GNU bug report logs - #77104
31.0.50; Transparent png image background is ignored in frames with alpha-background

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Message #17 received at 77104 <at> debbugs.gnu.org (full text, mbox):

From: Ihor Radchenko <yantar92 <at> posteo.net>
To: Alan Third <alan <at> idiocy.org>
Cc: Po Lu <luangruo <at> yahoo.com>, dybfysiat <at> 163.com, Eli Zaretskii <eliz <at> gnu.org>,
 77104 <at> debbugs.gnu.org
Subject: Re: bug#77104: 31.0.50; Transparent png image background is ignored
 in frames with alpha-background
Date: Wed, 19 Mar 2025 16:57:01 +0000

Alan Third <alan <at> idiocy.org> writes:

> I think the problem is that Emacs has never handled image
> transparency, so it sets the transparent pixels of the image to the
> frame's background colour. There's quite a bit of fiddling to manage
> this with changing backgrounds and so on.
>
> I'm not sure what would be required for drawing transparent images to
> the glass. On NS I think it would be near trivial as the toolkit will
> handle it for us, but I don't know about others. For example I have a
> memory of being told that some terms don't clear under images so
> drawing a transparent image might show the previous pixels.

Then, how does :mask 'heuristic works? It somehow manages to set certain
pixels to be truly transparent. If so, why is it a problem setting
pixels that have transparent color in the image truly transparent in
exactly the same way?

-- 
Ihor Radchenko // yantar92,
Org mode maintainer,
Learn more about Org mode at <https://orgmode.org/>.
Support Org development at <https://liberapay.com/org-mode>,
or support my work at <https://liberapay.com/yantar92>

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