The flags :


have disappeared from the surface->flags so how do I test if a surface has this support?

You can use SDL_GetColorKey to see if you have a color key set, or
SDL_ISPIXELFORMAT_ALPHA to see if your pixel format has an alpha channel.

Thanks found SDL_GetColorKey! Perfect!

Can I also use SDL_GetSurfaceAlphaMod to determine the SDL_SRCALPHA?

I could be wrong, but I think it is similar to what SDL_SetAlpha used to be. I’ve only used SDL2, but the wording of the documentation for 1.2 seems to imply that they’re similar.

To clarify. So because of that you feel SDL_ISPIXELFORMAT_ALPHA is a better fit?

Has this got something to do with the blend mode and if so maybe SDL_BlendMode???

No, sorry about that. SDL_ISPIXELFORMAT_ALPHA's recommendation was honestly me misinterpreting the question now that I look at it again. That’s used to tell if the format you’re using has an alpha channel or not. I thought SDL_SRCALPHA was a flag to enable alpha channels. I’m kinda leaning towards SDL_BlendMode being what you want, and you’ll need to set it with: SDL_SetRenderDrawBlendMode.