOnItemTouchListener = null; } else { mActiveOnItemTouchListener.onTouchEvent(this, e); if (action == MotionEvent.ACTION_CANCEL || action == MotionEvent.ACTION_UP) { // Clean up for the next gesture. mActiveOnItemTouchListener = null; } return true; } } // Listeners will have already received the ACTION_DOWN via dispatchOnItemTouchIntercept // as called from onInterceptTouchEvent; skip it. if (action != MotionEvent.ACTION_DOWN) { final int listenerCount = mOnItemTouchListeners.size(); for (int i = 0; i < listenerCount; i++) { final OnItemTouchListener listener = mOnItemTouchListeners.get(i); if (listener.onInterceptTouchEvent(this, e)) { mActiveOnItemTouchListener = listener; return true; } } } return false; } @Override public boolean onInterceptTouchEvent(MotionEvent e) { if (dispatchOnItemTouchIntercept(e)) { cancelTouch(); return true; } final boolean canScrollHorizontally = mLayout.canScrollHorizontally(); final boolean canScrollVertically = mLayout.canScrollVertically(); if (mVelocityTracker == null) { mVelocityTracker = VelocityTracker.obtain(); } mVelocityTracker.addMovement(e); final int action = MotionEventCompat.getActionMasked(e); final int actionIndex = MotionEventCompat.getActionIndex(e); switch (action) { case MotionEvent.ACTION_DOWN: mScrollPointerId = MotionEventCompat.getPointerId(e, 0); mInitialTouchX = mLastTouchX = (int) (e.getX() + 0.5f); mInitialTouchY = mLastTouchY = (int) (e.getY() + 0.5f); if (mScrollState == SCROLL_STATE_SETTLING) { getParent().requestDisallowInterceptTouchEvent(true); setScrollState(SCROLL_STATE_DRAGGING); } break; case MotionEventCompat.ACTION_POINTER_DOWN: mScrollPointerId = MotionEventCompat.getPointerId(e, actionIndex); mInitialTouchX = mLastTouchX = (int) (MotionEventCompat.getX(e, actionIndex) + 0.5f); mInitialTouchY = mLastTouchY = (int) (MotionEventCompat.getY(e, actionIndex) + 0.5f); break; case MotionEvent.ACTION_MOVE: { final int index = MotionEventCompat.findPointerIndex(e, mScrollPointerId); if (index < 0) { Log.e(TAG, "Error processing scroll; pointer index for id " + mScrollPointerId + " not found. Did any MotionEvents get skipped?"); return false; } final int x = (int) (MotionEventCompat.getX(e, index) + 0.5f); final int y = (int) (MotionEventCompat.getY(e, index) + 0.5f); if (mScrollState != SCROLL_STATE_DRAGGING) { final int dx = x - mInitialTouchX; final int dy = y - mInitialTouchY; boolean startScroll = false; if (canScrollHorizontally && Math.abs(dx) > mTouchSlop) { mLastTouchX = mInitialTouchX + mTouchSlop * (dx < 0 ? -1 : 1); startScroll = true; } if (canScrollVertically && Math.abs(dy) > mTouchSlop) { mLastTouchY = mInitialTouchY + mTouchSlop * (dy < 0 ? -1 : 1); startScroll = true; } if (startScroll) { setScrollState(SCROLL_STATE_DRAGGING); } } } break; case MotionEventCompat.ACTION_POINTER_UP: { onPointerUp(e); } break; case MotionEvent.ACTION_UP: { mVelocityTracker.clear(); } break; case MotionEvent.ACTION_CANCEL: { cancelTouch(); } } return mScrollState == SCROLL_STATE_DRAGGING; } @Override public boolean onTouchEvent(MotionEvent e) { if (dispatchOnItemTouch(e)) { cancelTouch(); return true; } final boolean canScrollHorizontally = mLayout.canScrollHorizontally(); final boolean canScrollVertically = mLayout.canScrollVertically(); if (mVelocityTracker == null) { mVelocityTracker = VelocityTracker.obtain(); } mVelocityTracker.addMovement(e); final int action = MotionEventCompat.getActionMasked(e); final int actionIndex = MotionEventCompat.getActionIndex(e); switch (action) { case MotionEvent.ACTION_DOWN: { mScrollPointerId = MotionEventCompat.getPointerId(e, 0); mInitialTouchX = mLastTouchX = (int) (e.getX() + 0.5f); mInitialTouchY = mLastTouchY = (int) (e.getY() + 0.5f); } break; case MotionEventCompat.ACTION_POINTER_DOWN: { mScrollPointerId = MotionEventCompat.getPointerId(e, actionIndex); mInitialTouchX = mLastTouchX = (int) (MotionEventCompat.getX(e, actionIndex) + 0.5f); mInitialTouchY = mLastTouchY = (int) (MotionEventCompat.getY(e, actionIndex) + 0.5f); } break; case MotionEvent.ACTION_MOVE: { final int index = MotionEventCompat.findPointerIndex(e, mScrollPointerId); if (index < 0) { Log.e(TAG, "Error processing scroll; pointer index for id " + mScrollPointerId + " not found. Did any MotionEvents get skipped?"); return false; } final int x = (int) (MotionEventCompat.getX(e, index) + 0.5f); final int y = (int) (MotionEventCompat.getY(e, index) + 0.5f); if (mScrollState != SCROLL_STATE_DRAGGING) { final int dx = x - mInitialTouchX; final int dy = y - mInitialTouchY; boolean startScroll = false; if (canScrollHorizontally && Math.abs(dx) > mTouchSlop) { mLastTouchX = mInitialTouchX + mTouchSlop * (dx < 0 ? -1 : 1); startScroll = true; } if (canScrollVertically && Math.abs(dy) > mTouchSlop) { mLastTouchY = mInitialTouchY + mTouchSlop * (dy < 0 ? -1 : 1); startScroll = true; } if (startScroll) { setScrollState(SCROLL_STATE_DRAGGING); } } if (mScrollState == SCROLL_STATE_DRAGGING) { final int dx = x - mLastTouchX; final int dy = y - mLastTouchY; if (scrollByInternal(canScrollHorizontally ? -dx : 0, canScrollVertically ? -dy : 0, true, x, y)) { getParent().requestDisallowInterceptTouchEvent(true); } } mLastTouchX = x; mLastTouchY = y; } break; case MotionEventCompat.ACTION_POINTER_UP: { onPointerUp(e); } break; case MotionEvent.ACTION_UP: { mVelocityTracker.computeCurrentVelocity(1000, mMaxFlingVelocity); final float xvel = canScrollHorizontally ? -VelocityTrackerCompat.getXVelocity(mVelocityTracker, mScrollPointerId) : 0; final float yvel = canScrollVertically ? -VelocityTrackerCompat.getYVelocity(mVelocityTracker, mScrollPointerId) : 0; if (!((xvel != 0 || yvel != 0) && fling((int) xvel, (int) yvel))) { setScrollState(SCROLL_STATE_IDLE); } mVelocityTracker.clear(); releaseGlows(); } break; case MotionEvent.ACTION_CANCEL: { cancelTouch(); } break; } return true; } private void cancelTouch() { if (mVelocityTracker != null) { mVelocityTracker.clear(); } releaseGlows(); setScrollState(SCROLL_STATE_IDLE); } private void onPointerUp(MotionEvent e) { final int actionIndex = MotionEventCompat.getActionIndex(e); if (MotionEventCompat.getPointerId(e, actionIndex) == mScrollPointerId) { // Pick a new pointer to pick up the slack. final int newIndex = actionIndex == 0 ? 1 : 0; mScrollPointerId = MotionEventCompat.getPointerId(e, newIndex); mInitialTouchX = mLastTouchX = (int) (MotionEventCompat.getX(e, newIndex) + 0.5f); mInitialTouchY = mLastTouchY = (int) (MotionEventCompat.getY(e, newIndex) + 0.5f); } } // @Override public boolean onGenericMotionEvent(MotionEvent event) { if (mLayout == null) { return false; } if ((MotionEventCompat.getSource(event) & InputDeviceCompat.SOURCE_CLASS_POINTER) != 0) { if (event.getAction() == MotionEventCompat.ACTION_SCROLL) { final float vScroll, hScroll; if (mLayout.canScrollVertically()) { vScroll = MotionEventCompat.getAxisValue(event, MotionEventCompat.AXIS_VSCROLL); } else { vScroll = 0f; } if (mLayout.canScrollHorizontally()) { hScroll = MotionEventCompat.getAxisValue(event, MotionEventCompat.AXIS_HSCROLL); } else { hScroll = 0f; } if (vScroll != 0 || hScroll != 0) { final float scrollFactor = getScrollFactor(); scrollBy((int) (hScroll * scrollFactor), (int) (vScroll * scrollFactor)); } } } return false; } /** * Ported from View.getVerticalScrollFactor. */ private float getScrollFactor() { if (mScrollFactor == Float.MIN_VALUE) { TypedValue outValue = new TypedValue(); if (getContext().getTheme().resolveAttribute(android.R.attr.listPreferredItemHeight, outValue, true)) { mScrollFactor = outValue.getDimension(getContext().getResources().getDisplayMetrics()); } else { return 0; //listPreferredItemHeight is not defined, no generic scrolling } } return mScrollFactor; } @Override protected void onMeasure(int widthSpec, int heightSpec) { if (mAdapterUpdateDuringMeasure) { eatRequestLayout(); processAdapterUpdatesAndSetAnimationFlags(); if (mState.mRunPredictiveAnimations) { // TODO: try to provide a better approach. // When RV decides to run predictive animations, we need to measure in pre-layout // state so that pre-layout pass results in correct layout. // On the other hand, this will prevent the layout manager from resizing properly. mState.mInPreLayout = true; } else { // consume remaining updates to provide a consistent state with the layout pass. mAdapterHelper.consumeUpdatesInOnePass(); mState.mInPreLayout = false; } mAdapterUpdateDuringMeasure = false; resumeRequestLayout(false); } if (mAdapter != null) { mState.mItemCount = mAdapter.getItemCount(); } else { mState.mItemCount = 0; } if (mLayout == null) { defaultOnMeasure(widthSpec, heightSpec); } else { mLayout.onMeasure(mRecycler, mState, widthSpec, heightSpec); } mState.mInPreLayout = false; // clear } /** * Used when onMeasure is called before layout manager is set */ private void defaultOnMeasure(int widthSpec, int heightSpec) { final int widthMode = MeasureSpec.getMode(widthSpec); final int heightMode = MeasureSpec.getMode(heightSpec); final int widthSize = MeasureSpec.getSize(widthSpec); final int heightSize = MeasureSpec.getSize(heightSpec); int width = 0; int height = 0; switch (widthMode) { case MeasureSpec.EXACTLY: case MeasureSpec.AT_MOST: width = widthSize; break; case MeasureSpec.UNSPECIFIED: default: width = ViewCompat.getMinimumWidth(this); break; } switch (heightMode) { case MeasureSpec.EXACTLY: case MeasureSpec.AT_MOST: height = heightSize; break; case MeasureSpec.UNSPECIFIED: default: height = ViewCompat.getMinimumHeight(this); break; } setMeasuredDimension(width, height); } @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { super.onSizeChanged(w, h, oldw, oldh); if (w != oldw || h != oldh) { invalidateGlows(); } } /** * Sets the {@link ItemAnimator} that will handle animations involving changes * to the items in this RecyclerView. By default, RecyclerView instantiates and * uses an instance of {@link DefaultItemAnimator}. Whether item animations are * enabled for the RecyclerView depends on the ItemAnimator and whether * the LayoutManager {@link LayoutManager#supportsPredictiveItemAnimations() * supports item animations}. * * @param animator The ItemAnimator being set. If null, no animations will occur * when changes occur to the items in this RecyclerView. */ public void setItemAnimator(ItemAnimator animator) { if (mItemAnimator != null) { mItemAnimator.endAnimations(); mItemAnimator.setListener(null); } mItemAnimator = animator; if (mItemAnimator != null) { mItemAnimator.setListener(mItemAnimatorListener); } } private void onEnterLayoutOrScroll() { mLayoutOrScrollCounter++; } private void onExitLayoutOrScroll() { mLayoutOrScrollCounter--; if (mLayoutOrScrollCounter < 1) { if (DEBUG && mLayoutOrScrollCounter < 0) { throw new IllegalStateException( "layout or scroll counter cannot go below zero." + "Some calls are not matching"); } mLayoutOrScrollCounter = 0; dispatchContentChangedIfNecessary(); } } private void dispatchContentChangedIfNecessary() { final int flags = mEatenAccessibilityChangeFlags; mEatenAccessibilityChangeFlags = 0; if (flags != 0 && mAccessibilityManager != null && mAccessibilityManager.isEnabled()) { final AccessibilityEvent event = AccessibilityEvent.obtain(); event.setEventType(AccessibilityEventCompat.TYPE_WINDOW_CONTENT_CHANGED); AccessibilityEventCompat.setContentChangeTypes(event, flags); sendAccessibilityEventUnchecked(event); } } boolean isRunningLayoutOrScroll() { return mLayoutOrScrollCounter > 0; } /** * Returns true if an accessibility event should not be dispatched now. This happens when an * accessibility request arrives while RecyclerView does not have a stable state which is very * hard to handle for a LayoutManager. Instead, this method records necessary information about * the event and dispatches a window change event after the critical section is finished. * * @return True if the accessibility event should be postponed. */ boolean shouldDeferAccessibilityEvent(AccessibilityEvent event) { if (isRunningLayoutOrScroll()) { int type = 0; if (event != null) { type = AccessibilityEventCompat.getContentChangeTypes(event); } if (type == 0) { type = AccessibilityEventCompat.CONTENT_CHANGE_TYPE_UNDEFINED; } mEatenAccessibilityChangeFlags |= type; return true; } return false; } @Override public void sendAccessibilityEventUnchecked(AccessibilityEvent event) { if (shouldDeferAccessibilityEvent(event)) { return; } super.sendAccessibilityEventUnchecked(event); } /** * Gets the current ItemAnimator for this RecyclerView. A null return value * indicates that there is no animator and that item changes will happen without * any animations. By default, RecyclerView instantiates and * uses an instance of {@link DefaultItemAnimator}. * * @return ItemAnimator The current ItemAnimator. If null, no animations will occur * when changes occur to the items in this RecyclerView. */ public ItemAnimator getItemAnimator() { return mItemAnimator; } private boolean supportsChangeAnimations() { return mItemAnimator != null && mItemAnimator.getSupportsChangeAnimations(); } /** * Post a runnable to the next frame to run pending item animations. Only the first such * request will be posted, governed by the mPostedAnimatorRunner flag. */ private void postAnimationRunner() { if (!mPostedAnimatorRunner && mIsAttached) { ViewCompat.postOnAnimation(this, mItemAnimatorRunner); mPostedAnimatorRunner = true; } } private boolean predictiveItemAnimationsEnabled() { return (mItemAnimator != null && mLayout.supportsPredictiveItemAnimations()); } /** * Consumes adapter updates and calculates which type of animations we want to run. * Called in onMeasure and dispatchLayout. * <p> * This method may process only the pre-layout state of updates or all of them. */ private void processAdapterUpdatesAndSetAnimationFlags() { if (mDataSetHasChangedAfterLayout) { // Processing these items have no value since data set changed unexpectedly. // Instead, we just reset it. mAdapterHelper.reset(); markKnownViewsInvalid(); mLayout.onItemsChanged(this); } // simple animations are a subset of advanced animations (which will cause a // pre-layout step) // If layout supports predictive animations, pre-process to decide if we want to run them if (mItemAnimator != null && mLayout.supportsPredictiveItemAnimations()) { mAdapterHelper.preProcess(); } else { mAdapterHelper.consumeUpdatesInOnePass(); } boolean animationTypeSupported = (mItemsAddedOrRemoved && !mItemsChanged) || (mItemsAddedOrRemoved || (mItemsChanged && supportsChangeAnimations())); mState.mRunSimpleAnimations = mFirstLayoutComplete && mItemAnimator != null && (mDataSetHasChangedAfterLayout || animationTypeSupported || mLayout.mRequestedSimpleAnimations) && (!mDataSetHasChangedAfterLayout || mAdapter.hasStableIds()); mState.mRunPredictiveAnimations = mState.mRunSimpleAnimations && animationTypeSupported && !mDataSetHasChangedAfterLayout && predictiveItemAnimationsEnabled(); } /** * Wrapper around layoutChildren() that handles animating changes caused by layout. * Animations work on the assumption that there are five different kinds of items * in play: * PERSISTENT: items are visible before and after layout * REMOVED: items were visible before layout and were removed by the app * ADDED: items did not exist before layout and were added by the app * DISAPPEARING: items exist in the data set before/after, but changed from * visible to non-visible in the process of layout (they were moved off * screen as a side-effect of other changes) * APPEARING: items exist in the data set before/after, but changed from * non-visible to visible in the process of layout (they were moved on * screen as a side-effect of other changes) * The overall approach figures out what items exist before/after layout and * infers one of the five above states for each of the items. Then the animations * are set up accordingly: * PERSISTENT views are moved ({@link ItemAnimator#animateMove(ViewHolder, int, int, int, int)}) * REMOVED views are removed ({@link ItemAnimator#animateRemove(ViewHolder)}) * ADDED views are added ({@link ItemAnimator#animateAdd(ViewHolder)}) * DISAPPEARING views are moved off screen * APPEARING views are moved on screen */ void dispatchLayout() { if (mAdapter == null) { Log.e(TAG, "No adapter attached; skipping layout"); return; } if (mLayout == null) { Log.e(TAG, "No layout manager attached; skipping layout"); return; } mState.mDisappearingViewsInLayoutPass.clear(); eatRequestLayout(); onEnterLayoutOrScroll(); processAdapterUpdatesAndSetAnimationFlags(); mState.mOldChangedHolders = mState.mRunSimpleAnimations && mItemsChanged && supportsChangeAnimations() ? new ArrayMap<Long, ViewHolder>() : null; mItemsAddedOrRemoved = mItemsChanged = false; ArrayMap<View, Rect> appearingViewInitialBounds = null; mState.mInPreLayout = mState.mRunPredictiveAnimations; mState.mItemCount = mAdapter.getItemCount(); findMinMaxChildLayoutPositions(mMinMaxLayoutPositions); if (mState.mRunSimpleAnimations) { // Step 0: Find out where all non-removed items are, pre-layout mState.mPreLayoutHolderMap.clear(); mState.mPostLayoutHolderMap.clear(); int count = mChildHelper.getChildCount(); for (int i = 0; i < count; ++i) { final ViewHolder holder = getChildViewHolderInt(mChildHelper.getChildAt(i)); if (holder.shouldIgnore() || (holder.isInvalid() && !mAdapter.hasStableIds())) { continue; } final View view = holder.itemView; mState.mPreLayoutHolderMap.put(holder, new ItemHolderInfo(holder, view.getLeft(), view.getTop(), view.getRight(), view.getBottom())); } } if (mState.mRunPredictiveAnimations) { // Step 1: run prelayout: This will use the old positions of items. The layout manager // is expected to layout everything, even removed items (though not to add removed // items back to the container). This gives the pre-layout position of APPEARING views // which come into existence as part of the real layout. // Save old positions so that LayoutManager can run its mapping logic. saveOldPositions(); // processAdapterUpdatesAndSetAnimationFlags already run pre-layout animations. if (mState.mOldChangedHolders != null) { int count = mChildHelper.getChildCount(); for (int i = 0; i < count; ++i) { final ViewHolder holder = getChildViewHolderInt(mChildHelper.getChildAt(i)); if (holder.isChanged() && !holder.isRemoved() && !holder.shouldIgnore()) { long key = getChangedHolderKey(holder); mState.mOldChangedHolders.put(key, holder); mState.mPreLayoutHolderMap.remove(holder); } } } final boolean didStructureChange = mState.mStructureChanged; mState.mStructureChanged = false; // temporarily disable flag because we are asking for previous layout mLayout.onLayoutChildren(mRecycler, mState); mState.mStructureChanged = didStructureChange; appearingViewInitialBounds = new ArrayMap<View, Rect>(); for (int i = 0; i < mChildHelper.getChildCount(); ++i) { boolean found = false; View child = mChildHelper.getChildAt(i); if (getChildViewHolderInt(child).shouldIgnore()) { continue; } for (int j = 0; j < mState.mPreLayoutHolderMap.size(); ++j) { ViewHolder holder = mState.mPreLayoutHolderMap.keyAt(j); if (holder.itemView == child) { found = true; break; } } if (!found) { appearingViewInitialBounds.put(child, new Rect(child.getLeft(), child.getTop(), child.getRight(), child.getBottom())); } } // we don't process disappearing list because they may re-appear in post layout pass. clearOldPositions(); mAdapterHelper.consumePostponedUpdates(); } else { clearOldPositions(); // in case pre layout did run but we decided not to run predictive animations. mAdapterHelper.consumeUpdatesInOnePass(); if (mState.mOldChangedHolders != null) { int count = mChildHelper.getChildCount(); for (int i = 0; i < count; ++i) { final ViewHolder holder = getChildViewHolderInt(mChildHelper.getChildAt(i)); if (holder.isChanged() && !holder.isRemoved() && !holder.shouldIgnore()) { long key = getChangedHolderKey(holder); mState.mOldChangedHolders.put(key, holder); mState.mPreLayoutHolderMap.remove(holder); } } } } mState.mItemCount = mAdapter.getItemCount(); mState.mDeletedInvisibleItemCountSincePreviousLayout = 0; // Step 2: Run layout mState.mInPreLayout = false; mLayout.onLayoutChildren(mRecycler, mState); mState.mStructureChanged = false; mPendingSavedState = null; // onLayoutChildren may have caused client code to disable item animations; re-check mState.mRunSimpleAnimations = mState.mRunSimpleAnimations && mItemAnimator != null; if (mState.mRunSimpleAnimations) { // Step 3: Find out where things are now, post-layout ArrayMap<Long, ViewHolder> newChangedHolders = mState.mOldChangedHolders != null ? new ArrayMap<Long, ViewHolder>() : null; int count = mChildHelper.getChildCount(); for (int i = 0; i < count; ++i) { ViewHolder holder = getChildViewHolderInt(mChildHelper.getChildAt(i)); if (holder.shouldIgnore()) { continue; } final View view = holder.itemView; long key = getChangedHolderKey(holder); if (newChangedHolders != null && mState.mOldChangedHolders.get(key) != null) { newChangedHolders.put(key, holder); } else { mState.mPostLayoutHolderMap.put(holder, new ItemHolderInfo(holder, view.getLeft(), view.getTop(), view.getRight(), view.getBottom())); } } processDisappearingList(appearingViewInitialBounds); // Step 4: Animate DISAPPEARING and REMOVED items int preLayoutCount = mState.mPreLayoutHolderMap.size(); for (int i = preLayoutCount - 1; i >= 0; i--) { ViewHolder itemHolder = mState.mPreLayoutHolderMap.keyAt(i); if (!mState.mPostLayoutHolderMap.containsKey(itemHolder)) { ItemHolderInfo disappearingItem = mState.mPreLayoutHolderMap.valueAt(i); mState.mPreLayoutHolderMap.removeAt(i); View disappearingItemView = disappearingItem.holder.itemView; mRecycler.unscrapView(disappearingItem.holder); animateDisappearance(disappearingItem); } } // Step 5: Animate APPEARING and ADDED items int postLayoutCount = mState.mPostLayoutHolderMap.size(); if (postLayoutCount > 0) { for (int i = postLayoutCount - 1; i >= 0; i--) { ViewHolder itemHolder = mState.mPostLayoutHolderMap.keyAt(i); ItemHolderInfo info = mState.mPostLayoutHolderMap.valueAt(i); if ((mState.mPreLayoutHolderMap.isEmpty() || !mState.mPreLayoutHolderMap.containsKey(itemHolder))) { mState.mPostLayoutHolderMap.removeAt(i); Rect initialBounds = (appearingViewInitialBounds != null) ? appearingViewInitialBounds.get(itemHolder.itemView) : null; animateAppearance(itemHolder, initialBounds, info.left, info.top); } } } // Step 6: Animate PERSISTENT items count = mState.mPostLayoutHolderMap.size(); for (int i = 0; i < count; ++i) { ViewHolder postHolder = mState.mPostLayoutHolderMap.keyAt(i); ItemHolderInfo postInfo = mState.mPostLayoutHolderMap.valueAt(i); ItemHolderInfo preInfo = mState.mPreLayoutHolderMap.get(postHolder); if (preInfo != null && postInfo != null) { if (preInfo.left != postInfo.left || preInfo.top != postInfo.top) { postHolder.setIsRecyclable(false); if (DEBUG) { Log.d(TAG, "PERSISTENT: " + postHolder + " with view " + postHolder.itemView); } if (mItemAnimator.animateMove(postHolder, preInfo.left, preInfo.top, postInfo.left, postInfo.top)) { postAnimationRunner(); } } } } // Step 7: Animate CHANGING items count = mState.mOldChangedHolders != null ? mState.mOldChangedHolders.size() : 0; // traverse reverse in case view gets recycled while we are traversing the list. for (int i = count - 1; i >= 0; i--) { long key = mState.mOldChangedHolders.keyAt(i); ViewHolder oldHolder = mState.mOldChangedHolders.get(key); View oldView = oldHolder.itemView; if (oldHolder.shouldIgnore()) { continue; } // We probably don't need this check anymore since these views are removed from // the list if they are recycled. if (mRecycler.mChangedScrap != null && mRecycler.mChangedScrap.contains(oldHolder)) { animateChange(oldHolder, newChangedHolders.get(key)); } else if (DEBUG) { Log.e(TAG, "cannot find old changed holder in changed scrap :/" + oldHolder); } } } resumeRequestLayout(false); mLayout.removeAndRecycleScrapInt(mRecycler); mState.mPreviousLayoutItemCount = mState.mItemCount; mDataSetHasChangedAfterLayout = false; mState.mRunSimpleAnimations = false; mState.mRunPredictiveAnimations = false; onExitLayoutOrScroll(); mLayout.mRequestedSimpleAnimations = false; if (mRecycler.mChangedScrap != null) { mRecycler.mChangedScrap.clear(); } mState.mOldChangedHolders = null; if (didChildRangeChange(mMinMaxLayoutPositions[0], mMinMaxLayoutPositions[1])) { dispatchOnScrolled(0, 0); } } private void findMinMaxChildLayoutPositions(int[] into) { final int count = mChildHelper.getChildCount(); if (count == 0) { into[0] = 0; into[1] = 0; return; } int minPositionPreLayout = Integer.MAX_VALUE; int maxPositionPreLayout = Integer.MIN_VALUE; for (int i = 0; i < count; ++i) { final ViewHolder holder = getChildViewHolderInt(mChildHelper.getChildAt(i)); if (holder.shouldIgnore()) { continue; } final int pos = holder.getLayoutPosition(); if (pos < minPositionPreLayout) { minPositionPreLayout = pos; } if (pos > maxPositionPreLayout) { maxPositionPreLayout = pos; } } into[0] = minPositionPreLayout; into[1] = maxPositionPreLayout; } private boolean didChildRangeChange(int minPositionPreLayout, int maxPositionPreLayout) { int count = mChildHelper.getChildCount(); if (count == 0) { return minPositionPreLayout != 0 || maxPositionPreLayout != 0; } for (int i = 0; i < count; ++i) { final ViewHolder holder = getChildViewHolderInt(mChildHelper.getChildAt(i)); if (holder.shouldIgnore()) { continue; } final int pos = holder.getLayoutPosition(); if (pos < minPositionPreLayout || pos > maxPositionPreLayout) { return true; } } return false; } @Override protected void removeDetachedView(View child, boolean animate) { ViewHolder vh = getChildViewHolderInt(child); if (vh != null) { if (vh.isTmpDetached()) { vh.clearTmpDetachFlag(); } else if (!vh.shouldIgnore()) { throw new IllegalArgumentException( "Called removeDetachedView with a view which" + " is not flagged as tmp detached." + vh); } } dispatchChildDetached(child); super.removeDetachedView(child, animate); } /** * Returns a unique key to be used while handling change animations. * It might be child's position or stable id depending on the adapter type. */ long getChangedHolderKey(ViewHolder holder) { return mAdapter.hasStableIds() ? holder.getItemId() : holder.mPosition; } /** * A LayoutManager may want to layout a view just to animate disappearance. * This method handles those views and triggers remove animation on them. */ private void processDisappearingList(ArrayMap<View, Rect> appearingViews) { final List<View> disappearingList = mState.mDisappearingViewsInLayoutPass; for (int i = disappearingList.size() - 1; i >= 0; i--) { View view = disappearingList.get(i); ViewHolder vh = getChildViewHolderInt(view); final ItemHolderInfo info = mState.mPreLayoutHolderMap.remove(vh); if (!mState.isPreLayout()) { mState.mPostLayoutHolderMap.remove(vh); } if (appearingViews.remove(view) != null) { mLayout.removeAndRecycleView(view, mRecycler); continue; } if (info != null) { animateDisappearance(info); } else { // let it disappear from the position it becomes visible animateDisappearance( new ItemHolderInfo(vh, view.getLeft(), view.getTop(), view.getRight(), view.getBottom())); } } disappearingList.clear(); } private void animateAppearance(ViewHolder itemHolder, Rect beforeBounds, int afterLeft, int afterTop) { View newItemView = itemHolder.itemView; if (beforeBounds != null && (beforeBounds.left != afterLeft || beforeBounds.top != afterTop)) { // slide items in if before/after locations differ itemHolder.setIsRecyclable(false); if (DEBUG) { Log.d(TAG, "APPEARING: " + itemHolder + " with view " + newItemView); } if (mItemAnimator.animateMove(itemHolder, beforeBounds.left, beforeBounds.top, afterLeft, afterTop)) { postAnimationRunner(); } } else { if (DEBUG) { Log.d(TAG, "ADDED: " + itemHolder + " with view " + newItemView); } itemHolder.setIsRecyclable(false); if (mItemAnimator.animateAdd(itemHolder)) { postAnimationRunner(); } } } private void animateDisappearance(ItemHolderInfo disappearingItem) { View disappearingItemView = disappearingItem.holder.itemView; addAnimatingView(disappearingItem.holder); int oldLeft = disappearingItem.left; int oldTop = disappearingItem.top; int newLeft = disappearingItemView.getLeft(); int newTop = disappearingItemView.getTop(); if (oldLeft != newLeft || oldTop != newTop) { disappearingItem.holder.setIsRecyclable(false); disappearingItemView.layout(newLeft, newTop, newLeft + disappearingItemView.getWidth(), newTop + disappearingItemView.getHeight()); if (DEBUG) { Log.d(TAG, "DISAPPEARING: " + disappearingItem.holder + " with view " + disappearingItemView); } if (mItemAnimator.animateMove(disappearingItem.holder, oldLeft, oldTop, newLeft, newTop)) { postAnimationRunner(); } } else { if (DEBUG) { Log.d(TAG, "REMOVED: " + disappearingItem.holder + " with view " + disappearingItemView); } disappearingItem.holder.setIsRecyclable(false); if (mItemAnimator.animateRemove(disappearingItem.holder)) { postAnimationRunner(); } } } private void animateChange(ViewHolder oldHolder, ViewHolder newHolder) { oldHolder.setIsRecyclable(false); addAnimatingView(oldHolder); oldHolder.mShadowedHolder = newHolder; mRecycler.unscrapView(oldHolder); if (DEBUG) { Log.d(TAG, "CHANGED: " + oldHolder + " with view " + oldHolder.itemView); } final int fromLeft = oldHolder.itemView.getLeft(); final int fromTop = oldHolder.itemView.getTop(); final int toLeft, toTop; if (newHolder == null || newHolder.shouldIgnore()) { toLeft = fromLeft; toTop = fromTop; } else { toLeft = newHolder.itemView.getLeft(); toTop = newHolder.itemView.getTop(); newHolder.setIsRecyclable(false); newHolder.mShadowingHolder = oldHolder; } if (mItemAnimator.animateChange(oldHolder, newHolder, fromLeft, fromTop, toLeft, toTop)) { postAnimationRunner(); } } @Override protected void onLayout(boolean changed, int l, int t, int r, int b) { eatRequestLayout(); dispatchLayout(); resumeRequestLayout(false); mFirstLayoutComplete = true; } @Override public void requestLayout() { if (!mEatRequestLayout) { super.requestLayout(); } else { mLayoutRequestEaten = true; } } void markItemDecorInsetsDirty() { final int childCount = mChildHelper.getUnfilteredChildCount(); for (int i = 0; i < childCount; i++) { final View child = mChildHelper.getUnfilteredChildAt(i); ((LayoutParams) child.getLayoutParams()).mInsetsDirty = true; } mRecycler.markItemDecorInsetsDirty(); } @Override public void draw(Canvas c) { super.draw(c); final int count = mItemDecorations.size(); for (int i = 0; i < count; i++) { mItemDecorations.get(i).onDrawOver(c, this, mState); } // TODO If padding is not 0 and chilChildrenToPadding is false, to draw glows properly, we // need find children closest to edges. Not sure if it is worth the effort. boolean needsInvalidate = false; if (mLeftGlow != null && !mLeftGlow.isFinished()) { final int restore = c.save(); final int padding = mClipToPadding ? getPaddingBottom() : 0; c.rotate(270); c.translate(-getHeight() + padding, 0); needsInvalidate = mLeftGlow != null && mLeftGlow.draw(c); c.restoreToCount(restore); } if (mTopGlow != null && !mTopGlow.isFinished()) { final int restore = c.save(); if (mClipToPadding) { c.translate(getPaddingLeft(), getPaddingTop()); } needsInvalidate |= mTopGlow != null && mTopGlow.draw(c); c.restoreToCount(restore); } if (mRightGlow != null && !mRightGlow.isFinished()) { final int restore = c.save(); final int width = getWidth(); final int padding = mClipToPadding ? getPaddingTop() : 0; c.rotate(90); c.translate(-padding, -width); needsInvalidate |= mRightGlow != null && mRightGlow.draw(c); c.restoreToCount(restore); } if (mBottomGlow != null && !mBottomGlow.isFinished()) { final int restore = c.save(); c.rotate(180); if (mClipToPadding) { c.translate(-getWidth() + getPaddingRight(), -getHeight() + getPaddingBottom()); } else { c.translate(-getWidth(), -getHeight()); } needsInvalidate |= mBottomGlow != null && mBottomGlow.draw(c); c.restoreToCount(restore); } // If some views are animating, ItemDecorators are likely to move/change with them. // Invalidate RecyclerView to re-draw decorators. This is still efficient because children's // display lists are not invalidated. if (!needsInvalidate && mItemAnimator != null && mItemDecorations.size() > 0 && mItemAnimator.isRunning()) { needsInvalidate = true; } if (needsInvalidate) { ViewCompat.postInvalidateOnAnimation(this); } } @Override public void onDraw(Canvas c) { super.onDraw(c); final int count = mItemDecorations.size(); for (int i = 0; i < count; i++) { mItemDecorations.get(i).onDraw(c, this, mState); } } @Override protected boolean checkLayoutParams(ViewGroup.LayoutParams p) { return p instanceof LayoutParams && mLayout.checkLayoutParams((LayoutParams) p); } @Override protected ViewGroup.LayoutParams generateDefaultLayoutParams() { if (mLayout == null) { throw new IllegalStateException("RecyclerView has no LayoutManager"); } return mLayout.generateDefaultLayoutParams(); } @Override public ViewGroup.LayoutParams generateLayoutParams(AttributeSet attrs) { if (mLayout == null) { throw new IllegalStateException("RecyclerView has no LayoutManager"); } return mLayout.generateLayoutParams(getContext(), attrs); } @Override protected ViewGroup.LayoutParams generateLayoutParams(ViewGroup.LayoutParams p) { if (mLayout == null) { throw new IllegalStateException("RecyclerView has no LayoutManager"); } return mLayout.generateLayoutParams(p); } void saveOldPositions() { final int childCount = mChildHelper.getUnfilteredChildCount(); for (int i = 0; i < childCount; i++) { final ViewHolder holder = getChildViewHolderInt(mChildHelper.getUnfilteredChildAt(i)); if (DEBUG && holder.mPosition == -1 && !holder.isRemoved()) { throw new IllegalStateException("view holder cannot have position -1 unless it" + " is removed"); } if (!holder.shouldIgnore()) { holder.saveOldPosition(); } } } void clearOldPositions() { final int childCount = mChildHelper.getUnfilteredChildCount(); for (int i = 0; i < childCount; i++) { final ViewHolder holder = getChildViewHolderInt(mChildHelper.getUnfilteredChildAt(i)); if (!holder.shouldIgnore()) { holder.clearOldPosition(); } } mRecycler.clearOldPositions(); } void offsetPositionRecordsForMove(int from, int to) { final int childCount = mChildHelper.getUnfilteredChildCount(); final int start, end, inBetweenOffset; if (from < to) { start = from; end = to; inBetweenOffset = -1; } else { start = to; end = from; inBetweenOffset = 1; } for (int i = 0; i < childCount; i++) { final ViewHolder holder = getChildViewHolderInt(mChildHelper.getUnfilteredChildAt(i)); if (holder == null || holder.mPosition < start || holder.mPosition > end) { continue; } if (DEBUG) { Log.d(TAG, "offsetPositionRecordsForMove attached child " + i + " holder " + holder); } if (holder.mPosition == from) { holder.offsetPosition(to - from, false); } else { holder.offsetPosition(inBetweenOffset, false); } mState.mStructureChanged = true; } mRecycler.offsetPositionRecordsForMove(from, to); requestLayout(); } void offsetPositionRecordsForInsert(int positionStart, int itemCount) { final int childCount = mChildHelper.getUnfilteredChildCount(); for (int i = 0; i < childCount; i++) { final ViewHolder holder = getChildViewHolderInt(mChildHelper.getUnfilteredChildAt(i)); if (holder != null && !holder.shouldIgnore() && holder.mPosition >= positionStart) { if (DEBUG) { Log.d(TAG, "offsetPositionRecordsForInsert attached child " + i + " holder " + holder + " now at position " + (holder.mPosition + itemCount)); } holder.offsetPosition(itemCount, false); mState.mStructureChanged = true; } } mRecycler.offsetPositionRecordsForInsert(positionStart, itemCount); requestLayout(); } void offsetPositionRecordsForRemove(int positionStart, int itemCount, boolean applyToPreLayout) { final int positionEnd = positionStart + itemCount; final int childCount = mChildHelper.getUnfilteredChildCount(); for (int i = 0; i < childCount; i++) { final ViewHolder holder = getChildViewHolderInt(mChildHelper.getUnfilteredChildAt(i)); if (holder != null && !holder.shouldIgnore()) { if (holder.mPosition >= positionEnd) { if (DEBUG) { Log.d(TAG, "offsetPositionRecordsForRemove attached child " + i + " holder " + holder + " now at position " + (holder.mPosition - itemCount)); } holder.offsetPosition(-itemCount, applyToPreLayout); mState.mStructureChanged = true; } else if (holder.mPosition >= positionStart) { if (DEBUG) { Log.d(TAG, "offsetPositionRecordsForRemove attached child " + i + " holder " + holder + " now REMOVED"); } holder.flagRemovedAndOffsetPosition(positionStart - 1, -itemCount, applyToPreLayout); mState.mStructureChanged = true; } } } mRecycler.offsetPositionRecordsForRemove(positionStart, itemCount, applyToPreLayout); requestLayout(); } /** * Rebind existing views for the given range, or create as needed. * * @param positionStart Adapter position to start at * @param itemCount Number of views that must explicitly be rebound */ void viewRangeUpdate(int positionStart, int itemCount) { final int childCount = mChildHelper.getUnfilteredChildCount(); final int positionEnd = positionStart + itemCount; for (int i = 0; i < childCount; i++) { final View child = mChildHelper.getUnfilteredChildAt(i); final ViewHolder holder = getChildViewHolderInt(child); if (holder == null || holder.shouldIgnore()) { continue; } if (holder.mPosition >= positionStart && holder.mPosition < positionEnd) { // We re-bind these view holders after pre-processing is complete so that // ViewHolders have their final positions assigned. holder.addFlags(ViewHolder.FLAG_UPDATE); if (supportsChangeAnimations()) { holder.addFlags(ViewHolder.FLAG_CHANGED); } // lp cannot be null since we get ViewHolder from it. ((LayoutParams) child.getLayoutParams()).mInsetsDirty = true; } } mRecycler.viewRangeUpdate(positionStart, itemCount); } void rebindUpdatedViewHolders() { final int childCount = mChildHelper.getChildCount(); for (int i = 0; i < childCount; i++) { final ViewHolder holder = getChildViewHolderInt(mChildHelper.getChildAt(i)); // validate type is correct if (holder == null || holder.shouldIgnore()) { continue; } if (holder.isRemoved() || holder.isInvalid()) { requestLayout(); } else if (holder.needsUpdate()) { final int type = mAdapter.getItemViewType(holder.mPosition); if (holder.getItemViewType() == type) { // Binding an attached view will request a layout if needed. if (!holder.isChanged() || !supportsChangeAnimations()) { mAdapter.bindViewHolder(holder, holder.mPosition); } else { // Don't rebind changed holders if change animations are enabled. // We want the old contents for the animation and will get a new // holder for the new contents. requestLayout(); } } else { // binding to a new view will need re-layout anyways. We can as well trigger // it here so that it happens during layout requestLayout(); break; } } } } private void setDataSetChangedAfterLayout() { if (mDataSetHasChangedAfterLayout) { return; } mDataSetHasChangedAfterLayout = true; final int childCount = mChildHelper.getUnfilteredChildCount(); for (int i = 0; i < childCount; i++) { final ViewHolder holder = getChildViewHolderInt(mChildHelper.getUnfilteredChildAt(i)); if (holder != null && !holder.shouldIgnore()) { holder.addFlags(ViewHolder.FLAG_ADAPTER_POSITION_UNKNOWN); } } mRecycler.setAdapterPositionsAsUnknown(); } /** * Mark all known views as invalid. Used in response to a, "the whole world might have changed" * data change event. */ void markKnownViewsInvalid() { final int childCount = mChildHelper.getUnfilteredChildCount(); for (int i = 0; i < childCount; i++) { final ViewHolder holder = getChildViewHolderInt(mChildHelper.getUnfilteredChildAt(i)); if (holder != null && !holder.shouldIgnore()) { holder.addFlags(ViewHolder.FLAG_UPDATE | ViewHolder.FLAG_INVALID); } } markItemDecorInsetsDirty(); mRecycler.markKnownViewsInvalid(); } /** * Invalidates all ItemDecorations. If RecyclerView has item decorations, calling this method * will trigger a {@link #requestLayout()} call. */ public void invalidateItemDecorations() { if (mItemDecorations.size() == 0) { return; } if (mLayout != null) { mLayout.assertNotInLayoutOrScroll("Cannot invalidate item decorations during a scroll" + " or layout"); } markItemDecorInsetsDirty(); requestLayout(); } /** * Retrieve the {@link ViewHolder} for the given child view. * * @param child Child of this RecyclerView to query for its ViewHolder * @return The child view's ViewHolder */ public ViewHolder getChildViewHolder(View child) { final ViewParent parent = child.getParent(); if (parent != null && parent != this) { throw new IllegalArgumentException("View " + child + " is not a direct child of " + this); } return getChildViewHolderInt(child); } static ViewHolder getChildViewHolderInt(View child) { if (child == null) { return null; } return ((LayoutParams) child.getLayoutParams()).mViewHolder; } /** * @deprecated use {@link #getChildAdapterPosition(View)} or * {@link #getChildLayoutPosition(View)}. */ @Deprecated public int getChildPosition(View child) { return getChildAdapterPosition(child); } /** * Return the adapter position that the given child view corresponds to. * * @param child Child View to query * @return Adapter position corresponding to the given view or {@link #NO_POSITION} */ public int getChildAdapterPosition(View child) { final ViewHolder holder = getChildViewHolderInt(child); return holder != null ? holder.getAdapterPosition() : NO_POSITION; } /** * Return the adapter position of the given child view as of the latest completed layout pass. * <p> * This position may not be equal to Item's adapter position if there are pending changes * in the adapter which have not been reflected to the layout yet. * * @param child Child View to query * @return Adapter position of the given View as of last layout pass or {@link #NO_POSITION} if * the View is representing a removed item. */ public int getChildLayoutPosition(View child) { final ViewHolder holder = getChildViewHolderInt(child); return holder != null ? holder.getLayoutPosition() : NO_POSITION; } /** * Return the stable item id that the given child view corresponds to. * * @param child Child View to query * @return Item id corresponding to the given view or {@link #NO_ID} */ public long getChildItemId(View child) { if (mAdapter == null || !mAdapter.hasStableIds()) { return NO_ID; } final ViewHolder holder = getChildViewHolderInt(child); return holder != null ? holder.getItemId() : NO_ID; } /** * @deprecated use {@link #findViewHolderForLayoutPosition(int)} or * {@link #findViewHolderForAdapterPosition(int)} */ @Deprecated public ViewHolder findViewHolderForPosition(int position) { return findViewHolderForPosition(position, false); } /** * Return the ViewHolder for the item in the given position of the data set as of the latest * layout pass. * <p> * This method checks only the children of RecyclerView. If the item at the given * <code>position</code> is not laid out, it <em>will not</em> create a new one. * <p> * Note that when Adapter contents change, ViewHolder positions are not updated until the * next layout calculation. If there are pending adapter updates, the return value of this * method may not match your adapter contents. You can use * #{@link ViewHolder#getAdapterPosition()} to get the current adapter position of a ViewHolder. * * @param position The position of the item in the data set of the adapter * @return The ViewHolder at <code>position</code> or null if there is no such item */ public ViewHolder findViewHolderForLayoutPosition(int position) { return findViewHolderForPosition(position, false); } /** * Return the ViewHolder for the item in the given position of the data set. Unlike * {@link #findViewHolderForLayoutPosition(int)} this method takes into account any pending * adapter changes that may not be reflected to the layout yet. On the other hand, if * {@link Adapter#notifyDataSetChanged()} has been called but the new layout has not been * calculated yet, this method will return <code>null</code> since the new positions of views * are unknown until the layout is calculated. * <p> * This method checks only the children of RecyclerView. If the item at the given * <code>position</code> is not laid out, it <em>will not</em> create a new one. * * @param position The position of the item in the data set of the adapter * @return The ViewHolder at <code>position</code> or null if there is no such item */ public ViewHolder findViewHolderForAdapterPosition(int position) { if (mDataSetHasChangedAfterLayout) { return null; } final int childCount = mChildHelper.getUnfilteredChildCount(); for (int i = 0; i < childCount; i++) { final ViewHolder holder = getChildViewHolderInt(mChildHelper.getUnfilteredChildAt(i)); if (holder != null && !holder.isRemoved() && getAdapterPositionFor(holder) == position) { return holder; } } return null; } ViewHolder findViewHolderForPosition(int position, boolean checkNewPosition) { final int childCount = mChildHelper.getUnfilteredChildCount(); for (int i = 0; i < childCount; i++) { final ViewHolder holder = getChildViewHolderInt(mChildHelper.getUnfilteredChildAt(i)); if (holder != null && !holder.isRemoved()) { if (checkNewPosition) { if (holder.mPosition == position) { return holder; } } else if (holder.getLayoutPosition() == position) { return holder; } } } // This method should not query cached views. It creates a problem during adapter updates // when we are dealing with already laid out views. Also, for the public method, it is more // reasonable to return null if position is not laid out. return null; } /** * Return the ViewHolder for the item with the given id. The RecyclerView must * use an Adapter with {@link Adapter#setHasStableIds(boolean) stableIds} to * return a non-null value. * <p> * This method checks only the children of RecyclerView. If the item with the given * <code>id</code> is not laid out, it <em>will not</em> create a new one. * * @param id The id for the requested item * @return The ViewHolder with the given <code>id</code> or null if there is no such item */ public ViewHolder findViewHolderForItemId(long id) { final int childCount = mChildHelper.getUnfilteredChildCount(); for (int i = 0; i < childCount; i++) { final ViewHolder holder = getChildViewHolderInt(mChildHelper.getUnfilteredChildAt(i)); if (holder != null && holder.getItemId() == id) { return holder; } } // this method should not query cached views. They are not children so they // should not be returned in this public method return null; } /** * Find the topmost view under the given point. * * @param x Horizontal position in pixels to search * @param y Vertical position in pixels to search * @return The child view under (x, y) or null if no matching child is found */ public View findChildViewUnder(float x, float y) { final int count = mChildHelper.getChildCount(); for (int i = count - 1; i >= 0; i--) { final View child = mChildHelper.getChildAt(i); final float translationX = ViewCompat.getTranslationX(child); final float translationY = ViewCompat.getTranslationY(child); if (x >= child.getLeft() + translationX && x <= child.getRight() + translationX && y >= child.getTop() + translationY && y <= child.getBottom() + translationY) { return child; } } return null; } /** * Offset the bounds of all child views by <code>dy</code> pixels. * Useful for implementing simple scrolling in {@link LayoutManager LayoutManagers}. * * @param dy Vertical pixel offset to apply to the bounds of all child views */ public void offsetChildrenVertical(int dy) { final int childCount = mChildHelper.getChildCount(); for (int i = 0; i < childCount; i++) { mChildHelper.getChildAt(i).offsetTopAndBottom(dy); } } /** * Called when an item view is attached to this RecyclerView. * * <p>Subclasses of RecyclerView may want to perform extra bookkeeping or modifications * of child views as they become attached. This will be called before a * {@link LayoutManager} measures or lays out the view and is a good time to perform these * changes.</p> * * @param child Child view that is now attached to this RecyclerView and its associated window */ public void onChildAttachedToWindow(View child) { } /** * Called when an item view is detached from this RecyclerView. * * <p>Subclasses of RecyclerView may want to perform extra bookkeeping or modifications * of child views as they become detached. This will be called as a * {@link LayoutManager} fully detaches the child view from the parent and its window.</p> * * @param child Child view that is now detached from this RecyclerView and its associated window */ public void onChildDetachedFromWindow(View child) { } /** * Offset the bounds of all child views by <code>dx</code> pixels. * Useful for implementing simple scrolling in {@link LayoutManager LayoutManagers}. * * @param dx Horizontal pixel offset to apply to the bounds of all child views */ public void offsetChildrenHorizontal(int dx) { final int childCount = mChildHelper.getChildCount(); for (int i = 0; i < childCount; i++) { mChildHelper.getChildAt(i).offsetLeftAndRight(dx); } } Rect getItemDecorInsetsForChild(View child) { final LayoutParams lp = (LayoutParams) child.getLayoutParams(); if (!lp.mInsetsDirty) { return lp.mDecorInsets; } final Rect insets = lp.mDecorInsets; insets.set(0, 0, 0, 0); final int decorCount = mItemDecorations.size(); for (int i = 0; i < decorCount; i++) { mTempRect.set(0, 0, 0, 0); mItemDecorations.get(i).getItemOffsets(mTempRect, child, this, mState); insets.left += mTempRect.left; insets.top += mTempRect.top; insets.right += mTempRect.right; insets.bottom += mTempRect.bottom; } lp.mInsetsDirty = false; return insets; } /** * Called when the scroll position of this RecyclerView changes. Subclasses should use * this method to respond to scrolling within the adapter's data set instead of an explicit * listener. * * <p>This method will always be invoked before listeners. If a subclass needs to perform * any additional upkeep or bookkeeping after scrolling but before listeners run, * this is a good place to do so.</p> * * <p>This differs from {@link View#onScrollChanged(int, int, int, int)} in that it receives * the distance scrolled in either direction within the adapter's data set instead of absolute * scroll coordinates. Since RecyclerView cannot compute the absolute scroll position from * any arbitrary point in the data set, <code>onScrollChanged</code> will always receive * the current {@link View#getScrollX()} and {@link View#getScrollY()} values which * do not correspond to the data set scroll position. However, some subclasses may choose * to use these fields as special offsets.</p> * * @param dx horizontal distance scrolled in pixels * @param dy vertical distance scrolled in pixels */ public void onScrolled(int dx, int dy) { // Do nothing } void dispatchOnScrolled(int hresult, int vresult) { // Pass the current scrollX/scrollY values; no actual change in these properties occurred // but some general-purpose code may choose to respond to changes this way. final int scrollX = getScrollX(); final int scrollY = getScrollY(); onScrollChanged(scrollX, scrollY, scrollX, scrollY); // Pass the real deltas to onScrolled, the RecyclerView-specific method. onScrolled(hresult, vresult); // Invoke listeners last. Subclassed view methods always handle the event first. // All internal state is consistent by the time listeners are invoked. if (mScrollListener != null) { mScrollListener.onScrolled(this, hresult, vresult); } if (mScrollListeners != null) { for (int i = mScrollListeners.size() - 1; i >= 0; i--) { mScrollListeners.get(i).onScrolled(this, hresult, vresult); } } } /** * Called when the scroll state of this RecyclerView changes. Subclasses should use this * method to respond to state changes instead of an explicit listener. * * <p>This method will always be invoked before listeners, but after the LayoutManager * responds to the scroll state change.</p> * * @param state the new scroll state, one of {@link #SCROLL_STATE_IDLE}, * {@link #SCROLL_STATE_DRAGGING} or {@link #SCROLL_STATE_SETTLING} */ public void onScrollStateChanged(int state) { // Do nothing } void dispatchOnScrollStateChanged(int state) { // Let the LayoutManager go first; this allows it to bring any properties into // a consistent state before the RecyclerView subclass responds. if (mLayout != null) { mLayout.onScrollStateChanged(state); } // Let the RecyclerView subclass handle this event next; any LayoutManager property // changes will be reflected by this time. onScrollStateChanged(state); // Listeners go last. All other internal state is consistent by this point. if (mScrollListener != null) { mScrollListener.onScrollStateChanged(this, state); } if (mScrollListeners != null) { for (int i = mScrollListeners.size() - 1; i >= 0; i--) { mScrollListeners.get(i).onScrollStateChanged(this, state); } } } /** * Returns whether there are pending adapter updates which are not yet applied to the layout. * <p> * If this method returns <code>true</code>, it means that what user is currently seeing may not * reflect them adapter contents (depending on what has changed). * You may use this information to defer or cancel some operations. * <p> * This method returns true if RecyclerView has not yet calculated the first layout after it is * attached to the Window or the Adapter has been replaced. * * @return True if there are some adapter updates which are not yet reflected to layout or false * if layout is up to date. */ public boolean hasPendingAdapterUpdates() { return !mFirstLayoutComplete || mDataSetHasChangedAfterLayout || mAdapterHelper.hasPendingUpdates(); } private class ViewFlinger implements Runnable { private int mLastFlingX; private int mLastFlingY; private ScrollerCompat mScroller; private Interpolator mInterpolator = sQuinticInterpolator; // When set to true, postOnAnimation callbacks are delayed until the run method completes private boolean mEatRunOnAnimationRequest = false; // Tracks if postAnimationCallback should be re-attached when it is done private boolean mReSchedulePostAnimationCallback = false; public ViewFlinger() { mScroller = ScrollerCompat.create(getContext(), sQuinticInterpolator); } @Override public void run() { disableRunOnAnimationRequests(); consumePendingUpdateOperations(); // keep a local reference so that if it is changed during onAnimation method, it won't // cause unexpected behaviors final ScrollerCompat scroller = mScroller; final SmoothScroller smoothScroller = mLayout.mSmoothScroller; if (scroller.computeScrollOffset()) { final int x = scroller.getCurrX(); final int y = scroller.getCurrY(); final int dx = x - mLastFlingX; final int dy = y - mLastFlingY; int hresult = 0; int vresult = 0; mLastFlingX = x; mLastFlingY = y; int overscrollX = 0, overscrollY = 0; if (mAdapter != null) { eatRequestLayout(); onEnterLayoutOrScroll(); if (dx != 0) { hresult = mLayout.scrollHorizontallyBy(dx, mRecycler, mState); overscrollX = dx - hresult; } if (dy != 0) { vresult = mLayout.scrollVerticallyBy(dy, mRecycler, mState); overscrollY = dy - vresult; } if (supportsChangeAnimations()) { // Fix up shadow views used by changing animations int count = mChildHelper.getChildCount(); for (int i = 0; i < count; i++) { View view = mChildHelper.getChildAt(i); ViewHolder holder = getChildViewHolder(view); if (holder != null && holder.mShadowingHolder != null) { View shadowingView = holder.mShadowingHolder.itemView; int left = view.getLeft(); int top = view.getTop(); if (left != shadowingView.getLeft() || top != shadowingView.getTop()) { shadowingView.layout(left, top, left + shadowingView.getWidth(), top + shadowingView.getHeight()); } } } } if (smoothScroller != null && !smoothScroller.isPendingInitialRun() && smoothScroller.isRunning()) { final int adapterSize = mState.getItemCount(); if (adapterSize == 0) { smoothScroller.stop(); } else if (smoothScroller.getTargetPosition() >= adapterSize) { smoothScroller.setTargetPosition(adapterSize - 1); smoothScroller.onAnimation(dx - overscrollX, dy - overscrollY); } else { smoothScroller.onAnimation(dx - overscrollX, dy - overscrollY); } } onExitLayoutOrScroll(); resumeRequestLayout(false); } if (!mItemDecorations.isEmpty()) { invalidate(); } if (ViewCompat.getOverScrollMode(RecyclerView.this) != ViewCompat.OVER_SCROLL_NEVER) { considerReleasingGlowsOnScroll(dx, dy); } if (overscrollX != 0 || overscrollY != 0) { final int vel = (int) scroller.getCurrVelocity(); int velX = 0; if (overscrollX != x) { velX = overscrollX < 0 ? -vel : overscrollX > 0 ? vel : 0; } int velY = 0; if (overscrollY != y) { velY = overscrollY < 0 ? -vel : overscrollY > 0 ? vel : 0; } if (ViewCompat.getOverScrollMode(RecyclerView.this) != ViewCompat.OVER_SCROLL_NEVER) { absorbGlows(velX, velY); } if ((velX != 0 || overscrollX == x || scroller.getFinalX() == 0) && (velY != 0 || overscrollY == y || scroller.getFinalY() == 0)) { scroller.abortAnimation(); } } if (hresult != 0 || vresult != 0) { dispatchOnScrolled(hresult, vresult); } if (!awakenScrollBars()) { invalidate(); } final boolean fullyConsumedVertical = dy != 0 && mLayout.canScrollVertically() && vresult == dy; final boolean fullyConsumedHorizontal = dx != 0 && mLayout.canScrollHorizontally() && hresult == dx; final boolean fullyConsumedAny = (dx == 0 && dy == 0) || fullyConsumedHorizontal || fullyConsumedVertical; if (scroller.isFinished() || !fullyConsumedAny) { setScrollState(SCROLL_STATE_IDLE); // setting state to idle will stop this. } else { postOnAnimation(); } } // call this after the onAnimation is complete not to have inconsistent callbacks etc. if (smoothScroller != null && smoothScroller.isPendingInitialRun()) { smoothScroller.onAnimation(0, 0); } enableRunOnAnimationRequests(); } private void disableRunOnAnimationRequests() { mReSchedulePostAnimationCallback = false; mEatRunOnAnimationRequest = true; } private void enableRunOnAnimationRequests() { mEatRunOnAnimationRequest = false; if (mReSchedulePostAnimationCallback) { postOnAnimation(); } } void postOnAnimation() { if (mEatRunOnAnimationRequest) { mReSchedulePostAnimationCallback = true; } else { removeCallbacks(this); ViewCompat.postOnAnimation(RecyclerView.this, this); } } public void fling(int velocityX, int velocityY) { setScrollState(SCROLL_STATE_SETTLING); mLastFlingX = mLastFlingY = 0; mScroller.fling(0, 0, velocityX, velocityY, Integer.MIN_VALUE, Integer.MAX_VALUE, Integer.MIN_VALUE, Integer.MAX_VALUE); postOnAnimation(); } public void smoothScrollBy(int dx, int dy) { smoothScrollBy(dx, dy, 0, 0); } public void smoothScrollBy(int dx, int dy, int vx, int vy) { smoothScrollBy(dx, dy, computeScrollDuration(dx, dy, vx, vy)); } private float distanceInfluenceForSnapDuration(float f) { f -= 0.5f; // center the values about 0. f *= 0.3f * Math.PI / 2.0f; return (float) Math.sin(f); } private int computeScrollDuration(int dx, int dy, int vx, int vy) { final int absDx = Math.abs(dx); final int absDy = Math.abs(dy); final boolean horizontal = absDx > absDy; final int velocity = (int) Math.sqrt(vx * vx + vy * vy); final int delta = (int) Math.sqrt(dx * dx + dy * dy); final int containerSize = horizontal ? getWidth() : getHeight(); final int halfContainerSize = containerSize / 2; final float distanceRatio = Math.min(1.f, 1.f * delta / containerSize); final float distance = halfContainerSize + halfContainerSize * distanceInfluenceForSnapDuration(distanceRatio); final int duration; if (velocity > 0) { duration = 4 * Math.round(1000 * Math.abs(distance / velocity)); } else { float absDelta = (float) (horizontal ? absDx : absDy); duration = (int) (((absDelta / containerSize) + 1) * 300); } return Math.min(duration, MAX_SCROLL_DURATION); } public void smoothScrollBy(int dx, int dy, int duration) { smoothScrollBy(dx, dy, duration, sQuinticInterpolator); } public void smoothScrollBy(int dx, int dy, int duration, Interpolator interpolator) { if (mInterpolator != interpolator) { mInterpolator = interpolator; mScroller = ScrollerCompat.create(getContext(), interpolator); } setScrollState(SCROLL_STATE_SETTLING); mLastFlingX = mLastFlingY = 0; mScroller.startScroll(0, 0, dx, dy, duration); postOnAnimation(); } public void stop() { removeCallbacks(this); mScroller.abortAnimation(); } } private class RecyclerViewDataObserver extends AdapterDataObserver { @Override public void onChanged() { assertNotInLayoutOrScroll(null); if (mAdapter.hasStableIds()) { // TODO Determine what actually changed. // This is more important to implement now since this callback will disable all // animations because we cannot rely on positions. mState.mStructureChanged = true; setDataSetChangedAfterLayout(); } else { mState.mStructureChanged = true; setDataSetChangedAfterLayout(); } if (!mAdapterHelper.hasPendingUpdates()) { requestLayout(); } } @Override public void onItemRangeChanged(int positionStart, int itemCount) { assertNotInLayoutOrScroll(null); if (mAdapterHelper.onItemRangeChanged(positionStart, itemCount)) { triggerUpdateProcessor(); } } @Override public void onItemRangeInserted(int positionStart, int itemCount) { assertNotInLayoutOrScroll(null); if (mAdapterHelper.onItemRangeInserted(positionStart, itemCount)) { triggerUpdateProcessor(); } } @Override public void onItemRangeRemoved(int positionStart, int itemCount) { assertNotInLayoutOrScroll(null); if (mAdapterHelper.onItemRangeRemoved(positionStart, itemCount)) { triggerUpdateProcessor(); } } @Override public void onItemRangeMoved(int fromPosition, int toPosition, int itemCount) { assertNotInLayoutOrScroll(null); if (mAdapterHelper.onItemRangeMoved(fromPosition, toPosition, itemCount)) { triggerUpdateProcessor(); } } void triggerUpdateProcessor() { if (mPostUpdatesOnAnimation && mHasFixedSize && mIsAttached) { ViewCompat.postOnAnimation(RecyclerView.this, mUpdateChildViewsRunnable); } else { mAdapterUpdateDuringMeasure = true; requestLayout(); } } } /** * RecycledViewPool lets you share Views between multiple RecyclerViews. * <p> * If you want to recycle views across RecyclerViews, create an instance of RecycledViewPool * and use {@link RecyclerView#setRecycledViewPool(RecycledViewPool)}. * <p> * RecyclerView automatically creates a pool for itself if you don't provide one. * */ public static class RecycledViewPool { private SparseArray<ArrayList<ViewHolder>> mScrap = new SparseArray<ArrayList<ViewHolder>>(); private SparseIntArray mMaxScrap = new SparseIntArray(); private int mAttachCount = 0; private static final int DEFAULT_MAX_SCRAP = 5; public void clear() { mScrap.clear(); } public void setMaxRecycledViews(int viewType, int max) { mMaxScrap.put(viewType, max); final ArrayList<ViewHolder> scrapHeap = mScrap.get(viewType); if (scrapHeap != null) { while (scrapHeap.size() > max) { scrapHeap.remove(scrapHeap.size() - 1); } } } public ViewHolder getRecycledView(int viewType) { final ArrayList<ViewHolder> scrapHeap = mScrap.get(viewType); if (scrapHeap != null && !scrapHeap.isEmpty()) { final int index = scrapHeap.size() - 1; final ViewHolder scrap = scrapHeap.get(index); scrapHeap.remove(index); return scrap; } return null; } int size() { int count = 0; for (int i = 0; i < mScrap.size(); i++) { ArrayList<ViewHolder> viewHolders = mScrap.valueAt(i); if (viewHolders != null) { count += viewHolders.size(); } } return count; } public void putRecycledView(ViewHolder scrap) { final int viewType = scrap.getItemViewType(); final ArrayList scrapHeap = getScrapHeapForType(viewType); if (mMaxScrap.get(viewType) <= scrapHeap.size()) { return; } scrap.resetInternal(); scrapHeap.add(scrap); } void attach(Adapter adapter) { mAttachCount++; } void detach() { mAttachCount--; } /** * Detaches the old adapter and attaches the new one. * <p> * RecycledViewPool will clear its cache if it has only one adapter attached and the new * adapter uses a different ViewHolder than the oldAdapter. * * @param oldAdapter The previous adapter instance. Will be detached. * @param newAdapter The new adapter instance. Will be attached. * @param compatibleWithPrevious True if both oldAdapter and newAdapter are using the same * ViewHolder and view types. */ void onAdapterChanged(Adapter oldAdapter, Adapter newAdapter, boolean compatibleWithPrevious) { if (oldAdapter != null) { detach(); } if (!compatibleWithPrevious && mAttachCount == 0) { clear(); } if (newAdapter != null) { attach(newAdapter); } } private ArrayList<ViewHolder> getScrapHeapForType(int viewType) { ArrayList<ViewHolder> scrap = mScrap.get(viewType); if (scrap == null) { scrap = new ArrayList<ViewHolder>(); mScrap.put(viewType, scrap); if (mMaxScrap.indexOfKey(viewType) < 0) { mMaxScrap.put(viewType, DEFAULT_MAX_SCRAP); } } return scrap; } } /** * A Recycler is responsible for managing scrapped or detached item views for reuse. * * <p>A "scrapped" view is a view that is still attached to its parent RecyclerView but * that has been marked for removal or reuse.