[AppBarLayout ] AppBarLayout does not support fling dispatch feature when sliding down

Description: When AppBarLayout slides downwards, HeaderBehavior limits the maximum sliding distance, consumes all the sliding speed, is not distributed, and does not support nested sliding

Expected behavior: AppBarLayout support fling dispatch feature when sliding down

Android API version: 30

Material Library version: 1.5.0-alpha01

Code In HeaderBehavior:

final boolean fling(
      CoordinatorLayout coordinatorLayout,
      @NonNull V layout,
      int minOffset,
      int maxOffset,
      float velocityY) {
    if (flingRunnable != null) {
      layout.removeCallbacks(flingRunnable);
      flingRunnable = null;
    }

    if (scroller == null) {
      scroller = new OverScroller(layout.getContext());
    }

    scroller.fling(
        0,
        getTopAndBottomOffset(), // curr
        0,
        Math.round(velocityY), // velocity.
        0,
        0, // x
        minOffset,
        maxOffset); // y

    if (scroller.computeScrollOffset()) {
      flingRunnable = new FlingRunnable(coordinatorLayout, layout);
      ViewCompat.postOnAnimation(layout, flingRunnable);
      return true;
    } else {
      onFlingFinished(coordinatorLayout, layout);
      return false;
    }
}

private class FlingRunnable implements Runnable {
    private final CoordinatorLayout parent;
    private final V layout;

    FlingRunnable(CoordinatorLayout parent, V layout) {
      this.parent = parent;
      this.layout = layout;
    }

    @Override
    public void run() {
      if (layout != null && scroller != null) {
        if (scroller.computeScrollOffset()) {
          setHeaderTopBottomOffset(parent, layout, scroller.getCurrY());
          // Post ourselves so that we run on the next animation
          ViewCompat.postOnAnimation(layout, this);
        } else {
          onFlingFinished(parent, layout);
        }
      }
    }
}

Inizia con l’implementazione di HeaderBehavior.fling e FlingRunnable mostrata nel report, utilizzando il contesto di Android API 30 e Material Library 1.5.0-alpha01. Riproduci lo scorrimento verso il basso di AppBarLayout e verifica che la velocità del fling venga inoltrata anziché consumata, con il supporto allo scorrimento annidato e mantenendo la distanza massima prevista.