code: public void handleScroll(float distY) {
  
  		if (getHeight() > 0 && originalImage != null) {
  
  			if (scrollY <= originalImage.getHeight() - getHeight()) {
  				adaptedImage = Bitmap.createBitmap(originalImage, 0, (int) -distY, screenWidth, getHeight());
  
  				invalidate();
  			}
  		}
  
  	}
docs: Handle an external scroll and render the image by switching it by a
  distance
  
  @param distY
  the distance from the top