Android实现三段式滑动效果 Android实现三段式滑动效果

高德的效果：

高德的效果：
实现的效果：
【Android实现三段式滑动效果】
我们实现的效果和高德差距不是很大，也很顺滑。具体实现其实就是集成CoordinatorLayout.Behavior

/** * 高德首页滑动效果 */public class GaoDeBottomSheetBehavior extends CoordinatorLayout.Behavior {public static final int STATE_DRAGGING = 1; public static final int STATE_SETTLING = 2; public static final int STATE_EXPANDED = 3; public static final int STATE_COLLAPSED = 4; public static final int STATE_HIDDEN = 5; public static final int STATE_HALF_EXPANDED = 6; public static final int PEEK_HEIGHT_AUTO = -1; private static final float HIDE_THRESHOLD = 0.5F; private static final float HIDE_FRICTION = 0.1F; public static final int MIDDLE_HEIGHT_AUTO = -1; private boolean fitToContents = true; private float maximumVelocity; private int peekHeight; private boolean peekHeightAuto; private int peekHeightMin; private int lastPeekHeight; int fitToContentsOffset; int halfExpandedOffset; int collapsedOffset; boolean hideable; private boolean skipCollapsed; int state = STATE_COLLAPSED; ViewDragHelper viewDragHelper; private boolean ignoreEvents; private int lastNestedScrollDy; private boolean nestedScrolled; int parentHeight; WeakReference viewRef; WeakReference nestedScrollingChildRef; private GaoDeBottomSheetBehavior.BottomSheetCallback callback; private VelocityTracker velocityTracker; int activePointerId; private int initialY; boolean touchingScrollingChild; private Map importantForAccessibilityMap; private final Callback dragCallback; private int mMiddleHeight; private boolean mMiddleHeightAuto; public GaoDeBottomSheetBehavior() {this.dragCallback = new NamelessClass_1(); }public GaoDeBottomSheetBehavior(Context context, AttributeSet attrs) {super(context, attrs); this.dragCallback = new NamelessClass_1(); TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.BottomSheetBehavior_Layout); TypedValue value = https://www.it610.com/article/a.peekValue(R.styleable.BottomSheetBehavior_Layout_behavior_peekHeight); if (value != null && value.data == -1) {this.setPeekHeight(value.data); } else {this.setPeekHeight(a.getDimensionPixelSize(R.styleable.BottomSheetBehavior_Layout_behavior_peekHeight, -1)); }this.setHideable(a.getBoolean(R.styleable.BottomSheetBehavior_Layout_behavior_hideAble, false)); this.setFitToContents(a.getBoolean(R.styleable.BottomSheetBehavior_Layout_behavior_fitToContents, true)); this.setSkipCollapsed(a.getBoolean(R.styleable.BottomSheetBehavior_Layout_behavior_skipCollapse, false)); setMiddleHeight(a.getDimensionPixelSize(R.styleable.BottomSheetBehavior_Layout_behavior_middleHeight, MIDDLE_HEIGHT_AUTO)); a.recycle(); ViewConfiguration configuration = ViewConfiguration.get(context); this.maximumVelocity = (float) configuration.getScaledMaximumFlingVelocity(); }class NamelessClass_1 extends Callback {NamelessClass_1() {}@Overridepublic boolean tryCaptureView(@NonNull View child, int pointerId) {if (GaoDeBottomSheetBehavior.this.state == STATE_DRAGGING) {return false; } else if (GaoDeBottomSheetBehavior.this.touchingScrollingChild) {return false; } else {if (GaoDeBottomSheetBehavior.this.state == 3 && GaoDeBottomSheetBehavior.this.activePointerId == pointerId) {View scroll = (View) GaoDeBottomSheetBehavior.this.nestedScrollingChildRef.get(); if (scroll != null && scroll.canScrollVertically(-1)) {return false; }}return GaoDeBottomSheetBehavior.this.viewRef != null && GaoDeBottomSheetBehavior.this.viewRef.get() == child; }}@Overridepublic void onViewPositionChanged(@NonNull View changedView, int left, int top, int dx, int dy) {GaoDeBottomSheetBehavior.this.dispatchOnSlide(top); }@Overridepublic void onViewDragStateChanged(int state) {if (state == 1) {GaoDeBottomSheetBehavior.this.setStateInternal(STATE_DRAGGING); }}@Overridepublic void onViewReleased(@NonNull View releasedChild, float xvel, float yvel) {int top; byte targetState; int currentTop; if (yvel < 0.0F) {if (GaoDeBottomSheetBehavior.this.fitToContents) {currentTop = releasedChild.getTop(); if (currentTop < (collapsedOffset + HIDE_THRESHOLD) && currentTop>= halfExpandedOffset) {top = GaoDeBottomSheetBehavior.this.halfExpandedOffset; targetState = STATE_HALF_EXPANDED; } else {top = GaoDeBottomSheetBehavior.this.fitToContentsOffset; targetState = STATE_EXPANDED; }} else {currentTop = releasedChild.getTop(); if (currentTop > GaoDeBottomSheetBehavior.this.halfExpandedOffset) {top = GaoDeBottomSheetBehavior.this.halfExpandedOffset; targetState = STATE_HALF_EXPANDED; } else {top = 0; targetState = STATE_EXPANDED; }}} else if (!GaoDeBottomSheetBehavior.this.hideable || !GaoDeBottomSheetBehavior.this.shouldHide(releasedChild, yvel) || releasedChild.getTop() <= GaoDeBottomSheetBehavior.this.collapsedOffset && Math.abs(xvel) >= Math.abs(yvel)) {if (yvel != 0.0F && Math.abs(xvel) <= Math.abs(yvel)) {currentTop = releasedChild.getTop(); if (currentTop < halfExpandedOffset) {top = GaoDeBottomSheetBehavior.this.halfExpandedOffset; targetState = STATE_HALF_EXPANDED; } else {top = GaoDeBottomSheetBehavior.this.collapsedOffset; targetState = STATE_COLLAPSED; }} else {currentTop = releasedChild.getTop(); if (GaoDeBottomSheetBehavior.this.fitToContents) {if (Math.abs(currentTop - GaoDeBottomSheetBehavior.this.fitToContentsOffset) < Math.abs(currentTop - GaoDeBottomSheetBehavior.this.collapsedOffset)) {top = GaoDeBottomSheetBehavior.this.fitToContentsOffset; targetState = STATE_EXPANDED; } else {top = GaoDeBottomSheetBehavior.this.collapsedOffset; targetState = STATE_COLLAPSED; }} else if (currentTop < GaoDeBottomSheetBehavior.this.halfExpandedOffset) {if (currentTop < Math.abs(currentTop - GaoDeBottomSheetBehavior.this.collapsedOffset)) {top = 0; targetState = STATE_EXPANDED; } else {top = GaoDeBottomSheetBehavior.this.halfExpandedOffset; targetState = STATE_HALF_EXPANDED; }} else if (Math.abs(currentTop - GaoDeBottomSheetBehavior.this.halfExpandedOffset) < Math.abs(currentTop - GaoDeBottomSheetBehavior.this.collapsedOffset)) {top = GaoDeBottomSheetBehavior.this.halfExpandedOffset; targetState = STATE_HALF_EXPANDED; } else {top = GaoDeBottomSheetBehavior.this.collapsedOffset; targetState = STATE_COLLAPSED; }}} else {top = GaoDeBottomSheetBehavior.this.parentHeight; targetState = STATE_HIDDEN; }if (GaoDeBottomSheetBehavior.this.viewDragHelper.settleCapturedViewAt(releasedChild.getLeft(), top)) {GaoDeBottomSheetBehavior.this.setStateInternal(STATE_SETTLING); ViewCompat.postOnAnimation(releasedChild, GaoDeBottomSheetBehavior.this.new SettleRunnable(releasedChild, targetState)); } else {GaoDeBottomSheetBehavior.this.setStateInternal(targetState); }}@Overridepublic int clampViewPositionVertical(@NonNull View child, int top, int dy) {return MathUtils.clamp(top, GaoDeBottomSheetBehavior.this.getExpandedOffset(), GaoDeBottomSheetBehavior.this.hideable ? GaoDeBottomSheetBehavior.this.parentHeight : GaoDeBottomSheetBehavior.this.collapsedOffset); }@Overridepublic int clampViewPositionHorizontal(@NonNull View child, int left, int dx) {return child.getLeft(); }@Overridepublic int getViewVerticalDragRange(@NonNull View child) {return GaoDeBottomSheetBehavior.this.hideable ? GaoDeBottomSheetBehavior.this.parentHeight : GaoDeBottomSheetBehavior.this.collapsedOffset; }}@Overridepublic Parcelable onSaveInstanceState(CoordinatorLayout parent, V child) {return new GaoDeBottomSheetBehavior.SavedState(super.onSaveInstanceState(parent, child), this.state); }@Overridepublic void onRestoreInstanceState(CoordinatorLayout parent, V child, Parcelable state) {GaoDeBottomSheetBehavior.SavedState ss = (GaoDeBottomSheetBehavior.SavedState) state; super.onRestoreInstanceState(parent, child, ss.getSuperState()); if (ss.state != STATE_DRAGGING && ss.state != STATE_SETTLING) {this.state = ss.state; } else {this.state = STATE_COLLAPSED; }}@Overridepublic boolean onLayoutChild(CoordinatorLayout parent, V child, int layoutDirection) {if (ViewCompat.getFitsSystemWindows(parent) && !ViewCompat.getFitsSystemWindows(child)) {child.setFitsSystemWindows(true); }int savedTop = child.getTop(); parent.onLayoutChild(child, layoutDirection); this.parentHeight = parent.getHeight(); if (this.peekHeightAuto) {if (this.peekHeightMin == 0) {this.peekHeightMin = parent.getResources().getDimensionPixelSize(R.dimen.design_bottom_sheet_peek_height_min); }this.lastPeekHeight = Math.max(this.peekHeightMin, this.parentHeight - parent.getWidth() * 9 / 16); } else {this.lastPeekHeight = this.peekHeight; }if (mMiddleHeightAuto) {mMiddleHeight = this.parentHeight; }this.fitToContentsOffset = Math.max(0, this.parentHeight - child.getHeight()); this.halfExpandedOffset = this.parentHeight - mMiddleHeight; this.calculateCollapsedOffset(); if (this.state == STATE_EXPANDED) {ViewCompat.offsetTopAndBottom(child, this.getExpandedOffset()); } else if (this.state == STATE_HALF_EXPANDED) {ViewCompat.offsetTopAndBottom(child, this.halfExpandedOffset); } else if (this.hideable && this.state == STATE_HIDDEN) {ViewCompat.offsetTopAndBottom(child, this.parentHeight); } else if (this.state == STATE_COLLAPSED) {ViewCompat.offsetTopAndBottom(child, this.collapsedOffset); } else if (this.state == STATE_DRAGGING || this.state == STATE_SETTLING) {ViewCompat.offsetTopAndBottom(child, savedTop - child.getTop()); }if (this.viewDragHelper == null) {this.viewDragHelper = ViewDragHelper.create(parent, this.dragCallback); }this.viewRef = new WeakReference(child); this.nestedScrollingChildRef = new WeakReference(this.findScrollingChild(child)); return true; }@Overridepublic boolean onInterceptTouchEvent(CoordinatorLayout parent, V child, MotionEvent event) {if (!child.isShown()) {this.ignoreEvents = true; return false; } else {int action = event.getActionMasked(); if (action == 0) {this.reset(); }if (this.velocityTracker == null) {this.velocityTracker = VelocityTracker.obtain(); }this.velocityTracker.addMovement(event); switch (action) {case 0:int initialX = (int) event.getX(); this.initialY = (int) event.getY(); View scroll = this.nestedScrollingChildRef != null ? (View) this.nestedScrollingChildRef.get() : null; if (scroll != null && parent.isPointInChildBounds(scroll, initialX, this.initialY)) {this.activePointerId = event.getPointerId(event.getActionIndex()); this.touchingScrollingChild = true; }this.ignoreEvents = this.activePointerId == -1 && !parent.isPointInChildBounds(child, initialX, this.initialY); break; case 1:case 3:this.touchingScrollingChild = false; this.activePointerId = -1; if (this.ignoreEvents) {this.ignoreEvents = false; return false; }case 2:}if (!this.ignoreEvents && this.viewDragHelper != null && this.viewDragHelper.shouldInterceptTouchEvent(event)) {return true; } else {View scroll = this.nestedScrollingChildRef != null ? (View) this.nestedScrollingChildRef.get() : null; return action == 2 && scroll != null && !this.ignoreEvents && this.state != 1 && !parent.isPointInChildBounds(scroll, (int) event.getX(), (int) event.getY()) && this.viewDragHelper != null && Math.abs((float) this.initialY - event.getY()) > (float) this.viewDragHelper.getTouchSlop(); }}}@Overridepublic boolean onTouchEvent(CoordinatorLayout parent, V child, MotionEvent event) {if (!child.isShown()) {return false; } else {int action = event.getActionMasked(); if (this.state == STATE_DRAGGING && action == 0) {return true; } else {if (this.viewDragHelper != null) {this.viewDragHelper.processTouchEvent(event); }if (action == 0) {this.reset(); }if (this.velocityTracker == null) {this.velocityTracker = VelocityTracker.obtain(); }this.velocityTracker.addMovement(event); if (action == 2 && !this.ignoreEvents && Math.abs((float) this.initialY - event.getY()) > (float) this.viewDragHelper.getTouchSlop()) {this.viewDragHelper.captureChildView(child, event.getPointerId(event.getActionIndex())); }return !this.ignoreEvents; }}}@Overridepublic boolean onStartNestedScroll(@NonNull CoordinatorLayout coordinatorLayout, @NonNull V child, @NonNull View directTargetChild, @NonNull View target, int axes, int type) {this.lastNestedScrollDy = 0; this.nestedScrolled = false; return (axes & 2) != 0; }@Overridepublic void onNestedPreScroll(@NonNull CoordinatorLayout coordinatorLayout, @NonNull V child, @NonNull View target, int dx, int dy, @NonNull int[] consumed, int type) {if (type != 1) {View scrollingChild = (View) this.nestedScrollingChildRef.get(); if (target == scrollingChild) {int currentTop = child.getTop(); int newTop = currentTop - dy; if (dy > 0) {if (newTop < this.getExpandedOffset()) {consumed[1] = currentTop - this.getExpandedOffset(); ViewCompat.offsetTopAndBottom(child, -consumed[1]); this.setStateInternal(STATE_EXPANDED); } else {consumed[1] = dy; ViewCompat.offsetTopAndBottom(child, -dy); this.setStateInternal(STATE_DRAGGING); }} else if (dy < 0 && !target.canScrollVertically(-1)) {if (newTop > this.collapsedOffset && !this.hideable) {consumed[1] = currentTop - this.collapsedOffset; ViewCompat.offsetTopAndBottom(child, -consumed[1]); this.setStateInternal(STATE_COLLAPSED); } else {consumed[1] = dy; ViewCompat.offsetTopAndBottom(child, -dy); this.setStateInternal(STATE_DRAGGING); }}this.dispatchOnSlide(child.getTop()); this.lastNestedScrollDy = dy; this.nestedScrolled = true; }}}@Overridepublic void onStopNestedScroll(@NonNull CoordinatorLayout coordinatorLayout, @NonNull V child, @NonNull View target, int type) {if (child.getTop() == this.getExpandedOffset()) {this.setStateInternal(STATE_EXPANDED); } else if (target == this.nestedScrollingChildRef.get() && this.nestedScrolled) {int top; byte