colordialog/wheel/gradient: implemented basic UI components for color picking

app/render/color.cpp

@@ -1,5 +1,46 @@
 #include "color.h"
 
+Color Color::fromHsv(const float &h, const float &s, const float &v)
+{
+  float C = s * v;
+  float X = C * (1.0f - abs(fmod(h / 60.0f, 2.0f) - 1.0f));
+  float m = v - C;
+  float Rs, Gs, Bs;
+
+  if(h >= 0.0f && h < 60.0f) {
+    Rs = C;
+    Gs = X;
+    Bs = 0.0f;
+  }
+  else if(h >= 60.0f && h < 120.0f) {
+    Rs = X;
+    Gs = C;
+    Bs = 0.0f;
+  }
+  else if(h >= 120.0f && h < 180.0f) {
+    Rs = 0.0f;
+    Gs = C;
+    Bs = X;
+  }
+  else if(h >= 180.0f && h < 240.0f) {
+    Rs = 0.0f;
+    Gs = X;
+    Bs = C;
+  }
+  else if(h >= 240.0f && h < 300.0f) {
+    Rs = X;
+    Gs = 0.0f;
+    Bs = C;
+  }
+  else {
+    Rs = C;
+    Gs = 0.0f;
+    Bs = X;
+  }
+
+  return Color(Rs + m, Gs + m, Bs + m);
+}
+
 Color::Color(const char *data, const PixelFormat::Format &format)
 {
   OIIO::convert_type(PixelFormat::GetOIIOTypeDesc(format),
@@ -12,3 +53,57 @@ Color::Color(const char *data, const PixelFormat::Format &format)
     set_alpha(1.0f);
   }
 }
+
+void Color::toHsv(float *hue, float *sat, float *val) const
+{
+  float fCMax = qMax(qMax(red(), green()), blue());
+  float fCMin = qMin(qMin(red(), green()), blue());
+  float fDelta = fCMax - fCMin;
+
+  if(fDelta > 0) {
+    if(fCMax == red()) {
+      *hue = 60 * (fmod(((green() - blue()) / fDelta), 6));
+    } else if(fCMax == green()) {
+      *hue = 60 * (((blue() - red()) / fDelta) + 2);
+    } else if(fCMax == blue()) {
+      *hue = 60 * (((red() - green()) / fDelta) + 4);
+    }
+
+    if(fCMax > 0) {
+      *sat = fDelta / fCMax;
+    } else {
+      *sat = 0;
+    }
+
+    *val = fCMax;
+  } else {
+    *hue = 0;
+    *sat = 0;
+    *val = fCMax;
+  }
+
+  if(*hue < 0) {
+    *hue = 360 + *hue;
+  }
+}
+
+float Color::hue() const
+{
+  float h, s, v;
+  toHsv(&h, &s, &v);
+  return h;
+}
+
+float Color::saturation() const
+{
+  float h, s, v;
+  toHsv(&h, &s, &v);
+  return s;
+}
+
+float Color::value() const
+{
+  float h, s, v;
+  toHsv(&h, &s, &v);
+  return v;
+}