具有onItemLongclick的GestureDetector

Question

How can i integrate GestureDetector with onItemLongClick?

I have a GridView containing three images. When I touch on the first image, I want to display a Toast message. When I lift up my finger from the screen, I want to display a second Toast message.

I know that GestureDetector uses MotionEvent, but onItemLongClick does not. But in this case, I would need to keep track of the image's position ID in the grid, thus it is not possible to implement inside onTouch()?

Answer 1

You can track the motion of the cursor, whether its a onscreen touch or a TrackBall move, using this class and if it crosses over into the next picture you can handle that event then. Here is an example taken from the sdk examples:

    @Override public boolean onTouchEvent(MotionEvent event) {
        int action = event.getActionMasked();
        if (action != MotionEvent.ACTION_UP && action != MotionEvent.ACTION_CANCEL) {
            int N = event.getHistorySize();
            int P = event.getPointerCount();
            for (int i = 0; i < N; i++) {
                for (int j = 0; j < P; j++) {
                    mCurX = event.getHistoricalX(j, i);
                    mCurY = event.getHistoricalY(j, i);
                    drawPoint(mCurX, mCurY,
                            event.getHistoricalPressure(j, i),
                            event.getHistoricalTouchMajor(j, i));
                }
            }
            for (int j = 0; j < P; j++) {
                mCurX = event.getX(j);
                mCurY = event.getY(j);
                drawPoint(mCurX, mCurY, event.getPressure(j), event.getTouchMajor(j));
            }
        }
        return true;
    }

You can read more and see the file in your SDK at C:\\YourInstallDir\\android-sdk\\samples\\android-10\\ApiDemos\\src\\com\\example\\android\\apis\\graphics\\TouchPaint.java or just search the whole examples files for MotionEvent there's a few more uses in them.