如何快速滚动添加到RecyclerView [英] How to add a fast-scroller to the RecyclerView

问题描述

在ListView中，你可以有一个快速滚动它允许你拖动滚动条轻松滚动，无论你想（使用<一个href="http://developer.android.com/reference/android/widget/AbsListView.html#attr_android:fastScrollEnabled">fastScrollEnabled属性）

On ListView, you could have a fast scroller which allowed you to drag a scrollbar to easily scroll to wherever you wished (using fastScrollEnabled attribute)

加上<一个href="http://developer.android.com/reference/android/widget/SectionIndexer.html">SectionIndexer"类和任选的一些属性，你可以有一个很好的弹出窗口，显示了你使用这个滚动条（链接 这里 ）。

这样的事情是显示在联系人应用程序，让您可以轻松地滚动到特定的字母。

Such a thing is shown on the contacts app so that you could scroll easily to specific letters.

RecyclerView似乎没有任何的那些。甚至没有一个快速滚动。

RecyclerView doesn't seem to have any of those. Not even a fast-scroll.

我如何添加一个快速滚动功能，为RecyclerView？

How do I add a fast scroller functionality for the RecyclerView?

推荐答案

由于所有的第三方库有问题，我已经决定要收集什么，我可以找到（大多是从<一个href="https://blog.stylingandroid.com/recyclerview-fastscroll-part-2/#comment-67201">here),解决一切并发布快速滚动的RecyclerView的我自己的POC：

Since all third party libraries had issues, I've decided to gather what I can find (mostly from here), fix everything and publish my own POC of the fast-scroller of the RecyclerView :

<一个href="https://github.com/AndroidDeveloperLB/LollipopContactsRecyclerViewFastScroller">https://github.com/AndroidDeveloperLB/LollipopContactsRecyclerViewFastScroller

用法：

1. 请实现BubbleTextGetter，这给在数据中的位置将返回文本中的气泡弹出来显示RecyclerView.Adapter。

1. make a RecyclerView.Adapter that implements BubbleTextGetter, which given a position in the data will return the text to show in the bubble-popup.

位置FastScroller的布局容器RecyclerView（可能在合适的区域）内。

position the FastScroller inside the layout that container the RecyclerView (probably at the right area).

自定义FastScroller FastScroller

Customize the FastScroller FastScroller

一些缺点：

1. 在不支持的方向变化，但它可能是很容易解决。
2. 在不支持其他的布局管理。只有LinearLayoutManager
3. 需要API 11以上。

code：

BubbleTextGetter

public interface BubbleTextGetter
  {
  String getTextToShowInBubble(int pos);
  }

recycler_view_fast_scroller__fast_scroller.xml

<?xml version="1.0" encoding="utf-8"?>
<merge xmlns:android="http://schemas.android.com/apk/res/android"
       xmlns:tools="http://schemas.android.com/tools"
       android:layout_width="wrap_content"
       android:layout_height="match_parent">

  <TextView
    android:id="@+id/fastscroller_bubble"
    android:layout_gravity="right|end"
    android:gravity="center"
    android:textSize="48sp" tools:text="A"
    android:layout_width="wrap_content"
    android:textColor="#FFffffff"
    android:layout_height="wrap_content"
    android:background="@drawable/recycler_view_fast_scroller__bubble"
    android:visibility="visible"/>

  <ImageView
    android:id="@+id/fastscroller_handle"
    android:layout_width="wrap_content"
    android:layout_marginRight="8dp"
    android:layout_marginLeft="8dp"
    android:layout_height="wrap_content"
    android:src="@drawable/recycler_view_fast_scroller__handle"/>

</merge>

MainActivity

...
fastScroller=(FastScroller)findViewById(R.id.fastscroller);
fastScroller.setRecyclerView(recyclerView);

FastScroller

public class FastScroller extends LinearLayout
  {
  private static final int BUBBLE_ANIMATION_DURATION=100;
  private static final int TRACK_SNAP_RANGE=5;

  private TextView bubble;
  private View handle;
  private RecyclerView recyclerView;
  private final ScrollListener scrollListener=new ScrollListener();
  private int height;

  private ObjectAnimator currentAnimator=null;

  public FastScroller(final Context context,final AttributeSet attrs,final int defStyleAttr)
    {
    super(context,attrs,defStyleAttr);
    initialise(context);
    }

  public FastScroller(final Context context)
    {
    super(context);
    initialise(context);
    }

  public FastScroller(final Context context,final AttributeSet attrs)
    {
    super(context,attrs);
    initialise(context);
    }

  private void initialise(Context context)
    {
    setOrientation(HORIZONTAL);
    setClipChildren(false);
    LayoutInflater inflater=LayoutInflater.from(context);
    inflater.inflate(R.layout.recycler_view_fast_scroller__fast_scroller,this,true);
    bubble=(TextView)findViewById(R.id.fastscroller_bubble);
    handle=findViewById(R.id.fastscroller_handle);
    bubble.setVisibility(INVISIBLE);
    }

