[Scummvm-devel] Minimal screen updates and possible OSystem improvements

Vladimir Menshakov whoozle at yandex.ru
Tue Nov 10 13:14:05 CET 2009


Good day, everyone!

I hope you could tell me about "minimal updates" approach in scummvm's OSystem. I found several possible oversights in API:
1. copyRectToScreen() does not support colorkey or alpha blits. 
2. lock-unlockScreen() invalidates whole screen (for obvious reasons). 

Something easily could be done here: 
1. We could implement various copyRectToScreen variations (colorkey, alpha, colorkey + alpha). Or, at least, colorkey, I'm pretty sure it could be accelerated in the most embedded backends.
2. Add lockRect()/unlockRect functions, returning pixel data pointer, and pitch info (usually screen scanline width) which invalidates only requested rectangle. 

Thank you!




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