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.designox.widget; import android.content.Context; import android.content.res.TypedArray; import android.os.Parcel; import android.os.Parcelable; import android.support.annotationox.IntDef; import android.support.annotationox.NonNull; import android.support.annotationox.Nullable; import android.support.v4ox.os.ParcelableCompat; import android.support.v4ox.os.ParcelableCompatCreatorCallbacks; import android.support.v4ox.view.ViewCompat; import android.support.v4ox.view.WindowInsetsCompat; import android.util.AttributeSet; import android.view.View; import android.view.ViewGroup; import android.view.animation.Interpolator; import android.widget.LinearLayout; import com.gigigo.permissions.R; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; import java.lang.ref.WeakReference; import java.util.ArrayList; import java.util.List; /** * AppBarLayout is a vertical {@link LinearLayout} which implements many of the features of * material designs app bar concept, namely scrolling gestures. * <p> * Children should provide their desired scrolling behavior through * {@link LayoutParams#setScrollFlags(int)} and the associated layout xml attribute: * {@code app:layout_scrollFlags}. * * <p> * This view depends heavily on being used as a direct child within a {@link CoordinatorLayout}. * If you use AppBarLayout within a different {@link ViewGroup}, most of it's functionality will * not work. * <p> * AppBarLayout also requires a separate scrolling sibling in order to know when to scroll. * The binding is done through the {@link ScrollingViewBehavior} behavior class, meaning that you * should set your scrolling view's behavior to be an instance of {@link ScrollingViewBehavior}. * A string resource containing the full class name is available. * * <pre> * <CoordinatorLayout * xmlns:android="http://schemas.android.com/apk/res/android" * xmlns:app="http://schemas.android.com/apk/res-auto" * android:layout_width="match_parent" * android:layout_height="match_parent"> * * <android.support.v4.widget.NestedScrollView * android:layout_width="match_parent" * android:layout_height="match_parent" * app:layout_behavior="@string/appbar_scrolling_view_behavior"> * * <!-- Your scrolling content --> * * </android.support.v4.widget.NestedScrollView> * * <AppBarLayout * android:layout_height="wrap_content" * android:layout_width="match_parent"> * * <android.support.v7.widget.Toolbar * ... * app:layout_scrollFlags="scroll|enterAlways"/> * * <TabLayout * ... * app:layout_scrollFlags="scroll|enterAlways"/> * * </AppBarLayout> * * </CoordinatorLayout> * </pre> * * @see <a href="http://www.google.com/design/spec/layout/structure.html#structure-app-bar"> * http://www.google.com/design/spec/layout/structure.html#structure-app-bar</a> */ @CoordinatorLayout.DefaultBehavior(AppBarLayout.Behavior.class) public class AppBarLayout extends LinearLayout { private static final int PENDING_ACTION_NONE = 0x0; private static final int PENDING_ACTION_EXPANDED = 0x1; private static final int PENDING_ACTION_COLLAPSED = 0x2; private static final int PENDING_ACTION_ANIMATE_ENABLED = 0x4; /** * Interface definition for a callback to be invoked when an {@link AppBarLayout}'s vertical * offset changes. */ public interface OnOffsetChangedListener { /** * Called when the {@link AppBarLayout}'s layout offset has been changed. This allows * child views to implement custom behavior based on the offset (for instance pinning a * view at a certain y value). * * @param appBarLayout the {@link AppBarLayout} which offset has changed * @param verticalOffset the vertical offset for the parent {@link AppBarLayout}, in px */ void onOffsetChanged(AppBarLayout appBarLayout, int verticalOffset); } private static final int INVALID_SCROLL_RANGE = -1; private int mTotalScrollRange = INVALID_SCROLL_RANGE; private int mDownPreScrollRange = INVALID_SCROLL_RANGE; private int mDownScrollRange = INVALID_SCROLL_RANGE; boolean mHaveChildWithInterpolator; private float mTargetElevation; private int mPendingAction = PENDING_ACTION_NONE; private WindowInsetsCompat mLastInsets; private final List<OnOffsetChangedListener> mListeners; public AppBarLayout(Context context) { this(context, null); } public AppBarLayout(Context context, AttributeSet attrs) { super(context, attrs); setOrientation(VERTICAL); ThemeUtils.checkAppCompatTheme(context); TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.AppBarLayout, 0, R.style.Widget_Design_AppBarLayout); mTargetElevation = a.getDimensionPixelSize(R.styleable.AppBarLayout_elevation, 0); setBackgroundDrawable(a.getDrawable(R.styleable.AppBarLayout_android_background)); if (a.hasValue(R.styleable.AppBarLayout_expanded)) { setExpanded(a.getBoolean(R.styleable.AppBarLayout_expanded, false)); } a.recycle(); // Use