Java tutorial
/* * Copyright (C) 2015 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 android.support.v7.widget.helper; import android.graphics.Canvas; import android.graphics.Rect; import android.os.Build; import android.support.v4.animation.AnimatorCompatHelper; import android.support.v4.animation.AnimatorListenerCompat; import android.support.v4.animation.AnimatorUpdateListenerCompat; import android.support.v4.animation.ValueAnimatorCompat; import android.support.v4.view.GestureDetectorCompat; import android.support.v4.view.MotionEventCompat; import android.support.v4.view.VelocityTrackerCompat; import android.support.v4.view.ViewCompat; import android.support.v7.widget.LinearLayoutManager; import android.support.v7.widget.RecyclerView; import android.support.v7.widget.RecyclerView.OnItemTouchListener; import android.support.v7.widget.RecyclerView.ViewHolder; import android.util.Log; import android.view.GestureDetector; import android.view.HapticFeedbackConstants; import android.view.MotionEvent; import android.view.VelocityTracker; import android.view.View; import android.view.ViewConfiguration; import android.view.ViewParent; import android.view.animation.Interpolator; import com.android.launcher3.R; import java.util.ArrayList; import java.util.List; /** * This is a utility class to add swipe to dismiss and drag & drop support to RecyclerView. * <p> * It works with a RecyclerView and a Callback class, which configures what type of interactions * are enabled and also receives events when user performs these actions. * <p> * Depending on which functionality you support, you should override * {@link Callback#onMove(RecyclerView, ViewHolder, ViewHolder)} and / or * {@link Callback#onSwiped(ViewHolder, int)}. * <p> * This class is designed to work with any LayoutManager but for certain situations, it can be * optimized for your custom LayoutManager by extending methods in the * {@link Callback} class or implementing {@link ViewDropHandler} * interface in your LayoutManager. * <p> * By default, ItemTouchHelper moves the items' translateX/Y properties to reposition them. On * platforms older than Honeycomb, ItemTouchHelper uses canvas translations and View's visibility * property to move items in response to touch events. You can customize these behaviors by * overriding {@link Callback#onChildDraw(Canvas, RecyclerView, ViewHolder, float, float, int, * boolean)} * or {@link Callback#onChildDrawOver(Canvas, RecyclerView, ViewHolder, float, float, int, * boolean)}. * <p/> * Most of the time, you only need to override <code>onChildDraw</code> but due to limitations of * platform prior to Honeycomb, you may need to implement <code>onChildDrawOver</code> as well. */ public class ItemTouchHelper extends RecyclerView.ItemDecoration implements RecyclerView.OnChildAttachStateChangeListener { /** * Up direction, used for swipe & drag control. */ public static final int UP = 1; /** * Down direction, used for swipe & drag control. */ public static final int DOWN = 1 << 1; /** * Left direction, used for swipe & drag control. */ public static final int LEFT = 1 << 2; /** * Right direction, used for swipe & drag control. */ public static final int RIGHT = 1 << 3; // If you change these relative direction values, update Callback#convertToAbsoluteDirection, // Callback#convertToRelativeDirection. /** * Horizontal start direction. Resolved to LEFT or RIGHT depending on RecyclerView's layout * direction. Used for swipe & drag control. */ public static final int START = LEFT << 2; /** * Horizontal end direction. Resolved to LEFT or RIGHT depending on RecyclerView's layout * direction. Used for swipe & drag control. */ public static final int END = RIGHT << 2; /** * ItemTouchHelper is in idle state. At this state, either there is no related motion event by * the user or latest motion events have not yet triggered a swipe or drag. */ public static final int ACTION_STATE_IDLE = 0; /** * A View is currently being swiped. */ public static final int ACTION_STATE_SWIPE = 1; /** * A View is currently being dragged. */ public static final int ACTION_STATE_DRAG = 2; /** * Animation type for views which are swiped successfully. */ public static final int ANIMATION_TYPE_SWIPE_SUCCESS = 1 << 1; /** * Animation type for views which are not completely swiped thus will animate back to their * original position. */ public static final int ANIMATION_TYPE_SWIPE_CANCEL = 1 << 2; /** * Animation type for views that were dragged and now will animate to their final position. */ public static final int ANIMATION_TYPE_DRAG = 1 << 3; private static final String TAG = "ItemTouchHelper"; private static final boolean DEBUG = false; private static final int ACTIVE_POINTER_ID_NONE = -1; private static final int DIRECTION_FLAG_COUNT = 8; private static final int ACTION_MODE_IDLE_MASK = (1 << DIRECTION_FLAG_COUNT) - 1; private static final int ACTION_MODE_SWIPE_MASK = ACTION_MODE_IDLE_MASK << DIRECTION_FLAG_COUNT; private static final int ACTION_MODE_DRAG_MASK = ACTION_MODE_SWIPE_MASK << DIRECTION_FLAG_COUNT; /** * Views, whose state should be cleared after they are detached from RecyclerView. * This is necessary after swipe dismissing an item. We wait until animator finishes its job * to clean these views. */ final List<View> mPendingCleanup = new ArrayList<View>(); /** * Re-use array to calculate dx dy for a ViewHolder */ private final float[] mTmpPosition = new float[2]; /** * Currently selected view holder */ ViewHolder mSelected = null; /** * The reference coordinates for the action start. For drag & drop, this is the time long * press is completed vs for swipe, this is the initial touch point. */ float mInitialTouchX; float mInitialTouchY; /** * The diff between the last event and initial touch. */ float mDx; float mDy; /** * The coordinates of the selected view at the time it is selected. We record these values * when action starts so that we can consistently position it even if LayoutManager moves the * View. */ float mSelectedStartX; float mSelectedStartY; /** * The pointer we are tracking. */ int mActivePointerId = ACTIVE_POINTER_ID_NONE; /** * Developer callback which controls the behavior of ItemTouchHelper. */ Callback mCallback; /** * Current mode. */ int mActionState = ACTION_STATE_IDLE; /** * The direction flags obtained from unmasking * {@link Callback#getAbsoluteMovementFlags(RecyclerView, ViewHolder)} for the current * action state. */ int mSelectedFlags; /** * When a View is dragged or swiped and needs to go back to where it was, we create a Recover * Animation and animate it to its location using this custom Animator, instead of using * framework Animators. * Using framework animators has the side effect of clashing with ItemAnimator, creating * jumpy UIs. */ List<RecoverAnimation> mRecoverAnimations = new ArrayList<RecoverAnimation>(); private int mSlop; private RecyclerView mRecyclerView; /** * When user drags a view to the edge, we start scrolling the LayoutManager as long as View * is partially out of bounds. */ private final Runnable mScrollRunnable = new Runnable() { @Override public void run() { if (mSelected != null && scrollIfNecessary()) { if (mSelected != null) { //it might be lost during scrolling moveIfNecessary(mSelected); } mRecyclerView.removeCallbacks(mScrollRunnable); ViewCompat.postOnAnimation(mRecyclerView, this); } } }; /** * Used for detecting fling swipe */ private VelocityTracker mVelocityTracker; //re-used list for selecting a swap target private List<ViewHolder> mSwapTargets; //re used for for sorting swap targets private List<Integer> mDistances; /** * If drag & drop is supported, we use child drawing order to bring them to front. */ private RecyclerView.ChildDrawingOrderCallback mChildDrawingOrderCallback = null; /** * This keeps a reference to the child dragged by the user. Even after user stops dragging, * until view reaches its final position (end of recover animation), we keep a reference so * that it can be drawn above other children. */ private View mOverdrawChild = null; /** * We cache the position of the overdraw child to avoid recalculating it each time child * position callback is called. This value is invalidated whenever a child is attached or * detached. */ private int mOverdrawChildPosition = -1; /** * Used to detect long press. */ private GestureDetectorCompat mGestureDetector; private final OnItemTouchListener mOnItemTouchListener = new OnItemTouchListener() { @Override public boolean onInterceptTouchEvent(RecyclerView recyclerView, MotionEvent event) { mGestureDetector.onTouchEvent(event); if (DEBUG) { Log.d(TAG, "intercept: x:" + event.getX() + ",y:" + event.getY() + ", " + event); } final int action = MotionEventCompat.getActionMasked(event); if (action == MotionEvent.ACTION_DOWN) { mActivePointerId = MotionEventCompat.getPointerId(event, 0); mInitialTouchX = event.getX(); mInitialTouchY = event.getY(); obtainVelocityTracker(); if (mSelected == null) { final RecoverAnimation animation = findAnimation(event); if (animation != null) { mInitialTouchX -= animation.mX; mInitialTouchY -= animation.mY; endRecoverAnimation(animation.mViewHolder, true); if (mPendingCleanup.remove(animation.mViewHolder.itemView)) { mCallback.clearView(mRecyclerView, animation.mViewHolder); } select(animation.mViewHolder, animation.mActionState); updateDxDy(event, mSelectedFlags, 0); } } } else if (action == MotionEvent.ACTION_CANCEL || action == MotionEvent.ACTION_UP) { mActivePointerId = ACTIVE_POINTER_ID_NONE; select(null, ACTION_STATE_IDLE); } else if (mActivePointerId != ACTIVE_POINTER_ID_NONE) { // in a non scroll orientation, if distance change is above threshold, we // can select the item final int index = MotionEventCompat.findPointerIndex(event, mActivePointerId); if (DEBUG) { Log.d(TAG, "pointer index " + index); } if (index >= 0) { checkSelectForSwipe(action, event, index); } } if (mVelocityTracker != null) { mVelocityTracker.addMovement(event); } return mSelected != null; } @Override public void onTouchEvent(RecyclerView recyclerView, MotionEvent event) { mGestureDetector.onTouchEvent(event); if (DEBUG) { Log.d(TAG, "on touch: x:" + mInitialTouchX + ",y:" + mInitialTouchY + ", :" + event); } if (mVelocityTracker != null) { mVelocityTracker.addMovement(event); } if (mActivePointerId == ACTIVE_POINTER_ID_NONE) { return; } final int action = MotionEventCompat.getActionMasked(event); final int activePointerIndex = MotionEventCompat.findPointerIndex(event, mActivePointerId); if (activePointerIndex >= 0) { checkSelectForSwipe(action, event, activePointerIndex); } ViewHolder viewHolder = mSelected; if (viewHolder == null) { return; } switch (action) { case MotionEvent.ACTION_MOVE: { // Find the index of the active pointer and fetch its position if (activePointerIndex >= 0) { updateDxDy(event, mSelectedFlags, activePointerIndex); moveIfNecessary(viewHolder); mRecyclerView.removeCallbacks(mScrollRunnable); mScrollRunnable.run(); mRecyclerView.invalidate(); } break; } case MotionEvent.ACTION_CANCEL: case MotionEvent.ACTION_UP: if (mVelocityTracker != null) { mVelocityTracker.computeCurrentVelocity(1000, mRecyclerView.getMaxFlingVelocity()); } select(null, ACTION_STATE_IDLE); mActivePointerId = ACTIVE_POINTER_ID_NONE; break; case MotionEvent.ACTION_POINTER_UP: { final int pointerIndex = MotionEventCompat.getActionIndex(event); final int pointerId = MotionEventCompat.getPointerId(event, pointerIndex); if (pointerId == mActivePointerId) { if (mVelocityTracker != null) { mVelocityTracker.computeCurrentVelocity(1000, mRecyclerView.getMaxFlingVelocity()); } // This was our active pointer going up. Choose a new // active pointer and adjust accordingly. final int newPointerIndex = pointerIndex == 0 ? 1 : 0; mActivePointerId = MotionEventCompat.getPointerId(event, newPointerIndex); updateDxDy(event, mSelectedFlags, pointerIndex); } break; } } } @Override public void onRequestDisallowInterceptTouchEvent(boolean disallowIntercept) { if (!disallowIntercept) { return; } select(null, ACTION_STATE_IDLE); } }; /** * Temporary rect instance that is used when we need to lookup Item decorations. */ private Rect mTmpRect; /** * When user started to drag scroll. Reset when we don't scroll */ private long mDragScrollStartTimeInMs; /** * Creates an ItemTouchHelper that will work with the given Callback. * <p> * You can attach ItemTouchHelper to a RecyclerView via * {@link #attachToRecyclerView(RecyclerView)}. Upon attaching, it will add an item decoration, * an onItemTouchListener and a Child attach / detach listener to the RecyclerView. * * @param callback The Callback which controls the behavior of this touch helper. */ public ItemTouchHelper(Callback callback) { mCallback = callback; } private static boolean hitTest(View child, float x, float y, float left, float top) { return x >= left && x <= left + child.getWidth() && y >= top && y <= top + child.getHeight(); } /** * Attaches the ItemTouchHelper to the provided RecyclerView. If TouchHelper is already * attached * to a RecyclerView, it will first detach from the previous one. * * @param recyclerView The RecyclerView instance to which you want to add this helper. */ public void attachToRecyclerView(RecyclerView recyclerView) { if (mRecyclerView == recyclerView) { return; // nothing to do } if (mRecyclerView != null) { destroyCallbacks(); } mRecyclerView = recyclerView; if (mRecyclerView != null) { setupCallbacks(); } } private void setupCallbacks() { ViewConfiguration vc = ViewConfiguration.get(mRecyclerView.getContext()); mSlop = vc.getScaledTouchSlop(); mRecyclerView.addItemDecoration(this); mRecyclerView.addOnItemTouchListener(mOnItemTouchListener); mRecyclerView.addOnChildAttachStateChangeListener(this); initGestureDetector(); } private void destroyCallbacks() { mRecyclerView.removeItemDecoration(this); mRecyclerView.removeOnItemTouchListener(mOnItemTouchListener); mRecyclerView.removeOnChildAttachStateChangeListener(this); // clean all attached final int recoverAnimSize = mRecoverAnimations.size(); for (int i = recoverAnimSize - 1; i >= 0; i--) { final RecoverAnimation recoverAnimation = mRecoverAnimations.get(0); mCallback.clearView(mRecyclerView, recoverAnimation.mViewHolder); } mRecoverAnimations.clear(); mOverdrawChild = null; mOverdrawChildPosition = -1; releaseVelocityTracker(); } private void initGestureDetector() { if (mGestureDetector != null) { return; } mGestureDetector = new GestureDetectorCompat(mRecyclerView.getContext(), new ItemTouchHelperGestureListener()); } private void getSelectedDxDy(float[] outPosition) { if ((mSelectedFlags & (LEFT | RIGHT)) != 0) { outPosition[0] = mSelectedStartX + mDx - mSelected.itemView.getLeft(); } else { outPosition[0] = ViewCompat.getTranslationX(mSelected.itemView); } if ((mSelectedFlags & (UP | DOWN)) != 0) { outPosition[1] = mSelectedStartY + mDy - mSelected.itemView.getTop(); } else { outPosition[1] = ViewCompat.getTranslationY(mSelected.itemView); } } @Override public void onDrawOver(Canvas c, RecyclerView parent, RecyclerView.State state) { float dx = 0, dy = 0; if (mSelected != null) { getSelectedDxDy(mTmpPosition); dx = mTmpPosition[0]; dy = mTmpPosition[1]; } mCallback.onDrawOver(c, parent, mSelected, mRecoverAnimations, mActionState, dx, dy); } @Override public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) { // we don't know if RV changed something so we should invalidate this index. mOverdrawChildPosition = -1; float dx = 0, dy = 0; if (mSelected != null) { getSelectedDxDy(mTmpPosition); dx = mTmpPosition[0]; dy = mTmpPosition[1]; } mCallback.onDraw(c, parent, mSelected, mRecoverAnimations, mActionState, dx, dy); } /** * Starts dragging or swiping the given View. Call with null if you want to clear it. * * @param selected The ViewHolder to drag or swipe. Can be null if you want to cancel the * current action * @param actionState The type of action */ private void select(ViewHolder selected, int actionState) { if (selected == mSelected && actionState == mActionState) { return; } mDragScrollStartTimeInMs = Long.MIN_VALUE; final int prevActionState = mActionState; // prevent duplicate animations endRecoverAnimation(selected, true); mActionState = actionState; if (actionState == ACTION_STATE_DRAG) { // we remove after animation is complete. this means we only elevate the last drag // child but that should perform good enough as it is very hard to start dragging a // new child before the previous one settles. mOverdrawChild = selected.itemView; addChildDrawingOrderCallback(); } int actionStateMask = (1 << (DIRECTION_FLAG_COUNT + DIRECTION_FLAG_COUNT * actionState)) - 1; boolean preventLayout = false; if (mSelected != null) { final ViewHolder prevSelected = mSelected; if (prevSelected.itemView.getParent() != null) { final int swipeDir = prevActionState == ACTION_STATE_DRAG ? 0 : swipeIfNecessary(prevSelected); releaseVelocityTracker(); // find where we should animate to final float targetTranslateX, targetTranslateY; int animationType; switch (swipeDir) { case LEFT: case RIGHT: case START: case END: targetTranslateY = 0; targetTranslateX = Math.signum(mDx) * mRecyclerView.getWidth(); break; case UP: case DOWN: targetTranslateX = 0; targetTranslateY = Math.signum(mDy) * mRecyclerView.getHeight(); break; default: targetTranslateX = 0; targetTranslateY = 0; } if (prevActionState == ACTION_STATE_DRAG) { animationType = ANIMATION_TYPE_DRAG; } else if (swipeDir > 0) { animationType = ANIMATION_TYPE_SWIPE_SUCCESS; } else { animationType = ANIMATION_TYPE_SWIPE_CANCEL; } getSelectedDxDy(mTmpPosition); final float currentTranslateX = mTmpPosition[0]; final float currentTranslateY = mTmpPosition[1]; final RecoverAnimation rv = new RecoverAnimation(prevSelected, animationType, prevActionState, currentTranslateX, currentTranslateY, targetTranslateX, targetTranslateY) { @Override public void onAnimationEnd(ValueAnimatorCompat animation) { super.onAnimationEnd(animation); if (this.mOverridden) { return; } if (swipeDir <= 0) { // this is a drag or failed swipe. recover immediately mCallback.clearView(mRecyclerView, prevSelected); // full cleanup will happen on onDrawOver } else { // wait until remove animation is complete. mPendingCleanup.add(prevSelected.itemView); mIsPendingCleanup = true; if (swipeDir > 0) { // Animation might be ended by other animators during a layout. // We defer callback to avoid editing adapter during a layout. postDispatchSwipe(this, swipeDir); } } // removed from the list after it is drawn for the last time if (mOverdrawChild == prevSelected.itemView) { removeChildDrawingOrderCallbackIfNecessary(prevSelected.itemView); } } }; final long duration = mCallback.getAnimationDuration(mRecyclerView, animationType, targetTranslateX - currentTranslateX, targetTranslateY - currentTranslateY); rv.setDuration(duration); mRecoverAnimations.add(rv); rv.start(); preventLayout = true; } else { removeChildDrawingOrderCallbackIfNecessary(prevSelected.itemView); mCallback.clearView(mRecyclerView, prevSelected); } mSelected = null; } if (selected != null) { mSelectedFlags = (mCallback.getAbsoluteMovementFlags(mRecyclerView, selected) & actionStateMask) >> (mActionState * DIRECTION_FLAG_COUNT); mSelectedStartX = selected.itemView.getLeft(); mSelectedStartY = selected.itemView.getTop(); mSelected = selected; if (actionState == ACTION_STATE_DRAG) { mSelected.itemView.performHapticFeedback(HapticFeedbackConstants.LONG_PRESS); } } final