-;;; color.el --- Color manipulation laboratory routines -*- coding: utf-8; -*-
+;;; color.el --- Color manipulation library -*- coding: utf-8; -*-
;; Copyright (C) 2010-2011 Free Software Foundation, Inc.
-;; Author: Julien Danjou <julien@danjou.info>
-;; Keywords: html
+;; Authors: Julien Danjou <julien@danjou.info>
+;; Drew Adams <drew.adams@oracle.com>
+;; Keywords: lisp, faces, color, hex, rgb, hsv, hsl, cie-lab, background
;; This file is part of GNU Emacs.
;;; Commentary:
-;; This package provides color manipulation functions.
+;; This package provides functions for manipulating colors, including
+;; converting between color representations, computing color
+;; complements, and computing CIEDE2000 color distances.
+;;
+;; Supported color representations include RGB (red, green, blue), HSV
+;; (hue, saturation, value), HSL (hue, saturation, luminence), sRGB,
+;; CIE XYZ, and CIE L*a*b* color components.
;;; Code:
(unless (boundp 'float-pi)
(defconst float-pi (* 4 (atan 1)) "The value of Pi (3.1415926...).")))
-(defun color-rgb->hex (red green blue)
- "Return hexadecimal notation for RED GREEN BLUE color.
-RED GREEN BLUE must be values between 0 and 1 inclusively."
+;;;###autoload
+(defun color-name-to-rgb (color &optional frame)
+ "Convert COLOR string to a list of normalized RGB components.
+COLOR should be a color name (e.g. \"white\") or an RGB triplet
+string (e.g. \"#ff12ec\").
+
+Normally the return value is a list of three floating-point
+numbers, (RED GREEN BLUE), each between 0.0 and 1.0 inclusive.
+
+Optional arg FRAME specifies the frame where the color is to be
+displayed. If FRAME is omitted or nil, use the selected frame.
+If FRAME cannot display COLOR, return nil."
+ (mapcar (lambda (x) (/ x 65535.0)) (color-values color frame)))
+
+(defun color-rgb-to-hex (red green blue)
+ "Return hexadecimal notation for the color RED GREEN BLUE.
+RED GREEN BLUE must be numbers between 0.0 and 1.0 inclusive."
(format "#%02x%02x%02x"
(* red 255) (* green 255) (* blue 255)))
-(defun color-complement (color)
- "Return the color that is the complement of COLOR."
- (let ((color (color-rgb->normalize color)))
+(defun color-complement (color-name)
+ "Return the color that is the complement of COLOR-NAME.
+COLOR-NAME should be a string naming a color (e.g. \"white\"), or
+a string specifying a color's RGB components (e.g. \"#ff12ec\")."
+ (let ((color (color-name-to-rgb color-name)))
(list (- 1.0 (car color))
(- 1.0 (cadr color))
(- 1.0 (caddr color)))))
The color list builds a color gradient starting at color START to
color STOP. It does not include the START and STOP color in the
resulting list."
- (loop for i from 1 to step-number
- with red-step = (/ (- (car stop) (car start)) (1+ step-number))
- with green-step = (/ (- (cadr stop) (cadr start)) (1+ step-number))
- with blue-step = (/ (- (caddr stop) (caddr start)) (1+ step-number))
- collect (list
- (+ (car start) (* i red-step))
- (+ (cadr start) (* i green-step))
- (+ (caddr start) (* i blue-step)))))
+ (let* ((r (nth 0 start))
+ (g (nth 1 start))
+ (b (nth 2 start))
+ (r-step (/ (- (nth 0 stop) r) (1+ step-number)))
+ (g-step (/ (- (nth 1 stop) g) (1+ step-number)))
+ (b-step (/ (- (nth 2 stop) b) (1+ step-number)))
+ result)
+ (dotimes (n step-number)
+ (push (list (setq r (+ r r-step))
+ (setq g (+ g g-step))
+ (setq b (+ b b-step)))
+ result))
+ (nreverse result)))
(defun color-complement-hex (color)
"Return the color that is the complement of COLOR, in hexadecimal format."
