From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: David Kastrup Newsgroups: gmane.emacs.devel Subject: Re: face colors on 256 colors terminals Date: Wed, 06 Apr 2005 19:36:27 +0200 Message-ID: References: <200504060817.j368HDAH019106@scanner2.ics.uci.edu> <01c53acd$Blat.v2.4$7c0f2080@zahav.net.il> NNTP-Posting-Host: main.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: sea.gmane.org 1112810133 3815 80.91.229.2 (6 Apr 2005 17:55:33 GMT) X-Complaints-To: usenet@sea.gmane.org NNTP-Posting-Date: Wed, 6 Apr 2005 17:55:33 +0000 (UTC) Cc: Dan Nicolaescu , emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Wed Apr 06 19:55:31 2005 Return-path: Original-Received: from lists.gnu.org ([199.232.76.165]) by ciao.gmane.org with esmtp (Exim 4.43) id 1DJEjl-0007pm-MH for ged-emacs-devel@m.gmane.org; Wed, 06 Apr 2005 19:54:45 +0200 Original-Received: from localhost ([127.0.0.1] helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1DJEIu-00011Y-FT for ged-emacs-devel@m.gmane.org; Wed, 06 Apr 2005 13:27:00 -0400 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1DJEFo-0007iM-Ut for emacs-devel@gnu.org; Wed, 06 Apr 2005 13:23:49 -0400 Original-Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1DJEFo-0007ey-1M for emacs-devel@gnu.org; Wed, 06 Apr 2005 13:23:48 -0400 Original-Received: from [199.232.76.164] (helo=fencepost.gnu.org) by monty-python.gnu.org with esmtp (Exim 4.34) id 1DJESg-0005C6-5c for emacs-devel@gnu.org; Wed, 06 Apr 2005 13:37:06 -0400 Original-Received: from localhost ([127.0.0.1] helo=lola.goethe.zz) by fencepost.gnu.org with esmtp (Exim 4.34) id 1DJERq-0005kI-Gn; Wed, 06 Apr 2005 13:36:17 -0400 Original-To: Eli Zaretskii In-Reply-To: <01c53acd$Blat.v2.4$7c0f2080@zahav.net.il> (Eli Zaretskii's message of "Wed, 06 Apr 2005 20:23:24 +0300") User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.0.50 (gnu/linux) X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:35647 X-Report-Spam: http://spam.gmane.org/gmane.emacs.devel:35647 "Eli Zaretskii" writes: >> From: Dan Nicolaescu >> Date: Wed, 06 Apr 2005 01:17:11 -0700 >> >> This comment in tty-colors.el:tty-color-standard-values >> >> ;; Translate the string "#XXYYZZ" into a list >> ;; of numbers (XX YY ZZ). If the primary colors >> ;; are specified with less than 4 hex digits, >> ;; the used digits represent the most significant >> ;; bits of the value (e.g. #XYZ = #X000Y000Z000). >> >> does not seem to match the way the `color-name-rgb-alist' seem to have >> been created from the values in rgb.txt. >> A random example: >> >From color-name-rgb-alist: >> ("lavenderblush" 65535 61680 62965) >> ^^^^ ^^^^ ^^^^ >> 0xffff 0xf0f0 0xf5f5 >> >> >From rgb.txt: lavender blush 255 240 245 >> 0xff 0xf0 0xf5 >> So the 8 to 16 bit conversion seems use the same byte value for both >> the high and low byte value. > > The comment you cited reflects what I found in the X documentation. > Here, for example, is an excerpt from the X(7) man page on a Debian > GNU/Linux box (fencepost.gnu.org): > > For backward compatibility, an older syntax for RGB Device > is supported, but its continued use is not encouraged. > The syntax is an initial sharp sign character followed by > a numeric specification, in one of the following formats: > > #RGB (4 bits each) > #RRGGBB (8 bits each) > #RRRGGGBBB (12 bits each) > #RRRRGGGGBBBB (16 bits each) > > The R, G, and B represent single hexadecimal digits. When > fewer than 16 bits each are specified, they represent the > most-significant bits of the value (unlike the "rgb:" syn- > tax, in which values are scaled). For example, #3a7 is > the same as #3000a0007000. > > So I think the code in tty-colors.el is correct in this matter. It > is, however, possible that the RGB values in color-name-rgb-alist were > incorrectly scaled from 8-bit variants, and need to be amended. Actually, it does not make sense to scale in that way. #3a7 really should be the same as #3333aaaa7777, so that #fff is the same as #ffffffffffff, pure white. Somebody should tell the X people to do that. I just have no idea who to tell, and it would appear that there is a bit of previous art that might rely on the current behavior... -- David Kastrup, Kriemhildstr. 15, 44793 Bochum