</p> * * <p>Typical use of a Recycler by a {@link LayoutManager} will be to obtain views for * an adapter's data set representing the data at a given position or item ID. * If the view to be reused is considered "dirty" the adapter will be asked to rebind it. * If not, the view can be quickly reused by the LayoutManager with no further work. * Clean views that have not {@link android.view.View#isLayoutRequested() requested layout} * may be repositioned by a LayoutManager without remeasurement.</p> */ public final class Recycler { final ArrayList<ViewHolder> mAttachedScrap = new ArrayList<ViewHolder>(); private ArrayList<ViewHolder> mChangedScrap = null; final ArrayList<ViewHolder> mCachedViews = new ArrayList<ViewHolder>(); private final List<ViewHolder> mUnmodifiableAttachedScrap = Collections.unmodifiableList(mAttachedScrap); private int mViewCacheMax = DEFAULT_CACHE_SIZE; private RecycledViewPool mRecyclerPool; private ViewCacheExtension mViewCacheExtension; private static final int DEFAULT_CACHE_SIZE = 2; /** * Clear scrap views out of this recycler. Detached views contained within a * recycled view pool will remain. */ public void clear() { mAttachedScrap.clear(); recycleAndClearCachedViews(); } /** * Set the maximum number of detached, valid views we should retain for later use. * * @param viewCount Number of views to keep before sending views to the shared pool */ public void setViewCacheSize(int viewCount) { mViewCacheMax = viewCount; // first, try the views that can be recycled for (int i = mCachedViews.size() - 1; i >= 0 && mCachedViews.size() > viewCount; i--) { recycleCachedViewAt(i); } } /** * Returns an unmodifiable list of ViewHolders that are currently in the scrap list. * * @return List of ViewHolders in the scrap list. */ public List<ViewHolder> getScrapList() { return mUnmodifiableAttachedScrap; } /** * Helper method for getViewForPosition. * <p> * Checks whether a given view holder can be used for the provided position. * * @param holder ViewHolder * @return true if ViewHolder matches the provided position, false otherwise */ boolean validateViewHolderForOffsetPosition(ViewHolder holder) { // if it is a removed holder, nothing to verify since we cannot ask adapter anymore // if it is not removed, verify the type and id. if (holder.isRemoved()) { return true; } if (holder.mPosition < 0 || holder.mPosition >= mAdapter.getItemCount()) { throw new IndexOutOfBoundsException( "Inconsistency detected. Invalid view holder " + "adapter position" + holder); } if (!mState.isPreLayout()) { // don't check type if it is pre-layout. final int type = mAdapter.getItemViewType(holder.mPosition); if (type != holder.getItemViewType()) { return false; } } if (mAdapter.hasStableIds()) { return holder.getItemId() == mAdapter.getItemId(holder.mPosition); } return true; } /** * Binds the given View to the position. The View can be a View previously retrieved via * {@link #getViewForPosition(int)} or created by * {@link Adapter#onCreateViewHolder(ViewGroup, int)}. * <p> * Generally, a LayoutManager should acquire its views via {@link #getViewForPosition(int)} * and let the RecyclerView handle caching. This is a helper method for LayoutManager who * wants to handle its own recycling logic. * <p> * Note that, {@link #getViewForPosition(int)} already binds the View to the position so * you don't need to call this method unless you want to bind this View to another position. * * @param view The view to update. * @param position The position of the item to bind to this View. */ public void bindViewToPosition(View view, int position) { ViewHolder holder = getChildViewHolderInt(view); if (holder == null) { throw new IllegalArgumentException("The view does not have a ViewHolder. You cannot" + " pass arbitrary views to this method, they should be created by the " + "Adapter"); } final int offsetPosition = mAdapterHelper.findPositionOffset(position); if (offsetPosition < 0 || offsetPosition >= mAdapter.getItemCount()) { throw new IndexOutOfBoundsException("Inconsistency detected. Invalid item " + "position " + position + "(offset:" + offsetPosition + ")." + "state:" + mState.getItemCount()); } holder.mOwnerRecyclerView = RecyclerView.this; mAdapter.bindViewHolder(holder, offsetPosition); attachAccessibilityDelegate(view); if (mState.isPreLayout()) { holder.mPreLayoutPosition = position; } final ViewGroup.LayoutParams lp = holder.itemView.getLayoutParams(); final LayoutParams rvLayoutParams; if (lp == null) { rvLayoutParams = (LayoutParams) generateDefaultLayoutParams(); holder.itemView.setLayoutParams(rvLayoutParams); } else if (!checkLayoutParams(lp)) { rvLayoutParams = (LayoutParams) generateLayoutParams(lp); holder.itemView.setLayoutParams(rvLayoutParams); } else { rvLayoutParams = (LayoutParams) lp; } rvLayoutParams.mInsetsDirty = true; rvLayoutParams.mViewHolder = holder; rvLayoutParams.mPendingInvalidate = holder.itemView.getParent() == null; } /** * RecyclerView provides artificial position range (item count) in pre-layout state and * automatically maps these positions to {@link Adapter} positions when * {@link #getViewForPosition(int)} or {@link #bindViewToPosition(View, int)} is called. * <p> * Usually, LayoutManager does not need to worry about this. However, in some cases, your * LayoutManager may need to call some custom component with item positions in which * case you need the actual adapter position instead of the pre layout position. You * can use this method to convert a pre-layout position to adapter (post layout) position. * <p> * Note that if the provided position belongs to a deleted ViewHolder, this method will * return -1. * <p> * Calling this method in post-layout state returns the same value back. * * @param position The pre-layout position to convert. Must be greater or equal to 0 and * less than {@link State#getItemCount()}. */ public int convertPreLayoutPositionToPostLayout(int position) { if (position < 0 || position >= mState.getItemCount()) { throw new IndexOutOfBoundsException( "invalid position " + position + ". State " + "item count is " + mState.getItemCount()); } if (!mState.isPreLayout()) { return position; } return mAdapterHelper.findPositionOffset(position); } /** * Obtain a view initialized for the given position. * * This method should be used by {@link LayoutManager} implementations to obtain * views to represent data from an {@link Adapter}. * <p> * The Recycler may reuse a scrap or detached view from a shared pool if one is * available for the correct view type. If the adapter has not indicated that the * data at the given position has changed, the Recycler will attempt to hand back * a scrap view that was previously initialized for that data without rebinding. * * @param position Position to obtain a view for * @return A view representing the data at <code>position</code> from <code>adapter</code> */ public View getViewForPosition(int position) { return getViewForPosition(position, false); } View getViewForPosition(int position, boolean dryRun) { if (position < 0 || position >= mState.getItemCount()) { throw new IndexOutOfBoundsException("Invalid item position " + position + "(" + position + "). Item count:" + mState.getItemCount()); } boolean fromScrap = false; ViewHolder holder = null; // 0) If there is a changed scrap, try to find from there if (mState.isPreLayout()) { holder = getChangedScrapViewForPosition(position); fromScrap = holder != null; } // 1) Find from scrap by position if (holder == null) { holder = getScrapViewForPosition(position, INVALID_TYPE, dryRun); if (holder != null) { if (!validateViewHolderForOffsetPosition(holder)) { // recycle this scrap if (!dryRun) { // we would like to recycle this but need to make sure it is not used by // animation logic etc. holder.addFlags(ViewHolder.FLAG_INVALID); if (holder.isScrap()) { removeDetachedView(holder.itemView, false); holder.unScrap(); } else if (holder.wasReturnedFromScrap()) { holder.clearReturnedFromScrapFlag(); } recycleViewHolderInternal(holder); } holder = null; } else { fromScrap = true; } } } if (holder == null) { final int offsetPosition = mAdapterHelper.findPositionOffset(position); if (offsetPosition < 0 || offsetPosition >= mAdapter.getItemCount()) { throw new IndexOutOfBoundsException("Inconsistency detected. Invalid item " + "position " + position + "(offset:" + offsetPosition + ")." + "state:" + mState.getItemCount()); } final int type = mAdapter.getItemViewType(offsetPosition); // 2) Find from scrap via stable ids, if exists if (mAdapter.hasStableIds()) { holder = getScrapViewForId(mAdapter.getItemId(offsetPosition), type, dryRun); if (holder != null) { // update position holder.mPosition = offsetPosition; fromScrap = true; } } if (holder == null && mViewCacheExtension != null) { // We are NOT sending the offsetPosition because LayoutManager does not // know it. final View view = mViewCacheExtension.getViewForPositionAndType(this, position, type); if (view != null) { holder = getChildViewHolder(view); if (holder == null) { throw new IllegalArgumentException("getViewForPositionAndType returned" + " a view which does not have a ViewHolder"); } else if (holder.shouldIgnore()) { throw new IllegalArgumentException("getViewForPositionAndType returned" + " a view that is ignored. You must call stopIgnoring before" + " returning this view."); } } } if (holder == null) { // fallback to recycler // try recycler. // Head to the shared pool. if (DEBUG) { Log.d(TAG, "getViewForPosition(" + position + ") fetching from shared " + "pool"); } holder = getRecycledViewPool().getRecycledView(type); if (holder != null) { holder.resetInternal(); if (FORCE_INVALIDATE_DISPLAY_LIST) { invalidateDisplayListInt(holder); } } } if (holder == null) { holder = mAdapter.createViewHolder(RecyclerView.this, type); if (DEBUG) { Log.d(TAG, "getViewForPosition created new ViewHolder"); } } } boolean bound = false; if (mState.isPreLayout() && holder.isBound()) { // do not update unless we absolutely have to. holder.mPreLayoutPosition = position; } else if (!holder.isBound() || holder.needsUpdate() || holder.isInvalid()) { if (DEBUG && holder.isRemoved()) { throw new IllegalStateException("Removed holder should be bound and it should" + " come here only in pre-layout. Holder: " + holder); } final int offsetPosition = mAdapterHelper.findPositionOffset(position); holder.mOwnerRecyclerView = RecyclerView.this; mAdapter.bindViewHolder(holder, offsetPosition); attachAccessibilityDelegate(holder.itemView); bound = true; if (mState.isPreLayout()) { holder.mPreLayoutPosition = position; } } final ViewGroup.LayoutParams lp = holder.itemView.getLayoutParams(); final LayoutParams rvLayoutParams; if (lp == null) { rvLayoutParams = (LayoutParams) generateDefaultLayoutParams(); holder.itemView.setLayoutParams(rvLayoutParams); } else if (!checkLayoutParams(lp)) { rvLayoutParams = (LayoutParams) generateLayoutParams(lp); holder.itemView.setLayoutParams(rvLayoutParams); } else { rvLayoutParams = (LayoutParams) lp; } rvLayoutParams.mViewHolder = holder; rvLayoutParams.mPendingInvalidate = fromScrap && bound; return holder.itemView; } private void attachAccessibilityDelegate(View itemView) { if (mAccessibilityManager != null && mAccessibilityManager.isEnabled()) { if (ViewCompat .getImportantForAccessibility(itemView) == ViewCompat.IMPORTANT_FOR_ACCESSIBILITY_AUTO) { ViewCompat.setImportantForAccessibility(itemView, ViewCompat.IMPORTANT_FOR_ACCESSIBILITY_YES); } if (!ViewCompat.hasAccessibilityDelegate(itemView)) { ViewCompat.setAccessibilityDelegate(itemView, mAccessibilityDelegate.getItemDelegate()); } } } private void invalidateDisplayListInt(ViewHolder holder) { if (holder.itemView instanceof ViewGroup) { invalidateDisplayListInt((ViewGroup) holder.itemView, false); } } private void invalidateDisplayListInt(ViewGroup viewGroup, boolean invalidateThis) { for (int i = viewGroup.getChildCount() - 1; i >= 0; i--) { final View view = viewGroup.getChildAt(i); if (view instanceof ViewGroup) { invalidateDisplayListInt((ViewGroup) view, true); } } if (!invalidateThis) { return; } // we need to force it to become invisible if (viewGroup.getVisibility() == View.INVISIBLE) { viewGroup.setVisibility(View.VISIBLE); viewGroup.setVisibility(View.INVISIBLE); } else { final int visibility = viewGroup.getVisibility(); viewGroup.setVisibility(View.INVISIBLE); viewGroup.setVisibility(visibility); } } /** * Recycle a detached view. The specified view will be added to a pool of views * for later rebinding and reuse. * * <p>A view must be fully detached (removed from parent) before it may be recycled. If the * View is scrapped, it will be removed from scrap list.</p> * * @param view Removed view for recycling * @see LayoutManager#removeAndRecycleView(View, Recycler) */ public void recycleView(View view) { // This public recycle method tries to make view recycle-able since layout manager // intended to recycle this view (e.g. even if it is in scrap or change cache) ViewHolder holder = getChildViewHolderInt(view); if (holder.isTmpDetached()) { removeDetachedView(view, false); } if (holder.isScrap()) { holder.unScrap(); } else if (holder.wasReturnedFromScrap()) { holder.clearReturnedFromScrapFlag(); } recycleViewHolderInternal(holder); } /** * Internally, use this method instead of {@link #recycleView(android.view.View)} to * catch potential bugs. * @param view */ void recycleViewInternal(View view) { recycleViewHolderInternal(getChildViewHolderInt(view)); } void recycleAndClearCachedViews() { final int count = mCachedViews.size(); for (int i = count - 1; i >= 0; i--) { recycleCachedViewAt(i); } mCachedViews.clear(); } /** * Recycles a cached view and removes the view from the list. Views are added to cache * if and only if they are recyclable, so this method does not check it again. * <p> * A small exception to this rule is when the view does not have an animator reference * but transient state is true (due to animations created outside ItemAnimator). In that * case, adapter may choose to recycle it. From RecyclerView's perspective, the view is * still recyclable since Adapter wants to do so. * * @param cachedViewIndex The index of the view in cached views list */ void recycleCachedViewAt(int cachedViewIndex) { if (DEBUG) { Log.d(TAG, "Recycling cached view at index " + cachedViewIndex); } ViewHolder viewHolder = mCachedViews.get(cachedViewIndex); if (DEBUG) { Log.d(TAG, "CachedViewHolder to be recycled: " + viewHolder); } addViewHolderToRecycledViewPool(viewHolder); mCachedViews.remove(cachedViewIndex); } /** * internal implementation checks if view is scrapped or attached and throws an exception * if so. * Public version un-scraps before calling recycle. */ void recycleViewHolderInternal(ViewHolder holder) { if (holder.isScrap() || holder.itemView.getParent() != null) { throw new IllegalArgumentException("Scrapped or attached views may not be recycled. isScrap:" + holder.isScrap() + " isAttached:" + (holder.itemView.getParent() != null)); } if (holder.isTmpDetached()) { throw new IllegalArgumentException("Tmp detached view should be removed " + "from RecyclerView before it can be recycled: " + holder); } if (holder.shouldIgnore()) { throw new IllegalArgumentException("Trying to recycle an ignored view holder. You" + " should first call stopIgnoringView(view) before calling recycle."); } //noinspection unchecked final boolean transientStatePreventsRecycling = holder.doesTransientStatePreventRecycling(); final boolean forceRecycle = mAdapter != null && transientStatePreventsRecycling && mAdapter.onFailedToRecycleView(holder); boolean cached = false; boolean recycled = false; if (forceRecycle || holder.isRecyclable()) { if (!holder.isInvalid() && !holder.isRemoved() && !holder.isChanged()) { // Retire oldest cached view final int cachedViewSize = mCachedViews.size(); if (cachedViewSize == mViewCacheMax && cachedViewSize > 0) { recycleCachedViewAt(0); } if (cachedViewSize < mViewCacheMax) { mCachedViews.add(holder); cached = true; } } if (!cached) { addViewHolderToRecycledViewPool(holder); recycled = true; } } else if (DEBUG) { Log.d(TAG, "trying to recycle a non-recycleable holder. Hopefully, it will " + "re-visit here. We are still removing it from animation lists"); } // even if the holder is not removed, we still call this method so that it is removed // from view holder lists. mState.onViewRecycled(holder); if (!cached && !recycled && transientStatePreventsRecycling) { holder.mOwnerRecyclerView = null; } } void addViewHolderToRecycledViewPool(ViewHolder holder) { ViewCompat.setAccessibilityDelegate(holder.itemView, null); dispatchViewRecycled(holder); holder.mOwnerRecyclerView = null; getRecycledViewPool().putRecycledView(holder); } /** * Used as a fast path for unscrapping and recycling a view during a bulk operation. * The caller must call {@link #clearScrap()} when it's done to update the recycler's * internal bookkeeping. */ void quickRecycleScrapView(View view) { final ViewHolder holder = getChildViewHolderInt(view); holder.mScrapContainer = null; holder.clearReturnedFromScrapFlag(); recycleViewHolderInternal(holder); } /** * Mark an attached view as scrap. * * <p>"Scrap" views are still attached to their parent RecyclerView but are eligible * for rebinding and reuse. Requests for a view for a given position may return a * reused or rebound scrap view instance.</p> * * @param view View to scrap */ void scrapView(View view) { final ViewHolder holder = getChildViewHolderInt(view); holder.setScrapContainer(this); if (!holder.isChanged() || !supportsChangeAnimations()) { if (holder.isInvalid() && !holder.isRemoved() && !mAdapter.hasStableIds()) { throw new IllegalArgumentException("Called scrap view with an invalid view." + " Invalid views cannot be reused from scrap, they should rebound from" + " recycler pool."); } mAttachedScrap.add(holder); } else { if (mChangedScrap == null) { mChangedScrap = new ArrayList<ViewHolder>(); } mChangedScrap.add(holder); } } /** * Remove a previously scrapped view from the pool of eligible scrap. * * <p>This view will no longer be eligible for reuse until re-scrapped or * until it is explicitly removed and recycled.</p> */ void unscrapView(ViewHolder holder) { if (!holder.isChanged() || !supportsChangeAnimations() || mChangedScrap == null) { mAttachedScrap.remove(holder); } else { mChangedScrap.remove(holder); } holder.mScrapContainer = null; holder.clearReturnedFromScrapFlag(); } int getScrapCount() { return mAttachedScrap.size(); } View getScrapViewAt(int index) { return mAttachedScrap.get(index).itemView; } void clearScrap() { mAttachedScrap.clear(); } ViewHolder getChangedScrapViewForPosition(int position) { // If pre-layout, check the changed scrap for an exact match. final int changedScrapSize; if (mChangedScrap == null || (changedScrapSize = mChangedScrap.size()) == 0) { return null; } // find by position for (int i = 0; i < changedScrapSize; i++) { final ViewHolder holder = mChangedScrap.get(i); if (!holder.wasReturnedFromScrap() && holder.getLayoutPosition() == position) { holder.addFlags(ViewHolder.FLAG_RETURNED_FROM_SCRAP); return holder; } } // find by id if (mAdapter.hasStableIds()) { final int offsetPosition = mAdapterHelper.findPositionOffset(position); if (offsetPosition > 0 && offsetPosition < mAdapter.getItemCount()) { final long id = mAdapter.getItemId(offsetPosition); for (int i = 0; i < changedScrapSize; i++) { final ViewHolder holder = mChangedScrap.get(i); if (!holder.wasReturnedFromScrap() && holder.getItemId() == id) { holder.addFlags(ViewHolder.FLAG_RETURNED_FROM_SCRAP); return holder; } } } } return null; } /** * Returns a scrap view for the position. If type is not INVALID_TYPE, it also checks if * ViewHolder's type matches the provided type. * * @param position Item position * @param type View type * @param dryRun Does a dry run, finds the ViewHolder but does not remove * @return a ViewHolder that can be re-used for this position. */ ViewHolder getScrapViewForPosition(int position, int type, boolean dryRun) { final int scrapCount = mAttachedScrap.size(); // Try first for an exact, non-invalid match from scrap. for (int i = 0; i < scrapCount; i++) { final ViewHolder holder = mAttachedScrap.get(i); if (!holder.wasReturnedFromScrap() && holder.getLayoutPosition() == position && !holder.isInvalid() && (mState.mInPreLayout || !holder.isRemoved())) { if (type != INVALID_TYPE && holder.getItemViewType() != type) { Log.e(TAG, "Scrap view for position " + position + " isn't dirty but has" + " wrong view type! (found " + holder.getItemViewType() + " but expected " + type + ")"); break; } holder.addFlags(ViewHolder.FLAG_RETURNED_FROM_SCRAP); return holder; } } if (!dryRun) { View view = mChildHelper.findHiddenNonRemovedView(position, type); if (view != null) { // ending the animation should cause it to get recycled before we reuse it mItemAnimator.endAnimation(getChildViewHolder(view)); } } // Search in our first-level recycled view cache. final int cacheSize = mCachedViews.size(); for (int i = 0; i < cacheSize; i++) { final ViewHolder holder = mCachedViews.get(i); // invalid view holders may be in cache if adapter has stable ids as they can be // retrieved via getScrapViewForId if (!holder.isInvalid() && holder.getLayoutPosition() == position) { if (!dryRun) { mCachedViews.remove(i); } if (DEBUG) { Log.d(TAG, "getScrapViewForPosition(" + position + ", " + type + ") found match in cache: " + holder); } return holder; } } return null; } ViewHolder getScrapViewForId(long id, int type, boolean dryRun) { // Look in our attached views first final int count = mAttachedScrap.size(); for (int i = count - 1; i >= 0; i--) { final ViewHolder holder = mAttachedScrap.get(i); if (holder.getItemId() == id && !holder.wasReturnedFromScrap()) { if (type == holder.getItemViewType()) { holder.addFlags(ViewHolder.FLAG_RETURNED_FROM_SCRAP); if (holder.isRemoved()) { // this might be valid in two cases: // > item is removed but we are in pre-layout pass // >> do nothing. return as is. make sure we don't rebind // > item is removed then added to another position and we are in // post layout. // >> remove removed and invalid flags, add update flag to rebind // because item was invisible to us and we don't know what happened in // between. if (!mState.isPreLayout()) { holder.setFlags(ViewHolder.FLAG_UPDATE, ViewHolder.FLAG_UPDATE | ViewHolder.FLAG_INVALID | ViewHolder.FLAG_REMOVED); } } return holder; } else if (!dryRun) { // Recycle this scrap. Type mismatch. mAttachedScrap.remove(i); removeDetachedView(holder.itemView, false); quickRecycleScrapView(holder.itemView); } } } // Search the first-level cache final int cacheSize = mCachedViews.size(); for (int i = cacheSize - 1; i >= 0; i--) { final ViewHolder holder = mCachedViews.get(i); if (holder.getItemId() == id) { if (type == holder.getItemViewType()) { if (!dryRun) { mCachedViews.remove(i); } return holder; } else if (!dryRun) { recycleCachedViewAt(i); } } } return null; } void dispatchViewRecycled(ViewHolder holder) { if (mRecyclerListener != null) { mRecyclerListener.onViewRecycled(holder); } if (mAdapter != null) { mAdapter.onViewRecycled(holder); } if (mState != null) { mState.onViewRecycled(holder); } if (DEBUG) Log.d(TAG, "dispatchViewRecycled: " + holder); } void onAdapterChanged(Adapter oldAdapter, Adapter newAdapter, boolean compatibleWithPrevious) { clear(); getRecycledViewPool().onAdapterChanged(oldAdapter, newAdapter, compatibleWithPrevious); } void offsetPositionRecordsForMove(int from, int to) { final int start, end, inBetweenOffset; if (from < to) { start = from; end = to; inBetweenOffset = -1; } else { start = to; end = from; inBetweenOffset = 1; } final int cachedCount = mCachedViews.size(); for (int i = 0; i < cachedCount; i++) { final ViewHolder holder = mCachedViews.get(i); if (holder == null || holder.mPosition < start || holder.mPosition > end) { continue; } if (holder.mPosition == from) { holder.offsetPosition(to - from, false); } else { holder.offsetPosition(inBetweenOffset, false); } if (DEBUG) { Log.d(TAG, "offsetPositionRecordsForMove cached child " + i + " holder " + holder); } } } void offsetPositionRecordsForInsert(int insertedAt, int count) { final int cachedCount = mCachedViews.size(); for (int i = 0; i < cachedCount; i++) { final ViewHolder holder = mCachedViews.get(i); if (holder != null && holder.getLayoutPosition() >= insertedAt) { if (DEBUG) { Log.d(TAG, "offsetPositionRecordsForInsert cached " + i + " holder " + holder + " now at position " + (holder.mPosition + count)); } holder.offsetPosition(count, true); } } } /** * @param removedFrom Remove start index * @param count Remove count * @param applyToPreLayout If true, changes will affect ViewHolder's pre-layout position, if * false, they'll be applied before the second layout pass */ void offsetPositionRecordsForRemove(int removedFrom, int count, boolean applyToPreLayout) { final int removedEnd = removedFrom + count; final int cachedCount = mCachedViews.size(); for (int i = cachedCount - 1; i >= 0; i--) { final ViewHolder holder = mCachedViews.get(i); if (holder != null) { if (holder.getLayoutPosition() >= removedEnd) { if (DEBUG) { Log.d(TAG, "offsetPositionRecordsForRemove cached " + i + " holder " + holder + " now at position " + (holder.mPosition - count)); } holder.offsetPosition(-count, applyToPreLayout); } else if (holder.getLayoutPosition() >= removedFrom) { // Item for this view was removed. Dump it from the cache. holder.addFlags(ViewHolder.FLAG_REMOVED); recycleCachedViewAt(i); } } } } void setViewCacheExtension(ViewCacheExtension extension) { mViewCacheExtension = extension; } void setRecycledViewPool(RecycledViewPool pool) { if (mRecyclerPool != null) { mRecyclerPool.detach(); } mRecyclerPool = pool; if (pool != null) { mRecyclerPool.attach(getAdapter()); } } RecycledViewPool getRecycledViewPool() { if (mRecyclerPool == null) { mRecyclerPool = new RecycledViewPool(); } return mRecyclerPool; } void viewRangeUpdate(int positionStart, int itemCount) { final int positionEnd = positionStart + itemCount; final int cachedCount = mCachedViews.size(); for (int i = 0; i < cachedCount; i++) { final ViewHolder holder = mCachedViews.get(i); if (holder == null) { continue; } final int pos = holder.getLayoutPosition(); if (pos >= positionStart && pos < positionEnd) { holder.addFlags(ViewHolder.FLAG_UPDATE); // cached views should not be flagged as changed because this will cause them // to animate when they are returned from cache. } } } void setAdapterPositionsAsUnknown() { final int cachedCount = mCachedViews.size(); for (int i = 0; i < cachedCount; i++) { final ViewHolder holder = mCachedViews.get(i); if (holder != null) { holder.addFlags(ViewHolder.FLAG_ADAPTER_POSITION_UNKNOWN); } } } void markKnownViewsInvalid() { if (mAdapter != null && mAdapter.hasStableIds()) { final int cachedCount = mCachedViews.size(); for (int i = 0; i < cachedCount; i++) { final ViewHolder holder = mCachedViews.get(i); if (holder != null) { holder.addFlags(ViewHolder.FLAG_UPDATE | ViewHolder.FLAG_INVALID); } } } else { // we cannot re-use cached views in this case. Recycle them all recycleAndClearCachedViews(); } } void clearOldPositions() { final int cachedCount = mCachedViews.size(); for (int i = 0; i < cachedCount; i++) { final ViewHolder holder = mCachedViews.get(i); holder.clearOldPosition(); } final int scrapCount = mAttachedScrap.size(); for (int i = 0; i < scrapCount; i++) { mAttachedScrap.get(i).clearOldPosition(); } if (mChangedScrap != null) { final int changedScrapCount = mChangedScrap.size(); for (int i = 0; i < changedScrapCount; i++) { mChangedScrap.get(i).clearOldPosition(); } } } void markItemDecorInsetsDirty() { final int cachedCount = mCachedViews.size(); for (int i = 0; i < cachedCount; i++) { final ViewHolder holder = mCachedViews.get(i); LayoutParams layoutParams = (LayoutParams) holder.itemView.getLayoutParams(); if (layoutParams != null) { layoutParams.mInsetsDirty = true; } } } } /** * ViewCacheExtension is a helper class to provide an additional layer of view caching that can * ben controlled by the developer. * <p> * When {@link Recycler#getViewForPosition(int)} is called, Recycler checks attached scrap and * first level cache to find a matching View. If it cannot find a suitable View, Recycler will * call the {@link #getViewForPositionAndType(Recycler, int, int)} before checking * {@link RecycledViewPool}. * <p> * Note that, Recycler never sends Views to this method to be cached. It is developers * responsibility to decide whether they want to keep their Views in this custom cache or let * the default recycling policy handle it. */ public abstract static class ViewCacheExtension { /** * Returns a View that can be binded to the given Adapter position. * <p> * This method should <b>not</b> create a new View. Instead, it is expected to return * an already created View that can be re-used for the given type and position. * If the View is marked as ignored, it should first call * {@link LayoutManager#stopIgnoringView(View)} before returning the View. * <p> * RecyclerView will re-bind the returned View to the position if necessary. * * @param recycler The Recycler that can be used to bind the View * @param position The adapter position * @param type The type of the View, defined by adapter * @return A View that is bound to the given position or NULL if there is no View to re-use * @see LayoutManager#ignoreView(View) */ abstract public View getViewForPositionAndType(Recycler recycler, int position, int type); } /** * Base class for an Adapter * * <p>Adapters provide a binding from an app-specific data set to views that are displayed * within a {@link RecyclerView}.