scene/item: restrict frame callbacks based on the output rather than geometry
Sending frame callbacks based on whether or not the bounding rect intersects with the rendered output has two big problems:
- when a window is entirely off-screen, it never gets frame callbacks. This is particularly problematic when the application waits for frame callbacks to render the next frame, but KWin waits with moving them to an output until the application commits the surface
- when a window is on two outputs at once (like with cloning), then it gets twice the amount of frame callbacks - which means the application ends up rendering twice as fast, which doesn't make any sense
Edited by Xaver Hugl