Getting the dirty region inside draw()

Question

If I invalidate() a part of my custom view with a dirty rect parameter, how do I get the dirty rect inside the draw() method? The clipping rect of the canvas is not the same - in my experience, it's typically few times larger.

Answer 1

get the clipRect from the passed in Canvas object to onDraw method. This clipRect (Canvas::getClipBounds) is actually the invalidated Rect.

The clipRect is larger sometimes because different invalidated areas are unioned together so that one event is fired instead of firing multiple for performance reasons.

Answer 2

If the dirty rect is not the same as the one you passed to invalidate(), it is because another View or region of the screen was also invalidated.