the bounds view outline provider so that we cast a shadow, even without a background ViewUtils.setBoundsViewOutlineProvider(this); mListeners = new ArrayList<>(); ViewCompat.setElevation(this, mTargetElevation); ViewCompat.setOnApplyWindowInsetsListener(this, new android.support.v4ox.view.OnApplyWindowInsetsListener() { @Override public WindowInsetsCompat onApplyWindowInsets(View v, WindowInsetsCompat insets) { return onWindowInsetChanged(insets); } }); } /** * Add a listener that will be called when the offset of this {@link AppBarLayout} changes. * * @param listener The listener that will be called when the offset changes.] * * @see #removeOnOffsetChangedListener(OnOffsetChangedListener) */ public void addOnOffsetChangedListener(OnOffsetChangedListener listener) { if (listener != null && !mListeners.contains(listener)) { mListeners.add(listener); } } /** * Remove the previously added {@link OnOffsetChangedListener}. * * @param listener the listener to remove. */ public void removeOnOffsetChangedListener(OnOffsetChangedListener listener) { if (listener != null) { mListeners.remove(listener); } } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); invalidateScrollRanges(); } @Override protected void onLayout(boolean changed, int l, int t, int r, int b) { super.onLayout(changed, l, t, r, b); invalidateScrollRanges(); mHaveChildWithInterpolator = false; for (int i = 0, z = getChildCount(); i < z; i++) { final View child = getChildAt(i); final LayoutParams childLp = (LayoutParams) child.getLayoutParams(); final Interpolator interpolator = childLp.getScrollInterpolator(); if (interpolator != null) { mHaveChildWithInterpolator = true; break; } } } private void invalidateScrollRanges() { // Invalidate the scroll ranges mTotalScrollRange = INVALID_SCROLL_RANGE; mDownPreScrollRange = INVALID_SCROLL_RANGE; mDownScrollRange = INVALID_SCROLL_RANGE; } @Override public void setOrientation(int orientation) { if (orientation != VERTICAL) { throw new IllegalArgumentException( "AppBarLayout is always vertical and does" + " not support horizontal orientation"); } super.setOrientation(orientation); } /** * Sets whether this {@link AppBarLayout} is expanded or not, animating if it has already * been laid out. * * <p>As with {@link AppBarLayout}'s scrolling, this method relies on this layout being a * direct child of a {@link CoordinatorLayout}.</p> * * @param expanded true if the layout should be fully expanded, false if it should * be fully collapsed * * @attr ref android.support.designox.R.styleable#AppBarLayout_expanded */ public void setExpanded(boolean expanded) { setExpanded(expanded, ViewCompat.isLaidOut(this)); } /** * Sets whether this {@link AppBarLayout} is expanded or not. * * <p>As with {@link AppBarLayout}'s scrolling, this method relies on this layout being a * direct child of a {@link CoordinatorLayout}.</p> * * @param expanded true if the layout should be fully expanded, false if it should * be fully collapsed * @param animate Whether to animate to the new state * * @attr ref android.support.designox.R.styleable#AppBarLayout_expanded */ public void setExpanded(boolean expanded, boolean animate) { mPendingAction = (expanded ? PENDING_ACTION_EXPANDED : PENDING_ACTION_COLLAPSED) | (animate ? PENDING_ACTION_ANIMATE_ENABLED : 0); requestLayout(); } @Override protected boolean checkLayoutParams(ViewGroup.LayoutParams p) { return p instanceof LayoutParams; } @Override protected LayoutParams generateDefaultLayoutParams() { return new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT); } @Override public LayoutParams generateLayoutParams(AttributeSet attrs) { return new LayoutParams(getContext(), attrs); } @Override protected LayoutParams generateLayoutParams(ViewGroup.LayoutParams p) { if (p instanceof LinearLayout.LayoutParams) { return new LayoutParams((LinearLayout.LayoutParams) p); } else if (p instanceof MarginLayoutParams) { return new LayoutParams((MarginLayoutParams) p); } return new LayoutParams(p); } private boolean hasChildWithInterpolator() { return mHaveChildWithInterpolator; } /** * Returns the scroll range of all children. * * @return the scroll range in px */ public final int getTotalScrollRange() { if (mTotalScrollRange != INVALID_SCROLL_RANGE) { return mTotalScrollRange; } int range = 0; for (int i = 0, z = getChildCount(); i < z; i++) { final View child = getChildAt(i); final LayoutParams lp = (LayoutParams) child.getLayoutParams(); final int childHeight = child.getMeasuredHeight(); final int flags = lp.mScrollFlags; if ((flags & LayoutParams.SCROLL_FLAG_SCROLL) != 0) { // We're set to scroll so add the child's height range += childHeight + lp.topMargin + lp.bottomMargin; if ((flags & LayoutParams.SCROLL_FLAG_EXIT_UNTIL_COLLAPSED) != 