My game involves "wiping off" an image by touch:

After moving a finger over it, it looks like this:

At the moment, I'm implementing it with Canvas, like this:

9Paint pTouch;
9int X = 100;
9int Y = 100;
9Bitmap overlay;
9Canvas c2;
9Rect dest;

    pTouch = new Paint(Paint.ANTI_ALIAS_FLAG);         
    pTouch.setXfermode(new PorterDuffXfermode(Mode.SRC_OUT)); 
    pTouch.setColor(Color.TRANSPARENT);
    pTouch.setMaskFilter(new BlurMaskFilter(15, Blur.NORMAL));

    overlay = BitmapFactory.decodeResource(getResources(),R.drawable.wraith_spell).copy(Config.ARGB_8888, true); 

    c2 = new Canvas(overlay);

    dest = new Rect(0, 0, getWidth(), getHeight());
    Paint paint = new Paint();9       
    paint.setFilterBitmap(true);

    ...

    @Override
    protected void onDraw(Canvas canvas) {
        ...

        c2.drawCircle(X, Y, 80, pTouch);
        canvas.drawBitmap(overlay, 0, 0, null);

        ...
    }

    @Override
9public boolean onTouchEvent(MotionEvent event) {

        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
            case MotionEvent.ACTION_MOVE: {
                X = (int) event.getX();
                Y = (int) event.getY();9 
                invalidate();
                c2.drawCircle(X, Y, 80, pTouch);9               
                break;
            }   
        }
return true;
...

What I'm essentially doing is drawing transparency onto the canvas, over the red ball image.

Canvas and Bitmap feel old... Surely there is a way to do something similar with OpenGL ES. What is it called? How do I use it?

[EDIT]

I found that if I draw an image and above new image with alpha 0, it goes to be transparent, maybe that direction?

Something like:

gl.glColor4f(0.0f, 0.0f, 0.0f, 0.01f);