targetState; if (this.lastNestedScrollDy > 0) {int currentTop = child.getTop(); if (currentTop <= collapsedOffset - HIDE_THRESHOLD && currentTop >= halfExpandedOffset) {top = this.halfExpandedOffset; targetState = STATE_HALF_EXPANDED; } else {top = this.getExpandedOffset(); targetState = STATE_EXPANDED; }} else if (this.hideable && this.shouldHide(child, this.getYVelocity())) {top = this.parentHeight; targetState = STATE_HIDDEN; } else if (this.lastNestedScrollDy == 0) {int currentTop = child.getTop(); if (this.fitToContents) {if (Math.abs(currentTop - this.fitToContentsOffset) < Math.abs(currentTop - this.collapsedOffset)) {top = this.fitToContentsOffset; targetState = STATE_EXPANDED; } else {top = this.collapsedOffset; targetState = STATE_COLLAPSED; }} else if (currentTop < this.halfExpandedOffset) {if (currentTop < Math.abs(currentTop - this.collapsedOffset)) {top = 0; targetState = STATE_EXPANDED; } else {top = this.halfExpandedOffset; targetState = STATE_HALF_EXPANDED; }} else if (Math.abs(currentTop - this.halfExpandedOffset) < Math.abs(currentTop - this.collapsedOffset)) {top = this.halfExpandedOffset; targetState = STATE_HALF_EXPANDED; } else {top = this.collapsedOffset; targetState = STATE_COLLAPSED; }} else {int currentTop = child.getTop(); if (currentTop <= halfExpandedOffset + HIDE_THRESHOLD && currentTop > HIDE_THRESHOLD) {top = this.halfExpandedOffset; targetState = STATE_HALF_EXPANDED; } else {top = this.collapsedOffset; targetState = STATE_COLLAPSED; }}if (this.viewDragHelper.smoothSlideViewTo(child, child.getLeft(), top)) {this.setStateInternal(STATE_SETTLING); ViewCompat.postOnAnimation(child, new GaoDeBottomSheetBehavior.SettleRunnable(child, targetState)); } else {this.setStateInternal(targetState); }this.nestedScrolled = false; }}@Overridepublic boolean onNestedPreFling(@NonNull CoordinatorLayout coordinatorLayout, @NonNull V child, @NonNull View target, float velocityX, float velocityY) {return target == this.nestedScrollingChildRef.get() && (this.state != STATE_EXPANDED || super.onNestedPreFling(coordinatorLayout, child, target, velocityX, velocityY)); }public boolean isFitToContents() {return this.fitToContents; }public void setFitToContents(boolean fitToContents) {if (this.fitToContents != fitToContents) {this.fitToContents = fitToContents; if (this.viewRef != null) {this.calculateCollapsedOffset(); }this.setStateInternal(this.fitToContents && this.state == STATE_HALF_EXPANDED ? STATE_HALF_EXPANDED : this.state); }}public final void setPeekHeight(int peekHeight) {boolean layout = false; if (peekHeight == -1) {if (!this.peekHeightAuto) {this.peekHeightAuto = true; layout = true; }} else if (this.peekHeightAuto || this.peekHeight != peekHeight) {this.peekHeightAuto = false; this.peekHeight = Math.max(0, peekHeight); this.collapsedOffset = this.parentHeight - peekHeight; layout = true; }if (layout && this.state == STATE_COLLAPSED && this.viewRef != null) {V view = (V) this.viewRef.get(); if (view != null) {view.requestLayout(); }}}public final void setMiddleHeight(int middleHeight) {boolean layout = false; if (middleHeight == PEEK_HEIGHT_AUTO) {if (!mMiddleHeightAuto) {mMiddleHeightAuto = true; layout = true; }} else if (mMiddleHeightAuto || mMiddleHeight != middleHeight) {mMiddleHeightAuto = false; mMiddleHeight = Math.max(0, middleHeight); layout = true; }if (layout && this.state == STATE_COLLAPSED && viewRef != null) {V view = viewRef.get(); if (view != null) {view.requestLayout(); }}}public final int getPeekHeight() {return this.peekHeightAuto ? -1 : this.peekHeight; }public final int getMiddleHeight() {return this.mMiddleHeightAuto ? -1 : this.mMiddleHeight; }public final int getParentHeight() {return this.parentHeight; }public void setHideable(boolean hideable) {this.hideable = hideable; }public boolean isHideable() {return this.hideable; }public void setSkipCollapsed(boolean skipCollapsed) {this.skipCollapsed = skipCollapsed; }public boolean getSkipCollapsed() {return this.skipCollapsed; }public void setBottomSheetCallback(GaoDeBottomSheetBehavior.BottomSheetCallback callback) {this.callback = callback; }public final void setState(final int state) {if (state != this.state) {if (this.viewRef == null) {if (state == STATE_COLLAPSED || state == STATE_EXPANDED || state == STATE_HALF_EXPANDED || this.hideable && state == STATE_HIDDEN) {this.state = state; }} else {final V child = (V) this.viewRef.get(); if (child != null) {ViewParent parent = child.getParent(); if (parent != null && parent.isLayoutRequested() && ViewCompat.isAttachedToWindow(child)) {child.post(new Runnable() {@Overridepublic void run() {GaoDeBottomSheetBehavior.this.startSettlingAnimation(child, state); }}); } else {this.startSettlingAnimation(child, state); }}}}}public final int getState() {return this.state; }void setStateInternal(int state) {if (this.state != state) {this.state = state; if (state != STATE_HALF_EXPANDED && state != STATE_EXPANDED) {if (state == STATE_HIDDEN || state == STATE_COLLAPSED) {this.updateImportantForAccessibility(false); }} else {this.updateImportantForAccessibility(true); }View bottomSheet = (View) this.viewRef.get(); if (bottomSheet != null && this.callback != null) {this.callback.onStateChanged(bottomSheet, state); }}}private void calculateCollapsedOffset() {if (this.fitToContents) {this.collapsedOffset = Math.max(this.parentHeight - this.lastPeekHeight, this.fitToContentsOffset); } else {this.collapsedOffset = this.parentHeight - this.lastPeekHeight; }}private void reset() {this.activePointerId = -1; if (this.velocityTracker != null) {this.velocityTracker.recycle(); this.velocityTracker = null; }}boolean shouldHide(View child, float yvel) {if (this.skipCollapsed) {return true; } else if (child.getTop() < this.collapsedOffset) {return false; } else {float newTop = (float) child.getTop() + yvel * HIDE_FRICTION; return Math.abs(newTop - (float) this.collapsedOffset) / (float) this.peekHeight > HIDE_THRESHOLD; }}@VisibleForTestingView findScrollingChild(View view) {if (ViewCompat.isNestedScrollingEnabled(view)) {return view; } else {if (view instanceof ViewGroup) {ViewGroup group = (ViewGroup) view; int i = 0; for (int count = group.getChildCount(); i < count; ++i) {View scrollingChild = this.findScrollingChild(group.getChildAt(i)); if (scrollingChild != null) {return scrollingChild; }}}return null; }}private float getYVelocity() {if (this.velocityTracker == null) {return 0.0F; } else {this.velocityTracker.computeCurrentVelocity(1000, this.maximumVelocity); return this.velocityTracker.getYVelocity(this.activePointerId); }}private int getExpandedOffset() {return this.fitToContents ? this.fitToContentsOffset : 0; }void startSettlingAnimation(View child, int state) {int