大更新
因为有大约 4 或 5 个关于同一主题但具有不同要求的问题，我试图回答所有问题。一个不礼貌的管理员删除/关闭了它们，让我为每个人创建一张票并更改它们以避免“复制粘贴”。我会给你一个完整答案的链接，在那里你可以找到关于如何获得像谷歌地图这样的完整行为的所有解释。
回答您的问题
我怎样才能使用 BottomSheetBehavior 并获得这个额外的锚定状态？
您可以通过BottomSheetBehavior以下步骤修改默认添加一个统计信息来做到这一点：
- 创建一个 Java 类并从
CoordinatorLayout.Behavior<V>
- 将粘贴代码从默认
BottomSheetBehavior 文件复制到新文件。
clampViewPositionVertical使用以下代码修改方法：
@Override
public int clampViewPositionVertical(View child, int top, int dy) {
return constrain(top, mMinOffset, mHideable ? mParentHeight : mMaxOffset);
}
int constrain(int amount, int low, int high) {
return amount < low ? low : (amount > high ? high : amount);
}
添加新状态
public static final int STATE_ANCHOR_POINT = X;
修改下一个方法：onLayoutChild、、onStopNestedScroll和BottomSheetBehavior<V> from(V view)（setState可选）
我将添加那些修改后的方法和示例项目的链接
public boolean onLayoutChild(CoordinatorLayout parent, V child, int layoutDirection) {
// First let the parent lay it out
if (mState != STATE_DRAGGING && mState != STATE_SETTLING) {
if (ViewCompat.getFitsSystemWindows(parent) &&
!ViewCompat.getFitsSystemWindows(child)) {
ViewCompat.setFitsSystemWindows(child, true);
}
parent.onLayoutChild(child, layoutDirection);
}
// Offset the bottom sheet
mParentHeight = parent.getHeight();
mMinOffset = Math.max(0, mParentHeight - child.getHeight());
mMaxOffset = Math.max(mParentHeight - mPeekHeight, mMinOffset);
//if (mState == STATE_EXPANDED) {
// ViewCompat.offsetTopAndBottom(child, mMinOffset);
//} else if (mHideable && mState == STATE_HIDDEN...
if (mState == STATE_ANCHOR_POINT) {
ViewCompat.offsetTopAndBottom(child, mAnchorPoint);
} else if (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);
}
if (mViewDragHelper == null) {
mViewDragHelper = ViewDragHelper.create(parent, mDragCallback);
}
mViewRef = new WeakReference<>(child);
mNestedScrollingChildRef = new WeakReference<>(findScrollingChild(child));
return true;
}
public void onStopNestedScroll(CoordinatorLayout coordinatorLayout, V child, View target) {
if (child.getTop() == mMinOffset) {
setStateInternal(STATE_EXPANDED);
return;
}
if (target != mNestedScrollingChildRef.get() || !mNestedScrolled) {
return;
}
int top;
int targetState;
if (mLastNestedScrollDy > 0) {
//top = mMinOffset;
//targetState = STATE_EXPANDED;
int currentTop = child.getTop();
if (currentTop > mAnchorPoint) {
top = mAnchorPoint;
targetState = STATE_ANCHOR_POINT;
}
else {
top = mMinOffset;
targetState = STATE_EXPANDED;
}
} else if (mHideable && shouldHide(child, getYVelocity())) {
top = mParentHeight;
targetState = STATE_HIDDEN;
} else if (mLastNestedScrollDy == 0) {
int currentTop = child.getTop();
if (Math.abs(currentTop - mMinOffset) < Math.abs(currentTop - mMaxOffset)) {
top = mMinOffset;
targetState = STATE_EXPANDED;
} else {
top = mMaxOffset;
targetState = STATE_COLLAPSED;
}
} else {
//top = mMaxOffset;
//targetState = STATE_COLLAPSED;
int currentTop = child.getTop();
if (currentTop > mAnchorPoint) {
top = mMaxOffset;
targetState = STATE_COLLAPSED;
}
else {
top = mAnchorPoint;
targetState = STATE_ANCHOR_POINT;
}
}
if (mViewDragHelper.smoothSlideViewTo(child, child.getLeft(), top)) {
setStateInternal(STATE_SETTLING);
ViewCompat.postOnAnimation(child, new SettleRunnable(child, targetState));
} else {
setStateInternal(targetState);
}
mNestedScrolled = false;
}
public final void setState(@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
/**
* New behavior (added: state == STATE_ANCHOR_POINT ||)
*/
if (state == STATE_COLLAPSED || state == STATE_EXPANDED ||
state == STATE_ANCHOR_POINT ||
(mHideable && state == STATE_HIDDEN)) {
mState = state;
}
return;
}
V child = mViewRef.get();
if (child == null) {
return;
}
int top;
if (state == STATE_COLLAPSED) {
top = mMaxOffset;
} else if (state == STATE_ANCHOR_POINT) {
top = mAnchorPoint;
} else if (state == STATE_EXPANDED) {
top = mMinOffset;
} 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));
}
}
public static <V extends View> BottomSheetBehaviorGoogleMapsLike<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 BottomSheetBehaviorGoogleMapsLike)) {
throw new IllegalArgumentException(
"The view is not associated with BottomSheetBehaviorGoogleMapsLike");
}
return (BottomSheetBehaviorGoogleMapsLike<V>) behavior;
}
你甚至可以使用回调behavior.setBottomSheetCallback(new BottomSheetBehaviorGoogleMapsLike.BottomSheetCallback() {....
这是它的样子
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