- (apply 'color-rgb->hex (color-complement color)))
+ (apply 'color-rgb-to-hex (color-complement color)))
-(defun color-rgb->hsv (red green blue)
- "Convert RED GREEN BLUE values to HSV representation.
-Hue is in radians. Saturation and values are between 0 and 1
-inclusively."
- (let* ((r (float red))
+(defun color-rgb-to-hsv (red green blue)
+ "Convert RED, GREEN, and BLUE color components to HSV.
+RED, GREEN, and BLUE should each be numbers between 0.0 and 1.0,
+inclusive. Return a list (HUE, SATURATION, VALUE), where HUE is
+in radians and both SATURATION and VALUE are between 0.0 and 1.0,
+inclusive."
+ (let* ((r (float red))
(g (float green))
(b (float blue))
(max (max r g b))
(min (min r g b)))
- (list
- (/ (* 2 float-pi
- (cond ((and (= r g) (= g b)) 0)
- ((and (= r max)
- (>= g b))
- (* 60 (/ (- g b) (- max min))))
- ((and (= r max)
- (< g b))
- (+ 360 (* 60 (/ (- g b) (- max min)))))
- ((= max g)
- (+ 120 (* 60 (/ (- b r) (- max min)))))
- ((= max b)
- (+ 240 (* 60 (/ (- r g) (- max min)))))))
- 360)
- (if (= max 0)
- 0
- (- 1 (/ min max)))
- (/ max 255.0))))
-
-(defun color-rgb->hsl (red green blue)
+ (if (< (- max min) 1e-8)
+ (list 0.0 0.0 0.0)
+ (list
+ (/ (* 2 float-pi
+ (cond ((and (= r g) (= g b)) 0)
+ ((and (= r max)
+ (>= g b))
+ (* 60 (/ (- g b) (- max min))))
+ ((and (= r max)
+ (< g b))
+ (+ 360 (* 60 (/ (- g b) (- max min)))))
+ ((= max g)
+ (+ 120 (* 60 (/ (- b r) (- max min)))))
+ ((= max b)
+ (+ 240 (* 60 (/ (- r g) (- max min)))))))
+ 360)
+ (if (= max 0) 0 (- 1 (/ min max)))
+ (/ max 255.0)))))
+
+(defun color-rgb-to-hsl (red green blue)
"Convert RED GREEN BLUE colors to their HSL representation.
-RED, GREEN and BLUE must be between 0 and 1 inclusively."
+RED, GREEN, and BLUE should each be numbers between 0.0 and 1.0,
+inclusive.
+
+Return a list (HUE, SATURATION, LUMINENCE), where HUE is in radians
+and both SATURATION and LUMINENCE are between 0.0 and 1.0,
+inclusive."
(let* ((r red)
(g green)
(b blue)
(delta (- max min))
(l (/ (+ max min) 2.0)))
(list
- (if (= max min)
+ (if (< (- max min) 1e-8)
0
(* 2 float-pi
(/ (cond ((= max r)
(+ (/ (- g b) delta) (if (< g b) 6 0)))
((= max g)
- (+ (/ (- b r) delta) 2))
+ (+ (/ (- b r) delta) 2))
(t
(+ (/ (- r g) delta) 4)))
6)))
(/ delta (+ max min))))
l)))
-(defun color-srgb->xyz (red green blue)
- "Converts RED GREEN BLUE colors from the sRGB color space to CIE XYZ.
-RED, BLUE and GREEN must be between 0 and 1 inclusively."
+(defun color-srgb-to-xyz (red green blue)
+ "Convert RED GREEN BLUE colors from the sRGB color space to CIE XYZ.
+RED, BLUE and GREEN must be between 0 and 1, inclusive."
