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 com.trafi.anchorbottomsheetbehavior; import static android.support.annotation.RestrictTo.Scope.GROUP_ID; import android.content.Context; import android.content.res.TypedArray; import android.os.Parcel; import android.os.Parcelable; import android.support.annotation.IntDef; import android.support.annotation.NonNull; import android.support.annotation.RestrictTo; import android.support.annotation.VisibleForTesting; import android.support.design.widget.CoordinatorLayout; import android.support.v4.os.ParcelableCompat; import android.support.v4.os.ParcelableCompatCreatorCallbacks; import android.support.v4.view.AbsSavedState; import android.support.v4.view.MotionEventCompat; import android.support.v4.view.NestedScrollingChild; import android.support.v4.view.ViewCompat; import android.support.v4.view.ViewPager; import android.support.v4.view.ViewPagerUtils; import android.support.v4.widget.ViewDragHelper; import android.util.AttributeSet; import android.util.TypedValue; import android.view.MotionEvent; import android.view.VelocityTracker; import android.view.View; import android.view.ViewConfiguration; import android.view.ViewGroup; import android.view.ViewParent; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; import java.lang.ref.WeakReference; import java.util.ArrayList; import java.util.List; /** * An interaction behavior plugin for a child view of {@link CoordinatorLayout} to make it work as * a bottom sheet. */ public class AnchorBottomSheetBehavior<V extends View> extends CoordinatorLayout.Behavior<V> { /** * Callback for monitoring events about bottom sheets. */ public abstract static class BottomSheetCallback { /** * Called when the bottom sheet changes its state. * * @param bottomSheet The bottom sheet view. * @param newState The new state. This will be one of {@link #STATE_DRAGGING}, * {@link #STATE_SETTLING}, {@link #STATE_EXPANDED}, * {@link #STATE_COLLAPSED}, {@link #STATE_ANCHORED} or * {@link #STATE_HIDDEN}. */ public abstract void onStateChanged(@NonNull View bottomSheet, @State int newState); /** * Called when the bottom sheet is being dragged. * * @param bottomSheet The bottom sheet view. * @param slideOffset The new offset of this bottom sheet within [-1,1] range. Offset * increases as this bottom sheet is moving upward. From 0 to 1 the sheet * is between collapsed and expanded states and from -1 to 0 it is * between hidden and collapsed states. */ public abstract void onSlide(@NonNull View bottomSheet, float slideOffset); } /** * Stub/no-op implementations of all methods of {@link BottomSheetCallback}. * Override this if you only care about a few of the available callback methods. */ public abstract static class SimpleBottomSheetCallback extends BottomSheetCallback { @Override public void onStateChanged(@NonNull View bottomSheet, @State int newState) { } @Override public void onSlide(@NonNull View bottomSheet, float slideOffset) { } } /** * The bottom sheet is dragging. */ public static final int STATE_DRAGGING = 1; /** * The bottom sheet is settling. */ public static final int STATE_SETTLING = 2; /** * The bottom sheet is expanded. */ public static final int STATE_EXPANDED = 3; /** * The bottom sheet is collapsed. */ public static final int STATE_COLLAPSED = 4; /** * The bottom sheet is hidden. */ public static final int STATE_HIDDEN = 5; /** * The bottom sheet is anchored. */ public static final int STATE_ANCHORED = 6; /** * @hide */ @RestrictTo(GROUP_ID) @IntDef({ STATE_EXPANDED, STATE_COLLAPSED, STATE_DRAGGING, STATE_SETTLING, STATE_HIDDEN, STATE_ANCHORED }) @Retention(RetentionPolicy.SOURCE) public @interface State { } /** * Peek at the 16:9 ratio keyline of its parent. * <p> * <p>This can be used as a parameter for {@link #setPeekHeight(int)}. * {@link #getPeekHeight()} will return this when the value is set.