Re: gnome-games 2.16.0 released and branched for 2.17

["Richard Hoelscher" <rah rahga com>]

Jason D. Clinton said:
...
> Known issues:
>
>       * Rasterizing the Mahjongg and Aisleriot playing field takes too
>         long with the current SVG code paths. We, in cooperation with
>         the Cairo team, hope to optimize this rendering speed during the
>         maintenance of the 2.16 series.

Continuing my series "SDL is not an easier OpenGL, and 132 other
gnome-games misconceptions", and since I just can't commit with certainty
to work on this within gnome-games anymore [*]...

The problem has nothing to do with rasterizing the playing field, and
Cairo is a non-issue. Cairo does immediate mode drawing, and is great for
quickly rendering a scene once, but not several frames per second of
complex graphics like card decks. Aisleriot is using Cairo right now
within librsvg to render the decks to pixmaps. Aisleriot then moves those
pixmaps. THIS WORKS FINE. Going completely Cairo would be a bit like
playing solitaire in Windows Vista without a graphics accelerator, except
that Microsoft has the advantage of using raster images yet performance is
still horrible.

The problem is that SVGs for card games tend to be large, and Aisleriot
renders the entire deck in one pass because of the monolithic deck format.
It can't kick it out to another thread because of non-threadsafe Pango
(IIRC ATM). As long as you are doing this, resizing the window or starting
the game will always hit a delay. The only real solutions are split the
elements into multiple SVG files, or to tag the elements with a name that
librsvg can use to render (then render each element during and idle loop,
yada yada...). While I had a testcase working for the latter in Mahjongg,
I'm afraid this would just be another solution that absolutely nobody in
the Inkscape community would grok because they (a) don't have decent layer
support, and (b) a scared stiff of text editors and XML [*].

Given the horrendous SVG XML that Inkscape generates, I can actually
sympathize with them on point (b).

-Richard Hoelscher


[*] ... Among other things, bugs like #352084 simply broke my will to hack.