Internal interception method of incident conflict

       Internal interception means that the parent container does not intercept any events , All events are passed to child elements . If the child element needs this event, it directly consumes , Otherwise, it's left to the parent container for processing . The internal interception method needs to cooperate with requestDisallowInterceptTouchEvent Method can work normally , It's a little complicated to use .

        The internal interception law needs to be modified ：

1、 Internal sliding control dispatchTouchEvent() Method , Control the interception logic of the parent container ;

2、 External slide control （ Parent container ） Need to rewrite onInterceptTouchEvent() Method , Let the parent container not intercept down event , But intercept move and up event .

Go straight to the code

External slide control HorizontalScrollViewEx2

         Rewrote onInterceptTouchEvent(), Not blocked by default down event , But intercept other events . Why not intercept down The event is because if down Events have been intercepted , Then view You cannot get events .

         Rewrote onTouchEvent(), This part simply performs sliding related operations , It does not involve the code related to event interception , You can skip .

@Override
public boolean onInterceptTouchEvent(MotionEvent event) {
    int x = (int) event.getX();
    int y = (int) event.getY();
    int action = event.getAction();
    if (action == MotionEvent.ACTION_DOWN) {
        mLastX = x;
        mLastY = y;
        if (!mScroller.isFinished()) {
            mScroller.abortAnimation();
            return true;
        }
        return false;
    } else {
        return true;
    }
}

@Override
public boolean onTouchEvent(MotionEvent event) {
    Log.d(TAG, "onTouchEvent action:" + event.getAction());
    mVelocityTracker.addMovement(event);
    int x = (int) event.getX();
    int y = (int) event.getY();
    switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN: {
            if (!mScroller.isFinished()) {
                mScroller.abortAnimation();
            }
            break;
        }
        case MotionEvent.ACTION_MOVE: {
            int deltaX = x - mLastX;
            int deltaY = y - mLastY;
            Log.d(TAG, "move, deltaX:" + deltaX + " deltaY:" + deltaY);
            scrollBy(-deltaX, 0);
            break;
        }
        case MotionEvent.ACTION_UP: {
            int scrollX = getScrollX();
            int scrollToChildIndex = scrollX / mChildWidth;
            Log.d(TAG, "current index:" + scrollToChildIndex);
            mVelocityTracker.computeCurrentVelocity(1000);
            float xVelocity = mVelocityTracker.getXVelocity();
            if (Math.abs(xVelocity) >= 50) {
                mChildIndex = xVelocity > 0 ? mChildIndex - 1 : mChildIndex + 1;
            } else {
                mChildIndex = (scrollX + mChildWidth / 2) / mChildWidth;
            }
            mChildIndex = Math.max(0, Math.min(mChildIndex, mChildrenSize - 1));
            int dx = mChildIndex * mChildWidth - scrollX;
            smoothScrollBy(dx, 0);
            mVelocityTracker.clear();
            Log.d(TAG, "index:" + scrollToChildIndex + " dx:" + dx);
            break;
        }
        default:
            break;
    }

    mLastX = x;
    mLastY = y;
    return true;
}

Internal sliding control ListViewEx

        Rewrote dispatchTouchEvent() Method . As long as the event can be transmitted to ListViewEx, It will take so long to walk to dispatchTouchEvent() Methods the internal .

@Override
public boolean dispatchTouchEvent(MotionEvent event) {
    int x = (int) event.getX();
    int y = (int) event.getY();

    switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN: {
            mHorizontalScrollViewEx2.requestDisallowInterceptTouchEvent(true);
            break;
        }
        case MotionEvent.ACTION_MOVE: {
            int deltaX = x - mLastX;
            int deltaY = y - mLastY;
            Log.d(TAG, "dx:" + deltaX + " dy:" + deltaY);
            if (Math.abs(deltaX) > Math.abs(deltaY)) {
                mHorizontalScrollViewEx2.requestDisallowInterceptTouchEvent(false);
            }
            break;
        }
        case MotionEvent.ACTION_UP: {
            break;
        }
        default:
            break;
    }

    mLastX = x;
    mLastY = y;
    return super.dispatchTouchEvent(event);
}

Let's analyze how the event is transmitted to ListViewEx And how to solve sliding conflicts .

1、 First of all down event , down Events enter HorizontalScrollViewEx2 Of dispatchTouchEvent(), And can walk to onInterceptTouchEvent() in . But in onInterceptTouchEvent() Chinese vs down Events are not intercepted . therefore down The event will be passed to ListViewEx.

2、down The event passed on to ListViewEx, The first thing to enter is ListViewEx Of dispatchTouchEvent() Method .ListViewEx Rewrote dispatchTouchEvent() Method , If it is down Event calls the parent container object to execute requestDisallowInterceptTouchEvent(true), It's critical . Next ListViewEx Normal treatment down event ;

3、down The incident was ListViewEx The consumption . So the first one move After the event , First of all to enter HorizontalScrollViewEx2 Of dispatchTouchEvent(), And because of disallowIntercept It's true , As a result, the interception method will not be called onInterceptTouchEvent(). therefore move It is directly passed to ListViewEx.

4、ListViewEx Got the first one move After the event , The first thing to enter is dispatchTouchEvent(), It's internal to move Made a judgment on the direction of ： If it slides up and down , Call directly ListView Default implementation of , namely ListViewEx Consumption ; If it's sliding left and right , Then call the parent container object to execute requestDisallowInterceptTouchEvent(false), And then call ListViewEx Default implementation of , ListViewEx Try to consume .

5、 Then come to the second move event , Also go HorizontalScrollViewEx2 Of dispatchTouchEvent(), But at this time disallowIntercept For false , Be able to execute onInterceptTouchEvent() Method . And its internal interception move event . therefore HorizontalScrollViewEx2 Will distribute a ACTION_CANCLE Event to ListViewEx, also HorizontalScrollViewEx2 Will be able to mFirstTouchTarget Set to null. This can lead to ListViewEx You can no longer accept the events behind the same event sequence . And the events behind the same event sequence are directly HorizontalScrollViewEx2 Of onTouchEvent The consumption , And will no longer execute onInterceptTouchEvent() To determine whether to intercept .

6、 Subsequent events are directly HorizontalScrollViewEx2 Intercept consumption .