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/*
* nearcolor.c - map colours to nearest match in 88 or 256 colour palette
*
* This file is part of zsh, the Z shell.
*
* Copyright (c) 2018 Oliver Kiddle
* All rights reserved.
*
* Permission is hereby granted, without written agreement and without
* license or royalty fees, to use, copy, modify, and distribute this
* software and to distribute modified versions of this software for any
* purpose, provided that the above copyright notice and the following
* two paragraphs appear in all copies of this software.
*
* In no event shall Oliver Kiddle or the Zsh Development Group be liable
* to any party for direct, indirect, special, incidental, or consequential
* damages arising out of the use of this software and its documentation,
* even if Oliver Kiddle and the Zsh Development Group have been advised of
* the possibility of such damage.
*
* Oliver Kiddle and the Zsh Development Group specifically disclaim any
* warranties, including, but not limited to, the implied warranties of
* merchantability and fitness for a particular purpose. The software
* provided hereunder is on an "as is" basis, and Oliver Kiddle and the
* Zsh Development Group have no obligation to provide maintenance,
* support, updates, enhancements, or modifications.
*
*/
#include "nearcolor.mdh"
#include "nearcolor.pro"
#include <math.h>
struct cielab {
double L, a, b;
};
typedef struct cielab *Cielab;
static double
deltae(Cielab lab1, Cielab lab2)
{
/* taking square root unnecessary as we're just comparing values */
return pow(lab1->L - lab2->L, 2) +
pow(lab1->a - lab2->a, 2) +
pow(lab1->b - lab2->b, 2);
}
static void
RGBtoLAB(int red, int green, int blue, Cielab lab)
{
double R = red / 255.0;
double G = green / 255.0;
double B = blue / 255.0;
R = 100.0 * (R > 0.04045 ? pow((R + 0.055) / 1.055, 2.4) : R / 12.92);
G = 100.0 * (G > 0.04045 ? pow((G + 0.055) / 1.055, 2.4) : G / 12.92);
B = 100.0 * (B > 0.04045 ? pow((B + 0.055) / 1.055, 2.4) : B / 12.92);
/* Observer. = 2 degrees, Illuminant = D65 */
double X = (R * 0.4124 + G * 0.3576 + B * 0.1805) / 95.047;
double Y = (R * 0.2126 + G * 0.7152 + B * 0.0722) / 100.0;
double Z = (R * 0.0193 + G * 0.1192 + B * 0.9505) / 108.883;
X = (X > 0.008856) ? pow(X, 1.0/3.0) : (7.787 * X) + (16.0 / 116.0);
Y = (Y > 0.008856) ? pow(Y, 1.0/3.0) : (7.787 * Y) + (16.0 / 116.0);
Z = (Z > 0.008856) ? pow(Z, 1.0/3.0) : (7.787 * Z) + (16.0 / 116.0);
lab->L = (116.0 * Y) - 16.0;
lab->a = 500.0 * (X - Y);
lab->b = 200.0 * (Y - Z);
}
static int
mapRGBto88(int red, int green, int blue)
{
int component[] = { 0, 0x8b, 0xcd, 0xff, 0x2e, 0x5c, 0x8b, 0xa2, 0xb9, 0xd0, 0xe7 };
struct cielab orig, next;
double nextl, bestl = -1;
int r, g, b;
int comp_r = 0, comp_g = 0, comp_b = 0;
/* Get original value */
RGBtoLAB(red, green, blue, &orig);
/* try every one of the 72 colours */
for (r = 0; r < 11; r++) {
for (g = 0; g <= 3; g++) {
for (b = 0; b <= 3; b++) {
if (r > 3) g = b = r; /* advance inner loops to the block of greys */
RGBtoLAB(component[r], component[g], component[b], &next);
nextl = deltae(&orig, &next);
if (nextl < bestl || bestl < 0) {
bestl = nextl;
comp_r = r;
comp_g = g;
comp_b = b;
}
}
}
}
return (comp_r > 3) ? 77 + comp_r :
16 + (comp_r * 16) + (comp_g * 4) + comp_b;
}
/*
* Convert RGB to nearest colour in the 256 colour range
*/
static int
mapRGBto256(int red, int green, int blue)
{
int component[] = {
0, 0x5f, 0x87, 0xaf, 0xd7, 0xff,
0x8, 0x12, 0x1c, 0x26, 0x30, 0x3a, 0x44, 0x4e,
0x58, 0x62, 0x6c, 0x76, 0x80, 0x8a, 0x94, 0x9e,
0xa8, 0xb2, 0xbc, 0xc6, 0xd0, 0xda, 0xe4, 0xee
};
struct cielab orig, next;
double nextl, bestl = -1;
int r, g, b;
int comp_r = 0, comp_g = 0, comp_b = 0;
/* Get original value */
RGBtoLAB(red, green, blue, &orig);
for (r = 0; r < sizeof(component)/sizeof(*component); r++) {
for (g = 0; g <= 5; g++) {
for (b = 0; b <= 5; b++) {
if (r > 5) g = b = r; /* advance inner loops to the block of greys */
RGBtoLAB(component[r], component[g], component[b], &next);
nextl = deltae(&orig, &next);
if (nextl < bestl || bestl < 0) {
bestl = nextl;
comp_r = r;
comp_g = g;
comp_b = b;
}
}
}
}
return (comp_r > 5) ? 226 + comp_r :
16 + (comp_r * 36) + (comp_g * 6) + comp_b;
}
static int
getnearestcolor(UNUSED(Hookdef dummy), Color_rgb col)
{
/* we add 1 to the colours so that colour 0 (black) is
* distinguished from runhookdef() indicating that no
* hook function is registered */
if (tccolours == 256)
return mapRGBto256(col->red, col->green, col->blue) + 1;
if (tccolours == 88)
return mapRGBto88(col->red, col->green, col->blue) + 1;
return -1;
}
static struct features module_features = {
NULL, 0,
NULL, 0,
NULL, 0,
NULL, 0,
0
};
/**/
int
setup_(UNUSED(Module m))
{
return 0;
}
/**/
int
features_(Module m, char ***features)
{
*features = featuresarray(m, &module_features);
return 0;
}
/**/
int
enables_(Module m, int **enables)
{
return handlefeatures(m, &module_features, enables);
}
/**/
int
boot_(Module m)
{
addhookfunc("get_color_attr", (Hookfn) getnearestcolor);
return 0;
}
/**/
int
cleanup_(Module m)
{
deletehookfunc("get_color_attr", (Hookfn) getnearestcolor);
return setfeatureenables(m, &module_features, NULL);
}
/**/
int
finish_(UNUSED(Module m))
{
return 0;
}
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