back

by raphlinus·8y ago·view on hn ↗
DirectComposition. It's been there since Windows 8, and is used by Chrome among other apps (see https://bugs.chromium.org/p/chromium/issues/detail?id=524838).

It's possible some hardware already does overlays, given that the talk I linked above was 2 years ago. I haven't researched this carefully.

There's a bunch of stuff in the interface to support video and also integrated 3D content ("create swapchain for composition"), but I don't know how well it works. In my experiments and reading through the Chromium bug tracker, Microsoft's implementation of all this stuff is far from perfect, and it's hard, for example, to completely avoid artifacts on resizing.

2 comments
> It's possible some hardware already does overlays, given that the talk I linked above was 2 years ago. I haven't researched this carefully.

All hardware does some overlays, though not a large number. (You can see Intel GPU overlay setup at [1].) One scanout overlay is already in use on all major OS's, to draw the mouse cursor.

[1]: https://github.com/torvalds/linux/blob/e60e1ee60630cafef5e43...

Typically hardware will have the base layer, a cursor layer, and possibly a video overlay. But in many cases, the video "overlay" is actually emulated by the driver using a shader to do the colorspace conversion and the texture hardware to do scaling.