FloatActionButton滚动时没有隐藏

Question

当我在“活动”中向下滚动但不起作用时，我正试图隐藏我的FAB。为什么？？？片段标签内部包含RecyclerView片段。

这是我的Activity xml代码：

<androidx.coordinatorlayout.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:id="@+id/coordinator"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".activities.principal.PrincipalActivity">

<fragment
        android:id="@+id/PrincipalActivity_navHostFragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:defaultNavHost="true"
        app:navGraph="@navigation/principal_nav_graph" />

<com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/PrincipalActivity_bottom_navigation"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:background="@color/colorPrimary"
        app:itemIconTint="@drawable/bottom_navigation_colors"
        app:itemTextColor="@android:color/white"
        app:layout_anchor="@id/PrincipalActivity_navHostFragment"
        app:layout_anchorGravity="bottom"
        app:menu="@menu/bottom_navigation_menu_principal" />

<com.google.android.material.floatingactionbutton.FloatingActionButton
        android:id="@+id/PrincipalActivity_fabItensPedido"
        style="@style/Widget.MaterialComponents.FloatingActionButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="16dp"
        android:layout_marginBottom="70dp"
        android:src="@drawable/ic_carrinho"
        app:backgroundTint="@color/colorAccent"
        app:fabSize="auto"
        app:layout_anchor="@id/PrincipalActivity_navHostFragment"
        app:layout_anchorGravity="bottom|end"
        app:layout_behavior=".utils.ScrollAnimationFAB" />

</androidx.coordinatorlayout.widget.CoordinatorLayout>

这是我在FAB按钮中使用的布局行为，但不适用于活动，仅在片段标记内的片段中有效。

class ScrollAnimationFAB extends CoordinatorLayout.Behavior<FloatingActionButton> {

    public ScrollAnimationFAB(){
        super();
    }

    public ScrollAnimationFAB(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    public boolean onStartNestedScroll(@NonNull CoordinatorLayout coordinatorLayout, @NonNull FloatingActionButton child, @NonNull View directTargetChild, @NonNull View target, int axes, int type) {
        return axes == ViewCompat.SCROLL_AXIS_VERTICAL ||
                super.onStartNestedScroll(coordinatorLayout, child, directTargetChild, target,
                        axes, ViewCompat.TYPE_TOUCH);
    }

    @Override
    public void onNestedScroll(@NonNull CoordinatorLayout coordinatorLayout, @NonNull FloatingActionButton child, @NonNull View target, int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed, int type, @NonNull int[] consumed) {

        Log.v("Msg", "dyConsumed: " + dyConsumed + ", dyUnConsumed: " + dyUnconsumed);
        if (dyConsumed > 0 && child.getVisibility() == View.VISIBLE) {
            child.hide(new FloatingActionButton.OnVisibilityChangedListener() {
                @Override
                public void onHidden(FloatingActionButton fab) {
                    super.onHidden(fab);
                    fab.setVisibility(View.INVISIBLE);
                }
            });
        } else if (dyConsumed < 0 && dyUnconsumed == 0 && child.getVisibility() != View.VISIBLE) {
            child.show();
        }
    }
}

请帮助我。

Answer 1

浮动操作按钮为您提供了一种很好的方法fab.hide()

Answer 2

如果FloatingActionButton位于CoordinatorLayout中-您应使用以下代码：

    CoordinatorLayout.LayoutParams p = (CoordinatorLayout.LayoutParams) playlist_FAB_start.getLayoutParams();
    p.setAnchorId(View.NO_ID);
    playlist_FAB_start.setLayoutParams(p);
    playlist_FAB_start.setVisibility(View.GONE);