170 lines
3.5 KiB
C++
170 lines
3.5 KiB
C++
#include <algorithm>
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#include <cmath>
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#include <utils/HslTransform.h>
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HslTransform::HslTransform()
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: _saturationGain(1.0)
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, _luminanceGain(1.0)
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, _luminanceMinimum(0.0)
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{
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}
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HslTransform::HslTransform(double saturationGain, double luminanceGain, double luminanceMinimum) :
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_saturationGain(saturationGain),
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_luminanceGain(luminanceGain),
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_luminanceMinimum(luminanceMinimum)
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{
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}
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HslTransform::~HslTransform()
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{
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}
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void HslTransform::setSaturationGain(double saturationGain)
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{
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_saturationGain = saturationGain;
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}
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double HslTransform::getSaturationGain() const
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{
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return _saturationGain;
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}
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void HslTransform::setLuminanceGain(double luminanceGain)
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{
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_luminanceGain = luminanceGain;
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}
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double HslTransform::getLuminanceGain() const
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{
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return _luminanceGain;
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}
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void HslTransform::setLuminanceMinimum(double luminanceMinimum)
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{
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_luminanceMinimum = luminanceMinimum;
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}
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double HslTransform::getLuminanceMinimum() const
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{
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return _luminanceMinimum;
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}
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void HslTransform::transform(uint8_t & red, uint8_t & green, uint8_t & blue) const
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{
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if (_saturationGain != 1.0 || _luminanceGain != 1.0 || _luminanceMinimum != 0.0)
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{
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uint16_t hue;
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float saturation, luminance;
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rgb2hsl(red, green, blue, hue, saturation, luminance);
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float s = saturation * _saturationGain;
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saturation = std::min(s, 1.0f);
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float l = luminance * _luminanceGain;
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if (l < _luminanceMinimum)
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{
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saturation = 0;
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l = _luminanceMinimum;
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}
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luminance = std::min(l, 1.0f);
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hsl2rgb(hue, saturation, luminance, red, green, blue);
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}
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}
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void HslTransform::rgb2hsl(uint8_t red, uint8_t green, uint8_t blue, uint16_t & hue, float & saturation, float & luminance)
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{
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float r = (float)red / 255.0f;
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float g = (float)green / 255.0f;
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float b = (float)blue / 255.0f;
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float rgbMin = std::min(r,std::min(g,b));
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float rgbMax = std::max(r,std::max(g,b));
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float diff = rgbMax - rgbMin;
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//luminance
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luminance = (rgbMin + rgbMax) / 2.0f;
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if (diff == 0.0f)
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{
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saturation = 0.0f;
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hue = 0;
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return;
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}
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//saturation
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saturation = (luminance < 0.5f)
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? (diff / (rgbMin + rgbMax))
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: (diff / (2.0f - rgbMin - rgbMax));
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if (rgbMax == r)
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{
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// start from 360 to be sure that we won't assign a negative number to the unsigned hue value
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hue = 360 + 60 * (g - b) / (rgbMax - rgbMin);
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if (hue > 359)
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hue -= 360;
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}
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else if (rgbMax == g)
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{
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hue = 120 + 60 * (b - r) / (rgbMax - rgbMin);
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}
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else
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{
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hue = 240 + 60 * (r - g) / (rgbMax - rgbMin);
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}
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}
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void HslTransform::hsl2rgb(uint16_t hue, float saturation, float luminance, uint8_t & red, uint8_t & green, uint8_t & blue)
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{
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if (saturation == 0.0f)
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{
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red = (uint8_t)(luminance * 255.0f);
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green = (uint8_t)(luminance * 255.0f);
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blue = (uint8_t)(luminance * 255.0f);
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return;
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}
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float q = (luminance < 0.5f)
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? luminance * (1.0f + saturation)
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: (luminance + saturation) - (luminance * saturation);
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float p = (2.0f * luminance) - q;
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float h = hue / 360.0f;
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float t[3];
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t[0] = h + (1.0f / 3.0f);
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t[1] = h;
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t[2] = h - (1.0f / 3.0f);
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for (int i = 0; i < 3; i++)
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{
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if (t[i] < 0.0f)
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t[i] += 1.0f;
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if (t[i] > 1.0f)
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t[i] -= 1.0f;
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}
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float out[3];
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for (int i = 0; i < 3; i++)
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{
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if (t[i] * 6.0f < 1.0f)
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out[i] = p + (q - p) * 6.0f * t[i];
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else if (t[i] * 2.0f < 1.0f)
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out[i] = q;
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else if (t[i] * 3.0f < 2.0f)
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out[i] = p + (q - p) * ((2.0f / 3.0f) - t[i]) * 6.0f;
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else out[i] = p;
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}
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//convert back to 0...255 range
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red = (uint8_t)(out[0] * 255.0f);
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green = (uint8_t)(out[1] * 255.0f);
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blue = (uint8_t)(out[2] * 255.0f);
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}
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