From: Chong Yidong <cyd@stupidchicken.com>
To: Miles Bader <miles@gnu.org>
Cc: emacs-devel@gnu.org
Subject: Re: PNG image files with alpha channel
Date: Thu, 08 May 2008 07:48:25 -0400 [thread overview]
Message-ID: <87ve1pdnjq.fsf@stupidchicken.com> (raw)
In-Reply-To: <buo8wyljtcr.fsf@dhapc248.dev.necel.com> (Miles Bader's message of "Thu, 08 May 2008 13:46:28 +0900")
Miles Bader <miles.bader@necel.com> writes:
> Is Emacs supposed to properly handle an alpha channel in a PNG file?
Yeah. See the png_load function in image.c.
> I vaguely recall that it used to do something halfway reasonable (even
> if just merging in the default bg color), but now it seem to simply
> ignore an alpha channel.
It merges in the :background spec if there is one; otherwise, it uses
the frame background color.
> If you don't have an alpha-channel-bearing image, try this:
>
> http://download.savannah.gnu.org/releases/emacs/icons/emacs5-256.png
>
> The "background" around the sphere has an alpha channel that's mostly zero.
Hmm, I'm not sure what's wrong with this image. For an example of a png
image with alpha background rendered correctly in Emacs, see
http://www.w3.org/Graphics/PNG/alphatest.png
next prev parent reply other threads:[~2008-05-08 11:48 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-05-08 4:46 PNG image files with alpha channel Miles Bader
2008-05-08 11:48 ` Chong Yidong [this message]
2008-05-08 12:05 ` Jason Rumney
2008-05-08 15:02 ` Miles Bader
2008-05-08 15:18 ` Jason Rumney
2008-05-08 15:39 ` Miles Bader
2008-05-08 15:51 ` Jason Rumney
2008-05-08 18:19 ` Chong Yidong
2008-05-09 1:00 ` Chong Yidong
2008-05-09 1:10 ` Miles Bader
2008-05-09 2:35 ` Chong Yidong
2008-05-08 23:47 ` James Cloos
2008-05-09 0:43 ` Miles Bader
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