Re: images / alpha-blending

[YAMAMOTO Mitsuharu]

>>>>> On Sat, 18 Feb 2006 10:00:33 +0000, David Reitter <address@hidden> said:

> I am trying to use a few new icons for the tool-bar and after a bit
> of fruitless research, I have the impression that alpha-blending is
> not supported. I can only use bitmasks, even with image types such
> as PNG that have an alpha channel. Is that correct?

It would work as expected only when :background is given explicitly.
Otherwise, transparent parts are merged with the frame background
color:

  http://lists.gnu.org/archive/html/emacs-devel/2004-04/msg00623.html

> (I have only tried this with the Carbon port, but I understand that
> X11 currently doesn't support alpha-blending anyways.)

I have some experimental code of alpha channel support for the Carbon
port using Quartz 2D, but I have the impression that full alpha
channel support is a post-release issue from the above post.  ("22.1"
didn't mean the next release there.)

                                     YAMAMOTO Mitsuharu
                                address@hidden