2 Copyright (C) 2014 Paul Davis
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2 of the License, or
7 (at your option) any later version.
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software
16 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
23 #include "canvas/colors.h"
26 using namespace ArdourCanvas;
32 ArdourCanvas::color_to_hsv (Color color, double& h, double& s, double& v)
39 color_to_rgba (color, r, g, b, a);
58 // r = g = b == 0 ... v is undefined, s = 0
65 h = fmod ((g - b)/delta, 6.0);
66 } else if (cmax == g) {
67 h = ((b - r)/delta) + 2;
69 h = ((r - g)/delta) + 4;
75 if (delta == 0 || cmax == 0) {
84 ArdourCanvas::hsv_to_color (double h, double s, double v, double a)
86 s = min (1.0, max (0.0, s));
87 v = min (1.0, max (0.0, v));
91 return rgba_to_color (v, v, v, a);
94 h = min (360.0, max (0.0, h));
97 double x = c * (1.0 - fabs(fmod(h / 60.0, 2) - 1.0));
100 if (h >= 0.0 && h < 60.0) {
101 return rgba_to_color (c + m, x + m, m, a);
102 } else if (h >= 60.0 && h < 120.0) {
103 return rgba_to_color (x + m, c + m, m, a);
104 } else if (h >= 120.0 && h < 180.0) {
105 return rgba_to_color (m, c + m, x + m, a);
106 } else if (h >= 180.0 && h < 240.0) {
107 return rgba_to_color (m, x + m, c + m, a);
108 } else if (h >= 240.0 && h < 300.0) {
109 return rgba_to_color (x + m, m, c + m, a);
110 } else if (h >= 300.0 && h < 360.0) {
111 return rgba_to_color (c + m, m, x + m, a);
113 return rgba_to_color (m, m, m, a);
117 ArdourCanvas::color_to_rgba (Color color, double& r, double& g, double& b, double& a)
119 r = ((color >> 24) & 0xff) / 255.0;
120 g = ((color >> 16) & 0xff) / 255.0;
121 b = ((color >> 8) & 0xff) / 255.0;
122 a = ((color >> 0) & 0xff) / 255.0;
126 ArdourCanvas::rgba_to_color (double r, double g, double b, double a)
128 /* clamp to [0 .. 1] range */
130 r = min (1.0, max (0.0, r));
131 g = min (1.0, max (0.0, g));
132 b = min (1.0, max (0.0, b));
133 a = min (1.0, max (0.0, a));
135 /* convert to [0..255] range */
137 unsigned int rc, gc, bc, ac;
138 rc = rint (r * 255.0);
139 gc = rint (g * 255.0);
140 bc = rint (b * 255.0);
141 ac = rint (a * 255.0);
143 /* build-an-integer */
145 return (rc << 24) | (gc << 16) | (bc << 8) | ac;
148 // Inverse of sRGB "gamma" function.
150 inv_gam_sRGB (double c)
155 return pow(((c+0.055)/(1.055)),2.4);
159 // sRGB "gamma" function
163 if (v <= 0.0031308) {
166 v = 1.055 * pow (v, 1.0 / 2.4) - 0.055;
168 return int (v*255+.5);
172 luminance (uint32_t c)
174 // sRGB luminance(Y) values
175 const double rY = 0.212655;
176 const double gY = 0.715158;
177 const double bY = 0.072187;
181 ArdourCanvas::color_to_rgba (c, r, g, b, a);
183 return (gam_sRGB (rY*inv_gam_sRGB(r) + gY*inv_gam_sRGB(g) + bY*inv_gam_sRGB(b))) / 255.0;
187 ArdourCanvas::contrasting_text_color (uint32_t c)
189 static const uint32_t white = ArdourCanvas::rgba_to_color (1.0, 1.0, 1.0, 1.0);
190 static const uint32_t black = ArdourCanvas::rgba_to_color (0.0, 0.0, 0.0, 1.0);
192 return (luminance (c) < 0.50) ? white : black;