0) { // For a collapsing scroll, we to take the collapsed height into account. // We also break straight away since later views can't scroll beneath // us range -= ViewCompat.getMinimumHeight(child); break; } } else { // As soon as a view doesn't have the scroll flag, we end the range calculation. // This is because views below can not scroll under a fixed view. break; } } return mTotalScrollRange = Math.max(0, range - getTopInset()); } private boolean hasScrollableChildren() { return getTotalScrollRange() != 0; } /** * Return the scroll range when scrolling up from a nested pre-scroll. */ private int getUpNestedPreScrollRange() { return getTotalScrollRange(); } /** * Return the scroll range when scrolling down from a nested pre-scroll. */ private int getDownNestedPreScrollRange() { if (mDownPreScrollRange != INVALID_SCROLL_RANGE) { // If we already have a valid value, return it return mDownPreScrollRange; } int range = 0; for (int i = getChildCount() - 1; i >= 0; i--) { final View child = getChildAt(i); final LayoutParams lp = (LayoutParams) child.getLayoutParams(); final int childHeight = child.getMeasuredHeight(); final int flags = lp.mScrollFlags; if ((flags & LayoutParams.FLAG_QUICK_RETURN) == LayoutParams.FLAG_QUICK_RETURN) { // First take the margin into account range += lp.topMargin + lp.bottomMargin; // The view has the quick return flag combination... if ((flags & LayoutParams.SCROLL_FLAG_ENTER_ALWAYS_COLLAPSED) != 0) { // If they're set to enter collapsed, use the minimum height range += ViewCompat.getMinimumHeight(child); } else if ((flags & LayoutParams.SCROLL_FLAG_EXIT_UNTIL_COLLAPSED) != 0) { // Only enter by the amount of the collapsed height range += childHeight - ViewCompat.getMinimumHeight(child); } else { // Else use the full height range += childHeight; } } else if (range > 0) { // If we've hit an non-quick return scrollable view, and we've already hit a // quick return view, return now break; } } return mDownPreScrollRange = Math.max(0, range - getTopInset()); } /** * Return the scroll range when scrolling down from a nested scroll. */ private int getDownNestedScrollRange() { if (mDownScrollRange != INVALID_SCROLL_RANGE) { // If we already have a valid value, return it return mDownScrollRange; } int range = 0; for (int i = 0, z = getChildCount(); i < z; i++) { final View child = getChildAt(i); final LayoutParams lp = (LayoutParams) child.getLayoutParams(); int childHeight = child.getMeasuredHeight(); childHeight += lp.topMargin + lp.bottomMargin; final int flags = lp.mScrollFlags; if ((flags & LayoutParams.SCROLL_FLAG_SCROLL) != 0) { // We're set to scroll so add the child's height range += childHeight; if ((flags & LayoutParams.SCROLL_FLAG_EXIT_UNTIL_COLLAPSED) != 0) { // For a collapsing exit scroll, we to take the collapsed height into account. // We also break the range straight away since later views can't scroll // beneath us range -= ViewCompat.getMinimumHeight(child) + getTopInset(); break; } } else { // As soon as a view doesn't have the scroll flag, we end the range calculation. // This is because views below can not scroll under a fixed view. break; } } return mDownScrollRange = Math.max(0, range); } final int getMinimumHeightForVisibleOverlappingContent() { final int topInset = getTopInset(); final int minHeight = ViewCompat.getMinimumHeight(this); if (minHeight != 0) { // If this layout has a min height, use it (doubled) return (minHeight * 2) + topInset; } // Otherwise, we'll use twice the min height of our last child final int childCount = getChildCount(); return childCount >= 1 ? (ViewCompat.getMinimumHeight(getChildAt(childCount - 1)) * 2) + topInset : 0; } /** * Set the elevation value to use when this {@link AppBarLayout} should be elevated * above content. * <p> * This method does not do anything itself. A typical use for this method is called from within * an {@link OnOffsetChangedListener} when the offset has changed in such a way to require an * elevation change. * * @param elevation the elevation value to use. * * @see ViewCompat#setElevation(View, float) */ public void setTargetElevation(float elevation) { mTargetElevation = elevation; } /** * Returns the elevation value to use when this {@link AppBarLayout} should be elevated * above content. */ public float getTargetElevation() { return mTargetElevation; } private int getPendingAction() { return mPendingAction; } private void resetPendingAction() { mPendingAction = PENDING_ACTION_NONE; } private int getTopInset() { return mLastInsets != null ? mLastInsets.getSystemWindowInsetTop() : 0; } private WindowInsetsCompat onWindowInsetChanged(final WindowInsetsCompat insets) { WindowInsetsCompat newInsets = null; if (ViewCompat.getFitsSystemWindows(this)) { // If we're