[maemo-developers] Xsp pixel-doubling solutions for Nokia 770?

From: Arnim Sauerbier arnims at yahoo.com
Date: Sun May 6 09:19:41 EEST 2007
> If new Xomap doesn't work on the 770, I'd like to know about it.  (I
> don't have time to constantly test it, but I can -- and will -- fix it.)

I have found what triggers the Xsp disabling from SDL for IT 2005, 2006, and 2007 hacker ed.

Doubling gets disabled whenever we update less than the full 320x240 screen.

this breaks:  SDL_UpdateRect (SDL_Video, updated.x, updated.y, updated.w, updated.h);
this works:   SDL_UpdateRect (SDL_Video, 0, 0, 320, 240);

The same problem occurs in other SDL programs that do not update a full 320x240 screen each frame.

I have prepared a simple SDL demo that illustrates this.  It should be easier to understand and
modify than the Ur-Quan Masters sources.  Grab it here:


This contains a binary tgz for testing, as well as the source.  Untar to home directory and use F6
button (top left on device) to toggle xsp doubling.  

To verify that updates outside of the doubled window are not affecting the doubling, change

#define VIDWIN_X        800
#define VIDWIN_X        640

and disable my onscreen buttons by commenting out these lines

SDL_UpdateRect(screen, 0, 0, 0, 0);

I would appreciate anyone interested in SDL and pixel doubling taking time to look it over.  This
is about as simple a 'real world' test case as you're going to get.


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