自定义自动隐藏floatingActionButton行为不起作用

Question

我试图在NestedScrollView向下滚动时隐藏FloatingActionButton,并在NestedScrollView向上滚动时显示自己.

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();
        }
    }
}

这些代码对我不起作用,我想知道它是否与NestedScrollView的行为有关.任何帮助将不胜感激!

UPDATE

我找到了有线的东西!如果我在onNestedScroll中调用fab的方法(child.hide(),child.show()),则onStartNestedScroll和onNestedScroll永远不会再次调用,但如果我没有调用fab中的方法,则onStartNestedScroll和onNestedScroll会正常调用.

Answer 1

看看@woxingxiao 在这里说的是什么

onNestedScroll如果按钮的可见性,几乎不会被解雇GONE.所以,替换:

child.hide();

至:

child.hide(new FloatingActionButton.OnVisibilityChangedListener() {
    @Override
    public void onHidden(FloatingActionButton fab) {
        super.onHidden(fab);
        fab.setVisibility(View.INVISIBLE);
    }
});