From: no-spam@cua.dk (Kim F. Storm)
Cc: emacs-devel@gnu.org
Subject: Re: Several suggestions for image support
Date: 16 Apr 2004 16:02:52 +0200 [thread overview]
Message-ID: <m3k70g6mwj.fsf@kfs-l.imdomain.dk> (raw)
In-Reply-To: <wlzn9cgtjy.wl@church.math.s.chiba-u.ac.jp>
YAMAMOTO Mitsuharu <mituharu@math.s.chiba-u.ac.jp> writes:
> >>>>> On 16 Apr 2004 02:21:11 +0200, David Kastrup <dak@gnu.org> said:
>
> > PNG images support transparency. Emacs can't make use of it. You
> > can only have Emacs declare a particular color as transparent. This
> > is dissatisfactory. It should tell the PNG decoding routines Emacs'
> > background color for the purpose of transparency.
>
> As for PNG transparency, there was one thing that I noticed (and I've
> been forgotten to tell about it) while I was porting image support to
> Carbon Emacs.
>
> In png_load (image.c):
>
> user_bg.red = color.red >> PNG_BG_COLOR_SHIFT;
> user_bg.green = color.green >> PNG_BG_COLOR_SHIFT;
> user_bg.blue = color.blue >> PNG_BG_COLOR_SHIFT;
>
> fn_png_set_background (png_ptr, &user_bg,
> PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0);
>
> I think the background color should be specified in 8-bit depth here
> (thus PNG_BG_COLOR_SHIFT should be 8 for all the platforms) because
> the 4th argument (aka need_expand) for fn_png_set_background is 0 and
> the image data has been normalized in 8-bit depth at this stage.
I can indeed see that 8-bit shift is the right setting on X.
> You
> can observe the difference using
> http://www.w3.org/Graphics/PNG/alphatest.png. The same thing is also
> applied to the other place (in png_load) where fn_png_set_background
> is called with its 4th argument 0.
You are right. Shifting 8 bits here as well on X fixes transparent bg.
I will commit a fix for X shortly.
However, on W32, it seems that it explicitly scales things to 16 bits
in both cases. I cannot test this on W32, so I cannot say what's
the right thing to do.
Here is an easy way to test it -- after downloading the image you
mentioned:
(insert-image (create-image "alphatest.png"))
this should result in a light blue image with nice rounded
edges; a darker blue with rough edges indicates a problem.
--
Kim F. Storm <storm@cua.dk> http://www.cua.dk
next prev parent reply other threads:[~2004-04-16 14:02 UTC|newest]
Thread overview: 95+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-04-16 0:21 Several suggestions for image support David Kastrup
2004-04-16 9:29 ` YAMAMOTO Mitsuharu
2004-04-16 14:02 ` Kim F. Storm [this message]
2004-04-16 12:50 ` Jason Rumney
2004-04-16 16:59 ` Kim F. Storm
2004-04-16 15:18 ` Jason Rumney
2004-04-16 10:22 ` Kim F. Storm
2004-04-16 9:09 ` Jason Rumney
2004-04-16 10:06 ` David Kastrup
2004-04-16 12:38 ` Kim F. Storm
2004-04-16 11:09 ` Jason Rumney
2004-04-16 11:34 ` David Kastrup
2004-04-16 12:29 ` Jason Rumney
2004-04-16 12:56 ` David Kastrup
2004-04-16 17:08 ` Kim F. Storm
2004-04-16 13:39 ` Stefan Monnier
2004-04-16 13:49 ` David Kastrup
2004-04-17 7:16 ` Richard Stallman
2004-04-17 13:02 ` Werner LEMBERG