ViewParent rvParent = mRecyclerView.getParent(); if (rvParent != null) { rvParent.requestDisallowInterceptTouchEvent(mSelected != null); } if (!preventLayout) { mRecyclerView.getLayoutManager().requestSimpleAnimationsInNextLayout(); } mCallback.onSelectedChanged(mSelected, mActionState); mRecyclerView.invalidate(); } private void postDispatchSwipe(final RecoverAnimation anim, final int swipeDir) { // wait until animations are complete. mRecyclerView.post(new Runnable() { @Override public void run() { if (mRecyclerView != null && mRecyclerView.isAttachedToWindow() && !anim.mOverridden && anim.mViewHolder.getAdapterPosition() != RecyclerView.NO_POSITION) { final RecyclerView.ItemAnimator animator = mRecyclerView.getItemAnimator(); // if animator is running or we have other active recover animations, we try // not to call onSwiped because DefaultItemAnimator is not good at merging // animations. Instead, we wait and batch. if ((animator == null || !animator.isRunning(null)) && !hasRunningRecoverAnim()) { mCallback.onSwiped(anim.mViewHolder, swipeDir); } else { mRecyclerView.post(this); } } } }); } private boolean hasRunningRecoverAnim() { final int size = mRecoverAnimations.size(); for (int i = 0; i < size; i++) { if (!mRecoverAnimations.get(i).mEnded) { return true; } } return false; } /** * If user drags the view to the edge, trigger a scroll if necessary. */ private boolean scrollIfNecessary() { if (mSelected == null) { mDragScrollStartTimeInMs = Long.MIN_VALUE; return false; } final long now = System.currentTimeMillis(); final long scrollDuration = mDragScrollStartTimeInMs == Long.MIN_VALUE ? 0 : now - mDragScrollStartTimeInMs; RecyclerView.LayoutManager lm = mRecyclerView.getLayoutManager(); if (mTmpRect == null) { mTmpRect = new Rect(); } int scrollX = 0; int scrollY = 0; lm.calculateItemDecorationsForChild(mSelected.itemView, mTmpRect); if (lm.canScrollHorizontally()) { int curX = (int) (mSelectedStartX + mDx); final int leftDiff = curX - mTmpRect.left - mRecyclerView.getPaddingLeft(); if (mDx < 0 && leftDiff < 0) { scrollX = leftDiff; } else if (mDx > 0) { final int rightDiff = curX + mSelected.itemView.getWidth() + mTmpRect.right - (mRecyclerView.getWidth() - mRecyclerView.getPaddingRight()); if (rightDiff > 0) { scrollX = rightDiff; } } } if (lm.canScrollVertically()) { int curY = (int) (mSelectedStartY + mDy); final int topDiff = curY - mTmpRect.top - mRecyclerView.getPaddingTop(); if (mDy < 0 && topDiff < 0) { scrollY = topDiff; } else if (mDy > 0) { final int bottomDiff = curY + mSelected.itemView.getHeight() + mTmpRect.bottom - (mRecyclerView.getHeight() - mRecyclerView.getPaddingBottom()); if (bottomDiff > 0) { scrollY = bottomDiff; } } } if (scrollX != 0) { scrollX = mCallback.interpolateOutOfBoundsScroll(mRecyclerView, mSelected.itemView.getWidth(), scrollX, mRecyclerView.getWidth(), scrollDuration); } if (scrollY != 0) { scrollY = mCallback.interpolateOutOfBoundsScroll(mRecyclerView, mSelected.itemView.getHeight(), scrollY, mRecyclerView.getHeight(), scrollDuration); } if (scrollX != 0 || scrollY != 0) { if (mDragScrollStartTimeInMs == Long.MIN_VALUE) { mDragScrollStartTimeInMs = now; } mRecyclerView.scrollBy(scrollX, scrollY); return true; } mDragScrollStartTimeInMs = Long.MIN_VALUE; return false; } private List<ViewHolder> findSwapTargets(ViewHolder viewHolder) { if (mSwapTargets == null) { mSwapTargets = new ArrayList<ViewHolder>(); mDistances = new ArrayList<Integer>(); } else { mSwapTargets.clear(); mDistances.clear(); } final int margin = mCallback.getBoundingBoxMargin(); final int left = Math.round(mSelectedStartX + mDx) - margin; final int top = Math.round(mSelectedStartY + mDy) - margin; final int right = left + viewHolder.itemView.getWidth() + 2 * margin; final int bottom = top + viewHolder.itemView.getHeight() + 2 * margin; final int centerX = (left + right) / 2; final int centerY = (top + bottom) / 2; final RecyclerView.LayoutManager lm = mRecyclerView.getLayoutManager(); final int childCount = lm.getChildCount(); for (int i = 0; i < childCount; i++) { View other = lm.getChildAt(i); if (other == viewHolder.itemView) { continue;//myself! } if (other.getBottom() < top || other.getTop() > bottom || other.getRight() < left || other.getLeft() > right) { continue; } final ViewHolder otherVh = mRecyclerView.getChildViewHolder(other); if (mCallback.canDropOver(mRecyclerView, mSelected, otherVh)) { // find the index to add final int dx = Math.abs(centerX - (other.getLeft() + other.getRight()) / 2); final int dy = Math.abs(centerY - (other.getTop() + other.getBottom()) / 2); final int dist = dx * dx + dy * dy; int pos = 0; final int cnt = mSwapTargets.size(); for (int j = 0; j < cnt; j++) { if (dist > mDistances.get(j)) { pos++; } else { break; } } mSwapTargets.add(pos, otherVh); mDistances.add(pos, dist); } } return mSwapTargets; } /** * Checks if we should swap w/ another view holder. */ private void moveIfNecessary(ViewHolder viewHolder) { if (mRecyclerView.isLayoutRequested()) { return; } if (mActionState != ACTION_STATE_DRAG) { return; } final float threshold = mCallback.getMoveThreshold(viewHolder); final int x = (int) (mSelectedStartX + mDx); final int y = (int) (mSelectedStartY + mDy); if (Math.abs(y - viewHolder.itemView.getTop()) < viewHolder.itemView.getHeight() * threshold && Math.abs(x - viewHolder.itemView.getLeft()) < viewHolder.itemView.getWidth() * threshold) { return; } List<ViewHolder> swapTargets = findSwapTargets(viewHolder); if (swapTargets.size() == 0) { return; } // may swap. ViewHolder target = mCallback.chooseDropTarget(viewHolder, swapTargets, x, y); if (target == null) { mSwapTargets.clear(); mDistances.clear(); return; } final int toPosition = target.getAdapterPosition(); final int fromPosition = viewHolder.getAdapterPosition(); if (mCallback.onMove(mRecyclerView, viewHolder, target)) { // keep target visible mCallback.onMoved(mRecyclerView, viewHolder, fromPosition, target, toPosition, x, y); } } @Override public void onChildViewAttachedToWindow(View view) { } @Override public void onChildViewDetachedFromWindow(View view) { removeChildDrawingOrderCallbackIfNecessary(view); final ViewHolder holder = mRecyclerView.getChildViewHolder(view); if (holder == null) { return; } if (mSelected != null && holder == mSelected) { select(null, ACTION_STATE_IDLE); } else { endRecoverAnimation(holder, false); // this may push it into pending cleanup list. if (mPendingCleanup.remove(holder.itemView)) { mCallback.clearView(mRecyclerView, holder); } } } /** * Returns the animation type or 0 if cannot be found. */ private int endRecoverAnimation(ViewHolder viewHolder, boolean override) { final int recoverAnimSize = mRecoverAnimations.size(); for (int i = recoverAnimSize - 1; i >= 0; i--) { final RecoverAnimation anim = mRecoverAnimations.get(i); if (anim.mViewHolder == viewHolder) { anim.mOverridden |= override; if (!anim.mEnded) { anim.cancel(); } mRecoverAnimations.remove(i); anim.mViewHolder.setIsRecyclable(true); return anim.mAnimationType; } } return 0; } @Override public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) { outRect.setEmpty(); } private void obtainVelocityTracker() { if (mVelocityTracker != null) { mVelocityTracker.recycle(); } mVelocityTracker = VelocityTracker.obtain(); } private void releaseVelocityTracker() { if (mVelocityTracker != null) { mVelocityTracker.recycle(); mVelocityTracker = null; } } private ViewHolder findSwipedView(MotionEvent motionEvent) { final RecyclerView.LayoutManager lm = mRecyclerView.getLayoutManager(); if (mActivePointerId == ACTIVE_POINTER_ID_NONE) { return null; } final int pointerIndex = MotionEventCompat.findPointerIndex(motionEvent, mActivePointerId); final float dx = MotionEventCompat.getX(motionEvent, pointerIndex) - mInitialTouchX; final float dy = MotionEventCompat.getY(motionEvent, pointerIndex) - mInitialTouchY; final float absDx = Math.abs(dx); final float absDy = Math.abs(dy); if (absDx < mSlop && absDy < mSlop) { return null; } if (absDx > absDy && lm.canScrollHorizontally()) { return null; } else if (absDy > absDx && lm.canScrollVertically()) { return null; } View child = findChildView(motionEvent); if (child == null) { return null; } return mRecyclerView.getChildViewHolder(child); } /** * Checks whether we should select a View for swiping. */ private boolean checkSelectForSwipe(int action, MotionEvent motionEvent, int pointerIndex) { if (mSelected != null || action != MotionEvent.ACTION_MOVE || mActionState == ACTION_STATE_DRAG || !mCallback.isItemViewSwipeEnabled()) { return false; } if (mRecyclerView.getScrollState() == RecyclerView.SCROLL_STATE_DRAGGING) { return false; } final ViewHolder vh = findSwipedView(motionEvent); if (vh == null) { return false; } final int movementFlags = mCallback.getAbsoluteMovementFlags(mRecyclerView, vh); final int swipeFlags = (movementFlags & ACTION_MODE_SWIPE_MASK) >> (DIRECTION_FLAG_COUNT * ACTION_STATE_SWIPE); if (swipeFlags == 0) { return false; } // mDx and mDy are only set in allowed directions. We use custom x/y here instead of // updateDxDy to avoid swiping if user moves more in the other direction final float x = MotionEventCompat.getX(motionEvent, pointerIndex); final float y = MotionEventCompat.getY(motionEvent, pointerIndex); // Calculate the distance moved final float dx = x - mInitialTouchX; final float dy = y - mInitialTouchY; // swipe target is chose w/o applying flags so it does not really check if swiping in that // direction is allowed. This why here, we use mDx mDy to check slope value again. final float absDx = Math.abs(dx); final float absDy = Math.abs(dy); if (absDx < mSlop && absDy < mSlop) { return false; } if (absDx > absDy) { if (dx < 0 && (swipeFlags & LEFT) == 0) { return false; } if (dx > 0 && (swipeFlags & RIGHT) == 0) { return false; } } else { if (dy < 0 && (swipeFlags & UP) == 0) { return false; } if (dy > 0 && (swipeFlags & DOWN) == 0) { return false; } } mDx = mDy = 0f; mActivePointerId = MotionEventCompat.getPointerId(motionEvent, 0); select(vh, ACTION_STATE_SWIPE); return true; } private View findChildView(MotionEvent event) { // first check elevated views, if none, then call RV final float x = event.getX(); final float y = event.getY(); if (mSelected != null) { final View selectedView = mSelected.itemView; if (hitTest(selectedView, x, y, mSelectedStartX + mDx, mSelectedStartY + mDy)) { return selectedView; } } for (int i = mRecoverAnimations.size() - 1; i >= 0; i--) { final RecoverAnimation anim = mRecoverAnimations.get(i); final View view = anim.mViewHolder.itemView; if (hitTest(view, x, y, anim.mX, anim.mY)) { return view; } } return mRecyclerView.findChildViewUnder(x, y); } /** * Starts dragging the provided ViewHolder. By default, ItemTouchHelper starts a drag when a * View is long pressed. You can disable that behavior via * {@link Callback#isLongPressDragEnabled()}. * <p> * For this method to work: * <ul> * <li>The provided ViewHolder must be a child of the RecyclerView to which this * ItemTouchHelper * is attached.