Android: How to drag(move) PopupWindow?

问题:

I want to be able to move PopupWindow on touch dragging. I don't want UI to update on the release of the touch. I want PopupWindow to follow my touch.

This is something what I am doing:

mView = mLayoutInflater.inflate(R.layout.popup,
                null);
mPopupWindow = new PopupWindow(mView,
               LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT, false);
mPopupWindow.showAtLocation(parentView, Gravity.CENTER, -5, 30);

mView.setOnTouchListener(new OnTouchListener() {
        private int dx = 0;
        private int dy = 0;

        @Override
        public boolean onTouch(View view, MotionEvent motionEvent) {
            switch (motionEvent.getAction()) {
                case MotionEvent.ACTION_DOWN:
                    dx = (int) motionEvent.getX();
                    dy = (int) motionEvent.getY();
                    break;
                case MotionEvent.ACTION_MOVE:
                    int x = (int) motionEvent.getX();
                    int y = (int) motionEvent.getY();
                    int left =  (x - dx);
                    int top =   (y - dy);
                    Log.d("test", "x: " + left + " y: " + top);
                    mPopupWindow.update(left, top, -1, -1);
                    break;
            }
            return true;
        }
    });

What happens is, as I drag the popup window, it flickers back and forth on the original location and where my finger is.

Flickering Logcat Result:

x: -44 y: 4
x: -43 y: 37
x: -46 y: 4
x: -46 y: 38
x: -48 y: 4
x: -47 y: 38
x: -50 y: 4

But if I remove (comment out) "mPopupWindow.update(left, top, -1, -1);", it returns correct result. (But obviously UI won't update):

x: -33 y: 0
x: -37 y: 0
x: -41 y: 0
x: -43 y: 3
x: -46 y: 3
x: -50 y: 3
x: -54 y: 4
x: -57 y: 4

How would I move a PopupWindow correctly?

回答1:

In eclipse, when looking at the info on getX(), it says: getX(int) for the first pointer index . I am assuming that this should be the only used when setting the first x and y for ACTION.DOWN. When using ACTION.MOVE, getRawX() and getRawY(), eclipse says: original location of the event on the screen. Using it this way, popup window will not flicker and will remain at its location after moving until it's dismissed.

Updated code:

case MotionEvent.ACTION_DOWN:
    dx = (int) event.getX();
    dy = (int) event.getY();
    break;

case MotionEvent.ACTION_MOVE:
    xp = (int) event.getRawX();
    yp = (int) event.getRawY();
    sides = (xp - dx);
    topBot = (yp - dy);
    popup.update(sides, topBot, -1, -1, true);
    break;

回答2:

Try this:

mView = mLayoutInflater.inflate(R.layout.popup,
                null);
mPopupWindow = new PopupWindow(mView,
               LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT, false);
mPopupWindow.showAtLocation(parentView, Gravity.CENTER, mPosX, mPosY);

mView.setOnTouchListener(new OnTouchListener() {
        private int dx = 0;
        private int dy = 0;

        @Override
        public boolean onTouch(View view, MotionEvent motionEvent) {
            switch (motionEvent.getAction()) {
                case MotionEvent.ACTION_DOWN:
                    dx = mPosX - motionEvent.getRawX();
                    dy = mPosY - motionEvent.getRawY();
                    break;
                case MotionEvent.ACTION_MOVE:
                    mPosX = (int) (motionEvent.getRawX() + dx);
                    mPosY = (int) (motionEvent.getRawY() + dy);
                    pop.update(mPosX, mPosY, -1, -1);
                    break;
            }
            return true;
        }
    });

回答3:

Try getRawX() and getRawY() instead of getX() and getX(). It still bounces a little bit when you touch it again, but it's much smoother when moving. If you have a better solution please let us know.