top; if (state == STATE_COLLAPSED) {top = this.collapsedOffset; } else if (state == STATE_HALF_EXPANDED) {top = this.halfExpandedOffset; } else if (state == STATE_EXPANDED) {top = this.getExpandedOffset(); } else {if (!this.hideable || state != STATE_HIDDEN) {throw new IllegalArgumentException("Illegal state argument: " + state); }top = this.parentHeight; }if (this.viewDragHelper.smoothSlideViewTo(child, child.getLeft(), top)) {this.setStateInternal(STATE_SETTLING); ViewCompat.postOnAnimation(child, new GaoDeBottomSheetBehavior.SettleRunnable(child, state)); } else {this.setStateInternal(state); }}void dispatchOnSlide(int top) {View bottomSheet = (View) this.viewRef.get(); if (bottomSheet != null && this.callback != null) {if (top > this.collapsedOffset) {this.callback.onSlide(bottomSheet, (float) (this.collapsedOffset - top) / (float) (this.parentHeight - this.collapsedOffset)); } else {this.callback.onSlide(bottomSheet, (float) (this.collapsedOffset - top) / (float) (this.collapsedOffset - this.getExpandedOffset())); }}}@VisibleForTestingint getPeekHeightMin() {return this.peekHeightMin; }public static GaoDeBottomSheetBehavior from(V view) {LayoutParams params = view.getLayoutParams(); if (!(params instanceof CoordinatorLayout.LayoutParams)) {throw new IllegalArgumentException("The view is not a child of CoordinatorLayout"); } else {Behavior behavior = ((CoordinatorLayout.LayoutParams) params).getBehavior(); if (!(behavior instanceof GaoDeBottomSheetBehavior)) {throw new IllegalArgumentException("The view is not associated with BottomSheetBehavior"); } else {return (GaoDeBottomSheetBehavior) behavior; }}}@SuppressLint("WrongConstant")private void updateImportantForAccessibility(boolean expanded) {if (this.viewRef != null) {ViewParent viewParent = ((View) this.viewRef.get()).getParent(); if (viewParent instanceof CoordinatorLayout) {CoordinatorLayout parent = (CoordinatorLayout) viewParent; int childCount = parent.getChildCount(); if (VERSION.SDK_INT >= 16 && expanded) {if (this.importantForAccessibilityMap != null) {return; }this.importantForAccessibilityMap = new HashMap(childCount); }for (int i = 0; i < childCount; ++i) {View child = parent.getChildAt(i); if (child != this.viewRef.get()) {if (!expanded) {if (this.importantForAccessibilityMap != null && this.importantForAccessibilityMap.containsKey(child)) {ViewCompat.setImportantForAccessibility(child, (Integer) this.importantForAccessibilityMap.get(child)); }} else {if (VERSION.SDK_INT >= 16) {this.importantForAccessibilityMap.put(child, child.getImportantForAccessibility()); }ViewCompat.setImportantForAccessibility(child, 4); }}}if (!expanded) {this.importantForAccessibilityMap = null; }}}}protected static class SavedState extends AbsSavedState {final int state; public static final Creator CREATOR = new ClassLoaderCreator() {@Overridepublic GaoDeBottomSheetBehavior.SavedState createFromParcel(Parcel in, ClassLoader loader) {return new GaoDeBottomSheetBehavior.SavedState(in, loader); }@Overridepublic GaoDeBottomSheetBehavior.SavedState createFromParcel(Parcel in) {return new GaoDeBottomSheetBehavior.SavedState(in, (ClassLoader) null); }@Overridepublic GaoDeBottomSheetBehavior.SavedState[] newArray(int size) {return new GaoDeBottomSheetBehavior.SavedState[size]; }}; public SavedState(Parcel source) {this(source, (ClassLoader) null); }public