</p> */ public static abstract class Adapter<VH extends ViewHolder> { private final AdapterDataObservable mObservable = new AdapterDataObservable(); private boolean mHasStableIds = false; /** * Called when RecyclerView needs a new {@link ViewHolder} of the given type to represent * an item. * <p> * This new ViewHolder should be constructed with a new View that can represent the items * of the given type. You can either create a new View manually or inflate it from an XML * layout file. * <p> * The new ViewHolder will be used to display items of the adapter using * {@link #onBindViewHolder(ViewHolder, int)}. Since it will be re-used to display different * items in the data set, it is a good idea to cache references to sub views of the View to * avoid unnecessary {@link View#findViewById(int)} calls. * * @param parent The ViewGroup into which the new View will be added after it is bound to * an adapter position. * @param viewType The view type of the new View. * * @return A new ViewHolder that holds a View of the given view type. * @see #getItemViewType(int) * @see #onBindViewHolder(ViewHolder, int) */ public abstract VH onCreateViewHolder(ViewGroup parent, int viewType); /** * Called by RecyclerView to display the data at the specified position. This method * should update the contents of the {@link ViewHolder#itemView} to reflect the item at * the given position. * <p> * Note that unlike {@link android.widget.ListView}, RecyclerView will not call this * method again if the position of the item changes in the data set unless the item itself * is invalidated or the new position cannot be determined. For this reason, you should only * use the <code>position</code> parameter while acquiring the related data item inside this * method and should not keep a copy of it. If you need the position of an item later on * (e.g. in a click listener), use {@link ViewHolder#getAdapterPosition()} which will have * the updated adapter position. * * @param holder The ViewHolder which should be updated to represent the contents of the * item at the given position in the data set. * @param position The position of the item within the adapter's data set. */ public abstract void onBindViewHolder(VH holder, int position); /** * This method calls {@link #onCreateViewHolder(ViewGroup, int)} to create a new * {@link ViewHolder} and initializes some private fields to be used by RecyclerView. * * @see #onCreateViewHolder(ViewGroup, int) */ public final VH createViewHolder(ViewGroup parent, int viewType) { final VH holder = onCreateViewHolder(parent, viewType); holder.mItemViewType = viewType; return holder; } /** * This method internally calls {@link #onBindViewHolder(ViewHolder, int)} to update the * {@link ViewHolder} contents with the item at the given position and also sets up some * private fields to be used by RecyclerView. * * @see #onBindViewHolder(ViewHolder, int) */ public final void bindViewHolder(VH holder, int position) { holder.mPosition = position; if (hasStableIds()) { holder.mItemId = getItemId(position); } holder.setFlags(ViewHolder.FLAG_BOUND, ViewHolder.FLAG_BOUND | ViewHolder.FLAG_UPDATE | ViewHolder.FLAG_INVALID | ViewHolder.FLAG_ADAPTER_POSITION_UNKNOWN); onBindViewHolder(holder, position); } /** * Return the view type of the item at <code>position</code> for the purposes * of view recycling. * * <p>The default implementation of this method returns 0, making the assumption of * a single view type for the adapter. Unlike ListView adapters, types need not * be contiguous. Consider using id resources to uniquely identify item view types. * * @param position position to query * @return integer value identifying the type of the view needed to represent the item at * <code>position</code>. Type codes need not be contiguous. */ public int getItemViewType(int position) { return 0; } /** * Indicates whether each item in the data set can be represented with a unique identifier * of type {@link java.lang.Long}. * * @param hasStableIds Whether items in data set have unique identifiers or not. * @see #hasStableIds() * @see #getItemId(int) */ public void setHasStableIds(boolean hasStableIds) { if (hasObservers()) { throw new IllegalStateException("Cannot change whether this adapter has " + "stable IDs while the adapter has registered observers."); } mHasStableIds = hasStableIds; } /** * Return the stable ID for the item at <code>position</code>. If {@link #hasStableIds()} * would return false this method should return {@link #NO_ID}. The default implementation * of this method returns {@link #NO_ID}. * * @param position Adapter position to query * @return the stable ID of the item at position */ public long getItemId(int position) { return NO_ID; } /** * Returns the total number of items in the data set hold by the adapter. * * @return The total number of items in this adapter. */ public abstract int getItemCount(); /** * Returns true if this adapter publishes a unique <code>long</code> value that can * act as a key for the item at a given position in the data set. If that item is relocated * in the data set, the ID returned for that item should be the same. * * @return true if this adapter's items have stable IDs */ public final boolean hasStableIds() { return mHasStableIds; } /** * Called when a view created by this adapter has been recycled. * * <p>A view is recycled when a {@link LayoutManager} decides that it no longer * needs to be attached to its parent {@link RecyclerView}. This can be because it has * fallen out of visibility or a set of cached views represented by views still * attached to the parent RecyclerView. If an item view has large or expensive data * bound to it such as large bitmaps, this may be a good place to release those * resources.</p> * <p> * RecyclerView calls this method right before clearing ViewHolder's internal data and * sending it to RecycledViewPool. This way, if ViewHolder was holding valid information * before being recycled, you can call {@link ViewHolder#getAdapterPosition()} to get * its adapter position. * * @param holder The ViewHolder for the view being recycled */ public void onViewRecycled(VH holder) { } /** * Called by the RecyclerView if a ViewHolder created by this Adapter cannot be recycled * due to its transient state. Upon receiving this callback, Adapter can clear the * animation(s) that effect the View's transient state and return <code>true</code> so that * the View can be recycled. Keep in mind that the View in question is already removed from * the RecyclerView. * <p> * In some cases, it is acceptable to recycle a View although it has transient state. Most * of the time, this is a case where the transient state will be cleared in * {@link #onBindViewHolder(ViewHolder, int)} call when View is rebound to a new position. * For this reason, RecyclerView leaves the decision to the Adapter and uses the return * value of this method to decide whether the View should be recycled or not. * <p> * Note that when all animations are created by {@link RecyclerView.ItemAnimator}, you * should never receive this callback because RecyclerView keeps those Views as children * until their animations are complete. This callback is useful when children of the item * views create animations which may not be easy to implement using an {@link ItemAnimator}. * <p> * You should <em>never</em> fix this issue by calling * <code>holder.itemView.setHasTransientState(false);</code> unless you've previously called * <code>holder.itemView.setHasTransientState(true);</code>. Each * <code>View.setHasTransientState(true)</code> call must be matched by a * <code>View.setHasTransientState(false)</code> call, otherwise, the state of the View * may become inconsistent. You should always prefer to end or cancel animations that are * triggering the transient state instead of handling it manually. * * @param holder The ViewHolder containing the View that could not be recycled due to its * transient state. * @return True if the View should be recycled, false otherwise. Note that if this method * returns <code>true</code>, RecyclerView <em>will ignore</em> the transient state of * the View and recycle it regardless. If this method returns <code>false</code>, * RecyclerView will check the View's transient state again before giving a final decision. * Default implementation returns false. */ public boolean onFailedToRecycleView(VH holder) { return false; } /** * Called when a view created by this adapter has been attached to a window. * * <p>This can be used as a reasonable signal that the view is about to be seen * by the user. If the adapter previously freed any resources in * {@link #onViewDetachedFromWindow(RecyclerView.ViewHolder) onViewDetachedFromWindow} * those resources should be restored here.</p> * * @param holder Holder of the view being attached */ public void onViewAttachedToWindow(VH holder) { } /** * Called when a view created by this adapter has been detached from its window. * * <p>Becoming detached from the window is not necessarily a permanent condition; * the consumer of an Adapter's views may choose to cache views offscreen while they * are not visible, attaching an detaching them as appropriate.</p> * * @param holder Holder of the view being detached */ public void onViewDetachedFromWindow(VH holder) { } /** * Returns true if one or more observers are attached to this adapter. * * @return true if this adapter has observers */ public final boolean hasObservers() { return mObservable.hasObservers(); } /** * Register a new observer to listen for data changes. * * <p>The adapter may publish a variety of events describing specific changes. * Not all adapters may support all change types and some may fall back to a generic * {@link android.support.v7.widget.RecyclerView.AdapterDataObserver#onChanged() * "something changed"} event if more specific data is not available.</p> * * <p>Components registering observers with an adapter are responsible for * {@link #unregisterAdapterDataObserver(RecyclerView.AdapterDataObserver) * unregistering} those observers when finished.</p> * * @param observer Observer to register * * @see #unregisterAdapterDataObserver(RecyclerView.AdapterDataObserver) */ public void registerAdapterDataObserver(AdapterDataObserver observer) { mObservable.registerObserver(observer); } /** * Unregister an observer currently listening for data changes. * * <p>The unregistered observer will no longer receive events about changes * to the adapter.</p> * * @param observer Observer to unregister * * @see #registerAdapterDataObserver(RecyclerView.AdapterDataObserver) */ public void unregisterAdapterDataObserver(AdapterDataObserver observer) { mObservable.unregisterObserver(observer); } /** * Called by RecyclerView when it starts observing this Adapter. * <p> * Keep in mind that same adapter may be observed by multiple RecyclerViews. * * @param recyclerView The RecyclerView instance which started observing this adapter. * @see #onDetachedFromRecyclerView(RecyclerView) */ public void onAttachedToRecyclerView(RecyclerView recyclerView) { } /** * Called by RecyclerView when it stops observing this Adapter. * * @param recyclerView The RecyclerView instance which stopped observing this adapter. * @see #onAttachedToRecyclerView(RecyclerView) */ public void onDetachedFromRecyclerView(RecyclerView recyclerView) { } /** * Notify any registered observers that the data set has changed. * * <p>There are two different classes of data change events, item changes and structural * changes. Item changes are when a single item has its data updated but no positional * changes have occurred. Structural changes are when items are inserted, removed or moved * within the data set.</p> * * <p>This event does not specify what about the data set has changed, forcing * any observers to assume that all existing items and structure may no longer be valid. * LayoutManagers will be forced to fully rebind and relayout all visible views.</p> * * <p><code>RecyclerView</code> will attempt to synthesize visible structural change events * for adapters that report that they have {@link #hasStableIds() stable IDs} when * this method is used. This can help for the purposes of animation and visual * object persistence but individual item views will still need to be rebound * and relaid out.</p> * * <p>If you are writing an adapter it will always be more efficient to use the more * specific change events if you can. Rely on <code>notifyDataSetChanged()</code> * as a last resort.</p> * * @see #notifyItemChanged(int) * @see #notifyItemInserted(int) * @see #notifyItemRemoved(int) * @see #notifyItemRangeChanged(int, int) * @see #notifyItemRangeInserted(int, int) * @see #notifyItemRangeRemoved(int, int) */ public void notifyDataSetChanged() { mObservable.notifyChanged(); } /** * Notify any registered observers that the item at <code>position</code> has changed. * * <p>This is an item change event, not a structural change event. It indicates that any * reflection of the data at <code>position</code> is out of date and should be updated. * The item at <code>position</code> retains the same identity.</p> * * @param position Position of the item that has changed * * @see #notifyItemRangeChanged(int, int) */ public void notifyItemChanged(int position) { mObservable.notifyItemRangeChanged(position, 1); } /** * Notify any registered observers that the <code>itemCount</code> items starting at * position <code>positionStart</code> have changed. * * <p>This is an item change event, not a structural change event. It indicates that * any reflection of the data in the given position range is out of date and should * be updated. The items in the given range retain the same identity.</p> * * @param positionStart Position of the first item that has changed * @param itemCount Number of items that have changed * * @see #notifyItemChanged(int) */ public void notifyItemRangeChanged(int positionStart, int itemCount) { mObservable.notifyItemRangeChanged(positionStart, itemCount); } /** * Notify any registered observers that the item reflected at <code>position</code> * has been newly inserted. The item previously at <code>position</code> is now at * position <code>position + 1</code>. * * <p>This is a structural change event. Representations of other existing items in the * data set are still considered up to date and will not be rebound, though their * positions may be altered.</p> * * @param position Position of the newly inserted item in the data set * * @see #notifyItemRangeInserted(int, int) */ public void notifyItemInserted(int position) { mObservable.notifyItemRangeInserted(position, 1); } /** * Notify any registered observers that the item reflected at <code>fromPosition</code> * has been moved to <code>toPosition</code>. * * <p>This is a structural change event. Representations of other existing items in the * data set are still considered up to date and will not be rebound, though their * positions may be altered.</p> * * @param fromPosition Previous position of the item. * @param toPosition New position of the item. */ public void notifyItemMoved(int fromPosition, int toPosition) { mObservable.notifyItemMoved(fromPosition, toPosition); } /** * Notify any registered observers that the currently reflected <code>itemCount</code> * items starting at <code>positionStart</code> have been newly inserted. The items * previously located at <code>positionStart</code> and beyond can now be found starting * at position <code>positionStart + itemCount</code>. * * <p>This is a structural change event. Representations of other existing items in the * data set are still considered up to date and will not be rebound, though their positions * may be altered.</p> * * @param positionStart Position of the first item that was inserted * @param itemCount Number of items inserted * * @see #notifyItemInserted(int) */ public void notifyItemRangeInserted(int positionStart, int itemCount) { mObservable.notifyItemRangeInserted(positionStart, itemCount); } /** * Notify any registered observers that the item previously located at <code>position</code> * has been removed from the data set. The items previously located at and after * <code>position</code> may now be found at <code>oldPosition - 1</code>. * * <p>This is a structural change event. Representations of other existing items in the * data set are still considered up to date and will not be rebound, though their positions * may be altered.</p> * * @param position Position of the item that has now been removed * * @see #notifyItemRangeRemoved(int, int) */ public void notifyItemRemoved(int position) { mObservable.notifyItemRangeRemoved(position, 1); } /** * Notify any registered observers that the <code>itemCount</code> items previously * located at <code>positionStart</code> have been removed from the data set. The items * previously located at and after <code>positionStart + itemCount</code> may now be found * at <code>oldPosition - itemCount</code>. * * <p>This is a structural change event. Representations of other existing items in the data * set are still considered up to date and will not be rebound, though their positions * may be altered.</p> * * @param positionStart Previous position of the first item that was removed * @param itemCount Number of items removed from the data set */ public void notifyItemRangeRemoved(int positionStart, int itemCount) { mObservable.notifyItemRangeRemoved(positionStart, itemCount); } } private void dispatchChildDetached(View child) { if (mAdapter != null) { mAdapter.onViewDetachedFromWindow(getChildViewHolderInt(child)); } onChildDetachedFromWindow(child); } private void dispatchChildAttached(View child) { if (mAdapter != null) { mAdapter.onViewAttachedToWindow(getChildViewHolderInt(child)); } onChildAttachedToWindow(child); } /** * A <code>LayoutManager</code> is responsible for measuring and positioning item views * within a <code>RecyclerView</code> as well as determining the policy for when to recycle * item views that are no longer visible to the user. By changing the <code>LayoutManager</code> * a <code>RecyclerView</code> can be used to implement a standard vertically scrolling list, * a uniform grid, staggered grids, horizontally scrolling collections and more. Several stock * layout managers are provided for general use. */ public static abstract class LayoutManager { ChildHelper mChildHelper; RecyclerView mRecyclerView; @Nullable SmoothScroller mSmoothScroller; private boolean mRequestedSimpleAnimations = false; private boolean mIsAttachedToWindow = false; void setRecyclerView(RecyclerView recyclerView) { if (recyclerView == null) { mRecyclerView = null; mChildHelper = null; } else { mRecyclerView = recyclerView; mChildHelper = recyclerView.mChildHelper; } } /** * Calls {@code RecyclerView#requestLayout} on the underlying RecyclerView */ public void requestLayout() { if (mRecyclerView != null) { mRecyclerView.requestLayout(); } } /** * Checks if RecyclerView is in the middle of a layout or scroll and throws an * {@link IllegalStateException} if it <b>is not</b>. * * @param message The message for the exception. Can be null. * @see #assertNotInLayoutOrScroll(String) */ public void assertInLayoutOrScroll(String message) { if (mRecyclerView != null) { mRecyclerView.assertInLayoutOrScroll(message); } } /** * Checks if RecyclerView is in the middle of a layout or scroll and throws an * {@link IllegalStateException} if it <b>is</b>. * * @param message The message for the exception. Can be null. * @see #assertInLayoutOrScroll(String) */ public void assertNotInLayoutOrScroll(String message) { if (mRecyclerView != null) { mRecyclerView.assertNotInLayoutOrScroll(message); } } /** * Returns whether this LayoutManager supports automatic item animations. * A LayoutManager wishing to support item animations should obey certain * rules as outlined in {@link #onLayoutChildren(Recycler, State)}. * The default return value is <code>false</code>, so subclasses of LayoutManager * will not get predictive item animations by default. * * <p>Whether item animations are enabled in a RecyclerView is determined both * by the return value from this method and the * {@link RecyclerView#setItemAnimator(ItemAnimator) ItemAnimator} set on the * RecyclerView itself. If the RecyclerView has a non-null ItemAnimator but this * method returns false, then simple item animations will be enabled, in which * views that are moving onto or off of the screen are simply faded in/out. If * the RecyclerView has a non-null ItemAnimator and this method returns true, * then there will be two calls to {@link #onLayoutChildren(Recycler, State)} to * setup up the information needed to more intelligently predict where appearing * and disappearing views should be animated from/to.</p> * * @return true if predictive item animations should be enabled, false otherwise */ public boolean supportsPredictiveItemAnimations() { return false; } void dispatchAttachedToWindow(RecyclerView view) { mIsAttachedToWindow = true; onAttachedToWindow(view); } void dispatchDetachedFromWindow(RecyclerView view, Recycler recycler) { mIsAttachedToWindow = false; onDetachedFromWindow(view, recycler); } /** * Returns whether LayoutManager is currently attached to a RecyclerView which is attached * to a window. * * @return True if this LayoutManager is controlling a RecyclerView and the RecyclerView * is attached to window. */ public boolean isAttachedToWindow() { return mIsAttachedToWindow; } /** * Causes the Runnable to execute on the next animation time step. * The runnable will be run on the user interface thread. * <p> * Calling this method when LayoutManager is not attached to a RecyclerView has no effect. * * @param action The Runnable that will be executed. * * @see #removeCallbacks */ public void postOnAnimation(Runnable action) { if (mRecyclerView != null) { ViewCompat.postOnAnimation(mRecyclerView, action); } } /** * Removes the specified Runnable from the message queue. * <p> * Calling this method when LayoutManager is not attached to a RecyclerView has no effect. * * @param action The Runnable to remove from the message handling queue * * @return true if RecyclerView could ask the Handler to remove the Runnable, * false otherwise. When the returned value is true, the Runnable * may or may not have been actually removed from the message queue * (for instance, if the Runnable was not in the queue already.) * * @see #postOnAnimation */ public boolean removeCallbacks(Runnable action) { if (mRecyclerView != null) { return mRecyclerView.removeCallbacks(action); } return false; } /** * Called when this LayoutManager is both attached to a RecyclerView and that RecyclerView * is attached to a window. * * <p>Subclass implementations should always call through to the superclass implementation. * </p> * * @param view The RecyclerView this LayoutManager is bound to */ public void onAttachedToWindow(RecyclerView view) { } /** * @deprecated * override {@link #onDetachedFromWindow(RecyclerView, Recycler)} */ @Deprecated public void onDetachedFromWindow(RecyclerView view) { } /** * Called when this LayoutManager is detached from its parent RecyclerView or when * its parent RecyclerView is detached from its window. * * <p>Subclass implementations should always call through to the superclass implementation. * </p> * * @param view The RecyclerView this LayoutManager is bound to * @param recycler The recycler to use if you prefer to recycle your children instead of * keeping them around. */ public void onDetachedFromWindow(RecyclerView view, Recycler recycler) { onDetachedFromWindow(view); } /** * Check if the RecyclerView is configured to clip child views to its padding. * * @return true if this RecyclerView clips children to its padding, false otherwise */ public boolean getClipToPadding() { return mRecyclerView != null && mRecyclerView.mClipToPadding; } /** * Lay out all relevant child views from the given adapter. * * The LayoutManager is in charge of the behavior of item animations. By default, * RecyclerView has a non-null {@link #getItemAnimator() ItemAnimator}, and simple * item animations are enabled. This means that add/remove operations on the * adapter will result in animations to add new or appearing items, removed or * disappearing items, and moved items. If a LayoutManager returns false from * {@link #supportsPredictiveItemAnimations()}, which is the default, and runs a * normal layout operation during {@link #onLayoutChildren(Recycler, State)}, the * RecyclerView will have enough information to run those animations in a simple * way. For example, the default ItemAnimator, {@link DefaultItemAnimator}, will * simple fade views in and out, whether they are actuall added/removed or whether * they are moved on or off the screen due to other add/remove operations. * * <p>A LayoutManager wanting a better item animation experience, where items can be * animated onto and off of the screen according to where the items exist when they * are not on screen, then the LayoutManager should return true from * {@link #supportsPredictiveItemAnimations()} and add additional logic to * {@link #onLayoutChildren(Recycler, State)}. Supporting predictive animations * means that {@link #onLayoutChildren(Recycler, State)} will be called twice; * once as a "pre" layout step to determine where items would have been prior to * a real layout, and again to do the "real" layout. In the pre-layout phase, * items will remember their pre-layout positions to allow them to be laid out * appropriately. Also, {@link LayoutParams#isItemRemoved() removed} items will * be returned from the scrap to help determine correct placement of other items. * These removed items should not be added to the child list, but should be used * to help calculate correct positioning of other views, including views that * were not previously onscreen (referred to as APPEARING views), but whose * pre-layout offscreen position can be determined given the extra * information about the pre-layout removed views.</p> * * <p>The second layout pass is the real layout in which only non-removed views * will be used. The only additional requirement during this pass is, if * {@link #supportsPredictiveItemAnimations()} returns true, to note which * views exist in the child list prior to layout and which are not there after * layout (referred to as DISAPPEARING views), and to position/layout those views * appropriately, without regard to the actual bounds of the RecyclerView. This allows * the animation system to know the location to which to animate these disappearing * views.</p> * * <p>The default LayoutManager implementations for RecyclerView handle all of these * requirements for animations already. Clients of RecyclerView can either use one * of these layout managers directly or look at their implementations of * onLayoutChildren() to see how they account for the APPEARING and * DISAPPEARING views.</p> * * @param recycler Recycler to use for fetching potentially cached views for a * position * @param state Transient state of RecyclerView */ public void onLayoutChildren(Recycler recycler, State state) { Log.e(TAG, "You must override onLayoutChildren(Recycler recycler, State state) "); } /** * Create a default <code>LayoutParams</code> object for a child of the RecyclerView. * * <p>LayoutManagers will often want to use a custom <code>LayoutParams</code> type * to store extra information specific to the layout. Client code should subclass * {@link RecyclerView.LayoutParams} for this purpose.</p> * * <p><em>Important:</em> if you use your own custom <code>LayoutParams</code> type * you must also override * {@link #checkLayoutParams(LayoutParams)}, * {@link #generateLayoutParams(android.view.ViewGroup.LayoutParams)} and * {@link #generateLayoutParams(android.content.Context, android.util.AttributeSet)}.</p> * * @return A new LayoutParams for a child view */ public abstract LayoutParams generateDefaultLayoutParams(); /** * Determines the validity of the supplied LayoutParams object. * * <p>This should check to make sure that the object is of the correct type * and all values are within acceptable ranges. The default implementation * returns <code>true</code> for non-null params.</p> * * @param lp LayoutParams object to check * @return true if this LayoutParams object is valid, false otherwise */ public boolean checkLayoutParams(LayoutParams lp) { return lp != null; } /** * Create a LayoutParams object suitable for this LayoutManager, copying relevant * values from the supplied LayoutParams object if possible. * * <p><em>Important:</em> if you use your own custom <code>LayoutParams</code> type * you must also override * {@link #checkLayoutParams(LayoutParams)}, * {@link #generateLayoutParams(android.view.ViewGroup.LayoutParams)} and * {@link #generateLayoutParams(android.content.Context, android.util.AttributeSet)}.</p> * * @param lp Source LayoutParams object to copy values from * @return a new LayoutParams object */ public LayoutParams generateLayoutParams(ViewGroup.LayoutParams lp) { if (lp instanceof LayoutParams) { return new LayoutParams((LayoutParams) lp); } else if (lp instanceof MarginLayoutParams) { return new LayoutParams((MarginLayoutParams) lp); } else { return new LayoutParams(lp); } } /** * Create a LayoutParams object suitable for this LayoutManager from * an inflated layout resource. * * <p><em>Important:</em> if you use your own custom <code>LayoutParams</code> type * you must also override * {@link #checkLayoutParams(LayoutParams)}, * {@link #generateLayoutParams(android.view.ViewGroup.LayoutParams)} and * {@link #generateLayoutParams(android.content.Context, android.util.AttributeSet)}.</p> * * @param c Context for obtaining styled attributes * @param attrs AttributeSet describing the supplied arguments * @return a new LayoutParams object */ public LayoutParams generateLayoutParams(Context c, AttributeSet attrs) { return new LayoutParams(c, attrs); } /** * Scroll horizontally by dx pixels in screen coordinates and return the distance traveled. * The default implementation does nothing and returns 0. * * @param dx distance to scroll by in pixels. X increases as scroll position * approaches the right. * @param recycler Recycler to use for fetching potentially cached views for a * position * @param state Transient state of RecyclerView * @return The actual distance scrolled. The return value will be negative if dx was * negative and scrolling proceeeded in that direction. * <code>Math.abs(result)</code> may be less than dx if a boundary was reached. */ public int scrollHorizontallyBy(int dx, Recycler recycler, State state) { return 0; } /** * Scroll vertically by dy pixels in screen coordinates and return the distance traveled. * The default implementation does nothing and returns 0. * * @param dy distance to scroll in pixels. Y increases as scroll position * approaches the bottom. * @param recycler Recycler to use for fetching potentially cached views for a * position * @param state Transient state of RecyclerView * @return The actual distance scrolled. The return value will be negative if dy was * negative and scrolling proceeeded in that direction. * <code>Math.abs(result)</code> may be less than dy if a boundary was reached. */ public int scrollVerticallyBy(int dy, Recycler recycler, State state) { return 0; } /** * Query if horizontal scrolling is currently supported. The default implementation * returns false. * * @return True if this LayoutManager can scroll the current contents horizontally */ public boolean canScrollHorizontally() { return false; } /** * Query if vertical scrolling is currently supported. The default implementation * returns false. * * @return True if this LayoutManager can scroll the current contents vertically */ public boolean canScrollVertically() { return false; } /** * Scroll to the specified adapter position. * * Actual position of the item on the screen depends on the LayoutManager implementation. * @param position Scroll to this adapter position. */ public void scrollToPosition(int position) { if (DEBUG) { Log.e(TAG, "You MUST implement scrollToPosition. It will soon become abstract"); } } /** * <p>Smooth scroll to the specified adapter position.