13
0
livetrax/libs/canvas/colors.cc

655 lines
12 KiB
C++

/*
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 <sstream>
#include <cmath>
#include <stdint.h>
#include <cfloat>
#include "pbd/convert.h"
#include "pbd/failed_constructor.h"
#include "pbd/locale_guard.h"
#include "canvas/colors.h"
#include "canvas/colorspace.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 a;
color_to_hsva (color, h, s, v, a);
}
void
ArdourCanvas::color_to_hsva (Color color, double& h, double& s, double& v, double& a)
{
double r, g, b;
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 = 0.0;
return;
}
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 (h < 0.0) {
/* negative values are legal but confusing, because
they alias positive values.
*/
h = 360 + h;
}
}
if (delta == 0 || cmax == 0) {
s = 0;
} else {
s = delta / cmax;
}
}
ArdourCanvas::Color
ArdourCanvas::hsva_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) {
return rgba_to_color (v, v, v, a);
}
h = fmod (h + 360.0, 360.0);
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)
{
/* use a slightly off-white... XXX should really look this up */
static const uint32_t white = ArdourCanvas::rgba_to_color (0.98, 0.98, 0.98, 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;
}
HSV::HSV ()
: h (0.0)
, s (1.0)
, v (1.0)
, a (1.0)
{
}
HSV::HSV (double hh, double ss, double vv, double aa)
: h (hh)
, s (ss)
, v (vv)
, a (aa)
{
if (h < 0.0) {
/* normalize negative hue values into positive range */
h = 360.0 + h;
}
}
HSV::HSV (Color c)
{
color_to_hsva (c, h, s, v, a);
}
HSV::HSV (const std::string& str)
{
stringstream ss (str);
ss >> h;
ss >> s;
ss >> v;
ss >> a;
}
string
HSV::to_string () const
{
stringstream ss;
ss << h << ' ';
ss << s << ' ';
ss << v << ' ';
ss << a;
return ss.str();
}
bool
HSV::is_gray () const
{
return s == 0;
}
void
HSV::clamp ()
{
h = fmod (h, 360.0);
if (h < 0.0) {
/* normalize negative hue values into positive range */
h = 360.0 + h;
}
s = min (1.0, s);
v = min (1.0, v);
a = min (1.0, a);
}
HSV
HSV::operator+ (const HSV& operand) const
{
HSV hsv;
hsv.h = h + operand.h;
hsv.s = s + operand.s;
hsv.v = v + operand.v;
hsv.a = a + operand.a;
hsv.clamp ();
return hsv;
}
HSV
HSV::operator- (const HSV& operand) const
{
HSV hsv;
hsv.h = h - operand.h;
hsv.s = s - operand.s;
hsv.v = s - operand.v;
hsv.a = a - operand.a;
hsv.clamp ();
return hsv;
}
HSV&
HSV::operator=(Color c)
{
color_to_hsva (c, h, s, v, a);
clamp ();
return *this;
}
HSV&
HSV::operator=(const std::string& str)
{
uint32_t c;
c = strtol (str.c_str(), 0, 16);
color_to_hsva (c, h, s, v, a);
clamp ();
return *this;
}
bool
HSV::operator== (const HSV& other)
{
return h == other.h &&
s == other.s &&
v == other.v &&
a == other.a;
}
HSV
HSV::shade (double factor) const
{
HSV hsv (*this);
/* algorithm derived from a google palette website
and analysis of their color palettes.
basic rule: to make a color darker, increase its saturation
until it reaches 88%, but then additionally reduce value/lightness
by a larger amount.
invert rule to make a color lighter.
*/
if (factor > 1.0) {
if (s < 88) {
hsv.v += (hsv.v * (factor * 10.0));
}
hsv.s *= factor;
} else {
if (s < 88) {
hsv.v -= (hsv.v * (factor * 10.0));
}
hsv.s *= factor;
}
hsv.clamp();
return hsv;
}
HSV
HSV::outline () const
{
if (luminance (color()) < 0.50) {
/* light color, darker outline: black with 15% opacity */
return HSV (0.0, 0.0, 0.0, 0.15);
} else {
/* dark color, lighter outline: white with 15% opacity */
return HSV (0.0, 0.0, 1.0, 0.15);
}
}
HSV
HSV::mix (const HSV& other, double amount) const
{
HSV hsv;
hsv.h = h + (amount * (other.h - h));
hsv.v = v + (amount * (other.s - s));
hsv.s = s + (amount * (other.v - v));
hsv.clamp();
return hsv;
}
HSV
HSV::delta (const HSV& other) const
{
HSV d;
if (is_gray() && other.is_gray()) {
d.h = 0.0;
d.s = 0.0;
d.v = v - other.v;
} else {
d.h = h - other.h;
d.s = s - other.s;
d.v = v - other.v;
}
d.a = a - other.a;
/* do not clamp - we are returning a delta */
return d;
}
double
HSV::distance (const HSV& other) const
{
if (is_gray() && other.is_gray()) {
/* human color perception of achromatics generates about 450
distinct colors. By contrast, CIE94 could give a maximal
perceptual distance of sqrt ((360^2) + 1 + 1) = 360. The 450
are not evenly spread (Webers Law), so lets use 360 as an
approximation of the number of distinct achromatics.