SavedState(Parcel source, ClassLoader loader) {super(source, loader); this.state = source.readInt(); }public SavedState(Parcelable superState, int state) {super(superState); this.state = state; }@Overridepublic void writeToParcel(Parcel out, int flags) {super.writeToParcel(out, flags); out.writeInt(this.state); }}private class SettleRunnable implements Runnable {private final View view; private final int targetState; SettleRunnable(View view, int targetState) {this.view = view; this.targetState = targetState; }@Overridepublic void run() {if (GaoDeBottomSheetBehavior.this.viewDragHelper != null && GaoDeBottomSheetBehavior.this.viewDragHelper.continueSettling(true)) {ViewCompat.postOnAnimation(this.view, this); } else {GaoDeBottomSheetBehavior.this.setStateInternal(this.targetState); }}}@Retention(RetentionPolicy.SOURCE)@RestrictTo({Scope.LIBRARY_GROUP})public @interface State {}public abstract static class BottomSheetCallback {public BottomSheetCallback() {}public abstract void onStateChanged(@NonNull View var1, int var2); public abstract void onSlide(@NonNull View var1, float var2); }}

使用的时候直接设置：

//....

对于按钮滑动及通明度渐变隐藏显示也是通过实现behavior，因为比较的简单直接上代码：

/** * 高德首页按钮处理 */public class GaoDeBtnBehavior extends CoordinatorLayout.Behavior {private View rightActions; private View topActions; public GaoDeBtnBehavior() {}public GaoDeBtnBehavior(Context context, AttributeSet attrs) {super(context, attrs); }@Overridepublic boolean onLayoutChild(@NonNull CoordinatorLayout parent, @NonNull View child, int layoutDirection) {if (ViewCompat.getFitsSystemWindows(parent) && !ViewCompat.getFitsSystemWindows(child)) {child.setFitsSystemWindows(true); }if (rightActions == null) {rightActions = parent.findViewById(R.id.rightActions); }if (topActions == null) {topActions = parent.findViewById(R.id.topActions); }return super.onLayoutChild(parent, child, layoutDirection); }@Overridepublic boolean layoutDependsOn(@NonNull CoordinatorLayout parent, @NonNull View child, @NonNull View dependency) {return dependency instanceof LinearLayoutCompat || super.layoutDependsOn(parent, child, dependency); }@Overridepublic boolean onDependentViewChanged(@NonNull CoordinatorLayout parent, @NonNull View child, @NonNull View dependency) {//判断当前dependency 是内容布局if (dependency instanceof LinearLayoutCompat && dependency.getId() == R.id.bottom_sheet) {if (rightActions != null) {GaoDeBottomSheetBehavior behavior = GaoDeBottomSheetBehavior.from(dependency); int middleHeight = behavior.getParentHeight() - behavior.getMiddleHeight() - rightActions.getMeasuredHeight(); CoordinatorLayout.LayoutParams layoutParams = (CoordinatorLayout.LayoutParams) rightActions.getLayoutParams(); int newY = dependency.getTop() - rightActions.getHeight() - layoutParams.bottomMargin; if (newY >= middleHeight) {rightActions.setTranslationY(newY - layoutParams.bottomMargin); } else {rightActions.setTranslationY(middleHeight); }int offset = behavior.getParentHeight() - behavior.getMiddleHeight() - layoutParams.bottomMargin - dependency.getTop(); float alpha = 1f - offset * 1.0f / rightActions.getHeight(); rightActions.setAlpha(alpha); if (topActions != null) {topActions.setAlpha(alpha); }}}return super.onDependentViewChanged(parent, child, dependency); }}

源码地址：
https://github.com/yixiaolunhui/FGaoDeIndexDemo
到这里就结束啦。
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