</p> */ public static final int PEEK_HEIGHT_AUTO = -1; private static final float HIDE_THRESHOLD = 0.5f; private static final float HIDE_FRICTION = 0.1f; private static final float EXPAND_FRICTION = 0.2f; private static final float COLLAPSE_FRICTION = 0.2f; private float mMinimumVelocity; private float mMaximumVelocity; private int mPeekHeight; private boolean mPeekHeightAuto; private int mPeekHeightMin; private int mAnchorOffset; private boolean mAllowUserDragging = true; int mMinOffset; int mMaxOffset; boolean mHideable; private boolean mSkipCollapsed; @AnchorBottomSheetBehavior.State int mState = STATE_COLLAPSED; ViewDragHelper mViewDragHelper; private boolean mIgnoreEvents; private boolean mNestedScrolled; int mParentHeight; WeakReference<V> mViewRef; WeakReference<View> mNestedScrollingChildRef; private List<BottomSheetCallback> mCallbacks = new ArrayList<>(2); private VelocityTracker mVelocityTracker; int mActivePointerId; private int mInitialY; boolean mTouchingScrollingChild; private boolean mShouldAnchoredBeforeExpand = false; private boolean mShouldAnchoredBeforeCollapse = false; private boolean mExpandable = true; /** * Default constructor for instantiating AnchorBottomSheetBehaviors. */ public AnchorBottomSheetBehavior() { } /** * Default constructor for inflating AnchorBottomSheetBehaviors from layout. * * @param context The {@link Context}. * @param attrs The {@link AttributeSet}. */ public AnchorBottomSheetBehavior(Context context, AttributeSet attrs) { super(context, attrs); TypedArray a = context.obtainStyledAttributes(attrs, android.support.design.R.styleable.BottomSheetBehavior_Layout); TypedValue value = a .peekValue(android.support.design.R.styleable.BottomSheetBehavior_Layout_behavior_peekHeight); if (value != null && value.data == PEEK_HEIGHT_AUTO) { setPeekHeight(value.data); } else { setPeekHeight(a.getDimensionPixelSize( android.support.design.R.styleable.BottomSheetBehavior_Layout_behavior_peekHeight, PEEK_HEIGHT_AUTO)); } setHideable(a.getBoolean(android.support.design.R.styleable.BottomSheetBehavior_Layout_behavior_hideable, false)); setSkipCollapsed(a.getBoolean( android.support.design.R.styleable.BottomSheetBehavior_Layout_behavior_skipCollapsed, false)); a.recycle(); a = context.obtainStyledAttributes(attrs, R.styleable.AnchorBottomSheetBehavior_Layout); mAnchorOffset = (int) a.getDimension(R.styleable.AnchorBottomSheetBehavior_Layout_behavior_anchorOffset, 0); //noinspection WrongConstant mState = a.getInt(R.styleable.AnchorBottomSheetBehavior_Layout_behavior_defaultState, mState); mShouldAnchoredBeforeExpand = a.getBoolean( R.styleable.AnchorBottomSheetBehavior_Layout_behavior_shouldAnchoredBeforeExpand, false); mShouldAnchoredBeforeCollapse = a.getBoolean( R.styleable.AnchorBottomSheetBehavior_Layout_behavior_shouldAnchoredBeforeCollapse, false); mExpandable = a.getBoolean(R.styleable.AnchorBottomSheetBehavior_Layout_behavior_expandable, true); a.recycle(); ViewConfiguration configuration = ViewConfiguration.get(context); mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); mMinimumVelocity = configuration.getScaledMinimumFlingVelocity(); } void invalidateScrollingChild() { final View scrollingChild = findScrollingChild(mViewRef.get()); mNestedScrollingChildRef = new WeakReference<>(scrollingChild); } @Override public Parcelable onSaveInstanceState(CoordinatorLayout