[Tuxmath-devel] Prerendered PNG cache for SVG sprites

[Wenyuan G. <guo...@gm...>]

Hi all,

I have updated our Git repository, master branch with an improved version of
SVG sprite loader. It caches prerendered PNG versions of SVG sprites on
harddisk, and I'm happy to report that it greatly improves the initial
loading time as well as delay in switching between fullscreen and windowed
mode in-game! No new cache files will be generated as long as the user
doesn't change the resolution of his/her desktop. Please try it out if you
have time!

The modification is entirely transparent to other parts of the program and
the function signatures and usages are completely unchanged.

One difficulty I had was I had intended to use BMP files as cache, since SDL
has native "save" functions into that format. But it turns out that SDL's
saveBMP doesn't support alpha transparency, causing scrambled sprites. After
a good amount of googling, to my surprise, tuxpaint has a function to save
SDL surfaces into PNG format! So in my implementation I have "borrowed" that
function (after modifying it a bit to support alpha channel) and
everything's fine :D! Maybe that part can eventually to be factored out in
the common?

Cheers
Wenyuan