Oklab: Fix rollover error (#1529)

* oklab: Removed unnecessary type conversions

* oklab: Fixed rollover error in color conversion

Author: xkns

libsrc/utils/ColorSys.cpp

@@ -8,6 +8,11 @@ inline uint8_t clamp(int x)
 	return (x<0) ? 0 : ((x>255) ? 255 : uint8_t(x));
 }
 
+inline double clamp(double x)
+{
+	return std::max(0.0, std::min(x, 1.0));
+}
+
 void ColorSys::rgb2hsl(uint8_t red, uint8_t green, uint8_t blue, uint16_t & hue, float & saturation, float & luminance)
 {
 	QColor color(red,green,blue);
@@ -60,9 +65,9 @@ void ColorSys::yuv2rgb(uint8_t y, uint8_t u, uint8_t v, uint8_t &r, uint8_t &g,
 
 void ColorSys::rgb2okhsv(uint8_t red, uint8_t green, uint8_t blue, double & hue, double & saturation, double & value)
 {
-	ok_color::HSV color = ok_color::srgb_to_okhsv({ static_cast<float>(red)   / 255.F,
-													static_cast<float>(green) / 255.F,
-													static_cast<float>(blue)  / 255.F
+	ok_color::HSV color = ok_color::srgb_to_okhsv({ static_cast<double>(red)   / 255.0,
+													static_cast<double>(green) / 255.0,
+													static_cast<double>(blue)  / 255.0
 	});
 	hue = color.h;
 	saturation = color.s;
@@ -71,8 +76,9 @@ void ColorSys::rgb2okhsv(uint8_t red, uint8_t green, uint8_t blue, double & hue,
 
 void ColorSys::okhsv2rgb(double hue, double saturation, double value, uint8_t & red, uint8_t & green, uint8_t & blue)
 {
-	ok_color::RGB color = ok_color::okhsv_to_srgb({ static_cast<float>(hue), static_cast<float>(saturation), static_cast<float>(value) });
-	red = static_cast<uint8_t>(std::lround(color.r * 255));
-	green = static_cast<uint8_t>(std::lround(color.g * 255));
-	blue = static_cast<uint8_t>(std::lround(color.b * 255));
+	ok_color::RGB color = ok_color::okhsv_to_srgb({ hue, saturation, value });
+	// okhsv_to_srgb can output rgb colors with slightly negative components. Clamping them before casting prevents rollover errors
+	red = static_cast<uint8_t>(std::lround(clamp(color.r) * 255.0));
+	green = static_cast<uint8_t>(std::lround(clamp(color.g) * 255.0));
+	blue = static_cast<uint8_t>(std::lround(clamp(color.b) * 255.0));
 }

libsrc/utils/OkhsvTransform.cpp

@@ -4,7 +4,7 @@
 #include <utils/ColorSys.h>
 
 /// Clamps between 0.f and 1.f. Should generally be branchless
-double clamp(double value)
+inline double clamp(double value)
 {
 	return std::max(0.0, std::min(value, 1.0));
 }