</p> * <p>To support smooth scrolling, override this method, create your {@link SmoothScroller} * instance and call {@link #startSmoothScroll(SmoothScroller)}. * </p> * @param recyclerView The RecyclerView to which this layout manager is attached * @param state Current State of RecyclerView * @param position Scroll to this adapter position. */ public void smoothScrollToPosition(RecyclerView recyclerView, State state, int position) { Log.e(TAG, "You must override smoothScrollToPosition to support smooth scrolling"); } /** * <p>Starts a smooth scroll using the provided SmoothScroller.</p> * <p>Calling this method will cancel any previous smooth scroll request.</p> * @param smoothScroller Unstance which defines how smooth scroll should be animated */ public void startSmoothScroll(SmoothScroller smoothScroller) { if (mSmoothScroller != null && smoothScroller != mSmoothScroller && mSmoothScroller.isRunning()) { mSmoothScroller.stop(); } mSmoothScroller = smoothScroller; mSmoothScroller.start(mRecyclerView, this); } /** * @return true if RecycylerView is currently in the state of smooth scrolling. */ public boolean isSmoothScrolling() { return mSmoothScroller != null && mSmoothScroller.isRunning(); } /** * Returns the resolved layout direction for this RecyclerView. * * @return {@link android.support.v4.view.ViewCompat#LAYOUT_DIRECTION_RTL} if the layout * direction is RTL or returns * {@link android.support.v4.view.ViewCompat#LAYOUT_DIRECTION_LTR} if the layout direction * is not RTL. */ public int getLayoutDirection() { return ViewCompat.getLayoutDirection(mRecyclerView); } /** * Ends all animations on the view created by the {@link ItemAnimator}. * * @param view The View for which the animations should be ended. * @see RecyclerView.ItemAnimator#endAnimations() */ public void endAnimation(View view) { if (mRecyclerView.mItemAnimator != null) { mRecyclerView.mItemAnimator.endAnimation(getChildViewHolderInt(view)); } } /** * To be called only during {@link #onLayoutChildren(Recycler, State)} to add a view * to the layout that is known to be going away, either because it has been * {@link Adapter#notifyItemRemoved(int) removed} or because it is actually not in the * visible portion of the container but is being laid out in order to inform RecyclerView * in how to animate the item out of view. * <p> * Views added via this method are going to be invisible to LayoutManager after the * dispatchLayout pass is complete. They cannot be retrieved via {@link #getChildAt(int)} * or won't be included in {@link #getChildCount()} method. * * @param child View to add and then remove with animation. */ public void addDisappearingView(View child) { addDisappearingView(child, -1); } /** * To be called only during {@link #onLayoutChildren(Recycler, State)} to add a view * to the layout that is known to be going away, either because it has been * {@link Adapter#notifyItemRemoved(int) removed} or because it is actually not in the * visible portion of the container but is being laid out in order to inform RecyclerView * in how to animate the item out of view. * <p> * Views added via this method are going to be invisible to LayoutManager after the * dispatchLayout pass is complete. They cannot be retrieved via {@link #getChildAt(int)} * or won't be included in {@link #getChildCount()} method. * * @param child View to add and then remove with animation. * @param index Index of the view. */ public void addDisappearingView(View child, int index) { addViewInt(child, index, true); } /** * Add a view to the currently attached RecyclerView if needed. LayoutManagers should * use this method to add views obtained from a {@link Recycler} using * {@link Recycler#getViewForPosition(int)}. * * @param child View to add */ public void addView(View child) { addView(child, -1); } /** * Add a view to the currently attached RecyclerView if needed. LayoutManagers should * use this method to add views obtained from a {@link Recycler} using * {@link Recycler#getViewForPosition(int)}. * * @param child View to add * @param index Index to add child at */ public void addView(View child, int index) { addViewInt(child, index, false); } private void addViewInt(View child, int index, boolean disappearing) { final ViewHolder holder = getChildViewHolderInt(child); if (disappearing || holder.isRemoved()) { // these views will be hidden at the end of the layout pass. mRecyclerView.mState.addToDisappearingList(child); } else { // This may look like unnecessary but may happen if layout manager supports // predictive layouts and adapter removed then re-added the same item. // In this case, added version will be visible in the post layout (because add is // deferred) but RV will still bind it to the same View. // So if a View re-appears in post layout pass, remove it from disappearing list. mRecyclerView.mState.removeFromDisappearingList(child); } final LayoutParams lp = (LayoutParams) child.getLayoutParams(); if (holder.wasReturnedFromScrap() || holder.isScrap()) { if (holder.isScrap()) { holder.unScrap(); } else { holder.clearReturnedFromScrapFlag(); } mChildHelper.attachViewToParent(child, index, child.getLayoutParams(), false); if (DISPATCH_TEMP_DETACH) { ViewCompat.dispatchFinishTemporaryDetach(child); } } else if (child.getParent() == mRecyclerView) { // it was not a scrap but a valid child // ensure in correct position int currentIndex = mChildHelper.indexOfChild(child); if (index == -1) { index = mChildHelper.getChildCount(); } if (currentIndex == -1) { throw new IllegalStateException("Added View has RecyclerView as parent but" + " view is not a real child. Unfiltered index:" + mRecyclerView.indexOfChild(child)); } if (currentIndex != index) { mRecyclerView.mLayout.moveView(currentIndex, index); } } else { mChildHelper.addView(child, index, false); lp.mInsetsDirty = true; if (mSmoothScroller != null && mSmoothScroller.isRunning()) { mSmoothScroller.onChildAttachedToWindow(child); } } if (lp.mPendingInvalidate) { if (DEBUG) { Log.d(TAG, "consuming pending invalidate on child " + lp.mViewHolder); } holder.itemView.invalidate(); lp.mPendingInvalidate = false; } } /** * Remove a view from the currently attached RecyclerView if needed. LayoutManagers should * use this method to completely remove a child view that is no longer needed. * LayoutManagers should strongly consider recycling removed views using * {@link Recycler#recycleView(android.view.View)}. * * @param child View to remove */ public void removeView(View child) { mChildHelper.removeView(child); } /** * Remove a view from the currently attached RecyclerView if needed. LayoutManagers should * use this method to completely remove a child view that is no longer needed. * LayoutManagers should strongly consider recycling removed views using * {@link Recycler#recycleView(android.view.View)}. * * @param index Index of the child view to remove */ public void removeViewAt(int index) { final View child = getChildAt(index); if (child != null) { mChildHelper.removeViewAt(index); } } /** * Remove all views from the currently attached RecyclerView. This will not recycle * any of the affected views; the LayoutManager is responsible for doing so if desired. */ public void removeAllViews() { // Only remove non-animating views final int childCount = getChildCount(); for (int i = childCount - 1; i >= 0; i--) { mChildHelper.removeViewAt(i); } } /** * Returns offset of the RecyclerView's text baseline from the its top boundary. * * @return The offset of the RecyclerView's text baseline from the its top boundary; -1 if * there is no baseline. */ public int getBaseline() { return -1; } /** * Returns the adapter position of the item represented by the given View. This does not * contain any adapter changes that might have happened after the last layout. * * @param view The view to query * @return The adapter position of the item which is rendered by this View. */ public int getPosition(View view) { return ((RecyclerView.LayoutParams) view.getLayoutParams()).getViewLayoutPosition(); } /** * Returns the View type defined by the adapter. * * @param view The view to query * @return The type of the view assigned by the adapter. */ public int getItemViewType(View view) { return getChildViewHolderInt(view).getItemViewType(); } /** * Finds the view which represents the given adapter position. * <p> * This method traverses each child since it has no information about child order. * Override this method to improve performance if your LayoutManager keeps data about * child views. * <p> * If a view is ignored via {@link #ignoreView(View)}, it is also ignored by this method. * * @param position Position of the item in adapter * @return The child view that represents the given position or null if the position is not * laid out */ public View findViewByPosition(int position) { final int childCount = getChildCount(); for (int i = 0; i < childCount; i++) { View child = getChildAt(i); ViewHolder vh = getChildViewHolderInt(child); if (vh == null) { continue; } if (vh.getLayoutPosition() == position && !vh.shouldIgnore() && (mRecyclerView.mState.isPreLayout() || !vh.isRemoved())) { return child; } } return null; } /** * Temporarily detach a child view. * * <p>LayoutManagers may want to perform a lightweight detach operation to rearrange * views currently attached to the RecyclerView. Generally LayoutManager implementations * will want to use {@link #detachAndScrapView(android.view.View, RecyclerView.Recycler)} * so that the detached view may be rebound and reused.</p> * * <p>If a LayoutManager uses this method to detach a view, it <em>must</em> * {@link #attachView(android.view.View, int, RecyclerView.LayoutParams) reattach} * or {@link #removeDetachedView(android.view.View) fully remove} the detached view * before the LayoutManager entry point method called by RecyclerView returns.</p> * * @param child Child to detach */ public void detachView(View child) { final int ind = mChildHelper.indexOfChild(child); if (ind >= 0) { detachViewInternal(ind, child); } } /** * Temporarily detach a child view. * * <p>LayoutManagers may want to perform a lightweight detach operation to rearrange * views currently attached to the RecyclerView. Generally LayoutManager implementations * will want to use {@link #detachAndScrapView(android.view.View, RecyclerView.Recycler)} * so that the detached view may be rebound and reused.</p> * * <p>If a LayoutManager uses this method to detach a view, it <em>must</em> * {@link #attachView(android.view.View, int, RecyclerView.LayoutParams) reattach} * or {@link #removeDetachedView(android.view.View) fully remove} the detached view * before the LayoutManager entry point method called by RecyclerView returns.</p> * * @param index Index of the child to detach */ public void detachViewAt(int index) { detachViewInternal(index, getChildAt(index)); } private void detachViewInternal(int index, View view) { if (DISPATCH_TEMP_DETACH) { ViewCompat.dispatchStartTemporaryDetach(view); } mChildHelper.detachViewFromParent(index); } /** * Reattach a previously {@link #detachView(android.view.View) detached} view. * This method should not be used to reattach views that were previously * {@link #detachAndScrapView(android.view.View, RecyclerView.Recycler)} scrapped}. * * @param child Child to reattach * @param index Intended child index for child * @param lp LayoutParams for child */ public void attachView(View child, int index, LayoutParams lp) { ViewHolder vh = getChildViewHolderInt(child); if (vh.isRemoved()) { mRecyclerView.mState.addToDisappearingList(child); } else { mRecyclerView.mState.removeFromDisappearingList(child); } mChildHelper.attachViewToParent(child, index, lp, vh.isRemoved()); if (DISPATCH_TEMP_DETACH) { ViewCompat.dispatchFinishTemporaryDetach(child); } } /** * Reattach a previously {@link #detachView(android.view.View) detached} view. * This method should not be used to reattach views that were previously * {@link #detachAndScrapView(android.view.View, RecyclerView.Recycler)} scrapped}. * * @param child Child to reattach * @param index Intended child index for child */ public void attachView(View child, int index) { attachView(child, index, (LayoutParams) child.getLayoutParams()); } /** * Reattach a previously {@link #detachView(android.view.View) detached} view. * This method should not be used to reattach views that were previously * {@link #detachAndScrapView(android.view.View, RecyclerView.Recycler)} scrapped}. * * @param child Child to reattach */ public void attachView(View child) { attachView(child, -1); } /** * Finish removing a view that was previously temporarily * {@link #detachView(android.view.View) detached}. * * @param child Detached child to remove */ public void removeDetachedView(View child) { mRecyclerView.removeDetachedView(child, false); } /** * Moves a View from one position to another. * * @param fromIndex The View's initial index * @param toIndex The View's target index */ public void moveView(int fromIndex, int toIndex) { View view = getChildAt(fromIndex); if (view == null) { throw new IllegalArgumentException("Cannot move a child from non-existing index:" + fromIndex); } detachViewAt(fromIndex); attachView(view, toIndex); } /** * Detach a child view and add it to a {@link Recycler Recycler's} scrap heap. * * <p>Scrapping a view allows it to be rebound and reused to show updated or * different data.</p> * * @param child Child to detach and scrap * @param recycler Recycler to deposit the new scrap view into */ public void detachAndScrapView(View child, Recycler recycler) { int index = mChildHelper.indexOfChild(child); scrapOrRecycleView(recycler, index, child); } /** * Detach a child view and add it to a {@link Recycler Recycler's} scrap heap. * * <p>Scrapping a view allows it to be rebound and reused to show updated or * different data.</p> * * @param index Index of child to detach and scrap * @param recycler Recycler to deposit the new scrap view into */ public void detachAndScrapViewAt(int index, Recycler recycler) { final View child = getChildAt(index); scrapOrRecycleView(recycler, index, child); } /** * Remove a child view and recycle it using the given Recycler. * * @param child Child to remove and recycle * @param recycler Recycler to use to recycle child */ public void removeAndRecycleView(View child, Recycler recycler) { removeView(child); recycler.recycleView(child); } /** * Remove a child view and recycle it using the given Recycler. * * @param index Index of child to remove and recycle * @param recycler Recycler to use to recycle child */ public void removeAndRecycleViewAt(int index, Recycler recycler) { final View view = getChildAt(index); removeViewAt(index); recycler.recycleView(view); } /** * Return the current number of child views attached to the parent RecyclerView. * This does not include child views that were temporarily detached and/or scrapped. * * @return Number of attached children */ public int getChildCount() { return mChildHelper != null ? mChildHelper.getChildCount() : 0; } /** * Return the child view at the given index * @param index Index of child to return * @return Child view at index */ public View getChildAt(int index) { return mChildHelper != null ? mChildHelper.getChildAt(index) : null; } /** * Return the width of the parent RecyclerView * * @return Width in pixels */ public int getWidth() { return mRecyclerView != null ? mRecyclerView.getWidth() : 0; } /** * Return the height of the parent RecyclerView * * @return Height in pixels */ public int getHeight() { return mRecyclerView != null ? mRecyclerView.getHeight() : 0; } /** * Return the left padding of the parent RecyclerView * * @return Padding in pixels */ public int getPaddingLeft() { return mRecyclerView != null ? mRecyclerView.getPaddingLeft() : 0; } /** * Return the top padding of the parent RecyclerView * * @return Padding in pixels */ public int getPaddingTop() { return mRecyclerView != null ? mRecyclerView.getPaddingTop() : 0; } /** * Return the right padding of the parent RecyclerView * * @return Padding in pixels */ public int getPaddingRight() { return mRecyclerView != null ? mRecyclerView.getPaddingRight() : 0; } /** * Return the bottom padding of the parent RecyclerView * * @return Padding in pixels */ public int getPaddingBottom() { return mRecyclerView != null ? mRecyclerView.getPaddingBottom() : 0; } /** * Return the start padding of the parent RecyclerView * * @return Padding in pixels */ public int getPaddingStart() { return mRecyclerView != null ? ViewCompat.getPaddingStart(mRecyclerView) : 0; } /** * Return the end padding of the parent RecyclerView * * @return Padding in pixels */ public int getPaddingEnd() { return mRecyclerView != null ? ViewCompat.getPaddingEnd(mRecyclerView) : 0; } /** * Returns true if the RecyclerView this LayoutManager is bound to has focus. * * @return True if the RecyclerView has focus, false otherwise. * @see View#isFocused() */ public boolean isFocused() { return mRecyclerView != null && mRecyclerView.isFocused(); } /** * Returns true if the RecyclerView this LayoutManager is bound to has or contains focus. * * @return true if the RecyclerView has or contains focus * @see View#hasFocus() */ public boolean hasFocus() { return mRecyclerView != null && mRecyclerView.hasFocus(); } /** * Returns the item View which has or contains focus. * * @return A direct child of RecyclerView which has focus or contains the focused child. */ public View getFocusedChild() { if (mRecyclerView == null) { return null; } final View focused = mRecyclerView.getFocusedChild(); if (focused == null || mChildHelper.isHidden(focused)) { return null; } return focused; } /** * Returns the number of items in the adapter bound to the parent RecyclerView. * <p> * Note that this number is not necessarily equal to {@link State#getItemCount()}. In * methods where State is available, you should use {@link State#getItemCount()} instead. * For more details, check the documentation for {@link State#getItemCount()}. * * @return The number of items in the bound adapter * @see State#getItemCount() */ public int getItemCount() { final Adapter a = mRecyclerView != null ? mRecyclerView.getAdapter() : null; return a != null ? a.getItemCount() : 0; } /** * Offset all child views attached to the parent RecyclerView by dx pixels along * the horizontal axis. * * @param dx Pixels to offset by */ public void offsetChildrenHorizontal(int dx) { if (mRecyclerView != null) { mRecyclerView.offsetChildrenHorizontal(dx); } } /** * Offset all child views attached to the parent RecyclerView by dy pixels along * the vertical axis. * * @param dy Pixels to offset by */ public void offsetChildrenVertical(int dy) { if (mRecyclerView != null) { mRecyclerView.offsetChildrenVertical(dy); } } /** * Flags a view so that it will not be scrapped or recycled. * <p> * Scope of ignoring a child is strictly restricted to position tracking, scrapping and * recyling. Methods like {@link #removeAndRecycleAllViews(Recycler)} will ignore the child * whereas {@link #removeAllViews()} or {@link #offsetChildrenHorizontal(int)} will not * ignore the child. * <p> * Before this child can be recycled again, you have to call * {@link #stopIgnoringView(View)}. * <p> * You can call this method only if your LayoutManger is in onLayout or onScroll callback. * * @param view View to ignore. * @see #stopIgnoringView(View) */ public void ignoreView(View view) { if (view.getParent() != mRecyclerView || mRecyclerView.indexOfChild(view) == -1) { // checking this because calling this method on a recycled or detached view may // cause loss of state. throw new IllegalArgumentException("View should be fully attached to be ignored"); } final ViewHolder vh = getChildViewHolderInt(view); vh.addFlags(ViewHolder.FLAG_IGNORE); mRecyclerView.mState.onViewIgnored(vh); } /** * View can be scrapped and recycled again. * <p> * Note that calling this method removes all information in the view holder. * <p> * You can call this method only if your LayoutManger is in onLayout or onScroll callback. * * @param view View to ignore. */ public void stopIgnoringView(View view) { final ViewHolder vh = getChildViewHolderInt(view); vh.stopIgnoring(); vh.resetInternal(); vh.addFlags(ViewHolder.FLAG_INVALID); } /** * Temporarily detach and scrap all currently attached child views. Views will be scrapped * into the given Recycler. The Recycler may prefer to reuse scrap views before * other views that were previously recycled. * * @param recycler Recycler to scrap views into */ public void detachAndScrapAttachedViews(Recycler recycler) { final int childCount = getChildCount(); for (int i = childCount - 1; i >= 0; i--) { final View v = getChildAt(i); scrapOrRecycleView(recycler, i, v); } } private void scrapOrRecycleView(Recycler recycler, int index, View view) { final ViewHolder viewHolder = getChildViewHolderInt(view); if (viewHolder.shouldIgnore()) { if (DEBUG) { Log.d(TAG, "ignoring view " + viewHolder); } return; } if (viewHolder.isInvalid() && !viewHolder.isRemoved() && !viewHolder.isChanged() && !mRecyclerView.mAdapter.hasStableIds()) { removeViewAt(index); recycler.recycleViewHolderInternal(viewHolder); } else { detachViewAt(index); recycler.scrapView(view); } } /** * Recycles the scrapped views. * <p> * When a view is detached and removed, it does not trigger a ViewGroup invalidate. This is * the expected behavior if scrapped views are used for animations. Otherwise, we need to * call remove and invalidate RecyclerView to ensure UI update. * * @param recycler Recycler */ void removeAndRecycleScrapInt(Recycler recycler) { final int scrapCount = recycler.getScrapCount(); // Loop backward, recycler might be changed by removeDetachedView() for (int i = scrapCount - 1; i >= 0; i--) { final View scrap = recycler.getScrapViewAt(i); final ViewHolder vh = getChildViewHolderInt(scrap); if (vh.shouldIgnore()) { continue; } if (vh.isTmpDetached()) { mRecyclerView.removeDetachedView(scrap, false); } recycler.quickRecycleScrapView(scrap); } recycler.clearScrap(); if (scrapCount > 0) { mRecyclerView.invalidate(); } } /** * Measure a child view using standard measurement policy, taking the padding * of the parent RecyclerView and any added item decorations into account. * * <p>If the RecyclerView can be scrolled in either dimension the caller may * pass 0 as the widthUsed or heightUsed parameters as they will be irrelevant.</p> * * @param child Child view to measure * @param widthUsed Width in pixels currently consumed by other views, if relevant * @param heightUsed Height in pixels currently consumed by other views, if relevant */ public void measureChild(View child, int widthUsed, int heightUsed) { final LayoutParams lp = (LayoutParams) child.getLayoutParams(); final Rect insets = mRecyclerView.getItemDecorInsetsForChild(child); widthUsed += insets.left + insets.right; heightUsed += insets.top + insets.bottom; final int widthSpec = getChildMeasureSpec(getWidth(), getPaddingLeft() + getPaddingRight() + widthUsed, lp.width, canScrollHorizontally()); final int heightSpec = getChildMeasureSpec(getHeight(), getPaddingTop() + getPaddingBottom() + heightUsed, lp.height, canScrollVertically()); child.measure(widthSpec, heightSpec); } /** * Measure a child view using standard measurement policy, taking the padding * of the parent RecyclerView, any added item decorations and the child margins * into account. * * <p>If the RecyclerView can be scrolled in either dimension the caller may * pass 0 as the widthUsed or heightUsed parameters as they will be irrelevant.</p> * * @param child Child view to measure * @param widthUsed Width in pixels currently consumed by other views, if relevant * @param heightUsed Height in pixels currently consumed by other views, if relevant */ public void measureChildWithMargins(View child, int widthUsed, int heightUsed) { final LayoutParams lp = (LayoutParams) child.getLayoutParams(); final Rect insets = mRecyclerView.getItemDecorInsetsForChild(child); widthUsed += insets.left + insets.right; heightUsed += insets.top + insets.bottom; final int widthSpec = getChildMeasureSpec(getWidth(), getPaddingLeft() + getPaddingRight() + lp.leftMargin + lp.rightMargin + widthUsed, lp.width, canScrollHorizontally()); final int heightSpec = getChildMeasureSpec(getHeight(), getPaddingTop() + getPaddingBottom() + lp.topMargin + lp.bottomMargin + heightUsed, lp.height, canScrollVertically()); child.measure(widthSpec, heightSpec); } /** * Calculate a MeasureSpec value for measuring a child view in one dimension. * * @param parentSize Size of the parent view where the child will be placed * @param padding Total space currently consumed by other elements of parent * @param childDimension Desired size of the child view, or MATCH_PARENT/WRAP_CONTENT. * Generally obtained from the child view's LayoutParams * @param canScroll true if the parent RecyclerView can scroll in this dimension * * @return a MeasureSpec value for the child view */ public static int getChildMeasureSpec(int parentSize, int padding, int childDimension, boolean canScroll) { int size = Math.max(0, parentSize - padding); int resultSize = 0; int resultMode = 0; if (canScroll) { if (childDimension >= 0) { resultSize = childDimension; resultMode = MeasureSpec.EXACTLY; } else { // MATCH_PARENT can't be applied since we can scroll in this dimension, wrap // instead using UNSPECIFIED. resultSize = 0; resultMode = MeasureSpec.UNSPECIFIED; } } else { if (childDimension >= 0) { resultSize = childDimension; resultMode = MeasureSpec.EXACTLY; } else if (childDimension == LayoutParams.FILL_PARENT) { resultSize = size; resultMode = MeasureSpec.EXACTLY; } else if (childDimension == LayoutParams.WRAP_CONTENT) { resultSize = size; resultMode = MeasureSpec.AT_MOST; } } return MeasureSpec.makeMeasureSpec(resultSize, resultMode); } /** * Returns the measured width of the given child, plus the additional size of * any insets applied by {@link ItemDecoration ItemDecorations}. * * @param child Child view to query * @return child's measured width plus <code>ItemDecoration</code> insets * * @see View#getMeasuredWidth() */ public int getDecoratedMeasuredWidth(View child) { final Rect insets = ((LayoutParams) child.getLayoutParams()).mDecorInsets; return child.getMeasuredWidth() + insets.left + insets.right; } /** * Returns the measured height of the given child, plus the additional size of * any insets applied by {@link ItemDecoration ItemDecorations}. * * @param child Child view to query * @return child's measured height plus <code>ItemDecoration</code> insets * * @see View#getMeasuredHeight() */ public int getDecoratedMeasuredHeight(View child) { final Rect insets = ((LayoutParams) child.getLayoutParams()).mDecorInsets; return child.getMeasuredHeight() + insets.top + insets.bottom; } /** * Lay out the given child view within the RecyclerView using coordinates that * include any current {@link ItemDecoration ItemDecorations}. * * <p>LayoutManagers should prefer working in sizes and coordinates that include * item decoration insets whenever possible. This allows the LayoutManager to effectively * ignore decoration insets within measurement and layout code. See the following * methods:</p> * <ul> * <li>{@link #measureChild(View, int, int)}</li> * <li>{@link #measureChildWithMargins(View, int, int)}</li> * <li>{@link #getDecoratedLeft(View)}</li> * <li>{@link #getDecoratedTop(View)}</li> * <li>{@link #getDecoratedRight(View)}</li> * <li>{@link #getDecoratedBottom(View)}</li> * <li>{@link #getDecoratedMeasuredWidth(View)}</li> * <li>{@link #getDecoratedMeasuredHeight(View)}</li> * </ul> * * @param child Child to lay out * @param left Left edge, with item decoration insets included * @param top Top edge, with item decoration insets included * @param right Right edge, with item decoration insets included * @param bottom Bottom edge, with item decoration insets included * * @see View#layout(int, int, int, int) */ public void layoutDecorated(View child, int left, int top, int right, int bottom) { final Rect insets = ((LayoutParams) child.getLayoutParams()).mDecorInsets; child.layout(left + insets.left, top + insets.top, right - insets.right, bottom - insets.bottom); } /** * Returns the left edge of the given child view within its parent, offset by any applied * {@link ItemDecoration ItemDecorations}. * * @param child Child to query * @return Child left edge with offsets applied * @see #getLeftDecorationWidth(View) */ public int getDecoratedLeft(View child) { return child.getLeft() - getLeftDecorationWidth(child); } /** * Returns the top edge of the given child view within its parent, offset by any applied * {@link ItemDecoration ItemDecorations}. * * @param child Child to query * @return Child top edge with offsets applied * @see #getTopDecorationHeight(View) */ public int getDecoratedTop(View child) { return child.getTop() - getTopDecorationHeight(child); } /** * Returns the right edge of the given child view within its parent, offset by any applied * {@link ItemDecoration ItemDecorations}. * * @param child Child to query * @return Child right edge with offsets applied * @see #getRightDecorationWidth(View) */ public int getDecoratedRight(View child) { return child.getRight() + getRightDecorationWidth(child); } /** * Returns the bottom edge of the given child view within its parent, offset by any applied * {@link ItemDecoration ItemDecorations}. * * @param child Child to query * @return Child bottom edge with offsets applied * @see #getBottomDecorationHeight(View) */ public int getDecoratedBottom(View child) { return child.getBottom() + getBottomDecorationHeight(child); } /** * Calculates the item decor insets applied to the given child and updates the provided * Rect instance with the inset values. * <ul> * <li>The Rect's left is set to the total width of left decorations.</li> * <li>The Rect's top is set to the total height of top decorations.</li> * <li>The Rect's right is set to the total width of right decorations.</li> * <li>The Rect's bottom is set to total height of bottom decorations.