So, scale up the achromatic difference to give about
a maximal distance between v = 1.0 and v = 0.0 of 360.
A difference of about 0.0055 will generate a return value of
2, which is roughly the limit of human perceptual
discrimination for chromatics.
*/
return fabs (360.0 * (v - other.v));
}
if (is_gray() != other.is_gray()) {
/* no comparison possible */
return DBL_MAX;
}
/* Use CIE94 definition for now */
double sL, sA, sB;
double oL, oA, oB;
double r, g, b, alpha; // Careful, "a" is a field of this
Color c;
c = hsva_to_color (h, s, v, a);
color_to_rgba (c, r, g, b, alpha);
Rgb2Lab (&sL, &sA, &sB, r, g, b);
c = hsva_to_color (other.h, other.s, other.v, other.a);
color_to_rgba (c, r, g, b, alpha);
Rgb2Lab (&oL, &oA, &oB, r, g, b);
// Weighting factors depending on the application (1 = default)
const double whtL = 1.0;
const double whtC = 1.0;
const double whtH = 1.0;
const double xC1 = sqrt ((sA * sA) + (sB * oB));
const double xC2 = sqrt ((oA * oA) + (oB * oB));
double xDL = oL - sL;
double xDC = xC2 - xC1;
const double xDE = sqrt (((sL - oL) * (sL - oL))
+ ((sA - oA) * (sA - oA))
+ ((sB - oB) * (sB - oB)));
double xDH;
if (sqrt (xDE) > (sqrt (abs (xDL)) + sqrt (abs (xDC)))) {
xDH = sqrt ((xDE * xDE) - (xDL * xDL) - (xDC * xDC));
} else {
xDH = 0;
}
const double xSC = 1 + (0.045 * xC1);
const double xSH = 1 + (0.015 * xC1);
xDL /= whtL;
xDC /= whtC * xSC;
xDH /= whtH * xSH;
return sqrt ((xDL * xDL) + (xDC * xDC) + (xDH * xDH));
}
HSV
HSV::opposite () const
{
HSV hsv (*this);
hsv.h = fmod (h + 180.0, 360.0);
return hsv;
}
HSV
HSV::bw_text () const
{
return HSV (contrasting_text_color (color()));
}
HSV
HSV::text () const
{
return opposite ();
}
HSV
HSV::selected () const
{
/* XXX hack */
return HSV (Color (0xff0000));
}
void
HSV::print (std::ostream& o) const
{
if (!is_gray()) {
o << '(' << h << ',' << s << ',' << v << ',' << a << ')';
} else {
o << "gray(" << v << ')';
}
}
std::ostream& operator<<(std::ostream& o, const ArdourCanvas::HSV& hsv) { hsv.print (o); return o; }
HSV
HSV::mod (SVAModifier const & svam)
{
return svam (*this);
}
SVAModifier::SVAModifier (string const &str)
: type (Add)
, _s (0)
, _v (0)
, _a (0)
{
from_string (str);
}
void
SVAModifier::from_string (string const & str)
{
char op;
stringstream ss (str);
string mod;
ss >> op;
switch (op) {
case '*':
type = Multiply;
/* no-op values for multiply */
_s = 1.0;
_v = 1.0;
_a = 1.0;
break;
case '+':
type = Add;
/* no-op values for add */
_s = 0.0;
_v = 0.0;
_a = 0.0;
break;
case '=':
type = Assign;
/* this will avoid assignment in operator() (see below) */
_s = -1.0;
_v = -1.0;
_a = -1.0;
break;
default:
throw failed_constructor ();
}
string::size_type pos;
while (ss) {
ss >> mod;
if ((pos = mod.find ("alpha:")) != string::npos) {
_a = PBD::atof (mod.substr (pos+6));
} else if ((pos = mod.find ("saturate:")) != string::npos) {
_s = PBD::atof (mod.substr (pos+9));
} else if ((pos = mod.find ("darkness:")) != string::npos) {
_v = PBD::atof (mod.substr (pos+9));
} else {
throw failed_constructor ();
}
}
}
string
SVAModifier::to_string () const
{
PBD::LocaleGuard lg ("POSIX");
stringstream ss;
switch (type) {
case Add:
ss << '+';
break;
case Multiply:
ss << '*';
break;
case Assign:
ss << '=';
break;
}
if (_s >= 0.0) {
ss << " saturate:" << _s;
}
if (_v >= 0.0) {
ss << " darker:" << _v;
}
if (_a >= 0.0) {
ss << " alpha:" << _a;
}
return ss.str();
}
HSV
SVAModifier::operator () (HSV& hsv) const
{
HSV r (hsv);
switch (type) {
case Add:
r.s += _s;
r.v += _v;
r.a += _a;
break;
case Multiply:
r.s *= _s;
r.v *= _v;
r.a *= _a;
break;
case Assign:
if (_s >= 0.0) {
r.s = _s;
}
if (_v >= 0.) {
r.v = _v;
}
if (_a >= 0.0) {
r.a = _a;
}
break;
}
return r;
}