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move canvas colors code into its own file(s)

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Paul Davis 2014-11-07 14:24:13 -05:00
parent 1e8645bb8e
commit 69fd25f6f4
2 changed files with 228 additions and 0 deletions
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35
libs/canvas/canvas/colors.h Normal file
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/*
Copyright (C) 2011-2013 Paul Davis
Author: Carl Hetherington <cth@carlh.net>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <cairomm/context.h>
#include "canvas/visibility.h"
#include "canvas/types.h"
namespace ArdourCanvas {
extern LIBCANVAS_API void color_to_hsv (Color color, double& h, double& s, double& v);
extern LIBCANVAS_API Color hsv_to_color (double h, double s, double v, double a);
extern LIBCANVAS_API void color_to_rgba (Color, double& r, double& g, double& b, double& a);
extern LIBCANVAS_API Color rgba_to_color (double r, double g, double b, double a);
uint32_t LIBCANVAS_API contrasting_text_color (uint32_t c);
}

193
libs/canvas/colors.cc Normal file
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/*
Copyright (C) 2014 Paul Davis
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <algorithm>
#include <cmath>
#include <stdint.h>
#include "canvas/colors.h"
using namespace std;
using namespace ArdourCanvas;
using std::max;
using std::min;
void
ArdourCanvas::color_to_hsv (Color color, double& h, double& s, double& v)
{
double r, g, b, a;
double cmax;
double cmin;
double delta;
color_to_rgba (color, r, g, b, a);
if (r > g) {
cmax = max (r, b);
} else {
cmax = max (g, b);
}
if (r < g) {
cmin = min (r, b);
} else {
cmin = min (g, b);
}
v = cmax;
delta = cmax - cmin;
if (cmax == 0) {
// r = g = b == 0 ... v is undefined, s = 0
s = 0.0;
h = -1.0;
}
if (delta != 0.0) {
if (cmax == r) {
h = fmod ((g - b)/delta, 6.0);
} else if (cmax == g) {
h = ((b - r)/delta) + 2;
} else {
h = ((r - g)/delta) + 4;
}
h *= 60.0;
}
if (delta == 0 || cmax == 0) {
s = 0;
} else {
s = delta / cmax;
}
}
ArdourCanvas::Color
ArdourCanvas::hsv_to_color (double h, double s, double v, double a)
{
s = min (1.0, max (0.0, s));
v = min (1.0, max (0.0, v));
if (s == 0) {
// achromatic (grey)
return rgba_to_color (v, v, v, a);
}
h = min (360.0, max (0.0, h));
double c = v * s;
double x = c * (1.0 - fabs(fmod(h / 60.0, 2) - 1.0));
double m = v - c;
if (h >= 0.0 && h < 60.0) {
return rgba_to_color (c + m, x + m, m, a);
} else if (h >= 60.0 && h < 120.0) {
return rgba_to_color (x + m, c + m, m, a);
} else if (h >= 120.0 && h < 180.0) {
return rgba_to_color (m, c + m, x + m, a);
} else if (h >= 180.0 && h < 240.0) {
return rgba_to_color (m, x + m, c + m, a);
} else if (h >= 240.0 && h < 300.0) {
return rgba_to_color (x + m, m, c + m, a);
} else if (h >= 300.0 && h < 360.0) {
return rgba_to_color (c + m, m, x + m, a);
}
return rgba_to_color (m, m, m, a);
}
void
ArdourCanvas::color_to_rgba (Color color, double& r, double& g, double& b, double& a)
{
r = ((color >> 24) & 0xff) / 255.0;
g = ((color >> 16) & 0xff) / 255.0;
b = ((color >> 8) & 0xff) / 255.0;
a = ((color >> 0) & 0xff) / 255.0;
}
ArdourCanvas::Color
ArdourCanvas::rgba_to_color (double r, double g, double b, double a)
{
/* clamp to [0 .. 1] range */
r = min (1.0, max (0.0, r));
g = min (1.0, max (0.0, g));
b = min (1.0, max (0.0, b));
a = min (1.0, max (0.0, a));
/* convert to [0..255] range */
unsigned int rc, gc, bc, ac;
rc = rint (r * 255.0);
gc = rint (g * 255.0);
bc = rint (b * 255.0);
ac = rint (a * 255.0);
/* build-an-integer */
return (rc << 24) | (gc << 16) | (bc << 8) | ac;
}
// Inverse of sRGB "gamma" function.
static inline double
inv_gam_sRGB (double c)
{
if (c <= 0.04045) {
return c/12.92;
} else {
return pow(((c+0.055)/(1.055)),2.4);
}
}
// sRGB "gamma" function
static inline int
gam_sRGB(double v)
{
if (v <= 0.0031308) {
v *= 12.92;
} else {
v = 1.055 * pow (v, 1.0 / 2.4) - 0.055;
}
return int (v*255+.5);
}
static double
luminance (uint32_t c)
{
// sRGB luminance(Y) values
const double rY = 0.212655;
const double gY = 0.715158;
const double bY = 0.072187;
double r, g, b, a;
ArdourCanvas::color_to_rgba (c, r, g, b, a);
return (gam_sRGB (rY*inv_gam_sRGB(r) + gY*inv_gam_sRGB(g) + bY*inv_gam_sRGB(b))) / 255.0;
}
uint32_t
ArdourCanvas::contrasting_text_color (uint32_t c)
{
static const uint32_t white = ArdourCanvas::rgba_to_color (1.0, 1.0, 1.0, 1.0);
static const uint32_t black = ArdourCanvas::rgba_to_color (0.0, 0.0, 0.0, 1.0);
return (luminance (c) < 0.50) ? white : black;
}