當RecyclerView位於SwipeRefreshLayout中時，如何在使用行爲滾動RecyclerView時顯示/隱藏FloatingActionButton？

Question

當RecyclerView位於SwipeRefreshLayout的內部時，如何使用Behavior進行滾動時顯示/隱藏FloatingActionButtonRecyclerView？我正在使用支持設計庫的22.2.0版本。

<android.support.design.widget.CoordinatorLayout 
    android:layout_width="match_parent" 
    android:layout_height="match_parent"> 

    <android.support.v4.widget.SwipeRefreshLayout 
     android:id="@+id/swipe_refresh_layout" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent"> 

     <android.support.v7.widget.RecyclerView 
      android:id="@+id/recycler_view" 
      android:layout_width="match_parent" 
      android:layout_height="match_parent" 
      android:clipToPadding="false" 
      android:paddingBottom="@dimen/list_padding_bottom" 
      android:paddingTop="@dimen/list_padding_top" 
      android:scrollbars="vertical"/> 

    </android.support.v4.widget.SwipeRefreshLayout> 

    <android.support.design.widget.FloatingActionButton 
     android:id="@+id/fab" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_gravity="bottom|right" 
     android:layout_margin="@dimen/fab_margin" 
     android:src="@drawable/ic_bookmark"/> 

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

Answer 1

我用的是支持設計庫的過時的版本：

我附上我的佈局。更新到版本23.2.0解決了我的問題。

定製FAB Behavior（從文章How to hide/show Toolbar when list is scrolling (part 3)）：

public class ScrollingFABBehavior extends FloatingActionButton.Behavior { 
    private int toolbarHeight; 

    public ScrollingFABBehavior(Context context, AttributeSet attrs) { 
     super(); 
     this.toolbarHeight = Utils.getToolbarHeight(context); 
    } 

    @Override 
    public boolean layoutDependsOn(CoordinatorLayout parent, FloatingActionButton fab, View dependency) { 
     return super.layoutDependsOn(parent, fab, dependency) || (dependency instanceof AppBarLayout); 
    } 

    @Override 
    public boolean onDependentViewChanged(CoordinatorLayout parent, FloatingActionButton fab, View dependency) { 
     boolean returnValue = super.onDependentViewChanged(parent, fab, dependency); 
     if (dependency instanceof AppBarLayout) { 
       CoordinatorLayout.LayoutParams lp = (CoordinatorLayout.LayoutParams) fab.getLayoutParams(); 
       int fabBottomMargin = lp.bottomMargin; 
       int distanceToScroll = fab.getHeight() + fabBottomMargin; 
       float ratio = (float)dependency.getY()/(float)toolbarHeight; 
       fab.setTranslationY(-distanceToScroll * ratio); 
     } 
     return returnValue; 
    } 
} 

佈局：

<?xml version="1.0" encoding="utf-8"?> 
<android.support.design.widget.CoordinatorLayout 
    android:id="@+id/coordinatorLayout" 
    xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:app="http://schemas.android.com/apk/res-auto" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent"> 

    <android.support.design.widget.AppBarLayout 
     android:id="@+id/appBarLayout" 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content"> 

     <android.support.v7.widget.Toolbar 
      android:id="@+id/toolbar" 
      android:layout_width="match_parent" 
      android:layout_height="?attr/actionBarSize" 
      android:background="?attr/colorPrimary" 
      app:layout_scrollFlags="scroll|enterAlways"/> 

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

    <android.support.v4.widget.SwipeRefreshLayout 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     app:layout_behavior="@string/appbar_scrolling_view_behavior"> 

     <android.support.v7.widget.RecyclerView 
      android:id="@+id/recyclerView" 
      xmlns:android="http://schemas.android.com/apk/res/android" 
      android:layout_width="match_parent" 
      android:layout_height="match_parent"/> 

    </android.support.v4.widget.SwipeRefreshLayout> 

    <android.support.design.widget.FloatingActionButton 
     android:id="@+id/fabButton" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_gravity="end|bottom" 
     android:layout_margin="@dimen/fab_margin" 
     android:src="@drawable/ic_favorite_outline_white_24dp" 
     app:borderWidth="0dp" 
     app:layout_behavior="...ScrollingFABBehavior"/> 

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