[SDL] Blitting on 8 bit surfaces

[Sylvain Beucler]

Hi,

On Sun, Dec 23, 2007 at 11:27:56AM +0100, Christian Meyer wrote:
> Thanks for your answer :)
> 
> In my spezial case, I have surfaces where some indices have a spezial 
> meaning (e. g. marks areas where an animations will be displayed).
> 
> So if I understood this correctly, I have to do the following:
> 
> When all pixels with index n should be unchaged, I have to make sure, 
> that n points to the same RGB-value in both palettes.

I think this may not always work. For example, maybe the destination
palette has the same RGB-value than index 'n' _twice_: at index 'n'
and at another index. In that case, maybe the other index will be used.

I'm not sure if there's an easy way to do that using BlitSurface. If
you only work with 8bit surfaces, maybe you could easily implement
your own Blit function (see
http://www.libsdl.org/cgi/docwiki.cgi/Pixel_20Access).

> When the color of a pixel should be unchanged, I just have to make sure, 
> that the RGB-Value exists in the dest palette.

This should work :)

-- 
Sylvain