Use the CSS convention for #RGB colors (bug#36304)
* src/xterm.c (x_parse_color): Change interpretation of #RGB color triplets to match CSS rather than X conventions. * lisp/term/tty-colors.el (tty-color-standard-values): Change interpretation of #RGB color triplets to match CSS rather than X conventions. Allow upper-case digits. Fix rgb:R/G/B interpretation. * doc/emacs/display.texi (Colors): Specify the convention used for "#RGB" color triplets. * test/lisp/tty-colors-tests.el: New file. * etc/NEWS: Mention the change.
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Pip Cet
Eli Zaretskii
parent
e310843d9d
commit
357399014a
4 changed files with 88 additions and 44 deletions
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@ -556,14 +556,14 @@ Font Lock mode.
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@node Colors
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@section Colors for Faces
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@cindex color name
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@cindex RGB triplet
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Faces can have various foreground and background colors. When you
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specify a color for a face---for instance, when customizing the face
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(@pxref{Face Customization})---you can use either a @dfn{color name}
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or an @dfn{RGB triplet}.
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@subsection Color Names
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@cindex color name
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@findex list-colors-display
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@vindex list-colors-sort
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A color name is a pre-defined name, such as @samp{dark orange} or
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@ -578,12 +578,16 @@ such terminals. However, Emacs understands X11 color names even on
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text terminals; if a face is given a color specified by an X11 color
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name, it is displayed using the closest-matching terminal color.
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@subsection RGB Triplets
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@cindex RGB triplet
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An RGB triplet is a string of the form @samp{#RRGGBB}. Each of the
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R, G, and B components is a hexadecimal number specifying the
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component's relative intensity, one to four digits long (usually two
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digits are used). The components must have the same number of digits.
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For hexadecimal values A to F, either upper or lower case are
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acceptable.
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primary color components is represented by a hexadecimal number
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between @samp{00} (intensity 0) and @samp{FF} (the maximum intensity).
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It is also possible to use one, three, or four hex digits for each
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component, so @samp{red} can be represented as @samp{#F00},
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@samp{#fff000000}, or @samp{#ffff00000000}. The components must have
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the same number of digits. For hexadecimal values A to F, either
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upper or lower case are acceptable.
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The @kbd{M-x list-colors-display} command also shows the equivalent
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RGB triplet for each named color. For instance, @samp{medium sea
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7
etc/NEWS
7
etc/NEWS
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@ -407,6 +407,12 @@ names in xref buffers.
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** New variable `file-size-function' controls how file sizes are displayed.
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+++
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** Emacs now interprets RGB triplets like HTML, SVG, and CSS do.
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The X convention previously used differed slightly, particularly for
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RGB triplets with a single hexadecimal digit per component.
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* Editing Changes in Emacs 27.1
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@ -1509,7 +1515,6 @@ automatically updates. In the buffer, you can use 's q' or 's e' to
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signal a thread with quit or error respectively, or get a snapshot
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backtrace with 'b'.
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** thingatpt.el
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---
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@ -919,57 +919,63 @@ FRAME defaults to the selected frame."
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The result is a list of integer RGB values--(RED GREEN BLUE).
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These values range from 0 to 65535; white is (65535 65535 65535).
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The returned value reflects the standard X definition of COLOR,
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regardless of whether the terminal can display it, so the return value
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should be the same regardless of what display is being used."
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The returned value reflects the standard Emacs definition of
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COLOR (see the info node `(emacs) Colors'), regardless of whether
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the terminal can display it, so the return value should be the
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same regardless of what display is being used."
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(let ((len (length color)))
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(cond ((and (>= len 4) ;; X-style "#XXYYZZ" color spec
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(cond ((and (>= len 4) ;; HTML/CSS/SVG-style "#XXYYZZ" color spec
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(eq (aref color 0) ?#)
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(member (aref color 1)
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'(?0 ?1 ?2 ?3 ?4 ?5 ?6 ?7 ?8 ?9
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?a ?b ?c ?d ?e ?f)))
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;; Translate the string "#XXYYZZ" into a list
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;; of numbers (XX YY ZZ). If the primary colors
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;; are specified with less than 4 hex digits,
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;; the used digits represent the most significant
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;; bits of the value (e.g. #XYZ = #X000Y000Z000).
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?a ?b ?c ?d ?e ?f
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?A ?B ?C ?D ?E ?F)))
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;; Translate the string "#XXYYZZ" into a list of numbers
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;; (XX YY ZZ), scaling each to the {0..65535} range. This
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;; follows the HTML color convention, where both "#fff" and
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;; "#ffffff" represent the same color, white.