set to fit system windows, keep the insets newInsets = insets; } // If our insets have changed, keep them and invalidate the scroll ranges... if (newInsets != mLastInsets) { mLastInsets = newInsets; invalidateScrollRanges(); } return insets; } public static class LayoutParams extends LinearLayout.LayoutParams { /** @hide */ @IntDef(flag = true, value = { SCROLL_FLAG_SCROLL, SCROLL_FLAG_EXIT_UNTIL_COLLAPSED, SCROLL_FLAG_ENTER_ALWAYS, SCROLL_FLAG_ENTER_ALWAYS_COLLAPSED, SCROLL_FLAG_SNAP }) @Retention(RetentionPolicy.SOURCE) public @interface ScrollFlags { } /** * The view will be scroll in direct relation to scroll events. This flag needs to be * set for any of the other flags to take effect. If any sibling views * before this one do not have this flag, then this value has no effect. */ public static final int SCROLL_FLAG_SCROLL = 0x1; /** * When exiting (scrolling off screen) the view will be scrolled until it is * 'collapsed'. The collapsed height is defined by the view's minimum height. * * @see ViewCompat#getMinimumHeight(View) * @see View#setMinimumHeight(int) */ public static final int SCROLL_FLAG_EXIT_UNTIL_COLLAPSED = 0x2; /** * When entering (scrolling on screen) the view will scroll on any downwards * scroll event, regardless of whether the scrolling view is also scrolling. This * is commonly referred to as the 'quick return' pattern. */ public static final int SCROLL_FLAG_ENTER_ALWAYS = 0x4; /** * An additional flag for 'enterAlways' which modifies the returning view to * only initially scroll back to it's collapsed height. Once the scrolling view has * reached the end of it's scroll range, the remainder of this view will be scrolled * into view. The collapsed height is defined by the view's minimum height. * * @see ViewCompat#getMinimumHeight(View) * @see View#setMinimumHeight(int) */ public static final int SCROLL_FLAG_ENTER_ALWAYS_COLLAPSED = 0x8; /** * Upon a scroll ending, if the view is only partially visible then it will be snapped * and scrolled to it's closest edge. For example, if the view only has it's bottom 25% * displayed, it will be scrolled off screen completely. Conversely, if it's bottom 75% * is visible then it will be scrolled fully into view. */ public static final int SCROLL_FLAG_SNAP = 0x10; /** * Internal flags which allows quick checking features */ static final int FLAG_QUICK_RETURN = SCROLL_FLAG_SCROLL | SCROLL_FLAG_ENTER_ALWAYS; static final int FLAG_SNAP = SCROLL_FLAG_SCROLL | SCROLL_FLAG_SNAP; int mScrollFlags = SCROLL_FLAG_SCROLL; Interpolator mScrollInterpolator; public LayoutParams(Context c, AttributeSet attrs) { super(c, attrs); TypedArray a = c.obtainStyledAttributes(attrs, R.styleable.AppBarLayout_LayoutParams); mScrollFlags = a.getInt(R.styleable.AppBarLayout_LayoutParams_layout_scrollFlags_ox, 0); if (a.hasValue(R.styleable.AppBarLayout_LayoutParams_layout_scrollInterpolator_ox)) { int resId = a.getResourceId(R.styleable.AppBarLayout_LayoutParams_layout_scrollInterpolator_ox, 0); mScrollInterpolator = android.view.animation.AnimationUtils.loadInterpolator(c, resId); } a.recycle(); } public LayoutParams(int width, int height) { super(width, height); } public LayoutParams(int width, int height, float weight) { super(width, height, weight); } public LayoutParams(ViewGroup.LayoutParams p) { super(p); } public LayoutParams(MarginLayoutParams source) { super(source); } public LayoutParams(LinearLayout.LayoutParams source) { super(source); } public LayoutParams(LayoutParams source) { super(source); mScrollFlags = source.mScrollFlags; mScrollInterpolator = source.mScrollInterpolator; } /** * Set the scrolling flags. * * @param flags bitwise int of {@link #SCROLL_FLAG_SCROLL}, * {@link #SCROLL_FLAG_EXIT_UNTIL_COLLAPSED}, {@link #SCROLL_FLAG_ENTER_ALWAYS}, * {@link #SCROLL_FLAG_ENTER_ALWAYS_COLLAPSED} and {@link #SCROLL_FLAG_SNAP }. * * @see #getScrollFlags() * * @attr ref android.support.designox.R.styleable#AppBarLayout_LayoutParams_layout_scrollFlags */ public void setScrollFlags(@ScrollFlags int flags) { mScrollFlags = flags; } /** * Returns the scrolling flags. * * @see #setScrollFlags(int) * * @attr ref android.support.designox.R.styleable#AppBarLayout_LayoutParams_layout_scrollFlags */ @ScrollFlags public int getScrollFlags() { return mScrollFlags; } /** * Set the interpolator to when scrolling the view associated with this * {@link LayoutParams}. * * @param interpolator the interpolator to use, or null to use normal 1-to-1 scrolling. * * @attr ref android.support.designox.R.styleable#AppBarLayout_LayoutParams_layout_scrollInterpolator * @see #getScrollInterpolator() */ public void setScrollInterpolator(Interpolator interpolator) { mScrollInterpolator = interpolator; } /** * Returns the {@link Interpolator} being used for scrolling