2004-04-17 19:24 ` David Kastrup
2004-04-17 18:03 ` David Kastrup
2004-04-18 21:30 ` Kim F. Storm
2004-04-19 1:51 ` Stefan Monnier
2004-04-19 7:57 ` David Kastrup
2004-04-19 10:34 ` Kim F. Storm
2004-04-19 14:29 ` Stefan Monnier
2004-04-19 15:17 ` David Kastrup
2004-04-19 15:37 ` Stefan Monnier
2004-04-19 15:56 ` Kim F. Storm
2004-04-19 14:15 ` David Kastrup
2004-04-19 21:59 ` Kim F. Storm
2004-04-21 0:53 ` Kim F. Storm
2004-04-21 1:08 ` Kim F. Storm
2004-04-20 23:31 ` David Kastrup
2004-04-21 3:04 ` Piet van Oostrum
2004-04-22 0:43 ` Kim F. Storm
2004-04-22 1:18 ` YAMAMOTO Mitsuharu
2004-04-22 22:03 ` Piet van Oostrum
2004-04-23 4:02 ` YAMAMOTO Mitsuharu
2004-04-24 14:48 ` Piet van Oostrum
2004-04-21 10:10 ` Kim F. Storm
2004-04-21 8:51 ` David Kastrup
2004-04-21 12:51 ` Kim F. Storm
2004-04-22 17:40 ` Richard Stallman
2004-04-22 18:17 ` David Kastrup
2004-04-24 14:26 ` Richard Stallman
2004-04-22 23:53 ` Kim F. Storm
2004-04-22 23:02 ` David Kastrup
2004-04-23 12:36 ` Kim F. Storm
2004-04-23 15:02 ` Stefan Monnier
2004-04-23 15:05 ` David Kastrup
2004-04-23 0:33 ` Kenichi Handa
2004-04-23 0:51 ` David Kastrup
2004-04-23 12:58 ` Kenichi Handa
2004-04-23 14:53 ` David Kastrup
2004-04-24 14:27 ` Richard Stallman
2004-04-24 15:16 ` David Kastrup
2004-04-25 1:56 ` Kim F. Storm
2004-04-25 2:06 ` David Kastrup
2004-04-26 9:38 ` Kim F. Storm
2004-04-27 0:34 ` Kim F. Storm
2004-04-26 22:50 ` David Kastrup
2004-04-27 1:30 ` Miles Bader
2004-04-27 9:30 ` Kim F. Storm
2004-04-27 13:22 ` David Kastrup
2004-04-27 14:00 ` David Kastrup
2004-04-28 10:12 ` Richard Stallman
2004-04-28 10:58 ` David Kastrup
2004-04-29 0:29 ` Kim F. Storm
2004-04-28 22:52 ` David Kastrup
2004-04-29 13:31 ` Richard Stallman
2004-04-29 2:06 ` Kenichi Handa
2004-04-29 10:00 ` Kim F. Storm
2004-04-30 1:54 ` Kenichi Handa
2004-04-29 2:20 ` Kenichi Handa
2004-04-25 18:09 ` Richard Stallman
2004-04-29 0:17 ` Kim F. Storm
2004-04-28 23:02 ` David Kastrup
2004-04-29 9:51 ` Kim F. Storm
2004-04-29 8:08 ` David Kastrup
2004-04-29 11:24 ` Kim F. Storm
2004-04-30 1:07 ` Kim F. Storm
2004-04-30 11:31 ` David Kastrup
2004-04-30 14:21 ` Kim F. Storm
2004-04-30 13:30 ` David Kastrup
2004-04-30 13:49 ` preview-latex in Emacs (was: Several suggestions for image support) Stefan Monnier
2004-05-01 9:44 ` Several suggestions for image support Richard Stallman
2004-05-01 19:56 ` Kim F. Storm
2004-05-02 19:52 ` Richard Stallman
2004-05-03 9:19 ` David Kastrup
2004-04-30 9:02 ` Richard Stallman
2004-04-30 11:27 ` David Kastrup
2004-04-30 14:19 ` Kim F. Storm
[not found] ` <E1BGiB8-00087H-Tz@fencepost.gnu.org>
[not found] ` <x5brljkgk5.fsf@lola.goethe.zz>
2004-04-22 23:32 ` Kim F. Storm
2004-04-22 21:50 ` David Kastrup
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=m3k70g6mwj.fsf@kfs-l.imdomain.dk \
--to=no-spam@cua.dk \
--cc=emacs-devel@gnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this external index
https://git.savannah.gnu.org/cgit/emacs.git
https://git.savannah.gnu.org/cgit/emacs/org-mode.git
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.