hsl_colour hsl_colour::from_rgb(const colour& aColour)
{
double hue, saturation, lightness;
double r = aColour.red() / 255.0, g = aColour.green() / 255.0, b = aColour.blue() / 255.0;
double M = std::max(std::max(r, g), b);
double m = std::min(std::min(r, g), b);
double c = M - m;
double h2;
if (c == 0.0)
h2 = undefined_hue();
else if (M == r)
h2 = std::fmod((g - b) / c, 6.0);
else if (M == g)
h2 = (b - r) / c + 2.0;
else if (M == b)
h2 = (r - g) / c + 4.0;
else
h2 = undefined_hue();
if (h2 != undefined_hue())
{
hue = 60.0 * h2;
if (hue < 0.0)
hue += 360.0;
}
else
hue = undefined_hue();
lightness = 0.5f * (M + m);
lightness = std::max(std::min(lightness, 1.0), 0.0);
if (c == 0.0)
saturation = 0.0;
else
saturation = c / (1.0 - std::abs(2.0 * lightness - 1.0));
saturation = std::max(std::min(saturation, 1.0), 0.0);
return hsl_colour(hue, saturation, lightness);
}
hsv_colour hsv_colour::from_rgb(const colour& aColour)
{
double hue, saturation, value;
double r = aColour.red() / 255.0, g = aColour.green() / 255.0, b = aColour.blue() / 255.0;
double M = std::max(std::max(r, g), b);
double m = std::min(std::min(r, g), b);
double c = M - m;
double h2;
if (c == 0.0)
h2 = undefined_hue();
else if (M == r)
h2 = std::fmod((g - b) / c, 6.0);
else if (M == g)
h2 = (b - r) / c + 2.0;
else if (M == b)
h2 = (r - g) / c + 4.0;
else
h2 = undefined_hue();
if (h2 != undefined_hue())
{
hue = 60.0 * h2;
if (hue < 0.0)
hue += 360.0;
}
else
hue = undefined_hue();
value = M;
value = std::max(std::min(value, 1.0), 0.0);
if (c == 0.0)
saturation = 0.0;
else
saturation = c / value;
saturation = std::max(std::min(saturation, 1.0), 0.0);
return hsv_colour(hue, saturation, value, aColour.alpha() / 255.0);
}
colour hsl_colour::to_rgb(double aAlpha) const
{
double c = (1.0 - std::abs(2.0 * lightness() - 1.0)) * saturation();
double h2 = hue() / 60.0;
double x = c * (1.0 - std::abs(std::fmod(h2, 2.0) - 1.0));
double r, g, b;
if (hue() == undefined_hue())
r = g = b = 0.0;
else if (h2 >= 0.0 && h2 < 1.0)
r = c, g = x, b = 0.0;
else if (h2 >= 1.0 && h2 < 2.0)
r = x, g = c, b = 0.0;
else if (h2 >= 2.0 && h2 < 3.0)
r = 0.0, g = c, b = x;
else if (h2 >= 3.0 && h2 < 4.0)
r = 0.0, g = x, b = c;
else if (h2 >= 4.0 && h2 < 5.0)
r = x, g = 0.0, b = c;
else if (h2 >= 5.0 && h2 < 6.0)
r = c, g = 0.0, b = x;
else
r = g = b = 0.0;
double m = lightness() - 0.5f * c;
colour result(
static_cast<colour::component>(std::floor((r + m) * 255.0)),
static_cast<colour::component>(std::floor((g + m) * 255.0)),
static_cast<colour::component>(std::floor((b + m) * 255.0)),
static_cast<colour::component>(std::floor(aAlpha * 255.0)));
return result;
}
bool hsv_colour::hue_undefined() const
{
return iHue == undefined_hue();
}
double hsv_colour::hue() const
{
if (iHue != undefined_hue())
return iHue;
return 0.0;
}
hsv_colour::hsv_colour(double aHue, double aSaturation, double aValue, double aAlpha) :
iHue{aHue}, iSaturation{ aSaturation }, iValue{ aValue }, iAlpha{ aAlpha }
{
if (iHue != undefined_hue())
iHue = std::fmod(iHue, 360.0);
}
