Re: Notes on wip/gdk-gl2

[Alexander Larsson <alexl redhat com>]

On sön, 2014-10-12 at 18:47 -0400, Owen Taylor wrote:
> * It looks like there's a need to create a GdkGLContext for a window
> *before* the paint callback it is first used, since we use the existence
> of the internal paint GL context to know whether we are using GL for
> this paint; this is not documented.

I think if you don't do this then the first frame will fall back to the
software fallback, but next frame will work. I didn't test this though.

> * Does the paint GL context need to be always derived from the toplevel
> or nearest native ancestor of a GdkWindow? It looks to me like things
> might not work right if gdk_window_create_gl_context() is called on a
> client side subwindow.

I've tried to make it work for all client windows, i.e. it should get
the paint context for the nearest native window (the impl window). Its
possible i missed this somewhere, if so we should fix that.

> * The approach of continually creating the render buffer may not give
> good enough performance, but if we do that, it's definitely desirable to
> create a minimal sized render buffer instead of one that's the size of
> the widget, since the cost of allocating a buffer gets larger the more
> pages that have to be allocated.

We should probably keep the buffer allocated at least until the widget
has not redrawn in a while.

> * What's the intended event handling for GtkGLArea? It seems like you'd
> have to put it into a GtkEventBox and handle events on the GtkEventBox -
> maybe GtkGLArea should have an event window?

Yeah, we should probably add one as most gl areas will want some input
(and its pretty lightweight if not).

Will take a look at the other input later.