2 Finger Rotation gesture listener in android

Question

I'm trying to figure out the best way to make an image rotate along with a user's finger dragging it left or right, and the angle of rotation.

float x1 = lastEvent[0] - lastEvent[1];
float y1 = lastEvent[2] - lastEvent[3];    
float degrees1 = (float)(Math.atan2(y1, x1));      
float x2 = event.getX(0) - event.getX(1);
float y2 = event.getY(0) - event.getY(1);
float degrees2 = (float)(Math.atan2(y2, x2));   

float degrees = (float) Math.toDegrees(degrees2-degrees1);

But it doesn't rotate like i want it.. Is there any listener for rotation gesture? Thanks

Answer 1

/** Determine the degree between the first two fingers */
    private float rotation(MotionEvent event) { 
        double delta_x = (event.getX(0) - event.getX(1));
        double delta_y = (event.getY(0) - event.getY(1));
        double radians = Math.atan2(delta_y, delta_x);       
        if (Constant.TRACE) Log.d("Rotation ~~~~~~~~~~~~~~~~~", delta_x+" ## "+delta_y+" ## "+radians+" ## "
                        +Math.toDegrees(radians));
        return (float) Math.toDegrees(radians);
    }