嵌套滚动视图和 onInterceptTouchEvent

NestedScrollView and onInterceptTouchEvent

我确实扩展了 NestedScrollView 和 @Override 它的方法:onTouchEventonInterceptTouchEvent。问题是 super.onTouchEvent 从不调用 ACTION_DOWN (它由我的 onIntereceptTouchEvent 调用)并且因此 NestedScrollView 不会移动并且我得到错误:

Invalid pointerId=-1 in onTouchEvent

指针id在ACTION_DOWN触发时在NestedScrollView的onTouchEvent方法中设置。

mActivePointerId = MotionEventCompat.getPointerId(ev, 0);

我不能自己设置这个,重写整个 onTouchEvent 方法似乎是一个痛苦的计划。可以在这里使用帮助。当我单击不侦听触摸事件的视图时,NestedScrollView 确实移动了(基本上这样我的 onInterecptTouchEvent 方法就不会被调用并且 ACTION_DOWN 在 NestedScrollView onTouchEvent 中处理)。

@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
    Log.i(LOGTAG, String.valueOf(ev.getAction()));

    final int action = MotionEventCompat.getActionMasked(ev);

    if (action == MotionEvent.ACTION_CANCEL || action == MotionEvent.ACTION_UP) {
        mIsBeingDragged = false;
        Log.i(LOGTAG, "is scrolling" + String.valueOf(mIsBeingDragged));
        return false; // Do not intercept touch event, let the child handle it
    }

    switch (action) {
        case MotionEvent.ACTION_DOWN: {
            mStartY = ev.getY();
            break;
        }
        case MotionEvent.ACTION_MOVE: {
            if (mIsBeingDragged) {
                return true;
            }

            final int yDiff = calculateDistanceY(ev);
            Log.d(LOGTAG, "y difference: y");
            if (yDiff > mTouchSlop) {
                mIsBeingDragged = true;
                return true;
            }
            break;
        }
    }
    return false;
}

@Override
public boolean onTouchEvent(MotionEvent ev) {
    Log.i(LOGTAG, "onTouchEvent");
    if (ev.getAction() == MotionEvent.ACTION_CANCEL || ev.getAction() == MotionEvent.ACTION_UP) {
        mIsBeingDragged = false;
    }

    return super.onTouchEvent(ev);
}

下面是解决我的问题的代码,我不得不撒谎:

@Override
public boolean onTouchEvent(MotionEvent ev) {
    Log.i(LOGTAG, "onTouchEvent");
    if (ev.getAction() == MotionEvent.ACTION_CANCEL || ev.getAction() == MotionEvent.ACTION_UP) {
        mIsBeingDragged = true;
    }

    if (mFirstOnTouchEvent) {
        ev.setAction(MotionEvent.ACTION_DOWN);
        ev.setLocation(mStartX, mStartY);
        mFirstOnTouchEvent = false;
    }

    return super.onTouchEvent(ev);
}

并在onInterceptTouchEvent中触发ACTION_DOWN时将mFirstOnTouchEvent设置为true:

@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
  if (MotionEventCompat.getActionMasked(ev) == MotionEvent.ACTION_DOWN) {
    mFirstOnTouchEvent = true
  }

  ...
}