NestedScrollView和onInterceptTouchEvent

Question

我确实扩展了NestedScrollView和@重写它的方法：、onTouchEvent、和问题是super.onTouchEvent从不调用ACTION_DOWN (这是由我的onIntereceptTouchEvent调用的)，因为NestedScrollView不移动，所以我得到了错误：

onTouchEvent中无效的pointerId=-1

当触发onTouchEvent时，指针id是在NestedScrollView的ACTION_DOWN方法中设置的。

mActivePointerId = MotionEventCompat.getPointerId(ev, 0);

我无法亲自设置它，重写整个onTouchEvent方法似乎是痛苦的计划。这里可能需要帮助。当我单击“视图”(它不监听触摸事件)时，NestedScrollView确实会移动(基本上是这样，我的onInterecptTouchEvent方法没有被调用，ACTION_DOWN是在NestedScrollView onTouchEvent中处理的)。

@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);
}

Answer 1

下面是解决我问题的代码，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mFirstOnTouchEvent中触发ACTION_DOWN时，将onInterceptTouchEvent设置为真：

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

  ...
}