[Bf-committers] image editor / draw alpha

[Branan Riley]

Whilst looking at the rgb/bgr jpeg issue (which is very strange, still
needs messing with) I noticed something odd in the image code.

Rather than showing just the alpha as luminance as it should, it shows
ABGR (ARGB? does blender use RGB or BGR internally?) as a single
32-bit luminance value.

This isn't what's intended, I'd expect. I don't see how it can be
fixed easily, either. Off the top of my head, there are three
solutions:

(A) sperating the alpha data before re-drawing (slow)
(B) Doing (A) once when the image is created / loaded, and storing the
result with the image buffer
(C) getting rid of the ability to draw just the alpha.

I can implement (A) in a matter of minutes. (B) would involve changes
to how data is stored, which would mean SDNA stuff, which I know
nothing about. Anyone have an opinion on how best to fix this?