performance of goocanvas

[D M German <dmg uvic ca>]

Dear Damon,

first of all, thank you for helping me with porting xournal to
goocanvas. The work is almost complete. we only have to complete few
features, but it is now usable.

https://github.com/dmgerman/xournal/tree/gtk3

Today I compiled xournal for windows and tried in a relatively slow
tablet (lenovo thinkpad 2).

Unfortunately the performance of xournal using goocanvas is visibly
slower than libgnomecanvas. For instance:

1. When drawing we draw a line between the two last sampled
points. Goocanvas takes enough time to affect the responsiveness of the
drawing. I have fixed this problem by drawing directly to the canvas
using cairo, and once the pen is lifted, I draw the polygon using
goocanvas. So far this seems to be adequate.

2. Scrolling. This is where the performance is really affected. A page
full of text might have literally thousands of line segments that need
to be scrolled. Also, we currently support a mode in which the user can
have in a huge vertical canvas all the pages of a document (a huge
column with one page per row). The performance seems to be affected by
whether we use one page at a time, or all pages in the canvas.

Do you have any suggestions to improve performance?

thank you!

--daniel


--
Daniel M. German                  "Never attribute to malice
                                   that which can be adequately
    Robert Heinlein ->             explained by stupidity. "
http://turingmachine.org/
http://silvernegative.com/
dmg (at) uvic (dot) ca
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