913514 - Avoid extra back buffer with OMTC Basic on Windows

Status: RESOLVED WORKSFORME

(Core :: Graphics: Layers, defect)

Description

[Benoit Girard (:BenWa)]

With main thread compositing on windows we draw in the WM_PAINT message. With OMTC we use GetDC to draw to the window. Because that DC is live we can't draw directly to it without flickering so currently BasicCompositor allocates a back buffer and blits (Swaps) the back buffer to the DC at once to avoid the flickering.

This is an extra copy we want to avoid: 
* Assuming WM_PAINT does something similar then we're fine, we probably just want to do something smarter then allocates a new surface every time.
* Otherwise we can move the widget to the compositor where we can continue to composite from the WM_PAINT message but this is likely to add complexity.

Comment 1

[Chris Peterson [:cpeterson]]

Mass tracking-e10s flag change. Filter bugmail on "2be0fcce-e36a-4e2c-aa80-0e3d33eb5406".