GNU bug report logs - #36315
27.0.50; SVG transparency handling is inaccurate

Previous Next

Full log

View this message in rfc822 format

From: help-debbugs <at> gnu.org (GNU bug Tracking System)
To: Pip Cet <pipcet <at> gmail.com>
Subject: bug#36315: closed (Re: bug#36315: Incorrect SVG color)
Date: Fri, 18 Dec 2020 18:05:02 +0000

[Message part 1 (text/plain, inline)]

Your bug report

#36315: 27.0.50; SVG transparency handling is inaccurate

which was filed against the emacs package, has been closed.

The explanation is attached below, along with your original report.
If you require more details, please reply to 36315 <at> debbugs.gnu.org.

-- 
36315: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=36315
GNU Bug Tracking System
Contact help-debbugs <at> gnu.org with problems

[Message part 2 (message/rfc822, inline)]

From: Alan Third <alan <at> idiocy.org>
To: Qiantan Hong <qhong <at> mit.edu>
Cc: "36315 <at> debbugs.gnu.org" <36315-done <at> debbugs.gnu.org>
Subject: Re: bug#36315: Incorrect SVG color
Date: Fri, 18 Dec 2020 18:04:45 +0000

On Fri, Dec 18, 2020 at 04:42:03PM +0000, Qiantan Hong wrote:
> I fixed my build and it behaves correctly on macOS
> now.
> 
> M-x emacs-version
> GNU Emacs 28.0.50 (build 1, x86_64-apple-darwin18.7.0, NS appkit-1671.60 Version 10.14.6 (Build 18G6032)) of 2020-12-18

Excellent! Thanks for letting us know.

> To make sure I understand it, did we start outsourcing color some point after 27.1?

We pass the foreground and background colours into librsvg, which
creates the bitmap image that's displayed, in a commit that's just a
few months old. It will appear in Emacs 28.

I don't expect the change to be included in Emacs 27 since it's a
fairly large change introducing a number of new features and any new
Emacs 27 releases will be primarily bug fixes.
-- 
Alan Third

[Message part 3 (message/rfc822, inline)]

From: Pip Cet <pipcet <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: 27.0.50; SVG transparency handling is inaccurate
Date: Thu, 20 Jun 2019 20:26:53 +0000

[Message part 4 (text/plain, inline)]

Evaluate the following in emacs -Q:

(require 'svg)

(defun make-image (color)
  (let ((svg (svg-create 100 100)))
    (svg-rectangle svg 0 0 100 100 :fill color)
    (svg-image svg)))

(set-frame-parameter (window-frame) 'background-color "black")

(insert (propertize " " 'display (make-image "#f00000")))

The expected result is a rectangle (on black background) of color
#f00000. The actual result is a rectangle of color #ef0000. For black
backgrounds, white is no longer representable.

This is related to bug #36304, but much easier to fix.

Patch attached.

[0001-SVG-scale-color-values-properly.patch (text/x-patch, attachment)]

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.