parent, V child) { return new SavedState(super.onSaveInstanceState(parent, child), mState); } @Override public void onRestoreInstanceState(CoordinatorLayout parent, V child, Parcelable state) { SavedState ss = (SavedState) state; super.onRestoreInstanceState(parent, child, ss.getSuperState()); // Intermediate states are restored as collapsed state if (ss.state == STATE_DRAGGING || ss.state == STATE_SETTLING) { mState = STATE_COLLAPSED; } else { mState = ss.state; } } @Override public boolean onLayoutChild(CoordinatorLayout parent, V child, int layoutDirection) { if (ViewCompat.getFitsSystemWindows(parent) && !ViewCompat.getFitsSystemWindows(child)) { ViewCompat.setFitsSystemWindows(child, true); } int savedTop = child.getTop(); // First let the parent lay it out parent.onLayoutChild(child, layoutDirection); // Offset the bottom sheet mParentHeight = parent.getHeight(); int peekHeight; if (mPeekHeightAuto) { if (mPeekHeightMin == 0) { mPeekHeightMin = parent.getResources() .getDimensionPixelSize(android.support.design.R.dimen.design_bottom_sheet_peek_height_min); } peekHeight = Math.max(mPeekHeightMin, mParentHeight - parent.getWidth() * 9 / 16); } else { peekHeight = mPeekHeight; } mMinOffset = Math.max(0, mParentHeight - child.getHeight()); mMaxOffset = Math.max(mParentHeight - peekHeight, mMinOffset); if (shouldExpandFullPanel() && mState == STATE_EXPANDED) { ViewCompat.offsetTopAndBottom(child, mMinOffset); } else if (mHideable && mState == STATE_HIDDEN) { ViewCompat.offsetTopAndBottom(child, mParentHeight); } else if (mState == STATE_COLLAPSED) { ViewCompat.offsetTopAndBottom(child, mMaxOffset); } else if (mState == STATE_DRAGGING || mState == STATE_SETTLING) { ViewCompat.offsetTopAndBottom(child, savedTop - child.getTop()); } else if (mState == STATE_ANCHORED) { ViewCompat.offsetTopAndBottom(child, mAnchorOffset); } if (mViewDragHelper == null) { mViewDragHelper = ViewDragHelper.create(parent, mDragCallback); } mViewRef = new WeakReference<>(child); mNestedScrollingChildRef = new WeakReference<>(findScrollingChild(child)); return true; } @Override public boolean onInterceptTouchEvent(CoordinatorLayout parent, V child, MotionEvent event) { if (!child.isShown() || !mAllowUserDragging) { mIgnoreEvents = true; return false; } int action = MotionEventCompat.getActionMasked(event); // Record the velocity if (action == MotionEvent.ACTION_DOWN) { reset(); } if (mVelocityTracker == null) { mVelocityTracker = VelocityTracker.obtain(); } mVelocityTracker.addMovement(event); switch (action) { case MotionEvent.ACTION_UP: case MotionEvent.ACTION_CANCEL: mTouchingScrollingChild = false; mActivePointerId = MotionEvent.INVALID_POINTER_ID; // Reset the ignore flag if (mIgnoreEvents) { mIgnoreEvents = false; return false; } break; case MotionEvent.ACTION_DOWN: int initialX = (int) event.getX(); mInitialY = (int) event.getY(); View scroll = mNestedScrollingChildRef.get(); if (scroll != null && parent.isPointInChildBounds(scroll, initialX, mInitialY)) { mActivePointerId = event.getPointerId(event.getActionIndex()); mTouchingScrollingChild = true; } mIgnoreEvents = mActivePointerId == MotionEvent.INVALID_POINTER_ID && !parent.isPointInChildBounds(child, initialX, mInitialY); break; } if (!mIgnoreEvents && mViewDragHelper.shouldInterceptTouchEvent(event)) { return true; } // We have to handle cases that the ViewDragHelper does not capture the bottom sheet because // it is not the top most view of its parent. This is not necessary when the touch event is // happening over the scrolling content as nested scrolling logic handles that case. View scroll = mNestedScrollingChildRef.get(); return action == MotionEvent.ACTION_MOVE && scroll != null && !mIgnoreEvents && mState != STATE_DRAGGING && !parent.isPointInChildBounds(scroll, (int) event.getX(), (int) event.getY()) && Math.abs(mInitialY - event.getY()) > mViewDragHelper.getTouchSlop(); } @Override public boolean onTouchEvent(CoordinatorLayout parent, V child, MotionEvent event) { if (!child.isShown() || !mAllowUserDragging) { return false; } int action = MotionEventCompat.getActionMasked(event); if (mState == STATE_DRAGGING && action == MotionEvent.ACTION_DOWN) { return true; } if (mViewDragHelper != null) { mViewDragHelper.processTouchEvent(event); } // Record the velocity if (action == MotionEvent.ACTION_DOWN) { reset(); } if (mVelocityTracker == null) { mVelocityTracker = VelocityTracker.obtain(); } mVelocityTracker.addMovement(event); // The ViewDragHelper tries to capture only the top-most View. We have to explicitly tell it // to capture the bottom sheet in case it is not captured and the touch slop is passed. if (action == MotionEvent.ACTION_MOVE && !mIgnoreEvents) { if (Math.abs(mInitialY - event.getY()) > mViewDragHelper.getTouchSlop()) { mViewDragHelper.captureChildView(child, event.getPointerId(event.getActionIndex())); } } return !mIgnoreEvents; } @Override public boolean onStartNestedScroll(CoordinatorLayout coordinatorLayout, V child, View directTargetChild, View target, int nestedScrollAxes) { if (!mAllowUserDragging) { return false; } mNestedScrolled = false; return (nestedScrollAxes & ViewCompat.SCROLL_AXIS_VERTICAL) != 0; } @Override public void onNestedPreScroll(CoordinatorLayout coordinatorLayout, V child, View target, int dx, int dy, int[] consumed) { if (!mAllowUserDragging) { return; } View scrollingChild = mNestedScrollingChildRef.get(); if (target != scrollingChild) { return; } int currentTop = child.getTop(); int newTop = currentTop - dy; if (dy > 0) { // Upward int topOffset = shouldExpandFullPanel() ? mMinOffset : mAnchorOffset; if (newTop < topOffset) { consumed[1] = currentTop - topOffset; ViewCompat.offsetTopAndBottom(child, -consumed[1]); setStateInternal(shouldExpandFullPanel() ? STATE_EXPANDED : STATE_ANCHORED); } else { consumed[1] = dy; ViewCompat.offsetTopAndBottom(child, -dy); setStateInternal(STATE_DRAGGING); } } else if (dy < 0) { // Downward if (!ViewCompat.canScrollVertically(target, -1)) { if (newTop <= mMaxOffset || mHideable) { consumed[1] = dy; ViewCompat.offsetTopAndBottom(child, -dy); setStateInternal(STATE_DRAGGING); } else { consumed[1] = currentTop - mMaxOffset; ViewCompat.offsetTopAndBottom(child, -consumed[1]); setStateInternal(STATE_COLLAPSED); } } } dispatchOnSlide(child.getTop()); mNestedScrolled = true; } @Override public void onStopNestedScroll(CoordinatorLayout coordinatorLayout, V child, View target) { if (!mAllowUserDragging) { return; } if (shouldExpandFullPanel() && child.getTop() == mMinOffset) { setStateInternal(STATE_EXPANDED); return; } if (!shouldExpandFullPanel() && child.getTop() == mAnchorOffset) { setStateInternal(STATE_ANCHORED); return; } if (target != mNestedScrollingChildRef.get() || !mNestedScrolled) { return; } mVelocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); float xvel = mVelocityTracker.getXVelocity(mActivePointerId); float yvel = mVelocityTracker.getYVelocity(mActivePointerId); int[] out = new int[2]; calculateTopAndTargetState(child, xvel, yvel, out); int top = out[0]; int targetState = out[1]; if (mViewDragHelper.smoothSlideViewTo(child, child.getLeft(), top)) { setStateInternal(STATE_SETTLING); ViewCompat.postOnAnimation(child, new