Re: Heads-up: Potentially breaking changes to the GDK drawing model pushed

[Jean Brefort <jean brefort normalesup org>]

Le samedi 21 juin 2014 à 11:28 -0400, Jasper St. Pierre a écrit :
> On Sat, Jun 21, 2014 at 10:26 AM, Jasper St. Pierre
> <jstpierre mecheye net> wrote:
>         Honest question: which ones? The only requirement we have with
>         Wayland is that we know when a paint has begun and when it has
>         ended, and also the rough area of paint, so we can tell the
>         Wayland compositor when to swap buffers, and from which
>         rectangles.
>         
>         
>         The draw signal does this automatically, but we can expose
>         this in other places.
>         
>         I'm skeptical of the performance concerns of the draw signal.
>         With the new paint clock system we have, draw events are
>         throttled and locked to the compositor, so it should be faster
>         to queue a redraw and wait until the frame is drawn, and do it
>         all in one go. But I'm fine with changing begin_paint_region
>         so that it no longer clears to background, if only to help
>         people trying to port to the crazy new drawing world.
>         
>
>
> Heads-up: I went ahead and pushed a branch for this at
> https://git.gnome.org/browse/gtk+/log/?h=wip/paint-stack-cleanup
>
>
> Basically, gdk_window_begin_paint_region / gdk_window_begin_paint_rect
> no longer clear to the background automatically, which means you can
> use them out-of-band. To clear to the background explicitly, you can
> use gdk_window_paint_background.
>
>
> Since it adds new API, I'm not going to push it to master until I can
> get some peer review, which likely means it won't get pushed until
> Monday. If you could test with this branch and let me know the
> results, that would be great!
>
>
> I do encourage everyone to try using the "draw" event / "draw" signal
> again. With our recent paint clock and event throttling work from 3.8
> onwards, we should be able to make it fast without having to resort to
> hacks like gdk_cairo_create.
>
>
>
> Sorry for all the breakage! I really don't want to bug anybody too
> much, but I do want to make sure that our toolkit and all our
> applications can work out of the box on modern platforms like Wayland.

We still had the issue with gtk+-3.8.6 (it's by that time that we
started using gdk_create_cairo).

Jean