From: "Łukasz Stelmach" <stlman@poczta.fm>
To: 15837@debbugs.gnu.org
Subject: bug#15837: 24.3; invalid colour conversion from Gtk+3 to X11
Date: Fri, 08 Nov 2013 19:16:18 +0100 [thread overview]
Message-ID: <87mwle21zh.fsf%stlman@poczta.fm> (raw)
Hello,
The function[1] that reads foreground and background colours from Gtk+3
(GdkRGBA) and converts them to X11 ones (XColor) uses improper
intermediate representation. The Gtk coulour is formated as
rgbi:<red>/<green>/<blue>. Although values prefixed with rgbi: are meant
to be floating point values like the ones returned by
gtk_style_context_get_*() functions but unlike Gtk colours they are
meant to be linear intensity values and will be gamma corrected[2] using
the tables[3] in Xlib.
You can check the effect for yourself by running:
xterm -bg '#777'
xterm -bg 'rgb:7777/7777/7777'
xterm -bg 'rgb:0.46667/0.46667/0.46667'
The last one will be significantly lighter.
0.46667/0.46667/0.46667 is the value returned by Gtk when a colour is
set to #777.
A patch will follow this report.
References:
[1] http://git.savannah.gnu.org/cgit/emacs.git/tree/src/gtkutil.c?id=c09a36ec78af479cb2ea39bf4bca8743cecd08df#n601
[2] http://cgit.freedesktop.org/xorg/doc/xorg-docs/tree/man/X.man?id=66e800c69fa5348b01e4b9670d6274ba392db7e5#n562
[3] http://cgit.freedesktop.org/xorg/lib/libX11/tree/src/xcms/LRGB.c?id=6cb02b166361200da35ba14f52cd9aaa493eb0ea#n224
--
Było mi bardzo miło. --- Rurku. --- ...
>Łukasz< --- To dobrze, że mnie słuchasz.
... Droga wśród jabłoni prowadzi w nieznane...
next reply other threads:[~2013-11-08 18:16 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-08 18:16 Łukasz Stelmach [this message]
2013-11-08 18:41 ` bug#15837: [PATCH] Pass colours using rgb: instead of rgbi: Łukasz Stelmach
2013-11-09 11:20 ` Jan Djärv
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