SettleRunnable(child, targetState)); } else { setStateInternal(targetState); } mNestedScrolled = false; } @Override public boolean onNestedPreFling(CoordinatorLayout coordinatorLayout, V child, View target, float velocityX, float velocityY) { if (!mAllowUserDragging) { return false; } return target == mNestedScrollingChildRef.get() && (!isExpanded() || super.onNestedPreFling(coordinatorLayout, child, target, velocityX, velocityY)); } private boolean isExpanded() { if (shouldExpandFullPanel()) { return mState == STATE_EXPANDED; } return mState == STATE_ANCHORED; } private boolean shouldExpandFullPanel() { if (!mExpandable && mAnchorOffset > 0) { // Support partial expand return false; } return true; } /** * Sets the height of the bottom sheet when it is collapsed. * * @param peekHeight The height of the collapsed bottom sheet in pixels, or * {@link #PEEK_HEIGHT_AUTO} to configure the sheet to peek automatically * at 16:9 ratio keyline. * @attr ref android.support.design.R.styleable#BottomSheetBehavior_Layout_behavior_peekHeight */ public final void setPeekHeight(int peekHeight) { boolean layout = false; if (peekHeight == PEEK_HEIGHT_AUTO) { if (!mPeekHeightAuto) { mPeekHeightAuto = true; layout = true; } } else if (mPeekHeightAuto || mPeekHeight != peekHeight) { mPeekHeightAuto = false; mPeekHeight = Math.max(0, peekHeight); mMaxOffset = mParentHeight - peekHeight; layout = true; } if (layout && mState == STATE_COLLAPSED && mViewRef != null) { V view = mViewRef.get(); if (view != null) { view.requestLayout(); } } } /** * Gets the height of the bottom sheet when it is collapsed. * * @return The height of the collapsed bottom sheet in pixels, or {@link #PEEK_HEIGHT_AUTO} * if the sheet is configured to peek automatically at 16:9 ratio keyline * @attr ref android.support.design.R.styleable#BottomSheetBehavior_Layout_behavior_peekHeight */ public final int getPeekHeight() { return mPeekHeightAuto ? PEEK_HEIGHT_AUTO : mPeekHeight; } /** * Sets the offset of the bottom sheet when it is anchored. * * @param anchorOffset The offset of the anchored bottom sheet in pixels. * @attr ref com.trafi.anchorbottomsheetbehavior.R.styleable#AnchorBottomSheetBehavior_Layout_behavior_anchorOffset */ public final void setAnchorOffset(int anchorOffset) { if (mAnchorOffset != anchorOffset) { mAnchorOffset = anchorOffset; if (mState == STATE_ANCHORED) { setStateInternal(STATE_SETTLING); setState(STATE_ANCHORED); } } } /** * Gets the offset of the bottom sheet when it is anchored. * * @return The offset of the anchored bottom sheet in pixels. * @attr ref com.trafi.anchorbottomsheetbehavior.R.styleable#AnchorBottomSheetBehavior_Layout_behavior_anchorOffset */ public final int getAnchorOffset() { return mAnchorOffset; } /** * Sets whether this bottom sheet can hide when it is swiped down. * * @param hideable {@code true} to make this bottom sheet hideable. * @attr ref android.support.design.R.styleable#BottomSheetBehavior_Layout_behavior_hideable */ public void setHideable(boolean hideable) { mHideable = hideable; } /** * Gets whether this bottom sheet can hide when it is swiped down. * * @return {@code true} if this bottom sheet can hide. * @attr ref android.support.design.R.styleable#BottomSheetBehavior_Layout_behavior_hideable */ public boolean isHideable() { return mHideable; } /** * Sets whether this bottom sheet should skip the collapsed state when it is being hidden * after it is expanded once. Setting this to true has no effect unless the sheet is hideable. * * @param skipCollapsed True if the bottom sheet should skip the collapsed state. * @attr ref