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Bug 4469

Summary: make SDL_CreateTextureFromSurface pick a more appropriate format
Product: SDL Reporter: Sylvain <sylvain.becker>
Component: *don't know*Assignee: Ryan C. Gordon <icculus>
Status: RESOLVED FIXED QA Contact: Sam Lantinga <slouken>
Severity: normal    
Priority: P2 Keywords: target-2.0.10
Version: don't know   
Hardware: x86_64   
OS: All   
Attachments: patch

Description Sylvain 2019-01-24 12:05:29 UTC
Currently SDL_CreateTextureFromSurface picks first valid format, and do a conversion.

    format = renderer->info.texture_formats[0];
    for (i = 0; i < renderer->info.num_texture_formats; ++i) {
        if (!SDL_ISPIXELFORMAT_FOURCC(renderer->info.texture_formats[i]) &&
            SDL_ISPIXELFORMAT_ALPHA(renderer->info.texture_formats[i]) == needAlpha) {
            format = renderer->info.texture_formats[i];
            break;

It could try to find a better format, for instance : 

 if SDL_Surface has no Amask, but a colorkey :
   if surface fmt is RGB888, try to pick ARGB8888 renderer fmt
   if surface fmt is BGR888, try to pick ABGR8888 renderer fmt
 else 
   try to pick the same renderer format as surface fmt

if no format has been picked, use the fallback.


I think it goes with bug 4290 fastpath BlitNtoN
when you expand a surface with pixel format of size 24 to 32, there is a fast path possible.


So with this issue:

- if you have a surface with colorkey (RGB or BGR, not palette), it takes a renderer format where the conversion is faster.
  (it avoids, if possible, RGB -> ABGR which means switching RGB to BGR)

- if you have a surface ABGR format, it try to take the ABGR from the renderer. 
  (it avoids, if possible, ABGR -> ARGB, which means switch RGB to BGR)
Comment 1 Sylvain 2019-01-24 12:10:05 UTC
Created attachment 3583 [details]
patch

patch
Comment 2 Ryan C. Gordon 2019-05-18 18:48:54 UTC
Tagging a bunch of bugs with "target-2.0.10" so we have a clear list of things to address before a 2.0.10 release.

Please note that "addressing" one of these bugs might mean deciding to defer on it until after 2.0.10, or resolving it as WONTFIX, etc. This is just here to tell us we should look at it carefully, and soon.

If you have new information or feedback on this issue, this is a good time to add it to the conversation, as we're likely to be paying attention to this specific report in the next few days/weeks.

Thanks!

--ryan.
Comment 3 Sam Lantinga 2019-05-19 19:04:25 UTC
This looks good!
https://hg.libsdl.org/SDL/rev/ae1dd7bee797