</li> * <li>{@link Callback} must have dragging enabled.</li> * <li>There must be a previous touch event that was reported to the ItemTouchHelper * through RecyclerView's ItemTouchListener mechanism. As long as no other ItemTouchListener * grabs previous events, this should work as expected.</li> * </ul> * * For example, if you would like to let your user to be able to drag an Item by touching one * of its descendants, you may implement it as follows: * <pre> * viewHolder.dragButton.setOnTouchListener(new View.OnTouchListener() { * public boolean onTouch(View v, MotionEvent event) { * if (MotionEventCompat.getActionMasked(event) == MotionEvent.ACTION_DOWN) { * mItemTouchHelper.startDrag(viewHolder); * } * return false; * } * }); * </pre> * <p> * * @param viewHolder The ViewHolder to start dragging. It must be a direct child of * RecyclerView. * @see Callback#isItemViewSwipeEnabled() */ public void startDrag(ViewHolder viewHolder) { if (!mCallback.hasDragFlag(mRecyclerView, viewHolder)) { Log.e(TAG, "Start drag has been called but swiping is not enabled"); return; } if (viewHolder.itemView.getParent() != mRecyclerView) { Log.e(TAG, "Start drag has been called with a view holder which is not a child of " + "the RecyclerView which is controlled by this ItemTouchHelper."); return; } obtainVelocityTracker(); mDx = mDy = 0f; select(viewHolder, ACTION_STATE_DRAG); } /** * Starts swiping the provided ViewHolder. By default, ItemTouchHelper starts swiping a View * when user swipes their finger (or mouse pointer) over the View. You can disable this * behavior * by overriding {@link Callback} * <p> * For this method to work: * <ul> * <li>The provided ViewHolder must be a child of the RecyclerView to which this * ItemTouchHelper is attached.</li> * <li>{@link Callback} must have swiping enabled.</li> * <li>There must be a previous touch event that was reported to the ItemTouchHelper * through RecyclerView's ItemTouchListener mechanism. As long as no other ItemTouchListener * grabs previous events, this should work as expected.</li> * </ul> * * For example, if you would like to let your user to be able to swipe an Item by touching one * of its descendants, you may implement it as follows: * <pre> * viewHolder.dragButton.setOnTouchListener(new View.OnTouchListener() { * public boolean onTouch(View v, MotionEvent event) { * if (MotionEventCompat.getActionMasked(event) == MotionEvent.ACTION_DOWN) { * mItemTouchHelper.startSwipe(viewHolder); * } * return false; * } * }); * </pre> * * @param viewHolder The ViewHolder to start swiping. It must be a direct child of * RecyclerView. */ public void startSwipe(ViewHolder viewHolder) { if (!mCallback.hasSwipeFlag(mRecyclerView, viewHolder)) { Log.e(TAG, "Start swipe has been called but dragging is not enabled"); return; } if (viewHolder.itemView.getParent() != mRecyclerView) { Log.e(TAG, "Start swipe has been called with a view holder which is not a child of " + "the RecyclerView controlled by this ItemTouchHelper."); return; } obtainVelocityTracker(); mDx = mDy = 0f; select(viewHolder, ACTION_STATE_SWIPE); } private RecoverAnimation findAnimation(MotionEvent event) { if (mRecoverAnimations.isEmpty()) { return null; } View target = findChildView(event); for (int i = mRecoverAnimations.size() - 1; i >= 0; i--) { final RecoverAnimation anim = mRecoverAnimations.get(i); if (anim.mViewHolder.itemView == target) { return anim; } } return null; } private void updateDxDy(MotionEvent ev, int directionFlags, int pointerIndex) { final float x = MotionEventCompat.getX(ev, pointerIndex); final float y = MotionEventCompat.getY(ev, pointerIndex); // Calculate the distance moved mDx = x - mInitialTouchX; mDy = y - mInitialTouchY; if ((directionFlags & LEFT) == 0) { mDx = Math.max(0, mDx); } if ((directionFlags & RIGHT) == 0) { mDx = Math.min(0, mDx); } if ((directionFlags & UP) == 0) { mDy = Math.max(0, mDy); } if ((directionFlags & DOWN) == 0) { mDy = Math.min(0, mDy); } } private int swipeIfNecessary(ViewHolder viewHolder) { if (mActionState == ACTION_STATE_DRAG) { return 0; } final int originalMovementFlags = mCallback.getMovementFlags(mRecyclerView, viewHolder); final int absoluteMovementFlags = mCallback.convertToAbsoluteDirection(originalMovementFlags, ViewCompat.getLayoutDirection(mRecyclerView)); final int flags = (absoluteMovementFlags & ACTION_MODE_SWIPE_MASK) >> (ACTION_STATE_SWIPE * DIRECTION_FLAG_COUNT); if (flags == 0) { return 0; } final int originalFlags = (originalMovementFlags & ACTION_MODE_SWIPE_MASK) >> (ACTION_STATE_SWIPE * DIRECTION_FLAG_COUNT); int swipeDir; if (Math.abs(mDx) > Math.abs(mDy)) { if ((swipeDir = checkHorizontalSwipe(viewHolder, flags)) > 0) { // if swipe dir is not in original flags, it should be the relative direction if ((originalFlags & swipeDir) == 0) { // convert to relative return Callback.convertToRelativeDirection(swipeDir, ViewCompat.getLayoutDirection(mRecyclerView)); } return swipeDir; } if ((swipeDir = checkVerticalSwipe(viewHolder, flags)) > 0) { return swipeDir; } } else { if ((swipeDir = checkVerticalSwipe(viewHolder, flags)) > 0) { return swipeDir; } if ((swipeDir = checkHorizontalSwipe(viewHolder, flags)) > 0) { // if swipe dir is not in original flags, it should be the relative direction if ((originalFlags & swipeDir) == 0) { // convert to relative return Callback.convertToRelativeDirection(swipeDir, ViewCompat.getLayoutDirection(mRecyclerView)); } return swipeDir; } } return 0; } private int checkHorizontalSwipe(ViewHolder viewHolder, int flags) { if ((flags & (LEFT | RIGHT)) != 0) { final int dirFlag = mDx > 0 ? RIGHT : LEFT; if (mVelocityTracker != null && mActivePointerId > -1) { final float xVelocity = VelocityTrackerCompat.getXVelocity(mVelocityTracker, mActivePointerId); final int velDirFlag = xVelocity > 0f ? RIGHT : LEFT; if ((velDirFlag & flags) != 0 && dirFlag == velDirFlag && Math.abs(xVelocity) >= mRecyclerView.getMinFlingVelocity()) { return velDirFlag; } } final float threshold = mRecyclerView.getWidth() * mCallback.getSwipeThreshold(viewHolder); if ((flags & dirFlag) != 0 && Math.abs(mDx) > threshold) { return dirFlag; } } return 0; } private int checkVerticalSwipe(ViewHolder viewHolder, int flags) { if ((flags & (UP | DOWN)) != 0) { final int dirFlag = mDy > 0 ? DOWN : UP; if (mVelocityTracker != null && mActivePointerId > -1) { final float yVelocity = VelocityTrackerCompat.getYVelocity(mVelocityTracker, mActivePointerId); final int velDirFlag = yVelocity > 0f ? DOWN : UP; if ((velDirFlag & flags) != 0 && velDirFlag == dirFlag && Math.abs(yVelocity) >= mRecyclerView.getMinFlingVelocity()) { return velDirFlag; } } final float threshold = mRecyclerView.getHeight() * mCallback.getSwipeThreshold(viewHolder); if ((flags & dirFlag) != 0 && Math.abs(mDy) > threshold) { return dirFlag; } } return 0; } private void addChildDrawingOrderCallback() { if (Build.VERSION.SDK_INT >= 21) { return;// we use elevation on Lollipop } if (mChildDrawingOrderCallback == null) { mChildDrawingOrderCallback = new RecyclerView.ChildDrawingOrderCallback() { @Override public int onGetChildDrawingOrder(int childCount, int i) { if (mOverdrawChild == null) { return i; } int childPosition = mOverdrawChildPosition; if (childPosition == -1) { childPosition = mRecyclerView.indexOfChild(mOverdrawChild); mOverdrawChildPosition = childPosition; } if (i == childCount - 1) { return childPosition; } return i < childPosition ? i : i + 1; } }; } mRecyclerView.setChildDrawingOrderCallback(mChildDrawingOrderCallback); } private void removeChildDrawingOrderCallbackIfNecessary(View view) { if (view == mOverdrawChild) { mOverdrawChild = null; // only remove if we've added if (mChildDrawingOrderCallback != null) { mRecyclerView.setChildDrawingOrderCallback(null); } } } /** * An interface which can be implemented by LayoutManager for better integration with * {@link ItemTouchHelper}. */ public static interface ViewDropHandler { /** * Called by the {@link ItemTouchHelper} after a View is dropped over another View. * <p> * A LayoutManager should implement this interface to get ready for the upcoming move * operation. * <p> * For example, LinearLayoutManager sets up a "scrollToPositionWithOffset" calls so that * the View under drag will be used as an anchor View while calculating the next layout, * making layout stay consistent. * * @param view The View which is being dragged. It is very likely that user