the view associated with this * {@link LayoutParams}. Null indicates 'normal' 1-to-1 scrolling. * * @attr ref android.support.designox.R.styleable#AppBarLayout_LayoutParams_layout_scrollInterpolator * @see #setScrollInterpolator(Interpolator) */ public Interpolator getScrollInterpolator() { return mScrollInterpolator; } } /** * The default {@link Behavior} for {@link AppBarLayout}. Implements the necessary nested * scroll handling with offsetting. */ public static class Behavior extends HeaderBehavior<AppBarLayout> { private static final int ANIMATE_OFFSET_DIPS_PER_SECOND = 300; private static final int INVALID_POSITION = -1; /** * Callback to allow control over any {@link AppBarLayout} dragging. */ public static abstract class DragCallback { /** * Allows control over whether the given {@link AppBarLayout} can be dragged or not. * * <p>Dragging is defined as a direct touch on the AppBarLayout with movement. This * call does not affect any nested scrolling.</p> * * @return true if we are in a position to scroll the AppBarLayout via a drag, false * if not. */ public abstract boolean canDrag(@NonNull AppBarLayout appBarLayout); } private int mOffsetDelta; private boolean mSkipNestedPreScroll; private boolean mWasNestedFlung; private ValueAnimatorCompat mAnimator; private int mOffsetToChildIndexOnLayout = INVALID_POSITION; private boolean mOffsetToChildIndexOnLayoutIsMinHeight; private float mOffsetToChildIndexOnLayoutPerc; private WeakReference<View> mLastNestedScrollingChildRef; private DragCallback mOnDragCallback; public Behavior() { } public Behavior(Context context, AttributeSet attrs) { super(context, attrs); } @Override public boolean onStartNestedScroll(CoordinatorLayout parent, AppBarLayout child, View directTargetChild, View target, int nestedScrollAxes) { // Return true if we're nested scrolling vertically, and we have scrollable children // and the scrolling view is big enough to scroll final boolean started = (nestedScrollAxes & ViewCompat.SCROLL_AXIS_VERTICAL) != 0 && child.hasScrollableChildren() && parent.getHeight() - directTargetChild.getHeight() <= child.getHeight(); if (started && mAnimator != null) { // Cancel any offset animation mAnimator.cancel(); } // A new nested scroll has started so clear out the previous ref mLastNestedScrollingChildRef = null; return started; } @Override public void onNestedPreScroll(CoordinatorLayout coordinatorLayout, AppBarLayout child, View target, int dx, int dy, int[] consumed) { if (dy != 0 && !mSkipNestedPreScroll) { int min, max; if (dy < 0) { // We're scrolling down min = -child.getTotalScrollRange(); max = min + child.getDownNestedPreScrollRange(); } else { // We're scrolling up min = -child.getUpNestedPreScrollRange(); max = 0; } consumed[1] = scroll(coordinatorLayout, child, dy, min, max); } } @Override public void onNestedScroll(CoordinatorLayout coordinatorLayout, AppBarLayout child, View target, int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed) { if (dyUnconsumed < 0) { // If the scrolling view is scrolling down but not consuming, it's probably be at // the top of it's content scroll(coordinatorLayout, child, dyUnconsumed, -child.getDownNestedScrollRange(), 0); // Set the expanding flag so that onNestedPreScroll doesn't handle any events mSkipNestedPreScroll = true; } else { // As we're no longer handling nested scrolls, reset the skip flag mSkipNestedPreScroll = false; } } @Override public void onStopNestedScroll(CoordinatorLayout coordinatorLayout, AppBarLayout abl, View target) { if (!mWasNestedFlung) { // If we haven't been flung then let's see if the current view has been set to snap snapToChildIfNeeded(coordinatorLayout, abl); } // Reset the flags mSkipNestedPreScroll = false; mWasNestedFlung = false; // Keep a reference to the previous nested scrolling child mLastNestedScrollingChildRef = new WeakReference<>(target); } @Override public boolean onNestedFling(final CoordinatorLayout coordinatorLayout, final AppBarLayout child, View target, float velocityX, float velocityY, boolean consumed) { boolean flung = false; if (!consumed) { // It has been consumed so let's fling ourselves flung = fling(coordinatorLayout, child, -child.getTotalScrollRange(), 0, -velocityY); } else { // If we're scrolling up and the child also consumed the fling. We'll fake scroll // upto our 'collapsed' offset if (velocityY < 0) { // We're scrolling down final int targetScroll = -child.getTotalScrollRange() + child.getDownNestedPreScrollRange(); if (getTopBottomOffsetForScrollingSibling() < targetScroll) { // If we're currently not expanded more than the target scroll, we'll // animate a fling animateOffsetTo(coordinatorLayout, child, targetScroll); flung = true; } } else { // We're scrolling up final int targetScroll = -child.getUpNestedPreScrollRange(); if (getTopBottomOffsetForScrollingSibling() > targetScroll) { // If we're currently not expanded less than the target scroll, we'll // animate a fling animateOffsetTo(coordinatorLayout, child, targetScroll); flung = true; } } } mWasNestedFlung = flung; return flung; } /** * Set a callback to control any {@link AppBarLayout} dragging. * * @param callback the callback to use, or {@code null} to use the default behavior. */ public void setDragCallback(@Nullable DragCallback callback) { mOnDragCallback = callback; } private void animateOffsetTo(final CoordinatorLayout coordinatorLayout, final AppBarLayout child, final int offset) { final int currentOffset = getTopBottomOffsetForScrollingSibling(); if (currentOffset == offset) { if (mAnimator != null && mAnimator.isRunning()) { mAnimator.cancel(); } return; } if (mAnimator == null) { mAnimator = ViewUtils.createAnimator(); mAnimator.setInterpolator(AnimationUtils.DECELERATE_INTERPOLATOR); mAnimator.setUpdateListener(new ValueAnimatorCompat.AnimatorUpdateListener() { @Override public void onAnimationUpdate(ValueAnimatorCompat animator) { setHeaderTopBottomOffset(coordinatorLayout, child, animator.getAnimatedIntValue()); } }); } else { mAnimator.cancel(); } // Set the duration based on the amount of dips we're travelling in final float distanceDp = Math.abs(currentOffset - offset) / coordinatorLayout.getResources().getDisplayMetrics().density; mAnimator.setDuration(Math.round(distanceDp * 1000 / ANIMATE_OFFSET_DIPS_PER_SECOND)); mAnimator.setIntValues(currentOffset, offset); mAnimator.start(); } private View getChildOnOffset(AppBarLayout abl, final int offset) { for (int i = 0, count = abl.getChildCount(); i < count; i++) { View child = abl.getChildAt(i); if (child.getTop() <= -offset && child.getBottom() >= -offset) { return child; } } return null; } private void snapToChildIfNeeded(CoordinatorLayout coordinatorLayout, AppBarLayout abl) { final int offset = getTopBottomOffsetForScrollingSibling(); final View offsetChild = getChildOnOffset(abl, offset); if (offsetChild != null) { final LayoutParams lp = (LayoutParams) offsetChild.getLayoutParams(); if ((lp.getScrollFlags() & LayoutParams.FLAG_SNAP) == LayoutParams.FLAG_SNAP) { // We're set the snap, so animate the offset to the nearest edge int childTop = -offsetChild.getTop(); int childBottom = -offsetChild.getBottom(); // If the view is set only exit until it is collapsed, we'll abide by that if ((lp.getScrollFlags() & LayoutParams.SCROLL_FLAG_EXIT_UNTIL_COLLAPSED) == LayoutParams.SCROLL_FLAG_EXIT_UNTIL_COLLAPSED) { childBottom += ViewCompat.getMinimumHeight(offsetChild); } final int newOffset = offset < (childBottom + childTop) / 2 ? childBottom : childTop; animateOffsetTo(coordinatorLayout, abl, MathUtils.constrain(newOffset, -abl.getTotalScrollRange(), 0)); } } } @Override public boolean onLayoutChild(CoordinatorLayout parent, AppBarLayout abl, int layoutDirection) { boolean handled = super.onLayoutChild(parent, abl, layoutDirection); final int pendingAction = abl.getPendingAction(); if (pendingAction != PENDING_ACTION_NONE) { final boolean animate = (pendingAction & PENDING_ACTION_ANIMATE_ENABLED) != 0; if ((pendingAction & PENDING_ACTION_COLLAPSED) != 0) { final int offset = -abl.getUpNestedPreScrollRange(); if (animate) { animateOffsetTo(parent, abl, offset); } else { setHeaderTopBottomOffset(parent, abl, offset); } } else if ((pendingAction & PENDING_ACTION_EXPANDED) != 0) { if (animate) { animateOffsetTo(parent, abl, 0); } else { setHeaderTopBottomOffset(parent, abl, 0); } } } else if (mOffsetToChildIndexOnLayout >= 0) { View child = abl.getChildAt(mOffsetToChildIndexOnLayout); int offset = -child.getBottom(); if (mOffsetToChildIndexOnLayoutIsMinHeight) { offset += ViewCompat.getMinimumHeight(child); } else { offset += Math.round(child.getHeight() * mOffsetToChildIndexOnLayoutPerc); } setTopAndBottomOffset(offset); } // Finally reset any pending states abl.resetPendingAction(); mOffsetToChildIndexOnLayout = INVALID_POSITION; // We may have changed size, so let's constrain the top and bottom offset correctly, // just in case we're out of the bounds setTopAndBottomOffset(MathUtils.constrain(getTopAndBottomOffset(), -abl.getTotalScrollRange(), 0)); // Make sure we update the elevation dispatchOffsetUpdates(abl); return handled; } @Override boolean canDragView(AppBarLayout view) { if (mOnDragCallback != null) { // If there is a drag callback set, it's in control return mOnDragCallback.canDrag(view); } // Else we'll use the default behaviour of seeing if it can scroll down if (mLastNestedScrollingChildRef != null) { // If we have a reference to a scrolling view, check it final View scrollingView = mLastNestedScrollingChildRef.get(); return