Android invalidate(rect) ignores bounds

Question

When I call invalidate(rect) within a view, I want it to clear the 'rect' region on the canvas, and do what's specified in onDraw. The problem is, it ignores the 'rect' bounds given, and invalidates the entire view.

I made a small test program to show my problem. When the application is launched, the first line is drawn. When the user touches the screen, a second line is drawn (and invalidate(rect) is called on that region). Line 1 is deliberately not redrawn. The problem is Line 1 disappears, and only line 2 is shown on the screen.

Code:

    public class TestInval extends View
    {

        ...    

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

            Log.d(TAG, "onDraw bounds: " + canvas.getClipBounds()); //Logs: Rect(0, 0 - 720, 1134)

            if (drawOtherLine)
                canvas.drawLine(50, 50, 100, 100, defaultPaint);
            else
                canvas.drawLine(0, 0, 50, 50, defaultPaint);
        }
   
        ..
        public boolean onTouch(View view, MotionEvent motionEvent)
        {
            if (motionEvent.getAction() == MotionEvent.ACTION_UP)
            {
                drawOtherLine = true;

                Rect invalidateRect = new Rect(50, 50, 100, 100);

                invalidate(invalidateRect);
            }

            return true;
        }
        

        @Override
        public void invalidate(Rect dirty)
        {
            Log.d(TAG, "invalidate: " + dirty); //Logs: Rect(50, 50 - 100, 100)
            super.invalidate(dirty);
        } 

UPDATE:

My device, Samsung Galaxy S3 running 4.1.2 not rooted, seems to be the problem. Running the same test app on the android emulator gives the expected clipping bounds. Still not sure why this is the case on my device.