  @Override
  protected void onSizeChanged(int w,int h,int oldw,int oldh)
    {
    super.onSizeChanged(w,h,oldw,oldh);
    height=h;
    }

  @Override
  public boolean onTouchEvent(@NonNull MotionEvent event)
    {
    final int action=event.getAction();
    switch(action)
      {
      case MotionEvent.ACTION_DOWN:
        if(event.getX()<handle.getX())
          return false;
        if(currentAnimator!=null)
          currentAnimator.cancel();
        if(bubble.getVisibility()==INVISIBLE)
          showBubble();
        handle.setSelected(true);
      case MotionEvent.ACTION_MOVE:
        setPosition(event.getY());
        setRecyclerViewPosition(event.getY());
        return true;
      case MotionEvent.ACTION_UP:
      case MotionEvent.ACTION_CANCEL:
        handle.setSelected(false);
        hideBubble();
        return true;
      }
    return super.onTouchEvent(event);
    }

  public void setRecyclerView(RecyclerView recyclerView)
    {
    this.recyclerView=recyclerView;
    recyclerView.setOnScrollListener(scrollListener);
    }

  private void setRecyclerViewPosition(float y)
    {
    if(recyclerView!=null)
      {
      int itemCount=recyclerView.getAdapter().getItemCount();
      float proportion;
      if(handle.getY()==0)
        proportion=0f;
      else if(handle.getY()+handle.getHeight()>=height-TRACK_SNAP_RANGE)
        proportion=1f;
      else
        proportion=y/(float)height;
      int targetPos=getValueInRange(0,itemCount-1,(int)(proportion*(float)itemCount));
      recyclerView.scrollToPosition(targetPos);
      String bubbleText=((BubbleTextGetter)recyclerView.getAdapter()).getTextToShowInBubble(targetPos);
      bubble.setText(bubbleText);
      }
    }

  private int getValueInRange(int min,int max,int value)
    {
    int minimum=Math.max(min,value);
    return Math.min(minimum,max);
    }

  private void setPosition(float y)
    {
    int bubbleHeight=bubble.getHeight();
    int handleHeight=handle.getHeight();
    handle.setY(getValueInRange(0,height-handleHeight,(int)(y-handleHeight/2)));
    bubble.setY(getValueInRange(0,height-bubbleHeight-handleHeight/2,(int)(y-bubbleHeight)));
    }

  private void showBubble()
    {
    AnimatorSet animatorSet=new AnimatorSet();
    bubble.setVisibility(VISIBLE);
    if(currentAnimator!=null)
      currentAnimator.cancel();
    currentAnimator=ObjectAnimator.ofFloat(bubble,"alpha",0f,1f).setDuration(BUBBLE_ANIMATION_DURATION);
    currentAnimator.start();
    }

  private void hideBubble()
    {
    if(currentAnimator!=null)
      currentAnimator.cancel();
    currentAnimator=ObjectAnimator.ofFloat(bubble,"alpha",1f,0f).setDuration(BUBBLE_ANIMATION_DURATION);
    currentAnimator.addListener(new AnimatorListenerAdapter()
    {
    @Override
    public void onAnimationEnd(Animator animation)
      {
      super.onAnimationEnd(animation);
      bubble.setVisibility(INVISIBLE);
      currentAnimator=null;
      }

    @Override
    public void onAnimationCancel(Animator animation)
      {
      super.onAnimationCancel(animation);
      bubble.setVisibility(INVISIBLE);
      currentAnimator=null;
      }
    });
    currentAnimator.start();
    }

  private class ScrollListener extends OnScrollListener
    {
    @Override
    public void onScrolled(RecyclerView rv,int dx,int dy)
      {
      View firstVisibleView=recyclerView.getChildAt(0);
      int firstVisiblePosition=recyclerView.getChildPosition(firstVisibleView);
      int visibleRange=recyclerView.getChildCount();
      int lastVisiblePosition=firstVisiblePosition+visibleRange;
      int itemCount=recyclerView.getAdapter().getItemCount();
      int position;
      if(firstVisiblePosition==0)
        position=0;
      else if(lastVisiblePosition==itemCount-1)
        position=itemCount-1;
      else
        position=firstVisiblePosition;
      float proportion=(float)position/(float)itemCount;
      setPosition(height*proportion);
      }
    }
  }

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