浮动动作按钮（fab）滚动动作不起作用

Question

我试图让“fab”在向上滚动时消失并在向下滚动时出现但没有任何反应

此布局包含在其他drawerlayout

中

     <android.support.design.widget.CoordinatorLayout 
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:fresco="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/coord_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
android:layoutDirection="rtl"
tools:context="co.broccli.n5rogfeen.ProfileActivity">
<!--#android:fitsSystemWindows="true"
tools:openDrawer="start">-->
<include layout="@layout/content_scrolling" />

<View
    android:layout_width="match_parent"
    android:layout_height="30dp"

    android:background="@drawable/toolbar_dropshadow"
    app:layout_anchor="@id/appbar"
    app:layout_anchorGravity="bottom" />
<android.support.design.widget.AppBarLayout
    android:id="@+id/appbar"
    android:layout_width="match_parent"
    android:layout_height="190dp"
    android:theme="@style/AppTheme.AppBarOverlay"
    tools:layout_editor_absoluteY="-2dp"

    >

    <android.support.design.widget.CollapsingToolbarLayout
        android:id="@+id/toolbar_layout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:fitsSystemWindows="true"
        app:contentScrim="?attr/colorPrimary"
        app:layout_scrollFlags="scroll|exitUntilCollapsed"
        app:toolbarId="@+id/toolbar">


        <android.support.v7.widget.LinearLayoutCompat
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="bottom|center_horizontal"
            android:orientation="vertical"
            android:paddingBottom="10dp"
            app:layout_collapseMode="parallax">

            <com.facebook.drawee.view.SimpleDraweeView
                android:id="@+id/my_image_view"
                android:layout_width="75dp"
                android:layout_height="75dp"
                android:layout_gravity="center_vertical|center_horizontal"
                fresco:placeholderImage="@color/colorAccent"
                fresco:roundAsCircle="true"
                fresco:viewAspectRatio="1.33"
                />

            <android.support.v7.widget.AppCompatTextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center_horizontal"
                android:text="name" />


            <android.support.v7.widget.AppCompatTextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center_horizontal"
                android:text="@string/acc_balance" />
        </android.support.v7.widget.LinearLayoutCompat>


        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:layout_gravity="top"
            app:layout_collapseMode="pin"
            app:popupTheme="@style/AppTheme.PopupOverlay">

            <TextView
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:gravity="center"
                android:text="@string/app_name"
                android:textAppearance="@style/Base.TextAppearance.AppCompat.Large" />
        </android.support.v7.widget.Toolbar>


    </android.support.design.widget.CollapsingToolbarLayout>


</android.support.design.widget.AppBarLayout>


<android.support.design.widget.FloatingActionButton
    android:id="@+id/floating_action_button"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="bottom|end"
    android:layout_margin="16dp"
    android:src="@drawable/ic_mode_edit_black_24px"
    android:background="@color/colorPrimary"
    app:backgroundTint="@color/colorPrimary"
    app:fabSize="normal"

   />

recyclerview 在包含的布局“content_scrolling”中

     final FloatingActionButton mFloatingActionButton = (FloatingActionButton) findViewById(R.id.floating_action_button);
    mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
        @Override
        public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
            super.onScrolled(recyclerView, dx, dy);
            if (dy > 0 && mFloatingActionButton.getVisibility() == View.VISIBLE) {
                mFloatingActionButton.hide();
            } else if (dy < 0 && mFloatingActionButton.getVisibility() != View.VISIBLE) {
                mFloatingActionButton.show();
            }
        }
    });

我虽然尝试使用浮动操作按钮行为，但仅在我滚动到末尾并且工厂消失时它不会再次出现时才起作用

   public class ScrollAwareFABBehavior extends FloatingActionButton.Behavior { private static final String TAG = "ScrollAwareFABBehavior";

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

public boolean onStartNestedScroll(CoordinatorLayout parent, FloatingActionButton child, View directTargetChild, View target, int nestedScrollAxes) {
    return true;
}

@Override
public boolean layoutDependsOn(CoordinatorLayout parent, FloatingActionButton child, View dependency) {
    if(dependency instanceof RecyclerView)
        return true;

    return false;
}

@Override
public void onNestedScroll(CoordinatorLayout coordinatorLayout,
                           FloatingActionButton child, View target, int dxConsumed,
                           int dyConsumed, int dxUnconsumed, int dyUnconsumed) {
    // TODO Auto-generated method stub
    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();
    }
}
} 

Answer 1

如果您查看ScrollAwareFABBehavior 的child.hide() 中hide() 方法的javadoc，它类似于：

/**
 * Hides the button.
 * <p>This method will animate the button hide if the view has already been laid out.</p>
 */
public void hide() {
    hide(/* listener: */ null); // The listener to notify when this view is hidden
}

因此，如果在没有listener 的情况下调用child.hide()，则传递null，因此它不会再次弹出。 您可以实现显示/隐藏为：

if (dyConsumed > 0 && child.getVisibility() == View.VISIBLE) {
    child.setVisibility(View.INVISIBLE);
} else if (dyConsumed < 0 && child.getVisibility() != View.VISIBLE) {
    child.setVisibility(View.VISIBLE);
}

Answer 2

至于ScrollAwareFABBehavior。 在调用 hide() 后，FAB 将不会再次显示，因为由于当前 CoordinatorLayout.onStartNestedScroll() 实现子视图（此处为 FAB）的行为，如果 onStartNestedScroll 方法的可见性消失，则不再调用它。

解决方案是在隐藏后立即将 FAB 的可见性设置为 INVISIBLE。在ScrollAwareFABBehavior 内创建监听器：

private val listener = object : FloatingActionButton.OnVisibilityChangedListener() {
    override fun onHidden(fab: FloatingActionButton?) {
        fab?.visibility = INVISIBLE
    }
}

然后：

hide(listener)