is still * dragging this View so there might be other * {@link #prepareForDrop(View, View, int, int)} after this one. * @param target The target view which is being dropped on. * @param x The <code>left</code> offset of the View that is being dragged. This value * includes the movement caused by the user. * @param y The <code>top</code> offset of the View that is being dragged. This value * includes the movement caused by the user. */ public void prepareForDrop(View view, View target, int x, int y); } /** * This class is the contract between ItemTouchHelper and your application. It lets you control * which touch behaviors are enabled per each ViewHolder and also receive callbacks when user * performs these actions. * <p> * To control which actions user can take on each view, you should override * {@link #getMovementFlags(RecyclerView, ViewHolder)} and return appropriate set * of direction flags. ({@link #LEFT}, {@link #RIGHT}, {@link #START}, {@link #END}, * {@link #UP}, {@link #DOWN}). You can use * {@link #makeMovementFlags(int, int)} to easily construct it. Alternatively, you can use * {@link SimpleCallback}. * <p> * If user drags an item, ItemTouchHelper will call * {@link Callback#onMove(RecyclerView, ViewHolder, ViewHolder) * onMove(recyclerView, dragged, target)}. * Upon receiving this callback, you should move the item from the old position * ({@code dragged.getAdapterPosition()}) to new position ({@code target.getAdapterPosition()}) * in your adapter and also call {@link RecyclerView.Adapter#notifyItemMoved(int, int)}. * To control where a View can be dropped, you can override * {@link #canDropOver(RecyclerView, ViewHolder, ViewHolder)}. When a * dragging View overlaps multiple other views, Callback chooses the closest View with which * dragged View might have changed positions. Although this approach works for many use cases, * if you have a custom LayoutManager, you can override * {@link #chooseDropTarget(ViewHolder, List, int, int)} to select a * custom drop target. * <p> * When a View is swiped, ItemTouchHelper animates it until it goes out of bounds, then calls * {@link #onSwiped(ViewHolder, int)}. At this point, you should update your * adapter (e.g. remove the item) and call related Adapter#notify event. */ @SuppressWarnings("UnusedParameters") public abstract static class Callback { public static final int DEFAULT_DRAG_ANIMATION_DURATION = 200; public static final int DEFAULT_SWIPE_ANIMATION_DURATION = 250; static final int RELATIVE_DIR_FLAGS = START | END | ((START | END) << DIRECTION_FLAG_COUNT) | ((START | END) << (2 * DIRECTION_FLAG_COUNT)); private static final ItemTouchUIUtil sUICallback; private static final int ABS_HORIZONTAL_DIR_FLAGS = LEFT | RIGHT | ((LEFT | RIGHT) << DIRECTION_FLAG_COUNT) | ((LEFT | RIGHT) << (2 * DIRECTION_FLAG_COUNT)); private static final Interpolator sDragScrollInterpolator = new Interpolator() { public float getInterpolation(float t) { return t * t * t * t * t; } }; private static final Interpolator sDragViewScrollCapInterpolator = new Interpolator() { public float getInterpolation(float t) { t -= 1.0f; return t * t * t * t * t + 1.0f; } }; /** * Drag scroll speed keeps accelerating until this many milliseconds before being capped. */ private static final long DRAG_SCROLL_ACCELERATION_LIMIT_TIME_MS = 2000; private int mCachedMaxScrollSpeed = -1; static { if (Build.VERSION.SDK_INT >= 21) { sUICallback = new ItemTouchUIUtilImpl.Lollipop(); } else if (Build.VERSION.SDK_INT >= 11) { sUICallback = new ItemTouchUIUtilImpl.Honeycomb(); } else { sUICallback = new ItemTouchUIUtilImpl.Gingerbread(); } } /** * Returns the {@link ItemTouchUIUtil} that is used by the {@link Callback} class for visual * changes on Views in response to user interactions. {@link ItemTouchUIUtil} has different * implementations for different platform versions. * <p> * By default, {@link Callback} applies these changes on * {@link ViewHolder#itemView}. * <p> * For example, if you have a use case where you only want the text to move when user * swipes over the view, you can do the following: * <pre> * public void clearView(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder){ * getDefaultUIUtil().clearView(((ItemTouchViewHolder) viewHolder).textView); * } * public void onSelectedChanged(RecyclerView.ViewHolder viewHolder, int actionState) { * if (viewHolder != null){ * getDefaultUIUtil().onSelected(((ItemTouchViewHolder) viewHolder).textView); * } * } * public void onChildDraw(Canvas c, RecyclerView recyclerView, * RecyclerView.ViewHolder viewHolder, float dX, float dY, int actionState, * boolean isCurrentlyActive) { * getDefaultUIUtil().onDraw(c, recyclerView, * ((ItemTouchViewHolder) viewHolder).textView, dX, dY, * actionState, isCurrentlyActive); * return true; * } * public void onChildDrawOver(Canvas c, RecyclerView recyclerView, * RecyclerView.ViewHolder viewHolder, float dX, float dY, int actionState, * boolean isCurrentlyActive) { * getDefaultUIUtil().onDrawOver(c, recyclerView, * ((ItemTouchViewHolder) viewHolder).textView, dX, dY, * actionState, isCurrentlyActive); * return true; * } * </pre> * * @return The {@link ItemTouchUIUtil} instance that is used by the {@link Callback} */ public static ItemTouchUIUtil getDefaultUIUtil() { return sUICallback; } /** * Replaces a movement direction with its relative version by taking layout direction into * account. * * @param flags The flag value that include any number of movement flags. * @param layoutDirection The layout direction of the View. Can be obtained from * {@link ViewCompat#getLayoutDirection(View)}. * @return Updated flags which uses relative flags ({@link #START}, {@link #END}) instead * of {@link #LEFT}, {@link #RIGHT}. * @see #convertToAbsoluteDirection(int, int) */ public static int convertToRelativeDirection(int flags, int layoutDirection) { int masked = flags & ABS_HORIZONTAL_DIR_FLAGS; if (masked == 0) { return flags;// does not have any abs flags, good. } flags &= ~masked; //remove left / right. if (layoutDirection == ViewCompat.LAYOUT_DIRECTION_LTR) { // no change. just OR with 2 bits shifted mask and return flags |= masked << 2; // START is 2 bits after LEFT, END is 2 bits after RIGHT. return flags; } else { // add RIGHT flag as START flags |= ((masked << 1) & ~ABS_HORIZONTAL_DIR_FLAGS); // first clean RIGHT bit then add LEFT flag as END flags |= ((masked << 1) & ABS_HORIZONTAL_DIR_FLAGS) << 2; } return flags; } /** * Convenience method to create movement flags. * <p> * For instance, if you want to let your items be drag & dropped vertically and swiped * left to be dismissed, you can call this method with: * <code>makeMovementFlags(UP | DOWN, LEFT);</code> * * @param dragFlags The directions in which the item can be dragged. * @param swipeFlags The directions in which the item can be swiped. * @return Returns an integer composed of the given drag and swipe flags. */ public static int makeMovementFlags(int dragFlags, int swipeFlags) { return makeFlag(ACTION_STATE_IDLE, swipeFlags | dragFlags) | makeFlag(ACTION_STATE_SWIPE, swipeFlags) | makeFlag(ACTION_STATE_DRAG, dragFlags); } /** * Shifts the given direction flags to the offset of the given action state. * * @param actionState The action state you want to get flags in. Should be one of * {@link #ACTION_STATE_IDLE}, {@link #ACTION_STATE_SWIPE} or * {@link #ACTION_STATE_DRAG}. * @param directions The direction flags. Can be composed from {@link #UP}, {@link #DOWN}, * {@link #RIGHT}, {@link #LEFT} {@link #START} and {@link #END}. * @return And integer that represents the given directions in the provided actionState. */ public static int makeFlag(int actionState, int directions) { return directions << (actionState * DIRECTION_FLAG_COUNT); } /** * Should return a composite flag which defines the enabled move directions in each state * (idle, swiping, dragging). * <p> * Instead of composing this flag manually, you can use {@link #makeMovementFlags(int, * int)} * or {@link #makeFlag(int, int)}. * <p> * This flag is composed of 3 sets of 8 bits, where first 8 bits are for IDLE state, next * 8 bits are for SWIPE state and third 8 bits are for DRAG state. * Each 8 bit sections can be constructed by simply OR'ing direction flags defined in * {@link ItemTouchHelper}. * <p> * For example, if you want it to allow swiping LEFT and RIGHT but only allow starting to * swipe by swiping RIGHT, you can return: * <pre> * makeFlag(ACTION_STATE_IDLE, RIGHT) | makeFlag(ACTION_STATE_SWIPE, LEFT | RIGHT); * </pre> * This means, allow right movement while IDLE and allow right and left movement while * swiping. * * @param recyclerView The RecyclerView to which ItemTouchHelper is attached. * @param viewHolder The ViewHolder for which the movement information is necessary. * @return flags specifying which movements are allowed on this ViewHolder. * @see #makeMovementFlags(int, int) * @see #makeFlag(int, int) */ public abstract int getMovementFlags(RecyclerView recyclerView, ViewHolder viewHolder); /** * Converts a given set of flags to absolution direction which means {@link #START} and * {@link #END} are replaced with {@link #LEFT} and {@link #RIGHT} depending on the layout * direction. * * @param flags The flag value that include any number of movement flags. * @param layoutDirection The layout direction of the RecyclerView. * @return Updated flags which includes only absolute direction values. */ public int convertToAbsoluteDirection(int flags, int layoutDirection) { int masked = flags & RELATIVE_DIR_FLAGS; if (masked == 0) { return flags;// does not have any relative flags, good. } flags &= ~masked; //remove start / end if (layoutDirection == ViewCompat.LAYOUT_DIRECTION_LTR) { // no change. just