</li> * </ul> * <p> * Note that item decorations are automatically calculated when one of the LayoutManager's * measure child methods is called. If you need to measure the child with custom specs via * {@link View#measure(int, int)}, you can use this method to get decorations. * * @param child The child view whose decorations should be calculated * @param outRect The Rect to hold result values */ public void calculateItemDecorationsForChild(View child, Rect outRect) { if (mRecyclerView == null) { outRect.set(0, 0, 0, 0); return; } Rect insets = mRecyclerView.getItemDecorInsetsForChild(child); outRect.set(insets); } /** * Returns the total height of item decorations applied to child's top. * <p> * Note that this value is not updated until the View is measured or * {@link #calculateItemDecorationsForChild(View, Rect)} is called. * * @param child Child to query * @return The total height of item decorations applied to the child's top. * @see #getDecoratedTop(View) * @see #calculateItemDecorationsForChild(View, Rect) */ public int getTopDecorationHeight(View child) { return ((LayoutParams) child.getLayoutParams()).mDecorInsets.top; } /** * Returns the total height of item decorations applied to child's bottom. * <p> * Note that this value is not updated until the View is measured or * {@link #calculateItemDecorationsForChild(View, Rect)} is called. * * @param child Child to query * @return The total height of item decorations applied to the child's bottom. * @see #getDecoratedBottom(View) * @see #calculateItemDecorationsForChild(View, Rect) */ public int getBottomDecorationHeight(View child) { return ((LayoutParams) child.getLayoutParams()).mDecorInsets.bottom; } /** * Returns the total width of item decorations applied to child's left. * <p> * Note that this value is not updated until the View is measured or * {@link #calculateItemDecorationsForChild(View, Rect)} is called. * * @param child Child to query * @return The total width of item decorations applied to the child's left. * @see #getDecoratedLeft(View) * @see #calculateItemDecorationsForChild(View, Rect) */ public int getLeftDecorationWidth(View child) { return ((LayoutParams) child.getLayoutParams()).mDecorInsets.left; } /** * Returns the total width of item decorations applied to child's right. * <p> * Note that this value is not updated until the View is measured or * {@link #calculateItemDecorationsForChild(View, Rect)} is called. * * @param child Child to query * @return The total width of item decorations applied to the child's right. * @see #getDecoratedRight(View) * @see #calculateItemDecorationsForChild(View, Rect) */ public int getRightDecorationWidth(View child) { return ((LayoutParams) child.getLayoutParams()).mDecorInsets.right; } /** * Called when searching for a focusable view in the given direction has failed * for the current content of the RecyclerView. * * <p>This is the LayoutManager's opportunity to populate views in the given direction * to fulfill the request if it can. The LayoutManager should attach and return * the view to be focused. The default implementation returns null.</p> * * @param focused The currently focused view * @param direction One of {@link View#FOCUS_UP}, {@link View#FOCUS_DOWN}, * {@link View#FOCUS_LEFT}, {@link View#FOCUS_RIGHT}, * {@link View#FOCUS_BACKWARD}, {@link View#FOCUS_FORWARD} * or 0 for not applicable * @param recycler The recycler to use for obtaining views for currently offscreen items * @param state Transient state of RecyclerView * @return The chosen view to be focused */ @Nullable public View onFocusSearchFailed(View focused, int direction, Recycler recycler, State state) { return null; } /** * This method gives a LayoutManager an opportunity to intercept the initial focus search * before the default behavior of {@link FocusFinder} is used. If this method returns * null FocusFinder will attempt to find a focusable child view. If it fails * then {@link #onFocusSearchFailed(View, int, RecyclerView.Recycler, RecyclerView.State)} * will be called to give the LayoutManager an opportunity to add new views for items * that did not have attached views representing them. The LayoutManager should not add * or remove views from this method. * * @param focused The currently focused view * @param direction One of {@link View#FOCUS_UP}, {@link View#FOCUS_DOWN}, * {@link View#FOCUS_LEFT}, {@link View#FOCUS_RIGHT}, * {@link View#FOCUS_BACKWARD}, {@link View#FOCUS_FORWARD} * @return A descendant view to focus or null to fall back to default behavior. * The default implementation returns null. */ public View onInterceptFocusSearch(View focused, int direction) { return null; } /** * Called when a child of the RecyclerView wants a particular rectangle to be positioned * onto the screen. See {@link ViewParent#requestChildRectangleOnScreen(android.view.View, * android.graphics.Rect, boolean)} for more details. * * <p>The base implementation will attempt to perform a standard programmatic scroll * to bring the given rect into view, within the padded area of the RecyclerView.</p> * * @param child The direct child making the request. * @param rect The rectangle in the child's coordinates the child * wishes to be on the screen. * @param immediate True to forbid animated or delayed scrolling, * false otherwise * @return Whether the group scrolled to handle the operation */ public boolean requestChildRectangleOnScreen(RecyclerView parent, View child, Rect rect, boolean immediate) { final int parentLeft = getPaddingLeft(); final int parentTop = getPaddingTop(); final int parentRight = getWidth() - getPaddingRight(); final int parentBottom = getHeight() - getPaddingBottom(); final int childLeft = child.getLeft() + rect.left; final int childTop = child.getTop() + rect.top; final int childRight = childLeft + rect.width(); final int childBottom = childTop + rect.height(); final int offScreenLeft = Math.min(0, childLeft - parentLeft); final int offScreenTop = Math.min(0, childTop - parentTop); final int offScreenRight = Math.max(0, childRight - parentRight); final int offScreenBottom = Math.max(0, childBottom - parentBottom); // Favor the "start" layout direction over the end when bringing one side or the other // of a large rect into view. If we decide to bring in end because start is already // visible, limit the scroll such that start won't go out of bounds. final int dx; if (getLayoutDirection() == ViewCompat.LAYOUT_DIRECTION_RTL) { dx = offScreenRight != 0 ? offScreenRight : Math.max(offScreenLeft, childRight - parentRight); } else { dx = offScreenLeft != 0 ? offScreenLeft : Math.min(childLeft - parentLeft, offScreenRight); } // Favor bringing the top into view over the bottom. If top is already visible and // we should scroll to make bottom visible, make sure top does not go out of bounds. final int dy = offScreenTop != 0 ? offScreenTop : Math.min(childTop - parentTop, offScreenBottom); if (dx != 0 || dy != 0) { if (immediate) { parent.scrollBy(dx, dy); } else { parent.smoothScrollBy(dx, dy); } return true; } return false; } /** * @deprecated Use {@link #onRequestChildFocus(RecyclerView, State, View, View)} */ @Deprecated public boolean onRequestChildFocus(RecyclerView parent, View child, View focused) { // eat the request if we are in the middle of a scroll or layout return isSmoothScrolling() || parent.isRunningLayoutOrScroll(); } /** * Called when a descendant view of the RecyclerView requests focus. * * <p>A LayoutManager wishing to keep focused views aligned in a specific * portion of the view may implement that behavior in an override of this method.</p> * * <p>If the LayoutManager executes different behavior that should override the default * behavior of scrolling the focused child on screen instead of running alongside it, * this method should return true.</p> * * @param parent The RecyclerView hosting this LayoutManager * @param state Current state of RecyclerView * @param child Direct child of the RecyclerView containing the newly focused view * @param focused The newly focused view. This may be the same view as child or it may be * null * @return true if the default scroll behavior should be suppressed */ public boolean onRequestChildFocus(RecyclerView parent, State state, View child, View focused) { return onRequestChildFocus(parent, child, focused); } /** * Called if the RecyclerView this LayoutManager is bound to has a different adapter set. * The LayoutManager may use this opportunity to clear caches and configure state such * that it can relayout appropriately with the new data and potentially new view types. * * <p>The default implementation removes all currently attached views.</p> * * @param oldAdapter The previous adapter instance. Will be null if there was previously no * adapter. * @param newAdapter The new adapter instance. Might be null if * {@link #setAdapter(RecyclerView.Adapter)} is called with {@code null}. */ public void onAdapterChanged(Adapter oldAdapter, Adapter newAdapter) { } /** * Called to populate focusable views within the RecyclerView. * * <p>The LayoutManager implementation should return <code>true</code> if the default * behavior of {@link ViewGroup#addFocusables(java.util.ArrayList, int)} should be * suppressed.</p> * * <p>The default implementation returns <code>false</code> to trigger RecyclerView * to fall back to the default ViewGroup behavior.</p> * * @param recyclerView The RecyclerView hosting this LayoutManager * @param views List of output views. This method should add valid focusable views * to this list. * @param direction One of {@link View#FOCUS_UP}, {@link View#FOCUS_DOWN}, * {@link View#FOCUS_LEFT}, {@link View#FOCUS_RIGHT}, * {@link View#FOCUS_BACKWARD}, {@link View#FOCUS_FORWARD} * @param focusableMode The type of focusables to be added. * * @return true to suppress the default behavior, false to add default focusables after * this method returns. * * @see #FOCUSABLES_ALL * @see #FOCUSABLES_TOUCH_MODE */ public boolean onAddFocusables(RecyclerView recyclerView, ArrayList<View> views, int direction, int focusableMode) { return false; } /** * Called when {@link Adapter#notifyDataSetChanged()} is triggered instead of giving * detailed information on what has actually changed. * * @param recyclerView */ public void onItemsChanged(RecyclerView recyclerView) { } /** * Called when items have been added to the adapter. The LayoutManager may choose to * requestLayout if the inserted items would require refreshing the currently visible set * of child views. (e.g. currently empty space would be filled by appended items, etc.) * * @param recyclerView * @param positionStart * @param itemCount */ public void onItemsAdded(RecyclerView recyclerView, int positionStart, int itemCount) { } /** * Called when items have been removed from the adapter. * * @param recyclerView * @param positionStart * @param itemCount */ public void onItemsRemoved(RecyclerView recyclerView, int positionStart, int itemCount) { } /** * Called when items have been changed in the adapter. * * @param recyclerView * @param positionStart * @param itemCount */ public void onItemsUpdated(RecyclerView recyclerView, int positionStart, int itemCount) { } /** * Called when an item is moved withing the adapter. * <p> * Note that, an item may also change position in response to another ADD/REMOVE/MOVE * operation. This callback is only called if and only if {@link Adapter#notifyItemMoved} * is called. * * @param recyclerView * @param from * @param to * @param itemCount */ public void onItemsMoved(RecyclerView recyclerView, int from, int to, int itemCount) { } /** * <p>Override this method if you want to support scroll bars.</p> * * <p>Read {@link RecyclerView#computeHorizontalScrollExtent()} for details.</p> * * <p>Default implementation returns 0.</p> * * @param state Current state of RecyclerView * @return The horizontal extent of the scrollbar's thumb * @see RecyclerView#computeHorizontalScrollExtent() */ public int computeHorizontalScrollExtent(State state) { return 0; } /** * <p>Override this method if you want to support scroll bars.</p> * * <p>Read {@link RecyclerView#computeHorizontalScrollOffset()} for details.</p> * * <p>Default implementation returns 0.</p> * * @param state Current State of RecyclerView where you can find total item count * @return The horizontal offset of the scrollbar's thumb * @see RecyclerView#computeHorizontalScrollOffset() */ public int computeHorizontalScrollOffset(State state) { return 0; } /** * <p>Override this method if you want to support scroll bars.</p> * * <p>Read {@link RecyclerView#computeHorizontalScrollRange()} for details.</p> * * <p>Default implementation returns 0.</p> * * @param state Current State of RecyclerView where you can find total item count * @return The total horizontal range represented by the vertical scrollbar * @see RecyclerView#computeHorizontalScrollRange() */ public int computeHorizontalScrollRange(State state) { return 0; } /** * <p>Override this method if you want to support scroll bars.</p> * * <p>Read {@link RecyclerView#computeVerticalScrollExtent()} for details.</p> * * <p>Default implementation returns 0.</p> * * @param state Current state of RecyclerView * @return The vertical extent of the scrollbar's thumb * @see RecyclerView#computeVerticalScrollExtent() */ public int computeVerticalScrollExtent(State state) { return 0; } /** * <p>Override this method if you want to support scroll bars.</p> * * <p>Read {@link RecyclerView#computeVerticalScrollOffset()} for details.</p> * * <p>Default implementation returns 0.</p> * * @param state Current State of RecyclerView where you can find total item count * @return The vertical offset of the scrollbar's thumb * @see RecyclerView#computeVerticalScrollOffset() */ public int computeVerticalScrollOffset(State state) { return 0; } /** * <p>Override this method if you want to support scroll bars.</p> * * <p>Read {@link RecyclerView#computeVerticalScrollRange()} for details.</p> * * <p>Default implementation returns 0.</p> * * @param state Current State of RecyclerView where you can find total item count * @return The total vertical range represented by the vertical scrollbar * @see RecyclerView#computeVerticalScrollRange() */ public int computeVerticalScrollRange(State state) { return 0; } /** * Measure the attached RecyclerView. Implementations must call * {@link #setMeasuredDimension(int, int)} before returning. * * <p>The default implementation will handle EXACTLY measurements and respect * the minimum width and height properties of the host RecyclerView if measured * as UNSPECIFIED. AT_MOST measurements will be treated as EXACTLY and the RecyclerView * will consume all available space.</p> * * @param recycler Recycler * @param state Transient state of RecyclerView * @param widthSpec Width {@link android.view.View.MeasureSpec} * @param heightSpec Height {@link android.view.View.MeasureSpec} */ public void onMeasure(Recycler recycler, State state, int widthSpec, int heightSpec) { mRecyclerView.defaultOnMeasure(widthSpec, heightSpec); } /** * {@link View#setMeasuredDimension(int, int) Set the measured dimensions} of the * host RecyclerView. * * @param widthSize Measured width * @param heightSize Measured height */ public void setMeasuredDimension(int widthSize, int heightSize) { mRecyclerView.setMeasuredDimension(widthSize, heightSize); } /** * @return The host RecyclerView's {@link View#getMinimumWidth()} */ public int getMinimumWidth() { return ViewCompat.getMinimumWidth(mRecyclerView); } /** * @return The host RecyclerView's {@link View#getMinimumHeight()} */ public int getMinimumHeight() { return ViewCompat.getMinimumHeight(mRecyclerView); } /** * <p>Called when the LayoutManager should save its state. This is a good time to save your * scroll position, configuration and anything else that may be required to restore the same * layout state if the LayoutManager is recreated.</p> * <p>RecyclerView does NOT verify if the LayoutManager has changed between state save and * restore. This will let you share information between your LayoutManagers but it is also * your responsibility to make sure they use the same parcelable class.</p> * * @return Necessary information for LayoutManager to be able to restore its state */ public Parcelable onSaveInstanceState() { return null; } public void onRestoreInstanceState(Parcelable state) { } void stopSmoothScroller() { if (mSmoothScroller != null) { mSmoothScroller.stop(); } } private void onSmoothScrollerStopped(SmoothScroller smoothScroller) { if (mSmoothScroller == smoothScroller) { mSmoothScroller = null; } } /** * RecyclerView calls this method to notify LayoutManager that scroll state has changed. * * @param state The new scroll state for RecyclerView */ public void onScrollStateChanged(int state) { } /** * Removes all views and recycles them using the given recycler. * <p> * If you want to clean cached views as well, you should call {@link Recycler#clear()} too. * <p> * If a View is marked as "ignored", it is not removed nor recycled. * * @param recycler Recycler to use to recycle children * @see #removeAndRecycleView(View, Recycler) * @see #removeAndRecycleViewAt(int, Recycler) * @see #ignoreView(View) */ public void removeAndRecycleAllViews(Recycler recycler) { for (int i = getChildCount() - 1; i >= 0; i--) { final View view = getChildAt(i); if (!getChildViewHolderInt(view).shouldIgnore()) { removeAndRecycleViewAt(i, recycler); } } } // called by accessibility delegate void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfoCompat info) { onInitializeAccessibilityNodeInfo(mRecyclerView.mRecycler, mRecyclerView.mState, info); } /** * Called by the AccessibilityDelegate when the information about the current layout should * be populated. * <p> * Default implementation adds a {@link * android.support.v4.view.accessibility.AccessibilityNodeInfoCompat.CollectionInfoCompat}. * <p> * You should override * {@link #getRowCountForAccessibility(RecyclerView.Recycler, RecyclerView.State)}, * {@link #getColumnCountForAccessibility(RecyclerView.Recycler, RecyclerView.State)}, * {@link #isLayoutHierarchical(RecyclerView.Recycler, RecyclerView.State)} and * {@link #getSelectionModeForAccessibility(RecyclerView.Recycler, RecyclerView.State)} for * more accurate accessibility information. * * @param recycler The Recycler that can be used to convert view positions into adapter * positions * @param state The current state of RecyclerView * @param info The info that should be filled by the LayoutManager * @see View#onInitializeAccessibilityNodeInfo( *android.view.accessibility.AccessibilityNodeInfo) * @see #getRowCountForAccessibility(RecyclerView.Recycler, RecyclerView.State) * @see #getColumnCountForAccessibility(RecyclerView.Recycler, RecyclerView.State) * @see #isLayoutHierarchical(RecyclerView.Recycler, RecyclerView.State) * @see #getSelectionModeForAccessibility(RecyclerView.Recycler, RecyclerView.State) */ public void onInitializeAccessibilityNodeInfo(Recycler recycler, State state, AccessibilityNodeInfoCompat info) { if (ViewCompat.canScrollVertically(mRecyclerView, -1) || ViewCompat.canScrollHorizontally(mRecyclerView, -1)) { info.addAction(AccessibilityNodeInfoCompat.ACTION_SCROLL_BACKWARD); info.setScrollable(true); } if (ViewCompat.canScrollVertically(mRecyclerView, 1) || ViewCompat.canScrollHorizontally(mRecyclerView, 1)) { info.addAction(AccessibilityNodeInfoCompat.ACTION_SCROLL_FORWARD); info.setScrollable(true); } final AccessibilityNodeInfoCompat.CollectionInfoCompat collectionInfo = AccessibilityNodeInfoCompat.CollectionInfoCompat .obtain(getRowCountForAccessibility(recycler, state), getColumnCountForAccessibility(recycler, state), isLayoutHierarchical(recycler, state), getSelectionModeForAccessibility(recycler, state)); info.setCollectionInfo(collectionInfo); } // called by accessibility delegate public void onInitializeAccessibilityEvent(AccessibilityEvent event) { onInitializeAccessibilityEvent(mRecyclerView.mRecycler, mRecyclerView.mState, event); } /** * Called by the accessibility delegate to initialize an accessibility event. * <p> * Default implementation adds item count and scroll information to the event. * * @param recycler The Recycler that can be used to convert view positions into adapter * positions * @param state The current state of RecyclerView * @param event The event instance to initialize * @see View#onInitializeAccessibilityEvent(android.view.accessibility.AccessibilityEvent) */ public void onInitializeAccessibilityEvent(Recycler recycler, State state, AccessibilityEvent event) { final AccessibilityRecordCompat record = AccessibilityEventCompat.asRecord(event); if (mRecyclerView == null || record == null) { return; } record.setScrollable(ViewCompat.canScrollVertically(mRecyclerView, 1) || ViewCompat.canScrollVertically(mRecyclerView, -1) || ViewCompat.canScrollHorizontally(mRecyclerView, -1) || ViewCompat.canScrollHorizontally(mRecyclerView, 1)); if (mRecyclerView.mAdapter != null) { record.setItemCount(mRecyclerView.mAdapter.getItemCount()); } } // called by accessibility delegate void onInitializeAccessibilityNodeInfoForItem(View host, AccessibilityNodeInfoCompat info) { final ViewHolder vh = getChildViewHolderInt(host); // avoid trying to create accessibility node info for removed children if (vh != null && !vh.isRemoved()) { onInitializeAccessibilityNodeInfoForItem(mRecyclerView.mRecycler, mRecyclerView.mState, host, info); } } /** * Called by the AccessibilityDelegate when the accessibility information for a specific * item should be populated. * <p> * Default implementation adds basic positioning information about the item. * * @param recycler The Recycler that can be used to convert view positions into adapter * positions * @param state The current state of RecyclerView * @param host The child for which accessibility node info should be populated * @param info The info to fill out about the item * @see android.widget.AbsListView#onInitializeAccessibilityNodeInfoForItem(View, int, * android.view.accessibility.AccessibilityNodeInfo) */ public void onInitializeAccessibilityNodeInfoForItem(Recycler recycler, State state, View host, AccessibilityNodeInfoCompat info) { int rowIndexGuess = canScrollVertically() ? getPosition(host) : 0; int columnIndexGuess = canScrollHorizontally() ? getPosition(host) : 0; final AccessibilityNodeInfoCompat.CollectionItemInfoCompat itemInfo = AccessibilityNodeInfoCompat.CollectionItemInfoCompat .obtain(rowIndexGuess, 1, columnIndexGuess, 1, false, false); info.setCollectionItemInfo(itemInfo); } /** * A LayoutManager can call this method to force RecyclerView to run simple animations in * the next layout pass, even if there is not any trigger to do so. (e.g. adapter data * change). * <p> * Note that, calling this method will not guarantee that RecyclerView will run animations * at all. For example, if there is not any {@link ItemAnimator} set, RecyclerView will * not run any animations but will still clear this flag after the layout is complete. * */ public void requestSimpleAnimationsInNextLayout() { mRequestedSimpleAnimations = true; } /** * Returns the selection mode for accessibility. Should be * {@link AccessibilityNodeInfoCompat.CollectionInfoCompat#SELECTION_MODE_NONE}, * {@link AccessibilityNodeInfoCompat.CollectionInfoCompat#SELECTION_MODE_SINGLE} or * {@link AccessibilityNodeInfoCompat.CollectionInfoCompat#SELECTION_MODE_MULTIPLE}. * <p> * Default implementation returns * {@link AccessibilityNodeInfoCompat.CollectionInfoCompat#SELECTION_MODE_NONE}. * * @param recycler The Recycler that can be used to convert view positions into adapter * positions * @param state The current state of RecyclerView * @return Selection mode for accessibility. Default implementation returns * {@link AccessibilityNodeInfoCompat.CollectionInfoCompat#SELECTION_MODE_NONE}. */ public int getSelectionModeForAccessibility(Recycler recycler, State state) { return AccessibilityNodeInfoCompat.CollectionInfoCompat.SELECTION_MODE_NONE; } /** * Returns the number of rows for accessibility. * <p> * Default implementation returns the number of items in the adapter if LayoutManager * supports vertical scrolling or 1 if LayoutManager does not support vertical * scrolling. * * @param recycler The Recycler that can be used to convert view positions into adapter * positions * @param state The current state of RecyclerView * @return The number of rows in LayoutManager for accessibility. */ public int getRowCountForAccessibility(Recycler recycler, State state) { if (mRecyclerView == null || mRecyclerView.mAdapter == null) { return 1; } return canScrollVertically() ? mRecyclerView.mAdapter.getItemCount() : 1; } /** * Returns the number of columns for accessibility. * <p> * Default implementation returns the number of items in the adapter if LayoutManager * supports horizontal scrolling or 1 if LayoutManager does not support horizontal * scrolling. * * @param recycler The Recycler that can be used to convert view positions into adapter * positions * @param state The current state of RecyclerView * @return The number of rows in LayoutManager for accessibility. */ public int getColumnCountForAccessibility(Recycler recycler, State state) { if (mRecyclerView == null || mRecyclerView.mAdapter == null) { return 1; } return canScrollHorizontally() ? mRecyclerView.mAdapter.getItemCount() : 1; } /** * Returns whether layout is hierarchical or not to be used for accessibility. * <p> * Default implementation returns false. * * @param recycler The Recycler that can be used to convert view positions into adapter * positions * @param state The current state of RecyclerView * @return True if layout is hierarchical. */ public boolean isLayoutHierarchical(Recycler recycler, State state) { return false; } // called by accessibility delegate boolean performAccessibilityAction(int action, Bundle args) { return performAccessibilityAction(mRecyclerView.mRecycler, mRecyclerView.mState, action, args); } /** * Called by AccessibilityDelegate when an action is requested from the RecyclerView. * * @param recycler The Recycler that can be used to convert view positions into adapter * positions * @param state The current state of RecyclerView * @param action The action to perform * @param args Optional action arguments * @see View#performAccessibilityAction(int, android.os.Bundle) */ public boolean performAccessibilityAction(Recycler recycler, State state, int action, Bundle args) { if (mRecyclerView == null) { return false; } int vScroll = 0, hScroll = 0; switch (action) { case AccessibilityNodeInfoCompat.ACTION_SCROLL_BACKWARD: if (ViewCompat.canScrollVertically(mRecyclerView, -1)) { vScroll = -(getHeight() - getPaddingTop() - getPaddingBottom()); } if (ViewCompat.canScrollHorizontally(mRecyclerView, -1)) { hScroll = -(getWidth() - getPaddingLeft() - getPaddingRight()); } break; case AccessibilityNodeInfoCompat.ACTION_SCROLL_FORWARD: if (ViewCompat.canScrollVertically(mRecyclerView, 1)) { vScroll = getHeight() - getPaddingTop() - getPaddingBottom(); } if (ViewCompat.canScrollHorizontally(mRecyclerView, 1)) { hScroll = getWidth() - getPaddingLeft() - getPaddingRight(); } break; } if (vScroll == 0 && hScroll == 0) { return false; } mRecyclerView.scrollBy(hScroll, vScroll); return true; } // called by accessibility delegate boolean performAccessibilityActionForItem(View view, int action, Bundle args) { return performAccessibilityActionForItem(mRecyclerView.mRecycler, mRecyclerView.mState, view, action, args); } /** * Called by AccessibilityDelegate when an accessibility action is requested on one of the * children of LayoutManager. * <p> * Default implementation does not do anything. * * @param recycler The Recycler that can be used to convert view positions into adapter * positions * @param state The current state of RecyclerView * @param view The child view on which the action is performed * @param action The action to perform * @param args Optional action arguments * @return true if action is handled * @see View#performAccessibilityAction(int, android.os.Bundle) */ public boolean performAccessibilityActionForItem(Recycler recycler, State state, View view, int action, Bundle args) { return false; } } /** * An ItemDecoration allows the application to add a special drawing and layout offset * to specific item views from the adapter's data set. This can be useful for drawing dividers * between items, highlights, visual grouping boundaries and more. * * <p>All ItemDecorations are drawn in the order they were added, before the item * views (in {@link ItemDecoration#onDraw(Canvas, RecyclerView, RecyclerView.State) onDraw()} * and after the items (in {@link ItemDecoration#onDrawOver(Canvas, RecyclerView, * RecyclerView.State)}.</p> */ public static abstract class ItemDecoration { /** * Draw any appropriate decorations into the Canvas supplied to the RecyclerView. * Any content drawn by this method will be drawn before the item views are drawn, * and will thus appear underneath the views. * * @param c Canvas to draw into * @param parent RecyclerView this ItemDecoration is drawing into * @param state The current state of RecyclerView */ public void onDraw(Canvas c, RecyclerView parent, State state) { onDraw(c, parent); } /** * @deprecated * Override {@link #onDraw(Canvas, RecyclerView, RecyclerView.State)} */ @Deprecated public void onDraw(Canvas c, RecyclerView parent) { } /** * Draw any appropriate decorations into the Canvas supplied to the RecyclerView. * Any content drawn by this method will be drawn after the item views are drawn * and will thus appear over the views. * * @param c Canvas to draw into * @param parent RecyclerView this ItemDecoration is drawing into * @param state The current state of RecyclerView. */ public void onDrawOver(Canvas c, RecyclerView parent, State state) { onDrawOver(c, parent); } /** * @deprecated * Override {@link #onDrawOver(Canvas, RecyclerView, RecyclerView.State)} */ @Deprecated public void onDrawOver(Canvas c, RecyclerView parent) { } /** * @deprecated * Use {@link #getItemOffsets(Rect, View, RecyclerView, State)} */ @Deprecated public void getItemOffsets(Rect outRect, int itemPosition, RecyclerView parent) { outRect.set(0, 0, 0, 0); } /** * Retrieve any offsets for the given item. Each field of <code>outRect</code> specifies * the number of pixels that the item view should be inset by, similar to padding or margin. * The default implementation sets the bounds of outRect to 0 and returns. * * <p> * If this ItemDecoration does not affect the positioning of item views, it should set * all four fields of <code>outRect</code> (left, top, right, bottom) to zero * before returning. * * <p> * If you need to access Adapter for additional data, you can call * {@link RecyclerView#getChildAdapterPosition(View)} to get the adapter position of the * View. * * @param outRect Rect to receive the output. * @param view The child view to decorate * @param parent RecyclerView this ItemDecoration is decorating * @param state The current state of RecyclerView. */ public void getItemOffsets(Rect outRect, View view, RecyclerView parent, State state) { getItemOffsets(outRect, ((LayoutParams) view.getLayoutParams()).getViewLayoutPosition(), parent); } } /** * An OnItemTouchListener allows the application to intercept touch events in progress at the * view hierarchy level of the RecyclerView before those touch events are considered for * RecyclerView's own scrolling behavior. * * <p>This can be useful for applications that wish to implement various forms of gestural * manipulation of item views within the RecyclerView. OnItemTouchListeners may intercept * a touch interaction already in progress even if the RecyclerView is already handling that * gesture stream itself for the purposes of scrolling.</p> */ public interface OnItemTouchListener { /** * Silently observe and/or take over touch events sent to the RecyclerView * before they are handled by either the RecyclerView itself or its child views. * * <p>The onInterceptTouchEvent methods of each attached OnItemTouchListener will be run * in the order in which each listener was added, before any other touch processing * by the RecyclerView itself or child views occurs.