[SDL] Text output - getting more speed in SDL

[Ryan C. Gordon]

> It looks rather horrifying.

I wouldn't have gone that far.

But I'm curious if keeping an array of memory offsets where a glyph's 
pixels exist would actually beat SDL's blitters...the method we're 
discussing writes to less memory that a default surface blit, but it 
doesn't take advantage of the possibility of blitting between hardware 
surfaces, or that pixel formats, alpha blending, and conversions can be 
handled without cluttering your application and possibly with 
MMX/Altivec/SSE behind the scenes.

Colorkey blitting with RLE encoding might achieve close to the same 
speed inside SDL for about the same memory usage, too.

(completed untested) I'd have probably kept a table of SDL_Surfaces, one 
glyph per surface, hashed by their codepoint and created/cached as 
needed, and just blitted from them as I needed to draw glyphs to a 
surface. If I wanted to gamble, I could try for things like colorkey 
blits and hardware surfaces.

...but I'd probably just build OpenGL display lists from the vertex data 
that Freetype can provide and get hardware-accelerated manipulation of 
the glyphs for "blitting" or a million other things, which is going to 
smoke any possible approach we take here in terms of performance, 
features, and application ease-of-use.

It might be nice to add a function to SDL_ttf to get a vertex buffer 
back instead of an SDL_Surface...

--ryan.