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(let* ((ndig (/ (- len 1) 3))
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(maxval (1- (ash 1 (* 4 ndig))))
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(i1 1)
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(i2 (+ i1 ndig))
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(i3 (+ i2 ndig)))
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(i3 (+ i2 ndig))
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(i4 (+ i3 ndig)))
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(list
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(ash
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(string-to-number (substring color i1 i2) 16)
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(* 4 (- 4 ndig)))
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(ash
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(string-to-number (substring color i2 i3) 16)
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(* 4 (- 4 ndig)))
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(ash
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(string-to-number (substring color i3) 16)
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(* 4 (- 4 ndig))))))
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((and (>= len 9) ;; X-style RGB:xx/yy/zz color spec
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(/ (* (string-to-number
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(substring color i1 i2) 16)
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65535)
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maxval)
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(/ (* (string-to-number
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(substring color i2 i3) 16)
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65535)
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maxval)
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(/ (* (string-to-number
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(substring color i3 i4) 16)
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65535)
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maxval))))
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((and (>= len 9) ;; X-style rgb:xx/yy/zz color spec
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(string= (substring color 0 4) "rgb:"))
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;; Translate the string "RGB:XX/YY/ZZ" into a list
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;; of numbers (XX YY ZZ). If fewer than 4 hex
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;; digits are used, they represent the fraction
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;; of the maximum value (RGB:X/Y/Z = #XXXXYYYYZZZZ).
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;; Translate the string "rgb:XX/YY/ZZ" into a list of
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;; numbers (XX YY ZZ), scaling each to the {0..65535}
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;; range. "rgb:F/F/F" is white.
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(let* ((ndig (/ (- len 3) 3))
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(maxval (1- (ash 1 (* 4 (- ndig 1)))))
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(i1 4)
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(i2 (+ i1 ndig))
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(i3 (+ i2 ndig)))
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(i3 (+ i2 ndig))
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(i4 (+ i3 ndig)))
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(list
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(/ (* (string-to-number
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(substring color i1 (- i2 1)) 16)
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255)
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65535)
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maxval)
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(/ (* (string-to-number
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(substring color i2 (- i3 1)) 16)
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255)
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65535)
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maxval)
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(/ (* (string-to-number
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(substring color i3) 16)
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255)
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(substring color i3 (1- i4)) 16)
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65535)
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maxval))))
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(t
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(cdr (assoc color color-name-rgb-alist))))))
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@ -977,9 +983,9 @@ should be the same regardless of what display is being used."
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(defun tty-color-translate (color &optional frame)
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"Given a color COLOR, return the index of the corresponding TTY color.
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COLOR must be a string that is either the color's name, or its X-style
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specification like \"#RRGGBB\" or \"RGB:rr/gg/bb\", where each primary.
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color can be given with 1 to 4 hex digits.
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COLOR must be a string that is either the color's name, or its
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color triplet specification like \"#RRGGBB\" or \"rgb:RR/GG/BB\",
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where each primary color can be given with 1 to 4 hex digits.
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If COLOR is a color name that is found among supported colors in
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`tty-color-alist', the associated index is returned. Otherwise, the
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@ -987,7 +993,7 @@ RGB values of the color, either as given by the argument or from
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looking up the name in `color-name-rgb-alist', are used to find the
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supported color that is the best approximation for COLOR in the RGB
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space.
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If COLOR is neither a valid X RGB specification of the color, nor a
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If COLOR is neither a valid RGB specification of the color, nor a
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name of a color in `color-name-rgb-alist', the returned value is nil.
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If FRAME is unspecified or nil, it defaults to the selected frame."
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33
src/xterm.c
33
src/xterm.c
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@ -2381,6 +2381,8 @@ x_query_frame_background_color (struct frame *f, XColor *bgcolor)
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x_query_colors (f, bgcolor, 1);
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}
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#define HEX_COLOR_NAME_LENGTH 32
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/* On frame F, translate the color name to RGB values. Use cached
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information, if possible.
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@ -2398,9 +2400,36 @@ Status x_parse_color (struct frame *f, const char *color_name,
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if (color_name[0] == '#')
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{
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/* The hex form is parsed directly by XParseColor without
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/* Don't pass #RGB strings directly to XParseColor, because that
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follows the X convention of zero-extending each channel
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value: #f00 means #f00000. We want the convention of scaling
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channel values, so #f00 means #ff0000, just as it does for
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HTML, SVG, and CSS.
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So we translate #f00 to rgb:f/0/0, which X handles
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differently. */
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char rgb_color_name[HEX_COLOR_NAME_LENGTH];
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int len = strlen (color_name);
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int digits_per_channel;
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if (len == 4)
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digits_per_channel = 1;
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else if (len == 7)
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digits_per_channel = 2;
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else if (len == 10)
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digits_per_channel = 3;
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else if (len == 13)
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digits_per_channel = 4;
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else
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return 0;
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snprintf (rgb_color_name, sizeof rgb_color_name, "rgb:%.*s/%.*s/%.*s",
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digits_per_channel, color_name + 1,
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digits_per_channel, color_name + digits_per_channel + 1,
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digits_per_channel, color_name + 2 * digits_per_channel + 1);
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/* The rgb form is parsed directly by XParseColor without
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talking to the X server. No need for caching. */
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return XParseColor (dpy, cmap, color_name, color);
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return XParseColor (dpy, cmap, rgb_color_name, color);
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}
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for (cache_entry = FRAME_DISPLAY_INFO (f)->color_names; cache_entry;
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