(let ((r (if (<= red 0.04045)
(/ red 12.95)
(expt (/ (+ red 0.055) 1.055) 2.4)))
(+ (* 0.21266729 r) (* 0.7151522 g) (* 0.0721750 b))
(+ (* 0.0193339 r) (* 0.1191920 g) (* 0.9503041 b)))))
-(defun color-xyz->srgb (X Y Z)
- "Converts CIE X Y Z colors to sRGB color space."
+(defun color-xyz-to-srgb (X Y Z)
+ "Convert CIE X Y Z colors to sRGB color space."
(let ((r (+ (* 3.2404542 X) (* -1.5371385 Y) (* -0.4985314 Z)))
(g (+ (* -0.9692660 X) (* 1.8760108 Y) (* 0.0415560 Z)))
(b (+ (* 0.0556434 X) (* -0.2040259 Y) (* 1.0572252 Z))))
(defconst color-cie-ε (/ 216 24389.0))
(defconst color-cie-κ (/ 24389 27.0))
-(defun color-xyz->lab (X Y Z &optional white-point)
- "Converts CIE XYZ to CIE L*a*b*.
-WHITE-POINT can be specified as (X Y Z) white point to use. If
-none is set, `color-d65-xyz' is used."
+(defun color-xyz-to-lab (X Y Z &optional white-point)
+ "Convert CIE XYZ to CIE L*a*b*.
+WHITE-POINT specifies the (X Y Z) white point for the
+conversion. If omitted or nil, use `color-d65-xyz'."
(destructuring-bind (Xr Yr Zr) (or white-point color-d65-xyz)
(let* ((xr (/ X Xr))
(yr (/ Y Yr))
(* 500 (- fx fy)) ; a
(* 200 (- fy fz)))))) ; b
-(defun color-lab->xyz (L a b &optional white-point)
- "Converts CIE L*a*b* to CIE XYZ.
-WHITE-POINT can be specified as (X Y Z) white point to use. If
-none is set, `color-d65-xyz' is used."
+(defun color-lab-to-xyz (L a b &optional white-point)
+ "Convert CIE L*a*b* to CIE XYZ.
+WHITE-POINT specifies the (X Y Z) white point for the
+conversion. If omitted or nil, use `color-d65-xyz'."
(destructuring-bind (Xr Yr Zr) (or white-point color-d65-xyz)
(let* ((fy (/ (+ L 16) 116.0))
(fz (- fy (/ b 200.0)))
(* yr Yr) ; Y
(* zr Zr))))) ; Z
-(defun color-srgb->lab (red green blue)
- "Converts RGB to CIE L*a*b*."
- (apply 'color-xyz->lab (color-srgb->xyz red green blue)))
-
-(defun color-rgb->normalize (color)
- "Normalize a RGB color to values between 0 and 1 inclusively."
- (mapcar (lambda (x) (/ x 65535.0)) (x-color-values color)))
+(defun color-srgb-to-lab (red green blue)
+ "Convert RGB to CIE L*a*b*."
+ (apply 'color-xyz-to-lab (color-srgb-to-xyz red green blue)))
-(defun color-lab->srgb (L a b)
- "Converts CIE L*a*b* to RGB."
- (apply 'color-xyz->srgb (color-lab->xyz L a b)))
+(defun color-lab-to-srgb (L a b)
+ "Convert CIE L*a*b* to RGB."
+ (apply 'color-xyz-to-srgb (color-lab-to-xyz L a b)))
(defun color-cie-de2000 (color1 color2 &optional kL kC kH)
- "Computes the CIEDE2000 color distance between COLOR1 and COLOR2.
-Colors must be in CIE L*a*b* format."
+ "Return the CIEDE2000 color distance between COLOR1 and COLOR2.
+Both COLOR1 and COLOR2 should be in CIE L*a*b* format, as
+returned by `color-srgb-to-lab' or `color-xyz-to-lab'."
(destructuring-bind (L₁ a₁ b₁) color1
(destructuring-bind (L₂ a₂ b₂) color2
(let* ((kL (or kL 1))
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