android.support.design.R.styleable#BottomSheetBehavior_Layout_behavior_skipCollapsed */ public void setSkipCollapsed(boolean skipCollapsed) { mSkipCollapsed = skipCollapsed; } /** * Sets whether this bottom sheet should skip the collapsed state when it is being hidden * after it is expanded once. * * @return Whether the bottom sheet should skip the collapsed state. * @attr ref android.support.design.R.styleable#BottomSheetBehavior_Layout_behavior_skipCollapsed */ public boolean getSkipCollapsed() { return mSkipCollapsed; } /** * Registers a callback to be notified of bottom sheet events. * * @param callback The callback to notify when bottom sheet events occur. */ public void addBottomSheetCallback(AnchorBottomSheetBehavior.BottomSheetCallback callback) { mCallbacks.add(callback); } public void removeBottomSheetCallback(AnchorBottomSheetBehavior.BottomSheetCallback callback) { mCallbacks.remove(callback); } public void setAllowUserDragging(boolean allowUserDragging) { mAllowUserDragging = allowUserDragging; } public boolean getAllowUserDragging() { return mAllowUserDragging; } /** * Sets the state of the bottom sheet. The bottom sheet will transition to that state with * animation. * * @param state One of {@link #STATE_COLLAPSED}, {@link #STATE_EXPANDED}, * {@link #STATE_ANCHORED} or{@link #STATE_HIDDEN}. */ public final void setState(final @AnchorBottomSheetBehavior.State int state) { if (state == mState) { return; } if (mViewRef == null) { // The view is not laid out yet; modify mState and let onLayoutChild handle it later if (state == STATE_COLLAPSED || state == STATE_EXPANDED || state == STATE_ANCHORED || (mHideable && state == STATE_HIDDEN)) { mState = state; } return; } final V child = mViewRef.get(); if (child == null) { return; } // Start the animation; wait until a pending layout if there is one. ViewParent parent = child.getParent(); if (parent != null && parent.isLayoutRequested() && ViewCompat.isAttachedToWindow(child)) { child.post(new Runnable() { @Override public void run() { startSettlingAnimation(child, state); } }); } else { startSettlingAnimation(child, state); } } /** * Gets the current state of the bottom sheet. * * @return One of {@link #STATE_EXPANDED}, {@link #STATE_ANCHORED}, {@link #STATE_COLLAPSED}, * {@link #STATE_DRAGGING}, and {@link #STATE_SETTLING}. */ @AnchorBottomSheetBehavior.State public final int getState() { return mState; } void setStateInternal(@AnchorBottomSheetBehavior.State int state) { if (mState == state) { return; } mState = state; View bottomSheet = mViewRef.get(); if (bottomSheet != null) { for (int i = 0; i < mCallbacks.size(); i++) { mCallbacks.get(i).onStateChanged(bottomSheet, state); } } } private void reset() { mActivePointerId = ViewDragHelper.INVALID_POINTER; if (mVelocityTracker != null) { mVelocityTracker.recycle(); mVelocityTracker = null; } } private void calculateTopAndTargetState(View child, float xvel, float yvel, int[] out) { int top; @AnchorBottomSheetBehavior.State int targetState; if (yvel < 0 && Math.abs(yvel) > mMinimumVelocity && Math.abs(yvel) > Math.abs(xvel)) { // scrolling up, i.e. expanding if (shouldExpand(child, yvel)) { top = mMinOffset; targetState = STATE_EXPANDED; } else { top = mAnchorOffset; targetState = STATE_ANCHORED; } } else if (mHideable && shouldHide(child, yvel)) { top = mParentHeight; targetState = STATE_HIDDEN; } else if (yvel > 0 && Math.abs(yvel) > mMinimumVelocity && Math.abs(yvel) > Math.abs(xvel)) { // scrolling down, i.e. collapsing if (shouldCollapse(child, yvel)) { top = mMaxOffset; targetState = STATE_COLLAPSED; } else { top = mAnchorOffset; targetState = STATE_ANCHORED; } } else { // not scrolling much, i.e. stationary int currentTop = child.getTop(); if (currentTop < mAnchorOffset) { if (Math.abs(currentTop - mMinOffset) < Math.abs(currentTop - mAnchorOffset)) { top = mMinOffset; targetState = STATE_EXPANDED; } else { top = mAnchorOffset; targetState = STATE_ANCHORED; } } else { if (Math.abs(currentTop - mMaxOffset) < Math.abs(currentTop - mAnchorOffset)) { top = mMaxOffset; targetState = STATE_COLLAPSED; } else { top = mAnchorOffset; targetState = STATE_ANCHORED; } } } out[0] = top; out[1] = targetState; } boolean shouldHide(View child, float yvel) { if (mSkipCollapsed) { return true; } if (child.getTop() < mMaxOffset) { // It should not hide, but collapse. return false; } final float newTop = child.getTop() + yvel * HIDE_FRICTION; return Math.abs(newTop - mMaxOffset) / (float) mPeekHeight > HIDE_THRESHOLD; } boolean shouldExpand(View child, float yvel) { if (!shouldExpandFullPanel()) { return false; } int currentTop = child.getTop(); if (currentTop < mAnchorOffset) { return true; } else if (mShouldAnchoredBeforeExpand) { return false; } final float newTop = currentTop + yvel * EXPAND_FRICTION; return newTop < mAnchorOffset; } boolean shouldCollapse(View child, float yvel) { int currentTop = child.getTop(); if (currentTop > mAnchorOffset) { return true; } else if (mShouldAnchoredBeforeCollapse) { return false; } final float newTop = currentTop + yvel * COLLAPSE_FRICTION; return newTop > mAnchorOffset; } private View findScrollingChild(View view) { if (view instanceof NestedScrollingChild) { return view; } if (view instanceof ViewPager) { ViewPager viewPager = (ViewPager) view; View currentViewPagerChild = ViewPagerUtils.getCurrentView(viewPager); View scrollingChild = findScrollingChild(currentViewPagerChild); if (scrollingChild != null) { return scrollingChild; } } else if (view instanceof ViewGroup) { ViewGroup group = (ViewGroup) view; for (int i = 0, count = group.getChildCount(); i < count; i++) { View scrollingChild = findScrollingChild(group.getChildAt(i)); if (scrollingChild != null) { return scrollingChild; } } } return null; } void startSettlingAnimation(View child, int state) { int top; if (state == STATE_COLLAPSED) { top = mMaxOffset; } else if (shouldExpandFullPanel() && state == STATE_EXPANDED) { top = mMinOffset; } else if (state == STATE_ANCHORED) { top = mAnchorOffset; } else if (mHideable && state == STATE_HIDDEN) { top = mParentHeight; } else { throw new IllegalArgumentException("Illegal state argument: " + state); } setStateInternal(STATE_SETTLING); if (mViewDragHelper.smoothSlideViewTo(child, child.getLeft(), top)) { ViewCompat.postOnAnimation(child, new SettleRunnable(child, state)); } } private final ViewDragHelper.Callback mDragCallback = new ViewDragHelper.Callback() { @Override public boolean tryCaptureView(View child, int pointerId) { if (mState == STATE_DRAGGING) { return false; } if (mTouchingScrollingChild) { return false; } if (mState == STATE_EXPANDED && mActivePointerId == pointerId) { View scroll = mNestedScrollingChildRef.get(); if (scroll != null && ViewCompat.canScrollVertically(scroll, -1)) { // Let the content scroll up return false; } } return mViewRef != null && mViewRef.get() == child; } @Override public void onViewPositionChanged(View changedView, int left, int top, int dx, int dy) { dispatchOnSlide(top); } @Override public void onViewDragStateChanged(int state) { if (state == ViewDragHelper.STATE_DRAGGING) { setStateInternal(STATE_DRAGGING); } } @Override public void onViewReleased(View releasedChild, float xvel, float yvel) { int[] out = new