Commit c8ad9e95 authored by Eli Zaretskii's avatar Eli Zaretskii
Browse files

(color-name-rgb-alist): Add a comment explaining why some "light*"

colors are deliberately absent from the alist.
parent 12385722
......@@ -36,29 +36,50 @@
;; rest of Emacs from including special code for this case.
;; Here's how it works. The support for terminal and MSDOS frames
;; maintains an alist, called `tty-color-alist', which associates
;; colors supported by the terminal driver with small integers.
;; (These small integers are passed to the library functions which set
;; the color, and are effectively indices of the colors in the
;; supported color palette.) When Emacs needs to send a color command
;; to the terminal, the color name is first looked up in
;; `tty-color-alist'. If not found, functions from this file can be
;; used to map the color to one of the supported colors.
;; maintains an alist, called `tty-defined-color-alist', which
;; associates colors supported by the terminal driver with small
;; integers. (These small integers are passed to the library
;; functions which set the color, and are effectively indices of the
;; colors in the supported color palette.) When Emacs needs to send a
;; color command to the terminal, the color name is first looked up in
;; `tty-defined-color-alist'. If not found, functions from this file
;; can be used to map the color to one of the supported colors.
;; Specifically, the X RGB values of the requested color are extracted
;; from `color-name-rgb-alist' and then the supported color is found
;; with the minimal distance in the RGB space from the requested
;; color.
;; `tty-color-alist' is created at startup by calling the function
;; `tty-color-define', defined below, passing it each supported color,
;; its index, and its RGB values. The standard list of colors
;; supported by many Unix color terminals, including xterm, FreeBSD,
;; and GNU/Linux, is supplied below in `tty-standard-colors'. If your
;; terminal supports different or additional colors, call
;; `tty-color-define' from your `.emacs' or `site-start.el'.
;; `tty-defined-color-alist' is created at startup by calling the
;; function `tty-color-define', defined below, passing it each
;; supported color, its index, and its RGB values. The standard list
;; of colors supported by many Unix color terminals, including xterm,
;; FreeBSD, and GNU/Linux, is supplied below in `tty-standard-colors'.
;; If your terminal supports different or additional colors, call
;; `tty-color-define' from your `.emacs' or `site-start.el'. For
;; more-or-less standard definitions of VGA text-mode colors, see the
;; beginning of lisp/term/pc-win.el.
;;; Code:
;; The following list is taken from rgb.txt distributed with X.
;;
;; WARNING: Some colors, such as "lightred", do not appear in this
;; list. If you think it's a good idea to add them, don't! The
;; problem is that the X-standard definition of "red" actually
;; corresponds to "lightred" on VGA (that's why pc-win.el and
;; w32-fns.el define "lightred" with the same RGB values as "red"
;; below). Adding "lightred" here would therefore create confusing
;; and counter-intuitive results, like "red" and "lightred" being the
;; same color. A similar situation exists with other "light*" colors.
;;
;; Nevertheless, "lightred" and other similar color names *are*
;; defined for the MS-DOS and MS-Windows consoles, because the users
;; on those systems expect these colors to be available.
;;
;; For these reasons, package maintaners are advised NOT to use color
;; names such as "lightred" or "lightblue", because they will have
;; different effect on different displays. Instead, use "red1" and
;; "blue1", respectively.
(defvar color-name-rgb-alist
'(("snow" 255 250 250)
("ghostwhite" 248 248 255)
......@@ -713,9 +734,9 @@
("darkgrey" 169 169 169)
("darkgray" 169 169 169)
("darkblue" 0 0 139)
("darkcyan" 0 139 139)
("darkcyan" 0 139 139) ; no "lightmagenta", see the comment above
("darkmagenta" 139 0 139)
("darkred" 139 0 0)
("darkred" 139 0 0) ; but no "lightred", see the comment above
("lightgreen" 144 238 144))
"An alist of X color names and associated 8-bit RGB values.")
......
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