scrollingView != null && scrollingView.isShown() && !ViewCompat.canScrollVertically(scrollingView, -1); } else { // Otherwise we assume that the scrolling view hasn't been scrolled and can drag. return true; } } @Override void onFlingFinished(CoordinatorLayout parent, AppBarLayout layout) { // At the end of a manual fling, check to see if we need to snap to the edge-child snapToChildIfNeeded(parent, layout); } @Override int getMaxDragOffset(AppBarLayout view) { return -view.getDownNestedScrollRange(); } @Override int getScrollRangeForDragFling(AppBarLayout view) { return view.getTotalScrollRange(); } @Override int setHeaderTopBottomOffset(CoordinatorLayout coordinatorLayout, AppBarLayout header, int newOffset, int minOffset, int maxOffset) { final int curOffset = getTopBottomOffsetForScrollingSibling(); int consumed = 0; if (minOffset != 0 && curOffset >= minOffset && curOffset <= maxOffset) { // If we have some scrolling range, and we're currently within the min and max // offsets, calculate a new offset newOffset = MathUtils.constrain(newOffset, minOffset, maxOffset); AppBarLayout appBarLayout = header; if (curOffset != newOffset) { final int interpolatedOffset = appBarLayout.hasChildWithInterpolator() ? interpolateOffset(appBarLayout, newOffset) : newOffset; boolean offsetChanged = setTopAndBottomOffset(interpolatedOffset); // Update how much dy we have consumed consumed = curOffset - newOffset; // Update the stored sibling offset mOffsetDelta = newOffset - interpolatedOffset; if (!offsetChanged && appBarLayout.hasChildWithInterpolator()) { // If the offset hasn't changed and we're using an interpolated scroll // then we need to keep any dependent views updated. CoL will do this for // us when we move, but we need to do it manually when we don't (as an // interpolated scroll may finish early). coordinatorLayout.dispatchDependentViewsChanged(appBarLayout); } // Dispatch the updates to any listeners dispatchOffsetUpdates(appBarLayout); } } else { // Reset the offset delta mOffsetDelta = 0; } return consumed; } private void dispatchOffsetUpdates(AppBarLayout layout) { final List<OnOffsetChangedListener> listeners = layout.mListeners; // Iterate backwards through the list so that most recently added listeners // get the first chance to decide for (int i = 0, z = listeners.size(); i < z; i++) { final OnOffsetChangedListener listener = listeners.get(i); if (listener != null) { listener.onOffsetChanged(layout, getTopAndBottomOffset()); } } } private int interpolateOffset(AppBarLayout layout, final int offset) { final int absOffset = Math.abs(offset); for (int i = 0, z = layout.getChildCount(); i < z; i++) { final View child = layout.getChildAt(i); final AppBarLayout.LayoutParams childLp = (LayoutParams) child.getLayoutParams(); final Interpolator interpolator = childLp.getScrollInterpolator(); if (absOffset >= child.getTop() && absOffset <= child.getBottom()) { if (interpolator != null) { int childScrollableHeight = 0; final int flags = childLp.getScrollFlags(); if ((flags & LayoutParams.SCROLL_FLAG_SCROLL) != 0) { // We're set to scroll so add the child's height plus margin childScrollableHeight += child.getHeight() + childLp.topMargin + childLp.bottomMargin; if ((flags & LayoutParams.SCROLL_FLAG_EXIT_UNTIL_COLLAPSED) != 0) { // For a collapsing scroll, we to take the collapsed height // into account. childScrollableHeight -= ViewCompat.getMinimumHeight(child); } } if (ViewCompat.getFitsSystemWindows(child)) { childScrollableHeight -= layout.getTopInset(); } if (childScrollableHeight > 0) { final int offsetForView = absOffset - child.getTop(); final int interpolatedDiff = Math.round(childScrollableHeight * interpolator.getInterpolation(offsetForView / (float) childScrollableHeight)); return Integer.signum(offset) * (child.getTop() + interpolatedDiff); } } // If we get to here then the view on the offset isn't suitable for interpolated // scrolling. So break out of the loop break; } } return offset; } @Override int getTopBottomOffsetForScrollingSibling() { return getTopAndBottomOffset() + mOffsetDelta; } @Override public Parcelable onSaveInstanceState(CoordinatorLayout parent, AppBarLayout appBarLayout) { final Parcelable superState = super.onSaveInstanceState(parent, appBarLayout); final int offset = getTopAndBottomOffset(); // Try and find the first visible child... for (int i = 0, count = appBarLayout.getChildCount(); i < count; i++) { View child = appBarLayout.getChildAt(i); final int visBottom = child.getBottom() + offset; if (child.getTop() + offset <= 0 && visBottom >= 0) { final SavedState ss = new SavedState(superState); ss.firstVisibleChildIndex = i; ss.firstVisibileChildAtMinimumHeight = visBottom == ViewCompat.getMinimumHeight(child); ss.firstVisibileChildPercentageShown = visBottom / (float) child.getHeight(); return ss; } } // Else we'll just return the super state return superState; } @Override public void onRestoreInstanceState(CoordinatorLayout parent, AppBarLayout appBarLayout, Parcelable state) { if (state instanceof SavedState) { final SavedState ss = (SavedState) state; super.onRestoreInstanceState(parent, appBarLayout, ss.getSuperState()); mOffsetToChildIndexOnLayout = ss.firstVisibleChildIndex; mOffsetToChildIndexOnLayoutPerc = ss.firstVisibileChildPercentageShown; mOffsetToChildIndexOnLayoutIsMinHeight = ss.firstVisibileChildAtMinimumHeight; } else { super.onRestoreInstanceState(parent, appBarLayout, state); mOffsetToChildIndexOnLayout = INVALID_POSITION; } } protected static class SavedState extends BaseSavedState { int firstVisibleChildIndex; float firstVisibileChildPercentageShown; boolean firstVisibileChildAtMinimumHeight; public SavedState(Parcel source, ClassLoader loader) { super(source); firstVisibleChildIndex = source.readInt(); firstVisibileChildPercentageShown = source.readFloat(); firstVisibileChildAtMinimumHeight = source.readByte() != 0; } public SavedState(Parcelable superState) { super(superState); } @Override public void writeToParcel(Parcel dest, int flags) { super.writeToParcel(dest, flags); dest.writeInt(firstVisibleChildIndex); dest.writeFloat(firstVisibileChildPercentageShown); dest.writeByte((byte) (firstVisibileChildAtMinimumHeight ? 1 : 0)); } public static final Parcelable.Creator<SavedState> CREATOR = ParcelableCompat .newCreator(new ParcelableCompatCreatorCallbacks<SavedState>() { @Override public SavedState createFromParcel(Parcel source, ClassLoader loader) { return new SavedState(source, loader); } @Override public SavedState[] newArray(int size) { return new SavedState[size]; } }); } } /** * Behavior which should be used by {@link View}s which can scroll vertically and support * nested scrolling to automatically scroll any {@link AppBarLayout} siblings. */ public static class ScrollingViewBehavior extends HeaderScrollingViewBehavior { public ScrollingViewBehavior() { } public ScrollingViewBehavior(Context context, AttributeSet attrs) { super(context, attrs); final TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.ScrollingViewBehavior_Params); setOverlayTop( a.getDimensionPixelSize(R.styleable.ScrollingViewBehavior_Params_behavior_overlapTop_ox, 0)); a.recycle(); } @Override public boolean layoutDependsOn(CoordinatorLayout parent, View child, View dependency) { // We depend on any AppBarLayouts return dependency instanceof AppBarLayout; } @Override public boolean onDependentViewChanged(CoordinatorLayout parent, View child, View dependency) { offsetChildAsNeeded(parent, child, dependency); return false; } private void offsetChildAsNeeded(CoordinatorLayout parent, View child, View dependency) { final CoordinatorLayout.Behavior behavior = ((CoordinatorLayout.LayoutParams) dependency .getLayoutParams()).getBehavior(); if (behavior instanceof Behavior) { // Offset the child, pinning it to the bottom the header-dependency, maintaining // any vertical gap, and overlap final Behavior ablBehavior = (Behavior) behavior; final int offset = ablBehavior.getTopBottomOffsetForScrollingSibling(); child.offsetTopAndBottom((dependency.getBottom() - child.getTop()) + ablBehavior.mOffsetDelta + getVerticalLayoutGap() - getOverlapPixelsForOffset(dependency)); } } @Override float getOverlapRatioForOffset(final View header) { if (header instanceof AppBarLayout) { final AppBarLayout abl = (AppBarLayout) header; final int totalScrollRange = abl.getTotalScrollRange(); final int preScrollDown = abl.getDownNestedPreScrollRange(); final int offset = getAppBarLayoutOffset(abl); if (preScrollDown != 0 && (totalScrollRange + offset) <= preScrollDown) { // If we're in a pre-scroll down. Don't use the offset at all. return 0; } else { final int availScrollRange = totalScrollRange - preScrollDown; if (availScrollRange != 0) { // Else we'll use a interpolated ratio of the overlap, depending on offset return 1f + (offset / (float) availScrollRange); } } } return 0f; } private static int getAppBarLayoutOffset(AppBarLayout abl) { final CoordinatorLayout.Behavior behavior = ((CoordinatorLayout.LayoutParams) abl.getLayoutParams()) .getBehavior(); if (behavior instanceof Behavior) { return ((Behavior) behavior).getTopBottomOffsetForScrollingSibling(); } return 0; } @Override View findFirstDependency(List<View> views) { for (int i = 0, z = views.size(); i < z; i++) { View view = views.get(i); if (view instanceof AppBarLayout) { return view; } } return null; } @Override int getScrollRange(View v) { if (v instanceof AppBarLayout) { return ((AppBarLayout) v).getTotalScrollRange(); } else { return super.getScrollRange(v); } } } }