</p> * * @param e MotionEvent describing the touch event. All coordinates are in * the RecyclerView's coordinate system. * @return true if this OnItemTouchListener wishes to begin intercepting touch events, false * to continue with the current behavior and continue observing future events in * the gesture. */ public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e); /** * Process a touch event as part of a gesture that was claimed by returning true from * a previous call to {@link #onInterceptTouchEvent}. * * @param e MotionEvent describing the touch event. All coordinates are in * the RecyclerView's coordinate system. */ public void onTouchEvent(RecyclerView rv, MotionEvent e); } /** * An OnScrollListener can be set on a RecyclerView to receive messages * when a scrolling event has occurred on that RecyclerView. * * @see RecyclerView#setOnScrollListener(OnScrollListener) and * RecyclerView#addOnScrollListener(OnScrollListener) * * If you are planning to have several listeners at the same time, use * RecyclerView#addOnScrollListener. If there will be only one listener at the time and you * want your components to be able to easily replace the listener use * RecyclerView#setOnScrollListener. */ abstract static public class OnScrollListener { /** * Callback method to be invoked when RecyclerView's scroll state changes. * * @param recyclerView The RecyclerView whose scroll state has changed. * @param newState The updated scroll state. One of {@link #SCROLL_STATE_IDLE}, * {@link #SCROLL_STATE_DRAGGING} or {@link #SCROLL_STATE_SETTLING}. */ public void onScrollStateChanged(RecyclerView recyclerView, int newState) { } /** * Callback method to be invoked when the RecyclerView has been scrolled. This will be * called after the scroll has completed. * <p> * This callback will also be called if visible item range changes after a layout * calculation. In that case, dx and dy will be 0. * * @param recyclerView The RecyclerView which scrolled. * @param dx The amount of horizontal scroll. * @param dy The amount of vertical scroll. */ public void onScrolled(RecyclerView recyclerView, int dx, int dy) { } } /** * A RecyclerListener can be set on a RecyclerView to receive messages whenever * a view is recycled. * * @see RecyclerView#setRecyclerListener(RecyclerListener) */ public interface RecyclerListener { /** * This method is called whenever the view in the ViewHolder is recycled. * * RecyclerView calls this method right before clearing ViewHolder's internal data and * sending it to RecycledViewPool. This way, if ViewHolder was holding valid information * before being recycled, you can call {@link ViewHolder#getAdapterPosition()} to get * its adapter position. * * @param holder The ViewHolder containing the view that was recycled */ public void onViewRecycled(ViewHolder holder); } /** * A ViewHolder describes an item view and metadata about its place within the RecyclerView. * * <p>{@link Adapter} implementations should subclass ViewHolder and add fields for caching * potentially expensive {@link View#findViewById(int)} results.</p> * * <p>While {@link LayoutParams} belong to the {@link LayoutManager}, * {@link ViewHolder ViewHolders} belong to the adapter. Adapters should feel free to use * their own custom ViewHolder implementations to store data that makes binding view contents * easier. Implementations should assume that individual item views will hold strong references * to <code>ViewHolder</code> objects and that <code>RecyclerView</code> instances may hold * strong references to extra off-screen item views for caching purposes</p> */ public static abstract class ViewHolder { public final View itemView; int mPosition = NO_POSITION; int mOldPosition = NO_POSITION; long mItemId = NO_ID; int mItemViewType = INVALID_TYPE; int mPreLayoutPosition = NO_POSITION; // The item that this holder is shadowing during an item change event/animation ViewHolder mShadowedHolder = null; // The item that is shadowing this holder during an item change event/animation ViewHolder mShadowingHolder = null; /** * This ViewHolder has been bound to a position; mPosition, mItemId and mItemViewType * are all valid. */ static final int FLAG_BOUND = 1 << 0; /** * The data this ViewHolder's view reflects is stale and needs to be rebound * by the adapter. mPosition and mItemId are consistent. */ static final int FLAG_UPDATE = 1 << 1; /** * This ViewHolder's data is invalid. The identity implied by mPosition and mItemId * are not to be trusted and may no longer match the item view type. * This ViewHolder must be fully rebound to different data. */ static final int FLAG_INVALID = 1 << 2; /** * This ViewHolder points at data that represents an item previously removed from the * data set. Its view may still be used for things like outgoing animations. */ static final int FLAG_REMOVED = 1 << 3; /** * This ViewHolder should not be recycled. This flag is set via setIsRecyclable() * and is intended to keep views around during animations. */ static final int FLAG_NOT_RECYCLABLE = 1 << 4; /** * This ViewHolder is returned from scrap which means we are expecting an addView call * for this itemView. When returned from scrap, ViewHolder stays in the scrap list until * the end of the layout pass and then recycled by RecyclerView if it is not added back to * the RecyclerView. */ static final int FLAG_RETURNED_FROM_SCRAP = 1 << 5; /** * This ViewHolder's contents have changed. This flag is used as an indication that * change animations may be used, if supported by the ItemAnimator. */ static final int FLAG_CHANGED = 1 << 6; /** * This ViewHolder is fully managed by the LayoutManager. We do not scrap, recycle or remove * it unless LayoutManager is replaced. * It is still fully visible to the LayoutManager. */ static final int FLAG_IGNORE = 1 << 7; /** * When the View is detached form the parent, we set this flag so that we can take correct * action when we need to remove it or add it back. */ static final int FLAG_TMP_DETACHED = 1 << 8; /** * Set when we can no longer determine the adapter position of this ViewHolder until it is * rebound to a new position. It is different than FLAG_INVALID because FLAG_INVALID is * set even when the type does not match. Also, FLAG_ADAPTER_POSITION_UNKNOWN is set as soon * as adapter notification arrives vs FLAG_INVALID is set lazily before layout is * re-calculated. */ static final int FLAG_ADAPTER_POSITION_UNKNOWN = 1 << 9; private int mFlags; private int mIsRecyclableCount = 0; // If non-null, view is currently considered scrap and may be reused for other data by the // scrap container. private Recycler mScrapContainer = null; /** * Is set when VH is bound from the adapter and cleaned right before it is sent to * {@link RecycledViewPool}. */ RecyclerView mOwnerRecyclerView; public ViewHolder(View itemView) { if (itemView == null) { throw new IllegalArgumentException("itemView may not be null"); } this.itemView = itemView; } void flagRemovedAndOffsetPosition(int mNewPosition, int offset, boolean applyToPreLayout) { addFlags(ViewHolder.FLAG_REMOVED); offsetPosition(offset, applyToPreLayout); mPosition = mNewPosition; } void offsetPosition(int offset, boolean applyToPreLayout) { if (mOldPosition == NO_POSITION) { mOldPosition = mPosition; } if (mPreLayoutPosition == NO_POSITION) { mPreLayoutPosition = mPosition; } if (applyToPreLayout) { mPreLayoutPosition += offset; } mPosition += offset; if (itemView.getLayoutParams() != null) { ((LayoutParams) itemView.getLayoutParams()).mInsetsDirty = true; } } void clearOldPosition() { mOldPosition = NO_POSITION; mPreLayoutPosition = NO_POSITION; } void saveOldPosition() { if (mOldPosition == NO_POSITION) { mOldPosition = mPosition; } } boolean shouldIgnore() { return (mFlags & FLAG_IGNORE) != 0; } /** * @deprecated This method is deprecated because its meaning is ambiguous due to the async * handling of adapter updates. Please use {@link #getLayoutPosition()} or * {@link #getAdapterPosition()} depending on your use case. * * @see #getLayoutPosition() * @see #getAdapterPosition() */ @Deprecated public final int getPosition() { return mPreLayoutPosition == NO_POSITION ? mPosition : mPreLayoutPosition; } /** * Returns the position of the ViewHolder in terms of the latest layout pass. * <p> * This position is mostly used by RecyclerView components to be consistent while * RecyclerView lazily processes adapter updates. * <p> * For performance and animation reasons, RecyclerView batches all adapter updates until the * next layout pass. This may cause mismatches between the Adapter position of the item and * the position it had in the latest layout calculations. * <p> * LayoutManagers should always call this method while doing calculations based on item * positions. All methods in {@link RecyclerView.LayoutManager}, {@link RecyclerView.State}, * {@link RecyclerView.Recycler} that receive a position expect it to be the layout position * of the item. * <p> * If LayoutManager needs to call an external method that requires the adapter position of * the item, it can use {@link #getAdapterPosition()} or * {@link RecyclerView.Recycler#convertPreLayoutPositionToPostLayout(int)}. * * @return Returns the adapter position of the ViewHolder in the latest layout pass. * @see #getAdapterPosition() */ public final int getLayoutPosition() { return mPreLayoutPosition == NO_POSITION ? mPosition : mPreLayoutPosition; } /** * Returns the Adapter position of the item represented by this ViewHolder. * <p> * Note that this might be different than the {@link #getLayoutPosition()} if there are * pending adapter updates but a new layout pass has not happened yet. * <p> * RecyclerView does not handle any adapter updates until the next layout traversal. This * may create temporary inconsistencies between what user sees on the screen and what * adapter contents have. This inconsistency is not important since it will be less than * 16ms but it might be a problem if you want to use ViewHolder position to access the * adapter. Sometimes, you may need to get the exact adapter position to do * some actions in response to user events. In that case, you should use this method which * will calculate the Adapter position of the ViewHolder. * <p> * Note that if you've called {@link RecyclerView.Adapter#notifyDataSetChanged()}, until the * next layout pass, the return value of this method will be {@link #NO_POSITION}. * * @return The adapter position of the item if it still exists in the adapter. * {@link RecyclerView#NO_POSITION} if item has been removed from the adapter, * {@link RecyclerView.Adapter#notifyDataSetChanged()} has been called after the last * layout pass or the ViewHolder has already been recycled. */ public final int getAdapterPosition() { if (mOwnerRecyclerView == null) { return NO_POSITION; } return mOwnerRecyclerView.getAdapterPositionFor(this); } /** * When LayoutManager supports animations, RecyclerView tracks 3 positions for ViewHolders * to perform animations. * <p> * If a ViewHolder was laid out in the previous onLayout call, old position will keep its * adapter index in the previous layout. * * @return The previous adapter index of the Item represented by this ViewHolder or * {@link #NO_POSITION} if old position does not exists or cleared (pre-layout is * complete). */ public final int getOldPosition() { return mOldPosition; } /** * Returns The itemId represented by this ViewHolder. * * @return The the item's id if adapter has stable ids, {@link RecyclerView#NO_ID} * otherwise */ public final long getItemId() { return mItemId; } /** * @return The view type of this ViewHolder. */ public final int getItemViewType() { return mItemViewType; } boolean isScrap() { return mScrapContainer != null; } void unScrap() { mScrapContainer.unscrapView(this); } boolean wasReturnedFromScrap() { return (mFlags & FLAG_RETURNED_FROM_SCRAP) != 0; } void clearReturnedFromScrapFlag() { mFlags = mFlags & ~FLAG_RETURNED_FROM_SCRAP; } void clearTmpDetachFlag() { mFlags = mFlags & ~FLAG_TMP_DETACHED; } void stopIgnoring() { mFlags = mFlags & ~FLAG_IGNORE; } void setScrapContainer(Recycler recycler) { mScrapContainer = recycler; } boolean isInvalid() { return (mFlags & FLAG_INVALID) != 0; } boolean needsUpdate() { return (mFlags & FLAG_UPDATE) != 0; } boolean isChanged() { return (mFlags & FLAG_CHANGED) != 0; } boolean isBound() { return (mFlags & FLAG_BOUND) != 0; } boolean isRemoved() { return (mFlags & FLAG_REMOVED) != 0; } boolean hasAnyOfTheFlags(int flags) { return (mFlags & flags) != 0; } boolean isTmpDetached() { return (mFlags & FLAG_TMP_DETACHED) != 0; } boolean isAdapterPositionUnknown() { return (mFlags & FLAG_ADAPTER_POSITION_UNKNOWN) != 0 || isInvalid(); } void setFlags(int flags, int mask) { mFlags = (mFlags & ~mask) | (flags & mask); } void addFlags(int flags) { mFlags |= flags; } void resetInternal() { mFlags = 0; mPosition = NO_POSITION; mOldPosition = NO_POSITION; mItemId = NO_ID; mPreLayoutPosition = NO_POSITION; mIsRecyclableCount = 0; mShadowedHolder = null; mShadowingHolder = null; } @Override public String toString() { final StringBuilder sb = new StringBuilder( "ViewHolder{" + Integer.toHexString(hashCode()) + " position=" + mPosition + " id=" + mItemId + ", oldPos=" + mOldPosition + ", pLpos:" + mPreLayoutPosition); if (isScrap()) sb.append(" scrap"); if (isInvalid()) sb.append(" invalid"); if (!isBound()) sb.append(" unbound"); if (needsUpdate()) sb.append(" update"); if (isRemoved()) sb.append(" removed"); if (shouldIgnore()) sb.append(" ignored"); if (isChanged()) sb.append(" changed"); if (isTmpDetached()) sb.append(" tmpDetached"); if (!isRecyclable()) sb.append(" not recyclable(" + mIsRecyclableCount + ")"); if (isAdapterPositionUnknown()) sb.append("undefined adapter position"); if (itemView.getParent() == null) sb.append(" no parent"); sb.append("}"); return sb.toString(); } /** * Informs the recycler whether this item can be recycled. Views which are not * recyclable will not be reused for other items until setIsRecyclable() is * later set to true. Calls to setIsRecyclable() should always be paired (one * call to setIsRecyclabe(false) should always be matched with a later call to * setIsRecyclable(true)). Pairs of calls may be nested, as the state is internally * reference-counted. * * @param recyclable Whether this item is available to be recycled. Default value * is true. */ public final void setIsRecyclable(boolean recyclable) { mIsRecyclableCount = recyclable ? mIsRecyclableCount - 1 : mIsRecyclableCount + 1; if (mIsRecyclableCount < 0) { mIsRecyclableCount = 0; if (DEBUG) { throw new RuntimeException("isRecyclable decremented below 0: " + "unmatched pair of setIsRecyable() calls for " + this); } Log.e(VIEW_LOG_TAG, "isRecyclable decremented below 0: " + "unmatched pair of setIsRecyable() calls for " + this); } else if (!recyclable && mIsRecyclableCount == 1) { mFlags |= FLAG_NOT_RECYCLABLE; } else if (recyclable && mIsRecyclableCount == 0) { mFlags &= ~FLAG_NOT_RECYCLABLE; } if (DEBUG) { Log.d(TAG, "setIsRecyclable val:" + recyclable + ":" + this); } } /** * @see {@link #setIsRecyclable(boolean)} * * @return true if this item is available to be recycled, false otherwise. */ public final boolean isRecyclable() { return (mFlags & FLAG_NOT_RECYCLABLE) == 0 && !ViewCompat.hasTransientState(itemView); } /** * Returns whether we have animations referring to this view holder or not. * This is similar to isRecyclable flag but does not check transient state. */ private boolean shouldBeKeptAsChild() { return (mFlags & FLAG_NOT_RECYCLABLE) != 0; } /** * @return True if ViewHolder is not refenrenced by RecyclerView animations but has * transient state which will prevent it from being recycled. */ private boolean doesTransientStatePreventRecycling() { return (mFlags & FLAG_NOT_RECYCLABLE) == 0 && ViewCompat.hasTransientState(itemView); } } private int getAdapterPositionFor(ViewHolder viewHolder) { if (viewHolder.hasAnyOfTheFlags( ViewHolder.FLAG_INVALID | ViewHolder.FLAG_REMOVED | ViewHolder.FLAG_ADAPTER_POSITION_UNKNOWN) || !viewHolder.isBound()) { return RecyclerView.NO_POSITION; } return mAdapterHelper.applyPendingUpdatesToPosition(viewHolder.mPosition); } /** * {@link android.view.ViewGroup.MarginLayoutParams LayoutParams} subclass for children of * {@link RecyclerView}. Custom {@link LayoutManager layout managers} are encouraged * to create their own subclass of this <code>LayoutParams</code> class * to store any additional required per-child view metadata about the layout. */ public static class LayoutParams extends android.view.ViewGroup.MarginLayoutParams { ViewHolder mViewHolder; final Rect mDecorInsets = new Rect(); boolean mInsetsDirty = true; // Flag is set to true if the view is bound while it is detached from RV. // In this case, we need to manually call invalidate after view is added to guarantee that // invalidation is populated through the View hierarchy boolean mPendingInvalidate = false; public LayoutParams(Context c, AttributeSet attrs) { super(c, attrs); } public LayoutParams(int width, int height) { super(width, height); } public LayoutParams(MarginLayoutParams source) { super(source); } public LayoutParams(ViewGroup.LayoutParams source) { super(source); } public LayoutParams(LayoutParams source) { super((ViewGroup.LayoutParams) source); } /** * Returns true if the view this LayoutParams is attached to needs to have its content * updated from the corresponding adapter. * * @return true if the view should have its content updated */ public boolean viewNeedsUpdate() { return mViewHolder.needsUpdate(); } /** * Returns true if the view this LayoutParams is attached to is now representing * potentially invalid data. A LayoutManager should scrap/recycle it. * * @return true if the view is invalid */ public boolean isViewInvalid() { return mViewHolder.isInvalid(); } /** * Returns true if the adapter data item corresponding to the view this LayoutParams * is attached to has been removed from the data set. A LayoutManager may choose to * treat it differently in order to animate its outgoing or disappearing state. * * @return true if the item the view corresponds to was removed from the data set */ public boolean isItemRemoved() { return mViewHolder.isRemoved(); } /** * Returns true if the adapter data item corresponding to the view this LayoutParams * is attached to has been changed in the data set. A LayoutManager may choose to * treat it differently in order to animate its changing state. * * @return true if the item the view corresponds to was changed in the data set */ public boolean isItemChanged() { return mViewHolder.isChanged(); } /** * @deprecated use {@link #getViewLayoutPosition()} or {@link #getViewAdapterPosition()} */ public int getViewPosition() { return mViewHolder.getPosition(); } /** * Returns the adapter position that the view this LayoutParams is attached to corresponds * to as of latest layout calculation. * * @return the adapter position this view as of latest layout pass */ public int getViewLayoutPosition() { return mViewHolder.getLayoutPosition(); } /** * Returns the up-to-date adapter position that the view this LayoutParams is attached to * corresponds to. * * @return the up-to-date adapter position this view. It may return * {@link RecyclerView#NO_POSITION} if item represented by this View has been removed or * its up-to-date position cannot be calculated. */ public int getViewAdapterPosition() { return mViewHolder.getAdapterPosition(); } } /** * Observer base class for watching changes to an {@link Adapter}. * See {@link Adapter#registerAdapterDataObserver(AdapterDataObserver)}. */ public static abstract class AdapterDataObserver { public void onChanged() { // Do nothing } public void onItemRangeChanged(int positionStart, int itemCount) { // do nothing } public void onItemRangeInserted(int positionStart, int itemCount) { // do nothing } public void onItemRangeRemoved(int positionStart, int itemCount) { // do nothing } public void onItemRangeMoved(int fromPosition, int toPosition, int itemCount) { // do nothing } } /** * <p>Base class for smooth scrolling. Handles basic tracking of the target view position and * provides methods to trigger a programmatic scroll.</p> * * @see LinearSmoothScroller */ public static abstract class SmoothScroller { private int mTargetPosition = RecyclerView.NO_POSITION; private RecyclerView mRecyclerView; private LayoutManager mLayoutManager; private boolean mPendingInitialRun; private boolean mRunning; private View mTargetView; private final Action mRecyclingAction; public SmoothScroller() { mRecyclingAction = new Action(0, 0); } /** * Starts a smooth scroll for the given target position. * <p>In each animation step, {@link RecyclerView} will check * for the target view and call either * {@link #onTargetFound(android.view.View, RecyclerView.State, SmoothScroller.Action)} or * {@link #onSeekTargetStep(int, int, RecyclerView.State, SmoothScroller.Action)} until * SmoothScroller is stopped.</p> * * <p>Note that if RecyclerView finds the target view, it will automatically stop the * SmoothScroller. This <b>does not</b> mean that scroll will stop, it only means it will * stop calling SmoothScroller in each animation step.</p> */ void start(RecyclerView recyclerView, LayoutManager layoutManager) { mRecyclerView = recyclerView; mLayoutManager = layoutManager; if (mTargetPosition == RecyclerView.NO_POSITION) { throw new IllegalArgumentException("Invalid target position"); } mRecyclerView.mState.mTargetPosition = mTargetPosition; mRunning = true; mPendingInitialRun = true; mTargetView = findViewByPosition(getTargetPosition()); onStart(); mRecyclerView.mViewFlinger.postOnAnimation(); } public void setTargetPosition(int targetPosition) { mTargetPosition = targetPosition; } /** * @return The LayoutManager to which this SmoothScroller is attached */ public LayoutManager getLayoutManager() { return mLayoutManager; } /** * Stops running the SmoothScroller in each animation callback. Note that this does not * cancel any existing {@link Action} updated by * {@link #onTargetFound(android.view.View, RecyclerView.State, SmoothScroller.Action)} or * {@link #onSeekTargetStep(int, int, RecyclerView.State, SmoothScroller.Action)}. */ final protected void stop() { if (!mRunning) { return; } onStop(); mRecyclerView.mState.mTargetPosition = RecyclerView.NO_POSITION; mTargetView = null; mTargetPosition = RecyclerView.NO_POSITION; mPendingInitialRun = false; mRunning = false; // trigger a cleanup mLayoutManager.onSmoothScrollerStopped(this); // clear references to avoid any potential leak by a custom smooth scroller mLayoutManager = null; mRecyclerView = null; } /** * Returns true if SmoothScroller has been started but has not received the first * animation * callback yet. * * @return True if this SmoothScroller is waiting to start */ public boolean isPendingInitialRun() { return mPendingInitialRun; } /** * @return True if SmoothScroller is currently active */ public boolean isRunning() { return mRunning; } /** * Returns the adapter position of the target item * * @return Adapter position of the target item or * {@link RecyclerView#NO_POSITION} if no target view is set. */ public int getTargetPosition() { return mTargetPosition; } private void onAnimation(int dx, int dy) { if (!mRunning || mTargetPosition == RecyclerView.NO_POSITION) { stop(); } mPendingInitialRun = false; if (mTargetView != null) { // verify target position if (getChildPosition(mTargetView) == mTargetPosition) { onTargetFound(mTargetView, mRecyclerView.mState, mRecyclingAction); mRecyclingAction.runIfNecessary(mRecyclerView); stop(); } else { Log.e(TAG, "Passed over target position while smooth scrolling."); mTargetView = null; } } if (mRunning) { onSeekTargetStep(dx, dy, mRecyclerView.mState, mRecyclingAction); mRecyclingAction.runIfNecessary(mRecyclerView); } } /** * @see RecyclerView#getChildLayoutPosition(android.view.View) */ public int getChildPosition(View view) { return mRecyclerView.getChildLayoutPosition(view); } /** * @see RecyclerView.LayoutManager#getChildCount() */ public int getChildCount() { return mRecyclerView.mLayout.getChildCount(); } /** * @see RecyclerView.LayoutManager#findViewByPosition(int) */ public View findViewByPosition(int position) { return mRecyclerView.mLayout.findViewByPosition(position); } /** * @see RecyclerView#scrollToPosition(int) */ public void instantScrollToPosition(int position) { mRecyclerView.scrollToPosition(position); } protected void onChildAttachedToWindow(View child) { if (getChildPosition(child) == getTargetPosition()) { mTargetView = child; if (DEBUG) { Log.d(TAG, "smooth scroll target view has been attached"); } } } /** * Normalizes the vector. * @param scrollVector The vector that points to the target scroll position */ protected void normalize(PointF scrollVector) { final double magnitute = Math.sqrt(scrollVector.x * scrollVector.x + scrollVector.y * scrollVector.y); scrollVector.x /= magnitute; scrollVector.y /= magnitute; } /** * Called when smooth scroll is started. This might be a good time to do setup. */ abstract protected void onStart(); /** * Called when smooth scroller is stopped. This is a good place to cleanup your state etc. * @see #stop() */ abstract protected void onStop(); /** * <p>RecyclerView will call this method each time it scrolls until it can find the target * position in the layout.</p> * <p>SmoothScroller should check dx, dy and if scroll should be changed, update the * provided {@link Action} to define the next scroll.</p> * * @param dx Last scroll amount horizontally * @param dy Last scroll amount verticaully * @param state Transient state of RecyclerView * @param action If you want to trigger a new smooth scroll and cancel the previous one, * update this object. */ abstract protected void onSeekTargetStep(int dx, int dy, State state, Action action); /** * Called when the target position is laid out. This is the last callback SmoothScroller * will receive and it should update the provided {@link Action} to define the scroll * details towards the target view. * @param targetView The view element which render the target position. * @param state Transient state of RecyclerView * @param action Action instance that you should update to define final scroll action * towards the targetView */ abstract protected void onTargetFound(View targetView, State state, Action action); /** * Holds information about a smooth scroll request by a {@link SmoothScroller}. */ public static class Action { public static final int UNDEFINED_DURATION = Integer.MIN_VALUE; private int mDx; private int mDy; private int mDuration; private Interpolator mInterpolator; private boolean changed = false; // we track this variable to inform custom implementer if they are updating the action // in every animation callback private int consecutiveUpdates = 0; /** * @param dx Pixels to scroll horizontally * @param dy Pixels to scroll vertically */ public Action(int dx, int dy) { this(dx, dy, UNDEFINED_DURATION, null); } /** * @param dx Pixels to scroll horizontally * @param dy Pixels to scroll vertically * @param duration Duration of the animation in milliseconds */ public Action(int dx, int dy, int duration) { this(dx, dy, duration, null); } /** * @param dx Pixels to scroll horizontally * @param dy Pixels to scroll vertically * @param duration Duration of the animation in milliseconds * @param interpolator Interpolator to be used when calculating scroll position in each * animation step */ public Action(int dx, int dy, int duration, Interpolator interpolator) { mDx = dx; mDy = dy; mDuration = duration; mInterpolator = interpolator; } private void runIfNecessary(RecyclerView recyclerView) { if (changed) { validate(); if (mInterpolator == null) { if (mDuration == UNDEFINED_DURATION) { recyclerView.mViewFlinger.smoothScrollBy(mDx, mDy); } else { recyclerView.mViewFlinger.smoothScrollBy(mDx, mDy, mDuration); } } else { recyclerView.mViewFlinger.smoothScrollBy(mDx, mDy, mDuration, mInterpolator); } consecutiveUpdates++; if (consecutiveUpdates > 10) { // A new action is being set in every animation step. This looks like a bad // implementation. Inform developer. Log.e(TAG, "Smooth Scroll action is being updated too frequently. Make sure" + " you are not changing it unless necessary"); } changed = false; } else { consecutiveUpdates = 0; } } private void validate() { if (mInterpolator != null && mDuration < 1) { throw new IllegalStateException( "If you provide an interpolator, you must" + " set a positive duration"); } else if (mDuration < 1) { throw new IllegalStateException("Scroll duration must be a positive number"); } } public int getDx() { return mDx; } public void setDx(int dx) { changed = true; mDx = dx; } public int getDy() { return mDy; } public void setDy(int dy) { changed = true; mDy = dy; } public int getDuration() { return mDuration; } public void setDuration(int duration) { changed = true; mDuration = duration; } public Interpolator getInterpolator() { return mInterpolator; } /** * Sets the interpolator to calculate scroll steps * @param interpolator The interpolator to use. If you specify an interpolator, you must * also set the duration. * @see #setDuration(int) */ public void setInterpolator(Interpolator interpolator) { changed = true; mInterpolator = interpolator; } /** * Updates the action with given parameters. * @param dx Pixels to scroll horizontally * @param dy Pixels to scroll vertically * @param duration Duration of the animation in milliseconds * @param interpolator Interpolator to be used when calculating scroll position in each * animation step */ public void update(int dx, int dy, int duration, Interpolator interpolator) { mDx = dx; mDy = dy; mDuration = duration; mInterpolator = interpolator; changed = true; } } } static class AdapterDataObservable extends Observable<AdapterDataObserver> { public boolean hasObservers() { return !mObservers.isEmpty(); } public void notifyChanged() { // since onChanged() is implemented by the app, it could do anything, including // removing itself from {@link mObservers} - and that could cause problems if // an iterator is used on the ArrayList {@link mObservers}. // to avoid such problems, just march thru the list in the reverse order. for (int i = mObservers.size() - 1; i >= 0; i--) { mObservers.get(i).onChanged(); } } public void notifyItemRangeChanged(int positionStart, int itemCount) { // since onItemRangeChanged() is implemented by the app, it could do anything, including // removing itself from {@link mObservers} - and that could cause problems if // an iterator is used on the ArrayList {@link mObservers}. // to avoid such problems, just march thru the list in the reverse order. for (int i = mObservers.size() - 1; i >= 0; i--) { mObservers.get(i).onItemRangeChanged(positionStart, itemCount); } } public void notifyItemRangeInserted(int positionStart, int itemCount) { // since onItemRangeInserted() is implemented by the app, it could do anything, // including removing itself from {@link mObservers} - and that could cause problems if // an iterator is used on the ArrayList {@link mObservers}. // to avoid such problems, just march thru the list in the reverse order. for (int i = mObservers.size() - 1; i >= 0; i--) { mObservers.get(i).onItemRangeInserted(positionStart, itemCount); } } public void notifyItemRangeRemoved(int positionStart, int itemCount) { // since onItemRangeRemoved() is implemented by the app, it could do anything, including // removing itself from {@link mObservers} - and that could cause problems if // an iterator is used on the ArrayList {@link mObservers}. // to avoid such problems, just march thru the list in the reverse order. for (int i = mObservers.size() - 1; i >= 0; i--) { mObservers.get(i).onItemRangeRemoved(positionStart, itemCount); } } public void notifyItemMoved(int fromPosition, int toPosition) { for (int i = mObservers.size() - 1; i >= 0; i--) { mObservers.get(i).onItemRangeMoved(fromPosition, toPosition, 1); } } } static class SavedState extends android.view.View.BaseSavedState { Parcelable mLayoutState; /** * called by CREATOR */ SavedState(Parcel in) { super(in); mLayoutState = in.readParcelable(LayoutManager.class.getClassLoader()); } /** * Called by onSaveInstanceState */ SavedState(Parcelable superState) { super(superState); } @Override public void writeToParcel(Parcel dest, int flags) { super.writeToParcel(dest, flags); dest.writeParcelable(mLayoutState, 0); } private void copyFrom(SavedState other) { mLayoutState = other.mLayoutState; } public static final Parcelable.Creator<SavedState> CREATOR = new Parcelable.Creator<SavedState>() { @Override public SavedState createFromParcel(Parcel in) { return new SavedState(in); } @Override public SavedState[] newArray(int size) { return new SavedState[size]; } }; } /** * <p>Contains useful information about the current RecyclerView state like target scroll * position or view focus. State object can also keep arbitrary data, identified by resource * ids.