OR with 2 bits shifted mask and return flags |= masked >> 2; // START is 2 bits after LEFT, END is 2 bits after RIGHT. return flags; } else { // add START flag as RIGHT flags |= ((masked >> 1) & ~RELATIVE_DIR_FLAGS); // first clean start bit then add END flag as LEFT flags |= ((masked >> 1) & RELATIVE_DIR_FLAGS) >> 2; } return flags; } final int getAbsoluteMovementFlags(RecyclerView recyclerView, ViewHolder viewHolder) { final int flags = getMovementFlags(recyclerView, viewHolder); return convertToAbsoluteDirection(flags, ViewCompat.getLayoutDirection(recyclerView)); } private boolean hasDragFlag(RecyclerView recyclerView, ViewHolder viewHolder) { final int flags = getAbsoluteMovementFlags(recyclerView, viewHolder); return (flags & ACTION_MODE_DRAG_MASK) != 0; } private boolean hasSwipeFlag(RecyclerView recyclerView, ViewHolder viewHolder) { final int flags = getAbsoluteMovementFlags(recyclerView, viewHolder); return (flags & ACTION_MODE_SWIPE_MASK) != 0; } /** * Return true if the current ViewHolder can be dropped over the the target ViewHolder. * <p> * This method is used when selecting drop target for the dragged View. After Views are * eliminated either via bounds check or via this method, resulting set of views will be * passed to {@link #chooseDropTarget(ViewHolder, List, int, int)}. * <p> * Default implementation returns true. * * @param recyclerView The RecyclerView to which ItemTouchHelper is attached to. * @param current The ViewHolder that user is dragging. * @param target The ViewHolder which is below the dragged ViewHolder. * @return True if the dragged ViewHolder can be replaced with the target ViewHolder, false * otherwise. */ public boolean canDropOver(RecyclerView recyclerView, ViewHolder current, ViewHolder target) { return true; } /** * Called when ItemTouchHelper wants to move the dragged item from its old position to * the new position. * <p> * If this method returns true, ItemTouchHelper assumes {@code viewHolder} has been moved * to the adapter position of {@code target} ViewHolder * ({@link ViewHolder#getAdapterPosition() * ViewHolder#getAdapterPosition()}). * <p> * If you don't support drag & drop, this method will never be called. * * @param recyclerView The RecyclerView to which ItemTouchHelper is attached to. * @param viewHolder The ViewHolder which is being dragged by the user. * @param target The ViewHolder over which the currently active item is being * dragged. * @return True if the {@code viewHolder} has been moved to the adapter position of * {@code target}. * @see #onMoved(RecyclerView, ViewHolder, int, ViewHolder, int, int, int) */ public abstract boolean onMove(RecyclerView recyclerView, ViewHolder viewHolder, ViewHolder target); /** * Returns whether ItemTouchHelper should start a drag and drop operation if an item is * long pressed. * <p> * Default value returns true but you may want to disable this if you want to start * dragging on a custom view touch using {@link #startDrag(ViewHolder)}. * * @return True if ItemTouchHelper should start dragging an item when it is long pressed, * false otherwise. Default value is <code>true</code>. * @see #startDrag(ViewHolder) */ public boolean isLongPressDragEnabled() { return true; } /** * Returns whether ItemTouchHelper should start a swipe operation if a pointer is swiped * over the View. * <p> * Default value returns true but you may want to disable this if you want to start * swiping on a custom view touch using {@link #startSwipe(ViewHolder)}. * * @return True if ItemTouchHelper should start swiping an item when user swipes a pointer * over the View, false otherwise. Default value is <code>true</code>. * @see #startSwipe(ViewHolder) */ public boolean isItemViewSwipeEnabled() { return true; } /** * When finding views under a dragged view, by default, ItemTouchHelper searches for views * that overlap with the dragged View. By overriding this method, you can extend or shrink * the search box. * * @return The extra margin to be added to the hit box of the dragged View. */ public int getBoundingBoxMargin() { return 0; } /** * Returns the fraction that the user should move the View to be considered as swiped. * The fraction is calculated with respect to RecyclerView's bounds. * <p> * Default value is .5f, which means, to swipe a View, user must move the View at least * half of RecyclerView's width or height, depending on the swipe direction. * * @param viewHolder The ViewHolder that is being dragged. * @return A float value that denotes the fraction of the View size. Default value * is .5f . */ public float getSwipeThreshold(ViewHolder viewHolder) { return .5f; } /** * Returns the fraction that the user should move the View to be considered as it is * dragged. After a view is moved this amount, ItemTouchHelper starts checking for Views * below it for a possible drop. * * @param viewHolder The ViewHolder that is being dragged. * @return A float value that denotes the fraction of the View size. Default value is * .5f . */ public float getMoveThreshold(ViewHolder viewHolder) { return .5f; } /** * Called by ItemTouchHelper to select a drop target from the list of ViewHolders that * are under the dragged View. * <p> * Default implementation filters the View with which dragged item have changed position * in the drag direction. For instance, if the view is dragged UP, it compares the * <code>view.getTop()</code> of the two views before and after drag started. If that value * is different, the target view passes the filter. * <p> * Among these Views which pass the test, the one closest to the dragged view is chosen. * <p> * This method is called on the main thread every time user moves the View. If you want to * override it, make sure it does not do any expensive operations. * * @param selected The ViewHolder being dragged by the user. * @param dropTargets The list of ViewHolder that are under the dragged View and * candidate as a drop. * @param curX The updated left value of the dragged View after drag translations * are applied. This value does not include margins added by * {@link RecyclerView.ItemDecoration}s. * @param curY The updated top value of the dragged View after drag translations * are applied. This value does not include margins added by * {@link RecyclerView.ItemDecoration}s. * @return A ViewHolder to whose position the dragged ViewHolder should be * moved to. */ public ViewHolder chooseDropTarget(ViewHolder selected, List<ViewHolder> dropTargets, int curX, int curY) { int right = curX + selected.itemView.getWidth(); int bottom = curY + selected.itemView.getHeight(); ViewHolder winner = null; int winnerScore = -1; final int dx = curX - selected.itemView.getLeft(); final int dy = curY - selected.itemView.getTop(); final int targetsSize = dropTargets.size(); for (int i = 0; i < targetsSize; i++) { final ViewHolder target = dropTargets.get(i); if (dx > 0) { int diff = target.itemView.getRight() - right; if (diff < 0 && target.itemView.getRight() > selected.itemView.getRight()) { final int score = Math.abs(diff); if (score > winnerScore) { winnerScore = score; winner = target; } } } if (dx < 0) { int diff = target.itemView.getLeft() - curX; if (diff > 0 && target.itemView.getLeft() < selected.itemView.getLeft()) { final int score = Math.abs(diff); if (score > winnerScore) { winnerScore = score; winner = target; } } } if (dy < 0) { int diff = target.itemView.getTop() - curY; if (diff > 0 && target.itemView.getTop() < selected.itemView.getTop()) { final int score = Math.abs(diff); if (score > winnerScore) { winnerScore = score; winner = target; } } } if (dy > 0) { int diff = target.itemView.getBottom() - bottom; if (diff < 0 && target.itemView.getBottom() > selected.itemView.getBottom()) { final int score = Math.abs(diff); if (score > winnerScore) { winnerScore = score; winner = target; } } } } return winner; } /** * Called when a ViewHolder is swiped by the user. * <p> * If you are returning relative directions ({@link #START} , {@link #END}) from the * {@link #getMovementFlags(RecyclerView, ViewHolder)} method, this method * will also use relative directions. Otherwise, it will use absolute directions. * <p> * If you don't support swiping, this method will never be called. * <p> * ItemTouchHelper will keep a reference to the View until it is detached from * RecyclerView. * As soon as it is detached, ItemTouchHelper will call * {@link #clearView(RecyclerView, ViewHolder)}. * * @param viewHolder The ViewHolder which has been swiped by the user. * @param direction The direction to which the ViewHolder is swiped. It is one of * {@link #UP}, {@link #DOWN}, * {@link #LEFT} or {@link #RIGHT}. If your * {@link #getMovementFlags(RecyclerView, ViewHolder)} * method * returned relative flags instead of {@link #LEFT} / {@link #RIGHT}; * `direction` will be relative as well. ({@link #START} or {@link * #END}). */ public abstract void onSwiped(ViewHolder viewHolder, int direction); /** * Called when the ViewHolder swiped or dragged by the ItemTouchHelper is changed. * <p/> * If you override this method, you should call super. * * @param viewHolder The new ViewHolder that is being swiped or dragged. Might be null if * it is cleared. * @param actionState One of {@link ItemTouchHelper#ACTION_STATE_IDLE}, * {@link ItemTouchHelper#ACTION_STATE_SWIPE} or * {@link ItemTouchHelper#ACTION_STATE_DRAG}. * * @see #clearView(RecyclerView, ViewHolder) */ public void onSelectedChanged(ViewHolder viewHolder, int actionState) { if (viewHolder != null) { sUICallback.onSelected(viewHolder.itemView); } } private int getMaxDragScroll(RecyclerView recyclerView) { if (mCachedMaxScrollSpeed == -1) { mCachedMaxScrollSpeed = recyclerView.getResources() .getDimensionPixelSize(R.dimen.item_touch_helper_max_drag_scroll_per_frame); } return mCachedMaxScrollSpeed; } /** * Called when {@link #onMove(RecyclerView, ViewHolder, ViewHolder)} returns true. * <p> * ItemTouchHelper does not create an extra Bitmap or View while dragging, instead, it * modifies the existing View. Because of this reason, it is important that the View is * still part of the layout after it is moved. This may not work as intended when swapped * Views are close to RecyclerView bounds or there are gaps between them (e.g. other Views * which were not eligible for dropping over). * <p> * This method is responsible to give necessary hint to the LayoutManager so that it will * keep the View in visible area. For example, for LinearLayoutManager, this is as simple * as calling {@link LinearLayoutManager#scrollToPositionWithOffset(int, int)}. * * Default implementation calls {@link RecyclerView#scrollToPosition(int)} if the View's * new position is likely to be out of bounds. * <p> * It is important to ensure the ViewHolder will stay visible as otherwise, it might be * removed by the LayoutManager if the move causes the View to go out of bounds. In that * case, drag will end prematurely. * * @param recyclerView The RecyclerView controlled by the ItemTouchHelper. * @param viewHolder The ViewHolder under user's control. * @param fromPos The previous adapter position of the dragged item (before it was * moved). * @param target The ViewHolder on which the currently active item has been dropped. * @param toPos The new adapter position of the dragged item. * @param x The updated left value of the dragged View after drag translations * are applied. This value does not include margins added by * {@link RecyclerView.ItemDecoration}s. * @param y The updated top value of the dragged View after drag translations * are applied. This value does not include margins added by * {@link RecyclerView.ItemDecoration}s. */ public void onMoved(final RecyclerView recyclerView, final ViewHolder viewHolder, int fromPos, final ViewHolder target, int toPos, int x, int y) { final RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager(); if (layoutManager instanceof ViewDropHandler) { ((ViewDropHandler) layoutManager).prepareForDrop(viewHolder.itemView, target.itemView, x, y); return; } // if layout manager cannot handle it, do some guesswork if (layoutManager.canScrollHorizontally()) { final int minLeft = layoutManager.getDecoratedLeft(target.itemView); if (minLeft <= recyclerView.getPaddingLeft()) { recyclerView.scrollToPosition(toPos); } final int maxRight = layoutManager.getDecoratedRight(target.itemView); if (maxRight >= recyclerView.getWidth() - recyclerView.getPaddingRight()) { recyclerView.scrollToPosition(toPos); } } if (layoutManager.canScrollVertically()) { final int minTop = layoutManager.getDecoratedTop(target.itemView); if (minTop <= recyclerView.getPaddingTop()) { recyclerView.scrollToPosition(toPos); } final int maxBottom = layoutManager.getDecoratedBottom(target.itemView); if (maxBottom >= recyclerView.getHeight() - recyclerView.getPaddingBottom()) { recyclerView.scrollToPosition(toPos); } } } private void onDraw(Canvas c, RecyclerView parent, ViewHolder selected, List<RecoverAnimation> recoverAnimationList, int actionState, float dX, float dY) { final int recoverAnimSize = recoverAnimationList.size(); for (int i = 0; i < recoverAnimSize; i++) { final RecoverAnimation anim = recoverAnimationList.get(i); anim.update(); final int count = c.save(); onChildDraw(c, parent, anim.mViewHolder, anim.mX, anim.mY, anim.mActionState, false); c.restoreToCount(count); } if (selected != null) { final int count = c.save(); onChildDraw(c, parent, selected, dX, dY, actionState, true); c.restoreToCount(count); } } private void onDrawOver(Canvas c, RecyclerView parent, ViewHolder selected, List<RecoverAnimation> recoverAnimationList, int actionState, float dX, float dY) { final int recoverAnimSize = recoverAnimationList.size(); for (int i = 0; i < recoverAnimSize; i++) { final RecoverAnimation anim = recoverAnimationList.get(i); final int count = c.save(); onChildDrawOver(c, parent, anim.mViewHolder, anim.mX, anim.mY, anim.mActionState, false); c.restoreToCount(count); } if (selected != null) { final int count = c.save(); onChildDrawOver(c, parent, selected, dX, dY, actionState, true); c.restoreToCount(count); } boolean hasRunningAnimation = false; for (int i = recoverAnimSize - 1; i >= 0; i--) { final RecoverAnimation anim = recoverAnimationList.get(i); if (anim.mEnded && !anim.mIsPendingCleanup) { recoverAnimationList.remove(i); anim.mViewHolder.setIsRecyclable(true); } else if (!anim.mEnded) { hasRunningAnimation = true; } } if (hasRunningAnimation) { parent.invalidate(); } } /** * Called by the ItemTouchHelper when the user interaction with an element is over and it * also completed its animation. * <p> * This is a good place to clear all changes on the View that was done in * {@link #onSelectedChanged(ViewHolder, int)}, * {@link #onChildDraw(Canvas, RecyclerView, ViewHolder, float, float, int, * boolean)} or * {@link #onChildDrawOver(Canvas, RecyclerView, ViewHolder, float, float, int, boolean)}. * * @param recyclerView The RecyclerView which is controlled by the ItemTouchHelper. * @param viewHolder The View that was interacted by the user. */ public void clearView(RecyclerView recyclerView, ViewHolder viewHolder) { sUICallback.clearView(viewHolder.itemView); } /** * Called by ItemTouchHelper on RecyclerView's onDraw callback. * <p> * If you would like to customize how your View's respond to user interactions, this is * a good place to override. * <p> * Default implementation translates the child by the given <code>dX</code>, * <code>dY</code>. * ItemTouchHelper also takes care of drawing the child after other children if it is being * dragged. This is done using child re-ordering mechanism. On platforms prior to L, this * is * achieved via {@link android.view.ViewGroup#getChildDrawingOrder(int, int)} and on L * and after, it changes View's elevation value to be greater than all other children.) * * @param c The canvas which RecyclerView is drawing its children * @param recyclerView The RecyclerView to which ItemTouchHelper is attached to * @param viewHolder The ViewHolder which is being interacted by the User or it was * interacted and simply animating to its original position * @param dX The amount of horizontal displacement caused by user's action * @param dY The amount of vertical displacement caused by user's action * @param actionState The type of interaction on the View. Is either {@link * #ACTION_STATE_DRAG} or {@link #ACTION_STATE_SWIPE}. * @param isCurrentlyActive True if this view is currently being controlled by the user or * false it is simply animating back to its original state. * @see #onChildDrawOver(Canvas, RecyclerView, ViewHolder, float, float, int, * boolean) */ public void onChildDraw(Canvas c, RecyclerView recyclerView, ViewHolder viewHolder, float dX, float dY, int actionState, boolean isCurrentlyActive) { sUICallback.onDraw(c, recyclerView, viewHolder.itemView, dX, dY, actionState, isCurrentlyActive); } /** * Called by ItemTouchHelper on RecyclerView's onDraw callback. * <p> * If you would like to customize how your View's respond to user interactions, this is * a good place to override. * <p> * Default implementation translates the child by the given <code>dX</code>, * <code>dY</code>. * ItemTouchHelper also takes care of drawing the child after other children if it is being * dragged. This is done using child re-ordering mechanism. On platforms prior to L, this * is * achieved via {@link android.view.ViewGroup#getChildDrawingOrder(int, int)} and on L * and after, it changes View's elevation value to be greater than all other children.) * * @param c The canvas which RecyclerView is drawing its children * @param recyclerView The RecyclerView to which ItemTouchHelper is attached to * @param viewHolder The ViewHolder which is being interacted by the User or it was * interacted and simply animating to its original position * @param dX The amount of horizontal displacement caused by user's action * @param dY The amount of vertical displacement caused by user's action * @param actionState The type of interaction on the View. Is either {@link * #ACTION_STATE_DRAG} or {@link #ACTION_STATE_SWIPE}. * @param isCurrentlyActive True if this view is currently being controlled by the user or * false it is simply animating back to its original state. * @see #onChildDrawOver(Canvas, RecyclerView, ViewHolder, float, float, int, * boolean) */ public void onChildDrawOver(Canvas c, RecyclerView recyclerView, ViewHolder viewHolder, float dX, float dY, int actionState, boolean isCurrentlyActive) { sUICallback.onDrawOver(c, recyclerView, viewHolder.itemView, dX, dY, actionState, isCurrentlyActive); } /** * Called by the ItemTouchHelper when user action finished on a ViewHolder and now the View * will be animated to its final position. * <p> * Default implementation uses ItemAnimator's duration values. If * <code>animationType</code> is {@link #ANIMATION_TYPE_DRAG}, it returns * {@link RecyclerView.ItemAnimator#getMoveDuration()}, otherwise, it returns * {@link RecyclerView.ItemAnimator#getRemoveDuration()}. If RecyclerView does not have * any {@link RecyclerView.ItemAnimator} attached, this method returns * {@code DEFAULT_DRAG_ANIMATION_DURATION} or {@code DEFAULT_SWIPE_ANIMATION_DURATION} * depending on the animation type. * * @param recyclerView The RecyclerView to which the ItemTouchHelper is attached to. * @param animationType The type of animation. Is one of {@link #ANIMATION_TYPE_DRAG}, * {@link #ANIMATION_TYPE_SWIPE_CANCEL} or * {@link #ANIMATION_TYPE_SWIPE_SUCCESS}. * @param animateDx The horizontal distance that the animation will offset * @param animateDy The vertical distance that the animation will offset * @return The duration for the animation */ public long getAnimationDuration(RecyclerView recyclerView, int animationType, float animateDx, float animateDy) { final RecyclerView.ItemAnimator itemAnimator = recyclerView.getItemAnimator(); if (itemAnimator == null) { return animationType == ANIMATION_TYPE_DRAG ? DEFAULT_DRAG_ANIMATION_DURATION : DEFAULT_SWIPE_ANIMATION_DURATION; } else { return animationType == ANIMATION_TYPE_DRAG ? itemAnimator.getMoveDuration() : itemAnimator.getRemoveDuration(); } } /** * Called by the ItemTouchHelper when user is dragging a view out of bounds. * <p> * You can override this method to decide how much RecyclerView should scroll in response * to this action. Default implementation calculates a value based on the amount of View * out of bounds and the time it spent there. The longer user keeps the View out of bounds, * the faster the list will scroll. Similarly, the larger portion of the View is out of * bounds, the faster the RecyclerView will scroll. * * @param recyclerView The RecyclerView instance to which ItemTouchHelper is attached * to. * @param viewSize The total size of the View in scroll direction, excluding * item decorations. * @param viewSizeOutOfBounds The total size of the View that is out of bounds. This value * is negative if the View is dragged towards left or top edge. * @param totalSize The total size of RecyclerView in the scroll direction. * @param msSinceStartScroll The time passed since View is kept out of bounds. * * @return The amount that RecyclerView should scroll. Keep in mind that this value will * be passed to {@link RecyclerView#scrollBy(int, int)} method. */ public int interpolateOutOfBoundsScroll(RecyclerView recyclerView, int viewSize, int viewSizeOutOfBounds, int totalSize, long msSinceStartScroll) { final int maxScroll = getMaxDragScroll(recyclerView); final int absOutOfBounds = Math.abs(viewSizeOutOfBounds); final int direction = (int) Math.signum(viewSizeOutOfBounds); // might be negative if other direction float outOfBoundsRatio = Math.min(1f, 1f * absOutOfBounds / viewSize); final int cappedScroll = (int) (direction * maxScroll * sDragViewScrollCapInterpolator.getInterpolation(outOfBoundsRatio)); final float timeRatio; if (msSinceStartScroll > DRAG_SCROLL_ACCELERATION_LIMIT_TIME_MS) { timeRatio = 1f; } else { timeRatio = (float) msSinceStartScroll / DRAG_SCROLL_ACCELERATION_LIMIT_TIME_MS; } final int value = (int) (cappedScroll * sDragScrollInterpolator.getInterpolation(timeRatio)); if (value == 0) { return viewSizeOutOfBounds > 0 ? 1 : -1; } return value; } } /** * A simple wrapper to the default Callback which you can construct with drag and swipe * directions and this class will handle the flag callbacks. You should still override onMove * or * onSwiped depending on your use case. * * <pre> * ItemTouchHelper mIth = new ItemTouchHelper( * new ItemTouchHelper.SimpleCallback(ItemTouchHelper.UP | ItemTouchHelper.DOWN, * ItemTouchHelper.LEFT) { * public abstract boolean onMove(RecyclerView recyclerView, * ViewHolder viewHolder, ViewHolder target) { * final int fromPos = viewHolder.getAdapterPosition(); * final int toPos = viewHolder.getAdapterPosition(); * // move item in `fromPos` to `toPos` in adapter. * return true;// true if moved, false otherwise * } * public void onSwiped(ViewHolder viewHolder, int direction) { * // remove from adapter * } * }); * </pre> */ public abstract static class SimpleCallback extends Callback { private int mDefaultSwipeDirs; private int mDefaultDragDirs; /** * Creates a Callback for the given drag and swipe allowance. These values serve as * defaults * and if you want to customize behavior per ViewHolder, you can override * {@link #getSwipeDirs(RecyclerView, ViewHolder)} * and / or {@link #getDragDirs(RecyclerView, ViewHolder)}. * * @param dragDirs Binary OR of direction flags in which the Views can be dragged. Must be * composed of {@link #LEFT}, {@link #RIGHT}, {@link #START}, {@link * #END}, * {@link #UP} and {@link #DOWN}. * @param swipeDirs Binary OR of direction flags in which the Views can be swiped. Must be * composed of {@link #LEFT}, {@link #RIGHT}, {@link #START}, {@link * #END}, * {@link #UP} and {@link #DOWN}. */ public SimpleCallback(int dragDirs, int swipeDirs) { mDefaultSwipeDirs = swipeDirs; mDefaultDragDirs = dragDirs; } /** * Updates the default swipe directions. For example, you can use this method to toggle * certain directions depending on your use case. * * @param defaultSwipeDirs Binary OR of directions in which the ViewHolders can be swiped. */ public void setDefaultSwipeDirs(int defaultSwipeDirs) { mDefaultSwipeDirs = defaultSwipeDirs; } /** * Updates the default drag directions. For example, you can use this method to toggle * certain directions depending on your use case. * * @param defaultDragDirs Binary OR of directions in which the ViewHolders can be dragged. */ public void setDefaultDragDirs(int defaultDragDirs) { mDefaultDragDirs = defaultDragDirs; } /** * Returns the swipe directions for the provided ViewHolder. * Default implementation returns the swipe directions that was set via constructor or * {@link #setDefaultSwipeDirs(int)}. * * @param recyclerView The RecyclerView to which the ItemTouchHelper is attached to. * @param viewHolder The RecyclerView for which the swipe drection is queried. * @return A binary OR of direction flags. */ public int getSwipeDirs(RecyclerView recyclerView, ViewHolder viewHolder) { return mDefaultSwipeDirs; } /** * Returns the drag directions for the provided ViewHolder. * Default implementation returns the drag directions that was set via constructor or * {@link #setDefaultDragDirs(int)}. * * @param recyclerView The RecyclerView to which the ItemTouchHelper is attached to. * @param viewHolder The RecyclerView for which the swipe drection is queried. * @return A binary OR of direction flags. */ public int getDragDirs(RecyclerView recyclerView, ViewHolder viewHolder) { return mDefaultDragDirs; } @Override public int getMovementFlags(RecyclerView recyclerView, ViewHolder viewHolder) { return makeMovementFlags(getDragDirs(recyclerView, viewHolder), getSwipeDirs(recyclerView, viewHolder)); } } private class ItemTouchHelperGestureListener extends GestureDetector.SimpleOnGestureListener { @Override public boolean onDown(MotionEvent e) { return true; } @Override public void onLongPress(MotionEvent e) { View child = findChildView(e); if (child != null) { ViewHolder vh = mRecyclerView.getChildViewHolder(child); if (vh != null) { if (!mCallback.hasDragFlag(mRecyclerView, vh)) { return; } int pointerId = MotionEventCompat.getPointerId(e, 0); // Long press is deferred. // Check w/ active pointer id to avoid selecting after motion // event is canceled. if (pointerId == mActivePointerId) { final int index = MotionEventCompat.findPointerIndex(e, mActivePointerId); final float x = MotionEventCompat.getX(e, index); final float y = MotionEventCompat.getY(e, index); mInitialTouchX = x; mInitialTouchY = y; mDx = mDy = 0f; if (DEBUG) { Log.d(TAG, "onlong press: x:" + mInitialTouchX + ",y:" + mInitialTouchY); } if (mCallback.isLongPressDragEnabled()) { select(vh, ACTION_STATE_DRAG); } } } } } } private class RecoverAnimation implements AnimatorListenerCompat { final float mStartDx; final float mStartDy; final float mTargetX; final float mTargetY; final ViewHolder mViewHolder; final int mActionState; private final ValueAnimatorCompat mValueAnimator; private final int mAnimationType; public boolean mIsPendingCleanup; float mX; float mY; // if user starts touching a recovering view, we put it into interaction mode again, // instantly. boolean mOverridden = false; private boolean mEnded = false; private float mFraction; public RecoverAnimation(ViewHolder viewHolder, int animationType, int actionState, float startDx, float startDy, float targetX, float targetY) { mActionState = actionState; mAnimationType = animationType; mViewHolder = viewHolder; mStartDx = startDx; mStartDy = startDy; mTargetX = targetX; mTargetY = targetY; mValueAnimator = AnimatorCompatHelper.emptyValueAnimator(); mValueAnimator.addUpdateListener(new AnimatorUpdateListenerCompat() { @Override public void onAnimationUpdate(ValueAnimatorCompat animation) { setFraction(animation.getAnimatedFraction()); } }); mValueAnimator.setTarget(viewHolder.itemView); mValueAnimator.addListener(this); setFraction(0f); } public void setDuration(long duration) { mValueAnimator.setDuration(duration); } public void start() { mViewHolder.setIsRecyclable(false); mValueAnimator.start(); } public void cancel() { mValueAnimator.cancel(); } public void setFraction(float fraction) { mFraction = fraction; } /** * We run updates on onDraw method but use the fraction from animator callback. * This way, we can sync translate x/y values w/ the animators to avoid one-off frames. */ public void update() { if (mStartDx == mTargetX) { mX = ViewCompat.getTranslationX(mViewHolder.itemView); } else { mX = mStartDx + mFraction * (mTargetX - mStartDx); } if (mStartDy == mTargetY) { mY = ViewCompat.getTranslationY(mViewHolder.itemView); } else { mY = mStartDy + mFraction * (mTargetY - mStartDy); } } @Override public void onAnimationStart(ValueAnimatorCompat animation) { } @Override public void onAnimationEnd(ValueAnimatorCompat animation) { mEnded = true; } @Override public void onAnimationCancel(ValueAnimatorCompat animation) { setFraction(1f); //make sure we recover the view's state. } @Override public void onAnimationRepeat(ValueAnimatorCompat animation) { } } }