Crop image ala Google Goggles

I'm trying to do some ROI (region of interest) selection in my app, but I don´t know, how to create some kind of resizable (by fingers) rectangle like you can see in Google Goggles. Can you help me? Is there any source code example?

My final solution is to draw and rectangle in the midle of a view and implement onTouchEvent() in my activity to set new corners coordinates like this:

@Override
public boolean onTouchEvent(MotionEvent me) {
    if(SETTING_ROI == true){
        if (me.getAction() == MotionEvent.ACTION_DOWN) {
            START_DRAGGING = true;
            myView.selectCorner((int) me.getRawX(), (int) me.getRawY()); // selecst nearest corner
        }
        if (me.getAction() == MotionEvent.ACTION_MOVE){
            Log.d(TAG, "ACTION_MOVE");
            myView.moveCorner((int) me.getRawX(), (int) me.getRawY()); // move selected corner continuously
        }
        if (me.getAction() == MotionEvent.ACTION_UP){
            if (START_DRAGGING == true) {
                START_DRAGGING = false;
                myView.moveCorner((int) me.getRawX(), (int) me.getRawY()); // final selected corner move
            }
        }
    }
    return false;
}