Re: [gtk-vnc-devel] [PATCH 5/7] Use X window backing store for the VNC window 2008-11-24 Federico Mena Quintero <federico@novell.com>

[Federico M. Q. <fed...@no...>]

On Wed, 2008-12-17 at 19:51 -0600, Anthony Liguori wrote:

[backing store]
> 
> Is this just double buffering in GTK parlance?  If you avoid disabling 
> double buffering, does that help?

Nope, it's different.  You can ask the X server to use backing store if
possible --- if the server can save the contents of a window, it can
avoid sending Expose events when the window is unobscured.  That is,
nothing goes over the wire in the ideal case.

[This is similar to requesting "save-unders" for temporary windows, but
it saves your actual contents, not the underlying contents.]

GTK+'s double-buffering is "create a temporary pixmap and draw
everything to it, then blast the pixmap to the screen" to avoid flicker
due to repainting overlapped areas.

For gtk-vnc, it doesn't really matter if you use GTK+'s double-buffering
or not, as it is pretty much just sending PutImage requests plus the
rectangles for the surrounding area.  It doesn't do overlapped drawing.

  Federico