Re: jerky viewport scrolling performance GTK+

Not sure if this is your problem, but I had very helpful mails a few month ago from Owen and Sven when I asked about diagonal scrolling slowness. Here's the one from Soeren:

Soeren Sandmann wrote:
John Cupitt <john cupitt ng-london org uk> writes:

One of the app's widgets is an image display window, and one of the
tools is a panner. Pure left/right and up/down pans are fast and
smooth, but diagonal drags are very choppy. I think this is because
gtk is sending me the bounding box of all exposes since the last
repaint, and for a diagonal drag, the bounding box of a thin strip
down the right and a thin strip across the bottom is the entire
window. Has anyone come across this before, and is there an easy

If your problem is as you describe (which may well be the case), then
look at the "region" field in the expose event. That field will
contain a GdkRegion indicating the exact area that needs to be

You can use gdk_region_get_rectangles() to convert the region to a
list of rectangles that needs to be repainted.


Lambert Schomaker wrote:
Hi GTK-ers,

 for those interested in my jerky scroll problem: here is
the .tgz with the .tif file that  shows it on my supposedly
fast 3 GHz system.

The binary is  here:
 > cd jerky-image-viewer/src/
> project2 (my intelligent name for the binary)

You may want to do a make on your own system.
All help is appreciated.

Best regards,

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