Android smoother pinch zoom?

Question

I have made my own code for my 'implementation' of a pinch zoom feature and it works, but it is not user-friendly at all. Often very sporadic and in general not pretty at all. I was wondering if any of you could help me out, maybe a easier way or different approach. Perhaps using the GestureListener I'm not sure how to use it though. Any help would be appreciative.

Below is my current code:

    public boolean onTouchEvent(MotionEvent event) {
        float cr, cr2 = 0.0f;
        cx = new float[2];
        cy = new float[2];
        float zx;
        final int action = event.getAction();
        switch (action) {
        case MotionEvent.ACTION_DOWN: {
            break;
        }
        case MotionEvent.ACTION_POINTER_DOWN: {
            break;
            }
        case MotionEvent.ACTION_MOVE: {
            for (int i = 0; i<event.getPointerCount(); i++) {
            if (run == true) { //see if it is the first time running program and set orig to the scale / screen res 
            Orig = scale * 800; //800 = screen res
            }
            cx[i] = event.getX(i); //get x and y for each finger
            cy[i] = event.getY(i);

            cr = (cx[0] - cx[1])*(cx[0] - cx[1]) + (cy[0] - cy[1])*(cy[0] - cy[1]); //get the distance between pointers
            cr2 = FloatMath.sqrt(cr);

            if (run == true) {
            scale = cr2/800;
            run = false;
            }
            else {
                if (scale >=  550.0f) {
                    scale = 1.0f;
                }
                if (scale <= 0.0f) {
                    scale = 1.0f;
                }
                nScale = Orig/cr2;
                scale = nScale * 0.5f;

            }
            }}  

This is probably not the best way to do this at all. Would taking the average over several events give better responses?

Thanks

Answer 1

See the zoom support tutorials on Sony Ericsson Developer World, hope they can give you some clue.

• How to take advantage of the pinch-to-zoom feature in your Xperia™ 10 apps – Part 2
• Android one finger zoom tutorial – Part 4