</p> * <p>Often times, RecyclerView components will need to pass information between each other. * To provide a well defined data bus between components, RecyclerView passes the same State * object to component callbacks and these components can use it to exchange data.</p> * <p>If you implement custom components, you can use State's put/get/remove methods to pass * data between your components without needing to manage their lifecycles.</p> */ public static class State { private int mTargetPosition = RecyclerView.NO_POSITION; ArrayMap<ViewHolder, ItemHolderInfo> mPreLayoutHolderMap = new ArrayMap<ViewHolder, ItemHolderInfo>(); ArrayMap<ViewHolder, ItemHolderInfo> mPostLayoutHolderMap = new ArrayMap<ViewHolder, ItemHolderInfo>(); // nullable ArrayMap<Long, ViewHolder> mOldChangedHolders = new ArrayMap<Long, ViewHolder>(); // we use this like a set final List<View> mDisappearingViewsInLayoutPass = new ArrayList<View>(); private SparseArray<Object> mData; /** * Number of items adapter has. */ int mItemCount = 0; /** * Number of items adapter had in the previous layout. */ private int mPreviousLayoutItemCount = 0; /** * Number of items that were NOT laid out but has been deleted from the adapter after the * previous layout. */ private int mDeletedInvisibleItemCountSincePreviousLayout = 0; private boolean mStructureChanged = false; private boolean mInPreLayout = false; private boolean mRunSimpleAnimations = false; private boolean mRunPredictiveAnimations = false; State reset() { mTargetPosition = RecyclerView.NO_POSITION; if (mData != null) { mData.clear(); } mItemCount = 0; mStructureChanged = false; return this; } public boolean isPreLayout() { return mInPreLayout; } /** * Returns whether RecyclerView will run predictive animations in this layout pass * or not. * * @return true if RecyclerView is calculating predictive animations to be run at the end * of the layout pass. */ public boolean willRunPredictiveAnimations() { return mRunPredictiveAnimations; } /** * Returns whether RecyclerView will run simple animations in this layout pass * or not. * * @return true if RecyclerView is calculating simple animations to be run at the end of * the layout pass. */ public boolean willRunSimpleAnimations() { return mRunSimpleAnimations; } /** * Removes the mapping from the specified id, if there was any. * @param resourceId Id of the resource you want to remove. It is suggested to use R.id.* to * preserve cross functionality and avoid conflicts. */ public void remove(int resourceId) { if (mData == null) { return; } mData.remove(resourceId); } /** * Gets the Object mapped from the specified id, or <code>null</code> * if no such data exists. * * @param resourceId Id of the resource you want to remove. It is suggested to use R.id.* * to * preserve cross functionality and avoid conflicts. */ public <T> T get(int resourceId) { if (mData == null) { return null; } return (T) mData.get(resourceId); } /** * Adds a mapping from the specified id to the specified value, replacing the previous * mapping from the specified key if there was one. * * @param resourceId Id of the resource you want to add. It is suggested to use R.id.* to * preserve cross functionality and avoid conflicts. * @param data The data you want to associate with the resourceId. */ public void put(int resourceId, Object data) { if (mData == null) { mData = new SparseArray<Object>(); } mData.put(resourceId, data); } /** * If scroll is triggered to make a certain item visible, this value will return the * adapter index of that item. * @return Adapter index of the target item or * {@link RecyclerView#NO_POSITION} if there is no target * position. */ public int getTargetScrollPosition() { return mTargetPosition; } /** * Returns if current scroll has a target position. * @return true if scroll is being triggered to make a certain position visible * @see #getTargetScrollPosition() */ public boolean hasTargetScrollPosition() { return mTargetPosition != RecyclerView.NO_POSITION; } /** * @return true if the structure of the data set has changed since the last call to * onLayoutChildren, false otherwise */ public boolean didStructureChange() { return mStructureChanged; } /** * Returns the total number of items that can be laid out. Note that this number is not * necessarily equal to the number of items in the adapter, so you should always use this * number for your position calculations and never access the adapter directly. * <p> * RecyclerView listens for Adapter's notify events and calculates the effects of adapter * data changes on existing Views. These calculations are used to decide which animations * should be run. * <p> * To support predictive animations, RecyclerView may rewrite or reorder Adapter changes to * present the correct state to LayoutManager in pre-layout pass. * <p> * For example, a newly added item is not included in pre-layout item count because * pre-layout reflects the contents of the adapter before the item is added. Behind the * scenes, RecyclerView offsets {@link Recycler#getViewForPosition(int)} calls such that * LayoutManager does not know about the new item's existence in pre-layout. The item will * be available in second layout pass and will be included in the item count. Similar * adjustments are made for moved and removed items as well. * <p> * You can get the adapter's item count via {@link LayoutManager#getItemCount()} method. * * @return The number of items currently available * @see LayoutManager#getItemCount() */ public int getItemCount() { return mInPreLayout ? (mPreviousLayoutItemCount - mDeletedInvisibleItemCountSincePreviousLayout) : mItemCount; } void onViewRecycled(ViewHolder holder) { mPreLayoutHolderMap.remove(holder); mPostLayoutHolderMap.remove(holder); if (mOldChangedHolders != null) { removeFrom(mOldChangedHolders, holder); } mDisappearingViewsInLayoutPass.remove(holder.itemView); // holder cannot be in new list. } public void onViewIgnored(ViewHolder holder) { onViewRecycled(holder); } private void removeFrom(ArrayMap<Long, ViewHolder> holderMap, ViewHolder holder) { for (int i = holderMap.size() - 1; i >= 0; i--) { if (holder == holderMap.valueAt(i)) { holderMap.removeAt(i); return; } } } void removeFromDisappearingList(View child) { mDisappearingViewsInLayoutPass.remove(child); } void addToDisappearingList(View child) { if (!mDisappearingViewsInLayoutPass.contains(child)) { mDisappearingViewsInLayoutPass.add(child); } } @Override public String toString() { return "State{" + "mTargetPosition=" + mTargetPosition + ", mPreLayoutHolderMap=" + mPreLayoutHolderMap + ", mPostLayoutHolderMap=" + mPostLayoutHolderMap + ", mData=" + mData + ", mItemCount=" + mItemCount + ", mPreviousLayoutItemCount=" + mPreviousLayoutItemCount + ", mDeletedInvisibleItemCountSincePreviousLayout=" + mDeletedInvisibleItemCountSincePreviousLayout + ", mStructureChanged=" + mStructureChanged + ", mInPreLayout=" + mInPreLayout + ", mRunSimpleAnimations=" + mRunSimpleAnimations + ", mRunPredictiveAnimations=" + mRunPredictiveAnimations + '}'; } } /** * Internal listener that manages items after animations finish. This is how items are * retained (not recycled) during animations, but allowed to be recycled afterwards. * It depends on the contract with the ItemAnimator to call the appropriate dispatch*Finished() * method on the animator's listener when it is done animating any item. */ private class ItemAnimatorRestoreListener implements ItemAnimator.ItemAnimatorListener { @Override public void onRemoveFinished(ViewHolder item) { item.setIsRecyclable(true); if (!removeAnimatingView(item.itemView) && item.isTmpDetached()) { removeDetachedView(item.itemView, false); } } @Override public void onAddFinished(ViewHolder item) { item.setIsRecyclable(true); if (!item.shouldBeKeptAsChild()) { removeAnimatingView(item.itemView); } } @Override public void onMoveFinished(ViewHolder item) { item.setIsRecyclable(true); if (!item.shouldBeKeptAsChild()) { removeAnimatingView(item.itemView); } } @Override public void onChangeFinished(ViewHolder item) { item.setIsRecyclable(true); /** * We check both shadowed and shadowing because a ViewHolder may get both roles at the * same time. * * Assume this flow: * item X is represented by VH_1. Then itemX changes, so we create VH_2 . * RV sets the following and calls item animator: * VH_1.shadowed = VH_2; * VH_1.mChanged = true; * VH_2.shadowing =VH_1; * * Then, before the first change finishes, item changes again so we create VH_3. * RV sets the following and calls item animator: * VH_2.shadowed = VH_3 * VH_2.mChanged = true * VH_3.shadowing = VH_2 * * Because VH_2 already has an animation, it will be cancelled. At this point VH_2 has * both shadowing and shadowed fields set. Shadowing information is obsolete now * because the first animation where VH_2 is newViewHolder is not valid anymore. * We ended up in this case because VH_2 played both roles. On the other hand, * we DO NOT want to clear its changed flag. * * If second change was simply reverting first change, we would find VH_1 in * {@link Recycler#getScrapViewForPosition(int, int, boolean)} and recycle it before * re-using */ if (item.mShadowedHolder != null && item.mShadowingHolder == null) { // old vh item.mShadowedHolder = null; item.setFlags(~ViewHolder.FLAG_CHANGED, item.mFlags); } // always null this because an OldViewHolder can never become NewViewHolder w/o being // recycled. item.mShadowingHolder = null; if (!item.shouldBeKeptAsChild()) { removeAnimatingView(item.itemView); } } }; /** * This class defines the animations that take place on items as changes are made * to the adapter. * * Subclasses of ItemAnimator can be used to implement custom animations for actions on * ViewHolder items. The RecyclerView will manage retaining these items while they * are being animated, but implementors must call the appropriate "Starting" * ({@link #dispatchRemoveStarting(ViewHolder)}, {@link #dispatchMoveStarting(ViewHolder)}, * {@link #dispatchChangeStarting(ViewHolder, boolean)}, or * {@link #dispatchAddStarting(ViewHolder)}) * and "Finished" ({@link #dispatchRemoveFinished(ViewHolder)}, * {@link #dispatchMoveFinished(ViewHolder)}, * {@link #dispatchChangeFinished(ViewHolder, boolean)}, * or {@link #dispatchAddFinished(ViewHolder)}) methods when each item animation is * being started and ended. * * <p>By default, RecyclerView uses {@link DefaultItemAnimator}</p> * * @see #setItemAnimator(ItemAnimator) */ public static abstract class ItemAnimator { private ItemAnimatorListener mListener = null; private ArrayList<ItemAnimatorFinishedListener> mFinishedListeners = new ArrayList<ItemAnimatorFinishedListener>(); private long mAddDuration = 120; private long mRemoveDuration = 120; private long mMoveDuration = 250; private long mChangeDuration = 250; private boolean mSupportsChangeAnimations = true; /** * Gets the current duration for which all move animations will run. * * @return The current move duration */ public long getMoveDuration() { return mMoveDuration; } /** * Sets the duration for which all move animations will run. * * @param moveDuration The move duration */ public void setMoveDuration(long moveDuration) { mMoveDuration = moveDuration; } /** * Gets the current duration for which all add animations will run. * * @return The current add duration */ public long getAddDuration() { return mAddDuration; } /** * Sets the duration for which all add animations will run. * * @param addDuration The add duration */ public void setAddDuration(long addDuration) { mAddDuration = addDuration; } /** * Gets the current duration for which all remove animations will run. * * @return The current remove duration */ public long getRemoveDuration() { return mRemoveDuration; } /** * Sets the duration for which all remove animations will run. * * @param removeDuration The remove duration */ public void setRemoveDuration(long removeDuration) { mRemoveDuration = removeDuration; } /** * Gets the current duration for which all change animations will run. * * @return The current change duration */ public long getChangeDuration() { return mChangeDuration; } /** * Sets the duration for which all change animations will run. * * @param changeDuration The change duration */ public void setChangeDuration(long changeDuration) { mChangeDuration = changeDuration; } /** * Returns whether this ItemAnimator supports animations of change events. * * @return true if change animations are supported, false otherwise */ public boolean getSupportsChangeAnimations() { return mSupportsChangeAnimations; } /** * Sets whether this ItemAnimator supports animations of item change events. * If you set this property to false, actions on the data set which change the * contents of items will not be animated. What those animations are is left * up to the discretion of the ItemAnimator subclass, in its * {@link #animateChange(ViewHolder, ViewHolder, int, int, int, int)} implementation. * The value of this property is true by default. * * @see Adapter#notifyItemChanged(int) * @see Adapter#notifyItemRangeChanged(int, int) * * @param supportsChangeAnimations true if change animations are supported by * this ItemAnimator, false otherwise. If the property is false, the ItemAnimator * will not receive a call to * {@link #animateChange(ViewHolder, ViewHolder, int, int, int, int)} when changes occur. */ public void setSupportsChangeAnimations(boolean supportsChangeAnimations) { mSupportsChangeAnimations = supportsChangeAnimations; } /** * Internal only: * Sets the listener that must be called when the animator is finished * animating the item (or immediately if no animation happens). This is set * internally and is not intended to be set by external code. * * @param listener The listener that must be called. */ void setListener(ItemAnimatorListener listener) { mListener = listener; } /** * Called when there are pending animations waiting to be started. This state * is governed by the return values from {@link #animateAdd(ViewHolder) animateAdd()}, * {@link #animateMove(ViewHolder, int, int, int, int) animateMove()}, and * {@link #animateRemove(ViewHolder) animateRemove()}, which inform the * RecyclerView that the ItemAnimator wants to be called later to start the * associated animations. runPendingAnimations() will be scheduled to be run * on the next frame. */ abstract public void runPendingAnimations(); /** * Called when an item is removed from the RecyclerView. Implementors can choose * whether and how to animate that change, but must always call * {@link #dispatchRemoveFinished(ViewHolder)} when done, either * immediately (if no animation will occur) or after the animation actually finishes. * The return value indicates whether an animation has been set up and whether the * ItemAnimator's {@link #runPendingAnimations()} method should be called at the * next opportunity. This mechanism allows ItemAnimator to set up individual animations * as separate calls to {@link #animateAdd(ViewHolder) animateAdd()}, * {@link #animateMove(ViewHolder, int, int, int, int) animateMove()}, * {@link #animateRemove(ViewHolder) animateRemove()}, and * {@link #animateChange(ViewHolder, ViewHolder, int, int, int, int)} come in one by one, * then start the animations together in the later call to {@link #runPendingAnimations()}. * * <p>This method may also be called for disappearing items which continue to exist in the * RecyclerView, but for which the system does not have enough information to animate * them out of view. In that case, the default animation for removing items is run * on those items as well.</p> * * @param holder The item that is being removed. * @return true if a later call to {@link #runPendingAnimations()} is requested, * false otherwise. */ abstract public boolean animateRemove(ViewHolder holder); /** * Called when an item is added to the RecyclerView. Implementors can choose * whether and how to animate that change, but must always call * {@link #dispatchAddFinished(ViewHolder)} when done, either * immediately (if no animation will occur) or after the animation actually finishes. * The return value indicates whether an animation has been set up and whether the * ItemAnimator's {@link #runPendingAnimations()} method should be called at the * next opportunity. This mechanism allows ItemAnimator to set up individual animations * as separate calls to {@link #animateAdd(ViewHolder) animateAdd()}, * {@link #animateMove(ViewHolder, int, int, int, int) animateMove()}, * {@link #animateRemove(ViewHolder) animateRemove()}, and * {@link #animateChange(ViewHolder, ViewHolder, int, int, int, int)} come in one by one, * then start the animations together in the later call to {@link #runPendingAnimations()}. * * <p>This method may also be called for appearing items which were already in the * RecyclerView, but for which the system does not have enough information to animate * them into view. In that case, the default animation for adding items is run * on those items as well.</p> * * @param holder The item that is being added. * @return true if a later call to {@link #runPendingAnimations()} is requested, * false otherwise. */ abstract public boolean animateAdd(ViewHolder holder); /** * Called when an item is moved in the RecyclerView. Implementors can choose * whether and how to animate that change, but must always call * {@link #dispatchMoveFinished(ViewHolder)} when done, either * immediately (if no animation will occur) or after the animation actually finishes. * The return value indicates whether an animation has been set up and whether the * ItemAnimator's {@link #runPendingAnimations()} method should be called at the * next opportunity. This mechanism allows ItemAnimator to set up individual animations * as separate calls to {@link #animateAdd(ViewHolder) animateAdd()}, * {@link #animateMove(ViewHolder, int, int, int, int) animateMove()}, * {@link #animateRemove(ViewHolder) animateRemove()}, and * {@link #animateChange(ViewHolder, ViewHolder, int, int, int, int)} come in one by one, * then start the animations together in the later call to {@link #runPendingAnimations()}. * * @param holder The item that is being moved. * @return true if a later call to {@link #runPendingAnimations()} is requested, * false otherwise. */ abstract public boolean animateMove(ViewHolder holder, int fromX, int fromY, int toX, int toY); /** * Called when an item is changed in the RecyclerView, as indicated by a call to * {@link Adapter#notifyItemChanged(int)} or * {@link Adapter#notifyItemRangeChanged(int, int)}. * <p> * Implementers can choose whether and how to animate changes, but must always call * {@link #dispatchChangeFinished(ViewHolder, boolean)} for each non-null ViewHolder, * either immediately (if no animation will occur) or after the animation actually finishes. * The return value indicates whether an animation has been set up and whether the * ItemAnimator's {@link #runPendingAnimations()} method should be called at the * next opportunity. This mechanism allows ItemAnimator to set up individual animations * as separate calls to {@link #animateAdd(ViewHolder) animateAdd()}, * {@link #animateMove(ViewHolder, int, int, int, int) animateMove()}, * {@link #animateRemove(ViewHolder) animateRemove()}, and * {@link #animateChange(ViewHolder, ViewHolder, int, int, int, int)} come in one by one, * then start the animations together in the later call to {@link #runPendingAnimations()}. * * @param oldHolder The original item that changed. * @param newHolder The new item that was created with the changed content. Might be null * @param fromLeft Left of the old view holder * @param fromTop Top of the old view holder * @param toLeft Left of the new view holder * @param toTop Top of the new view holder * @return true if a later call to {@link #runPendingAnimations()} is requested, * false otherwise. */ abstract public boolean animateChange(ViewHolder oldHolder, ViewHolder newHolder, int fromLeft, int fromTop, int toLeft, int toTop); /** * Method to be called by subclasses when a remove animation is done. * * @param item The item which has been removed */ public final void dispatchRemoveFinished(ViewHolder item) { onRemoveFinished(item); if (mListener != null) { mListener.onRemoveFinished(item); } } /** * Method to be called by subclasses when a move animation is done. * * @param item The item which has been moved */ public final void dispatchMoveFinished(ViewHolder item) { onMoveFinished(item); if (mListener != null) { mListener.onMoveFinished(item); } } /** * Method to be called by subclasses when an add animation is done. * * @param item The item which has been added */ public final void dispatchAddFinished(ViewHolder item) { onAddFinished(item); if (mListener != null) { mListener.onAddFinished(item); } } /** * Method to be called by subclasses when a change animation is done. * * @see #animateChange(ViewHolder, ViewHolder, int, int, int, int) * @param item The item which has been changed (this method must be called for * each non-null ViewHolder passed into * {@link #animateChange(ViewHolder, ViewHolder, int, int, int, int)}). * @param oldItem true if this is the old item that was changed, false if * it is the new item that replaced the old item. */ public final void dispatchChangeFinished(ViewHolder item, boolean oldItem) { onChangeFinished(item, oldItem); if (mListener != null) { mListener.onChangeFinished(item); } } /** * Method to be called by subclasses when a remove animation is being started. * * @param item The item being removed */ public final void dispatchRemoveStarting(ViewHolder item) { onRemoveStarting(item); } /** * Method to be called by subclasses when a move animation is being started. * * @param item The item being moved */ public final void dispatchMoveStarting(ViewHolder item) { onMoveStarting(item); } /** * Method to be called by subclasses when an add animation is being started. * * @param item The item being added */ public final void dispatchAddStarting(ViewHolder item) { onAddStarting(item); } /** * Method to be called by subclasses when a change animation is being started. * * @param item The item which has been changed (this method must be called for * each non-null ViewHolder passed into * {@link #animateChange(ViewHolder, ViewHolder, int, int, int, int)}). * @param oldItem true if this is the old item that was changed, false if * it is the new item that replaced the old item. */ public final void dispatchChangeStarting(ViewHolder item, boolean oldItem) { onChangeStarting(item, oldItem); } /** * Method called when an animation on a view should be ended immediately. * This could happen when other events, like scrolling, occur, so that * animating views can be quickly put into their proper end locations. * Implementations should ensure that any animations running on the item * are canceled and affected properties are set to their end values. * Also, appropriate dispatch methods (e.g., {@link #dispatchAddFinished(ViewHolder)} * should be called since the animations are effectively done when this * method is called. * * @param item The item for which an animation should be stopped. */ abstract public void endAnimation(ViewHolder item); /** * Method called when all item animations should be ended immediately. * This could happen when other events, like scrolling, occur, so that * animating views can be quickly put into their proper end locations. * Implementations should ensure that any animations running on any items * are canceled and affected properties are set to their end values. * Also, appropriate dispatch methods (e.g., {@link #dispatchAddFinished(ViewHolder)} * should be called since the animations are effectively done when this * method is called. */ abstract public void endAnimations(); /** * Method which returns whether there are any item animations currently running. * This method can be used to determine whether to delay other actions until * animations end. * * @return true if there are any item animations currently running, false otherwise. */ abstract public boolean isRunning(); /** * Like {@link #isRunning()}, this method returns whether there are any item * animations currently running. Addtionally, the listener passed in will be called * when there are no item animations running, either immediately (before the method * returns) if no animations are currently running, or when the currently running * animations are {@link #dispatchAnimationsFinished() finished}. * * <p>Note that the listener is transient - it is either called immediately and not * stored at all, or stored only until it is called when running animations * are finished sometime later.</p> * * @param listener A listener to be called immediately if no animations are running * or later when currently-running animations have finished. A null listener is * equivalent to calling {@link #isRunning()}. * @return true if there are any item animations currently running, false otherwise. */ public final boolean isRunning(ItemAnimatorFinishedListener listener) { boolean running = isRunning(); if (listener != null) { if (!running) { listener.onAnimationsFinished(); } else { mFinishedListeners.add(listener); } } return running; } /** * The interface to be implemented by listeners to animation events from this * ItemAnimator. This is used internally and is not intended for developers to * create directly. */ interface ItemAnimatorListener { void onRemoveFinished(ViewHolder item); void onAddFinished(ViewHolder item); void onMoveFinished(ViewHolder item); void onChangeFinished(ViewHolder item); } /** * This method should be called by ItemAnimator implementations to notify * any listeners that all pending and active item animations are finished. */ public final void dispatchAnimationsFinished() { final int count = mFinishedListeners.size(); for (int i = 0; i < count; ++i) { mFinishedListeners.get(i).onAnimationsFinished(); } mFinishedListeners.clear(); } /** * This interface is used to inform listeners when all pending or running animations * in an ItemAnimator are finished. This can be used, for example, to delay an action * in a data set until currently-running animations are complete. * * @see #isRunning(ItemAnimatorFinishedListener) */ public interface ItemAnimatorFinishedListener { void onAnimationsFinished(); } /** * Called when a remove animation is being started on the given ViewHolder. * The default implementation does nothing. Subclasses may wish to override * this method to handle any ViewHolder-specific operations linked to animation * lifecycles. * * @param item The ViewHolder being animated. */ public void onRemoveStarting(ViewHolder item) { } /** * Called when a remove animation has ended on the given ViewHolder. * The default implementation does nothing. Subclasses may wish to override * this method to handle any ViewHolder-specific operations linked to animation * lifecycles. * * @param item The ViewHolder being animated. */ public void onRemoveFinished(ViewHolder item) { } /** * Called when an add animation is being started on the given ViewHolder. * The default implementation does nothing. Subclasses may wish to override * this method to handle any ViewHolder-specific operations linked to animation * lifecycles. * * @param item The ViewHolder being animated. */ public void onAddStarting(ViewHolder item) { } /** * Called when an add animation has ended on the given ViewHolder. * The default implementation does nothing. Subclasses may wish to override * this method to handle any ViewHolder-specific operations linked to animation * lifecycles. * * @param item The ViewHolder being animated. */ public void onAddFinished(ViewHolder item) { } /** * Called when a move animation is being started on the given ViewHolder. * The default implementation does nothing. Subclasses may wish to override * this method to handle any ViewHolder-specific operations linked to animation * lifecycles. * * @param item The ViewHolder being animated. */ public void onMoveStarting(ViewHolder item) { } /** * Called when a move animation has ended on the given ViewHolder. * The default implementation does nothing. Subclasses may wish to override * this method to handle any ViewHolder-specific operations linked to animation * lifecycles. * * @param item The ViewHolder being animated. */ public void onMoveFinished(ViewHolder item) { } /** * Called when a change animation is being started on the given ViewHolder. * The default implementation does nothing. Subclasses may wish to override * this method to handle any ViewHolder-specific operations linked to animation * lifecycles. * * @param item The ViewHolder being animated. * @param oldItem true if this is the old item that was changed, false if * it is the new item that replaced the old item. */ public void onChangeStarting(ViewHolder item, boolean oldItem) { } /** * Called when a change animation has ended on the given ViewHolder. * The default implementation does nothing. Subclasses may wish to override * this method to handle any ViewHolder-specific operations linked to animation * lifecycles. * * @param item The ViewHolder being animated. * @param oldItem true if this is the old item that was changed, false if * it is the new item that replaced the old item. */ public void onChangeFinished(ViewHolder item, boolean oldItem) { } } /** * Internal data structure that holds information about an item's bounds. * This information is used in calculating item animations. */ private static class ItemHolderInfo { ViewHolder holder; int left, top, right, bottom; ItemHolderInfo(ViewHolder holder, int left, int top, int right, int bottom) { this.holder = holder; this.left = left; this.top = top; this.right = right; this.bottom = bottom; } } }