[SDL] Improving SDL'c RLE handling
Gunnar von Boehn
gunnar at greyhound-data.com
Fri Apr 7 03:25:40 PDT 2006
I have a small proposal for the way SDL handles RLE optimized surfaces.
The way SDL blittes RLE sprites that are partly clipped is not fully
When SDL copies sprites which are partly above the screen then SDL
currently needs to parse the Sprite data to find the first visible row.
Example: When we have a sprite of 100x100 pixel of which only the last
10 rows are on the screen, then SDL still has still to read all 10,000
pixel to find the visible 1,000 pixel.
My proposal is to not use the current magic (0,0) words to mark a
beginning a RLE row but instead to use a list of length-words (type
uint32) which point to the beginning of each row in the sprite data.
So a clipped sprite would only need to fetch one long to know where the
sprite data of the first visible row starts. This will speed up top
screen clipped sprites noticeable. A sprite will only take the time for
blitting the visible content and not need to read the whole sprite like
I hope you will find this idea usefull.
More information about the SDL