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

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

Also when you move a window, the window underneath
is intact (it's an opengl texture) so there are *no* expose events
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

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