水平recyclerview内垂直recyclerview滚动性能

Question

我几乎有这个：https : //github.com/RyanHurst/TvProgramRecyclerView。水平回收站视图作为垂直回收站视图的一个项目。每个水平 recyclerview 滚动都是同步的（仅可见项目）。

水平滚动非常流畅，但垂直滚动真的很糟糕。当在水平滚动上的位置 0 滚动时，它运行得非常好，但是向右滚动最多它变得最迟钝。我尽量不在 onBinViewHolder 中设置回收器适配器，并为每个水平回收器使用一个通用的回收器视图池，什么也没有。

Answer 1

对于外部垂直 RecyclerView，使用这个扩展类：

public class BetterRecyclerView extends RecyclerView{
  private static final int INVALID_POINTER = -1;
  private int mScrollPointerId = INVALID_POINTER;
  private int mInitialTouchX, mInitialTouchY;
  private int mTouchSlop;
  public BetterRecyclerView(Context context) {
    this(context, null);
  }

  public BetterRecyclerView(Context context, @Nullable AttributeSet attrs) {
    this(context, attrs, 0);
  }

  public BetterRecyclerView(Context context, @Nullable AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
    final ViewConfiguration vc = ViewConfiguration.get(getContext());
    mTouchSlop = vc.getScaledTouchSlop();
  }

  @Override
  public void setScrollingTouchSlop(int slopConstant) {
    super.setScrollingTouchSlop(slopConstant);
    final ViewConfiguration vc = ViewConfiguration.get(getContext());
    switch (slopConstant) {
      case TOUCH_SLOP_DEFAULT:
        mTouchSlop = vc.getScaledTouchSlop();
        break;
      case TOUCH_SLOP_PAGING:
        mTouchSlop = ViewConfigurationCompat.getScaledPagingTouchSlop(vc);
        break;
      default:
        break;
    }
  }

  @Override
  public boolean onInterceptTouchEvent(MotionEvent e) {
    final int action = MotionEventCompat.getActionMasked(e);
    final int actionIndex = MotionEventCompat.getActionIndex(e);

    switch (action) {
      case MotionEvent.ACTION_DOWN:
        mScrollPointerId = MotionEventCompat.getPointerId(e, 0);
        mInitialTouchX = (int) (e.getX() + 0.5f);
        mInitialTouchY = (int) (e.getY() + 0.5f);
        return super.onInterceptTouchEvent(e);

      case MotionEventCompat.ACTION_POINTER_DOWN:
        mScrollPointerId = MotionEventCompat.getPointerId(e, actionIndex);
        mInitialTouchX = (int) (MotionEventCompat.getX(e, actionIndex) + 0.5f);
        mInitialTouchY = (int) (MotionEventCompat.getY(e, actionIndex) + 0.5f);
        return super.onInterceptTouchEvent(e);

      case MotionEvent.ACTION_MOVE: {
        final int index = MotionEventCompat.findPointerIndex(e, mScrollPointerId);
        if (index < 0) {
          return false;
        }

        final int x = (int) (MotionEventCompat.getX(e, index) + 0.5f);
        final int y = (int) (MotionEventCompat.getY(e, index) + 0.5f);
        if (getScrollState() != SCROLL_STATE_DRAGGING) {
          final int dx = x - mInitialTouchX;
          final int dy = y - mInitialTouchY;
          final boolean canScrollHorizontally = getLayoutManager().canScrollHorizontally();
          final boolean canScrollVertically = getLayoutManager().canScrollVertically();
          boolean startScroll = false;
          if (canScrollHorizontally && Math.abs(dx) > mTouchSlop && (Math.abs(dx) >= Math.abs(dy) || canScrollVertically)) {
            startScroll = true;
          }
          if (canScrollVertically && Math.abs(dy) > mTouchSlop && (Math.abs(dy) >= Math.abs(dx) || canScrollHorizontally)) {
            startScroll = true;
          }
          return startScroll && super.onInterceptTouchEvent(e);
        }
        return super.onInterceptTouchEvent(e);
      }

      default:
        return super.onInterceptTouchEvent(e);
    }
  }
}

对于内部水平 RecyclerView，使用这个扩展类：

public class FeedRootRecyclerView extends BetterRecyclerView{  
  public FeedRootRecyclerView(Context context) {
    this(context, null);
  }

  public FeedRootRecyclerView(Context context, @Nullable AttributeSet attrs) {
    this(context, attrs, 0);
  }

  public FeedRootRecyclerView(Context context, @Nullable AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
  }

  @Override
  public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) {
 ``   /* do nothing */
  }
}