title: Draw a circle on an existing image
body: <p>I'm trying to draw a circle on an image which placed as <code>res/drawable/schoolboard.png</code>. the image fills the activity background. the following does not work:</p>
  
  <pre><code>    Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.schoolboard);
      Paint paint = new Paint();
      paint.setAntiAlias(true);
      paint.setColor(Color.BLUE);
  
      Canvas canvas = new Canvas(bitmap);
      canvas.drawCircle(60, 50, 25, paint);
  
      ImageView imageView = (ImageView)findViewById(R.drawable.schoolboard);
      imageView.setAdjustViewBounds(true);
      imageView.setImageBitmap(bitmap);
  </code></pre>
  
  <p>any help will be highly appreciated. thanks.</p>