Android实现三段式滑动效果

目录

• 高德的效果：

高德的效果：

实现的效果：

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<V extends View> extends CoordinatorLayout.Behavior<V> {
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<V> viewRef;
WeakReference<View> nestedScrollingChildRef;
private GaoDeBottomSheetBehavior.BottomSheetCallback callback;
private VelocityTracker velocityTracker;
int activePointerId;
private int initialY;
boolean touchingScrollingChild;
private Map<View, Integer> 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 = 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() {
}
@Override
public 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;
}
}
@Override
public void onViewPositionChanged(@NonNull View changedView, int left, int top, int dx, int dy) {
GaoDeBottomSheetBehavior.this.dispatchOnSlide(top);
}
@Override
public void onViewDragStateChanged(int state) {
if (state == 1) {
GaoDeBottomSheetBehavior.this.setStateInternal(STATE_DRAGGING);
}
}
@Override
public 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);
}
}
@Override
public 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);
}
@Override
public int clampViewPositionHorizontal(@NonNull View child, int left, int dx) {
return child.getLeft();
}
@Override
public int getViewVerticalDragRange(@NonNull View child) {
return GaoDeBottomSheetBehavior.this.hideable ? GaoDeBottomSheetBehavior.this.parentHeight : GaoDeBottomSheetBehavior.this.collapsedOffset;
}
}
@Override
public Parcelable onSaveInstanceState(CoordinatorLayout parent, V child) {
return new GaoDeBottomSheetBehavior.SavedState(super.onSaveInstanceState(parent, child), this.state);
}
@Override
public 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;
}
}
@Override
public 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;
}
@Override
public 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();
}
}
}
@Override
public 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;
}
}
}
@Override
public 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;
}
@Override
public 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;
}
}
}
@Override
public 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;
}
}
@Override
public 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() {
@Override
public 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;
}
}
@VisibleForTesting
View 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()));
}
}
}
@VisibleForTesting
int getPeekHeightMin() {
return this.peekHeightMin;
}
public static <V extends View> GaoDeBottomSheetBehavior<V> 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<GaoDeBottomSheetBehavior.SavedState> CREATOR = new ClassLoaderCreator<GaoDeBottomSheetBehavior.SavedState>() {
@Override
public GaoDeBottomSheetBehavior.SavedState createFromParcel(Parcel in, ClassLoader loader) {
return new GaoDeBottomSheetBehavior.SavedState(in, loader);
}
@Override
public GaoDeBottomSheetBehavior.SavedState createFromParcel(Parcel in) {
return new GaoDeBottomSheetBehavior.SavedState(in, (ClassLoader) null);
}
@Override
public 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;
}
@Override
public 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;
}
@Override
public 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：

<androidx.appcompat.widget.LinearLayoutCompat
android:id="@+id/bottom_sheet"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@android:color/white"
android:orientation="vertical"
android:visibility="visible"
app:behavior_hideable="false"
app:behavior_middleHeight="200dp"
app:behavior_peekHeight="80dp"
app:layout_behavior=".gaode.GaoDeBottomSheetBehavior"
tools:ignore="MissingPrefix">
//....
</androidx.appcompat.widget.LinearLayoutCompat>

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);
}
@Override
public 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);
}
@Override
public boolean layoutDependsOn(@NonNull CoordinatorLayout parent, @NonNull View child, @NonNull View dependency) {
return dependency instanceof LinearLayoutCompat || super.layoutDependsOn(parent, child, dependency);
}
@Override
public 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。

以上就是Android实现三段式滑动效果的详细内容，更多关于Android 三段式滑动效果的资料请关注华域联盟其它相关文章！