我正在尝试当NestedScrollView向下滚动时隐藏FloatingActionButton,而当NestedScrollView向上滚动时,使它重新显示。
这是我的布局:
<android.support.design.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true">
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:fitsSystemWindows="true">
<android.support.design.widget.CollapsingToolbarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:fitsSystemWindows="true"
app:layout_scrollFlags="scroll|enterAlways">
</android.support.design.widget.CollapsingToolbarLayout>
</android.support.design.widget.AppBarLayout>
<android.support.v4.widget.NestedScrollView
app:layout_behavior="@string/appbar_scrolling_view_behavior"/>
<android.support.design.widget.FloatingActionButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="@dimen/grid_2"
android:layout_gravity="bottom|end"
android:src="@drawable/ic_place_white"
android:clickable="true"
app:backgroundTint="@color/colorPrimary"
app:layout_behavior="com.myapp.ScrollAnimationFAB"/>
</android.support.design.widget.CoordinatorLayout>
这是我的floatingActionButton行为:
public class ScrollAnimationFAB extends FloatingActionButton.Behavior {
public ScrollAnimationFAB(Context context, AttributeSet attrs) {
super();
}
@Override
public boolean onStartNestedScroll(CoordinatorLayout coordinatorLayout, FloatingActionButton child, View directTargetChild, View target, int nestedScrollAxes) {
return nestedScrollAxes == ViewCompat.SCROLL_AXIS_VERTICAL ||
super.onStartNestedScroll(coordinatorLayout, child, directTargetChild, target,
nestedScrollAxes);
}
@Override
public void onNestedScroll(CoordinatorLayout coordinatorLayout, FloatingActionButton child, View target, int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed) {
super.onNestedScroll(coordinatorLayout, child, target, dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed);
if (dyConsumed > 0 && child.getVisibility() == View.VISIBLE) {
child.hide();
} else if (dyConsumed < 0 && child.getVisibility() != View.VISIBLE) {
child.show();
}
}
}
这些代码对我来说不起作用,我想知道它是否与NestedScrollView的行为有关。任何帮助都将不胜感激!
更新
我发现一些奇怪的事情!如果我在onNestedScroll中调用fab的方法(child.hide(),child.show()),那么onStartNestedScroll和onNestedScroll永远不会再次被调用,但是如果我不在fab中调用这些方法,则onStartNestedScroll和onNestedScroll会正常调用。