if (cmax == 0) {
// r = g = b == 0 ... v is undefined, s = 0
- s = 0.0;
+ s = 0.0;
h = 0.0;
return;
}
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);
}
}
// Inverse of sRGB "gamma" function.
-static inline double
-inv_gam_sRGB (double c)
+static inline double
+inv_gam_sRGB (double c)
{
if (c <= 0.04045) {
return c/12.92;
}
// sRGB "gamma" function
-static inline int
-gam_sRGB(double v)
+static inline int
+gam_sRGB(double v)
{
if (v <= 0.0031308) {
v *= 12.92;
return int (v*255+.5);
}
-static double
+static double
luminance (uint32_t c)
{
// sRGB luminance(Y) values
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)
: h (0.0)
, s (1.0)
, v (1.0)
- , a (1.0)
+ , a (1.0)
{
}
: h (hh)
, s (ss)
, v (vv)
- , a (aa)
+ , a (aa)
{
if (h < 0.0) {
/* normalize negative hue values into positive range */
/* 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
+ 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;
}
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
+ 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.
double sL, sA, sB;
double oL, oA, oB;
double r, g, b, alpha; // Careful, "a" is a field of this
- Color c;
+ Color c;
c = hsva_to_color (h, s, v, a);
color_to_rgba (c, r, g, b, alpha);
const double whtL = 1.0;
const double whtC = 1.0;
- const double whtH = 1.0;
+ const double whtH = 1.0;
const double xC1 = sqrt ((sA * sA) + (sB * oB));
const double xC2 = sqrt ((oA * oA) + (oB * oB));