如何在Android中实现滑动并保持手势？

Question

I am trying to implement a "swipe and hold" gesture in Android where the user swipes from a point on the left to another point on the right, then continues to hold at the right point until a server-side action is complete. The idea being that if the user lets go of the hold, the server-side action will be cancelled.

I've been trying to go about this the following way but have encountered an issue when getting to the hold part of the gesture. What I'd like to have happen is that when the user reaches point B on the right, the ACTION_MOVE is somehow converted into an ACTION DOWN for the view on the right and from then on, as long as the event ACTION_DOWN continues the gesture is valid, but if the user lets go or leaves the view area, it is invalid. So the question is, is it possible to chain the ACTION_MOVE from left to right into a "hold" gesture once the user reaches point B on the right? I've tried adding an onTouch to point B after the swipe, but the only way that works is if the user lets go of the swipe, then presses point B again. Will this be possible, or should I go about this a different way, such as drag and drop?

Point A and B as found below are currently image views, but that's more placeholder than anything.

private boolean mValidGesture = false;
Rect outRect = new Rect();
int[] location = new int[2];
private boolean isViewInBounds(View view, int x, int y){
    view.getDrawingRect(outRect);
    view.getLocationOnScreen(location);
    outRect.offset(location[0], location[1]);
    return outRect.contains(x, y);
}

...

    mPointA.setOnTouchListener(new View.OnTouchListener() {
        @Override
        public boolean onTouch(View v, MotionEvent event) {
            int x = (int)event.getRawX();
            int y = (int)event.getRawY();
            if(event.getAction() == MotionEvent.ACTION_MOVE){
                if (isViewInBounds(mPointB, x, y)) {
                    mPointB.dispatchTouchEvent(event);
                    Log.d(TAG, "onTouch ViewB");
                    Toast.makeText(MainActivity.this, "Swipe complete", Toast.LENGTH_SHORT).show();

                    //This is the part that happens only after you let go of the swipe :( 
                    mPointB.setOnTouchListener(new View.OnTouchListener() {
                        @Override
                        public boolean onTouch(View v, MotionEvent event) {
                            switch(event.getAction()) {
                                case MotionEvent.ACTION_DOWN:
                                    mValidGesture = true;
                                    Log.d(TAG, "Gesture: " + String.valueOf(mValidGesture));
                                    return true;
                                case MotionEvent.ACTION_UP:
                                    mValidGesture = false;
                                    Log.d(TAG, "Gesture: " + String.valueOf(mValidGesture));
                                    return true;
                            }
                            return false;
                        }
                    });
                } else if(isViewInBounds(mPointA, x, y)){
                    Log.d(TAG, "onTouch ViewA");
                }
            }
            // Further touch is not handled
            return false;
        }
    });

Answer 1

You don't need to put touchListener on pointB. Try something like this:

 boolean serverActionStarted = false;

 @Override
 public boolean onTouch(View v, MotionEvent event) {
    int x = (int)event.getRawX();
    int y = (int)event.getRawY();
    if(event.getAction() == MotionEvent.ACTION_MOVE){

            if (isViewInBounds(mPointB, x, y)) {
                // TODO : swipe completed. Start server action
                serverActionStarted=true;
            }
   }else if(event.getAction() == MotionEvent.ACTION_UP && serverActionStarted){
       // TODO : cancel the server action
       serverActionStarted = false;
   }

So basically, when the user swipes from pointA to pointB, you start the server action and set a boolean serverActionStarted to true. After that, if ACTION_UP event occurs, with the severAction having started, you cancel the server action.