Re: Gtk performance issues from a user's point of view

[Eero Tamminen <ext-eero tamminen nokia com>]

Hi,

ext Federico Mena Quintero wrote:
> There's work-in-progress documentation about the GTK+ drawing model
> here:
> http://primates.ximian.com/~federico/misc/gtk-drawing-model/index.html

This explains quite clearly why drawing a resized empty window is
much faster than drawing the same window containing a window-sized
button.

Plain window background is drawn at the X server side using the
background color (or pixmap) specified by Gtk, whereas button
drawing requires (client side) double buffering i.e. the _additional_
operations of:
- Drawing the button bg to offscreen double buffer
  (part of the parent window)
- Drawing the button contents (icon, label...) on top of that
- Blitting the double buffer to the screen
I.e. >3x data needs to be copied around.
Did I understand correctly?

(And if composite is used, then this went to X server side double
buffer (texture) from which it's composited onto screen.)


	- Eero