int[2]; calculateTopAndTargetState(releasedChild, xvel, yvel, out); int top = out[0]; @AnchorBottomSheetBehavior.State int targetState = out[1]; if (mViewDragHelper.settleCapturedViewAt(releasedChild.getLeft(), top)) { setStateInternal(STATE_SETTLING); ViewCompat.postOnAnimation(releasedChild, new SettleRunnable(releasedChild, targetState)); } else { setStateInternal(targetState); } } @Override public int clampViewPositionVertical(View child, int top, int dy) { return constrain(top, shouldExpandFullPanel() ? mMinOffset : mAnchorOffset, mHideable ? mParentHeight : mMaxOffset); } private int constrain(int amount, int low, int high) { return amount < low ? low : (amount > high ? high : amount); } @Override public int clampViewPositionHorizontal(View child, int left, int dx) { return child.getLeft(); } @Override public int getViewVerticalDragRange(View child) { if (mHideable) { return mParentHeight - mMinOffset; } else { return mMaxOffset - mMinOffset; } } }; void dispatchOnSlide(int top) { View bottomSheet = mViewRef.get(); if (bottomSheet != null) { float slideOffset; if (top > mMaxOffset) { slideOffset = (float) (mMaxOffset - top) / (mParentHeight - mMaxOffset); } else { slideOffset = (float) (mMaxOffset - top) / (mMaxOffset - mMinOffset); } for (int i = 0; i < mCallbacks.size(); i++) { mCallbacks.get(i).onSlide(bottomSheet, slideOffset); } } } @VisibleForTesting int getPeekHeightMin() { return mPeekHeightMin; } private class SettleRunnable implements Runnable { private final View mView; @AnchorBottomSheetBehavior.State private final int mTargetState; SettleRunnable(View view, @AnchorBottomSheetBehavior.State int targetState) { mView = view; mTargetState = targetState; } @Override public void run() { if (mViewDragHelper != null && mViewDragHelper.continueSettling(true)) { ViewCompat.postOnAnimation(mView, this); } else { setStateInternal(mTargetState); } } } protected static class SavedState extends AbsSavedState { @AnchorBottomSheetBehavior.State final int state; public SavedState(Parcel source) { this(source, null); } public SavedState(Parcel source, ClassLoader loader) { super(source, loader); //noinspection ResourceType state = source.readInt(); } public SavedState(Parcelable superState, @AnchorBottomSheetBehavior.State int state) { super(superState); this.state = state; } @Override public void writeToParcel(Parcel out, int flags) { super.writeToParcel(out, flags); out.writeInt(state); } public static final Creator<SavedState> CREATOR = ParcelableCompat .newCreator(new ParcelableCompatCreatorCallbacks<SavedState>() { @Override public SavedState createFromParcel(Parcel in, ClassLoader loader) { return new SavedState(in, loader); } @Override public SavedState[] newArray(int size) { return new SavedState[size]; } }); } /** * A utility function to get the {@link AnchorBottomSheetBehavior} associated with the {@code view}. * * @param view The {@link View} with {@link AnchorBottomSheetBehavior}. * @return The {@link AnchorBottomSheetBehavior} associated with the {@code view}. */ @SuppressWarnings("unchecked") public static <V extends View> AnchorBottomSheetBehavior<V> from(V view) { ViewGroup.LayoutParams params = view.getLayoutParams(); if (!(params instanceof CoordinatorLayout.LayoutParams)) { throw new IllegalArgumentException("The view is not a child of CoordinatorLayout"); } CoordinatorLayout.Behavior behavior = ((CoordinatorLayout.LayoutParams) params).getBehavior(); if (!(behavior instanceof AnchorBottomSheetBehavior)) { throw new IllegalArgumentException("The view is not associated with AnchorBottomSheetBehavior"); } return (AnchorBottomSheetBehavior<V>) behavior; } }