Re: GTK is double buffered by default ? on GNU/Linux and MS Windows ?

["Clemens Eisserer" <linuxhippy gmail com>]

Hi again,

Well there has been a lot of discussion about GTKs performance, wether
its fast or not.
I just found that moving a window on top of a GTK window on Windows I
get 100% CPU on a XP2200+/WindowsXP and visible repaint lags - be that
slow or fast ... I don't want to comment.

> Also when you drag a window, for example, the redrawing
> isn't synchronized to any particular clock, so you get tearing.  Windows
> also often has tearing when you drag a large window around.  Mac does
> not, for reasons I'll describe below
Tearing is caused by the fact that applications don't paint themself
fast enough, not because drawing is not synchronized. Draw a window on
top of a maximized xcalc and you won't see any tearing.

> screen.  Since the OpenGL drawing is very quick, this eliminates redraw
> flicker to a large degree (since the flicker is hidden off-screen where
> you can't see it).
This is basically wrong. Drawing primitives through OpenGL is very
likely to be a lot slower than through accalerated X11 drivers, I
would give x11perf a try on XGL.
I would not consider drawing to be the largest problem anymore,
espacially when it comes down to GTK+ performance problems. Readbacks
and

> Also when you move a window, the window underneath
> is intact (it's an opengl texture) so there are *no* expose events
> needed.
Well thats not OpenGL related and is basically what a Composition manager does.
However toolkits should be fast enough also without composition, and a
lot toolkits prove that it is no problem for them (Fox-toolkit, fltk,
qt, win32, ....).

lg Clemens