SDL_RenderCopyEx 8-bit alpha support [patch request]

Hi guys,

The software renderer implementation of SDL_RenderCopyEx currently
forcibly drops alpha down to 1bit when rotating or even just flipping
things.

It would be nice if through e.g. a render hint or a SDL_RenderCopyEx
flag, the software implementation could be forced to do full 8bit
alpha at the expense of speed, while still keeping the 1bit
implementation in for those who want to use it (since it’s a lot
faster I suppose).

I filed a bug about it here: http://bugzilla.libsdl.org/show_bug.cgi?id=1550

Now I’m not really much into SDL code but it still seems an issue
worth fixing to me (many images, especially if drawn with 8bit alpha
in mind, look downright hideous when rotated with the software
renderer).

So if there’s someone out there with an idea of the software renderer
code, maybe you could be bothered to have a look at it? :slight_smile: It seems
to be a limitation worth fixing.

Regards,
Jonas Thiem