[Impeller] Remove unused ColorHSB. (flutter/engine#54659)

I didn't realize I hadn't cleaned this up. We've never needed it in Impeller.

engine/src/flutter/impeller/geometry/color.cc

@@ -49,83 +49,6 @@ const char* BlendModeToString(BlendMode blend_mode) {
       blend_mode)];
 }
 
-ColorHSB ColorHSB::FromRGB(Color rgb) {
-  Scalar R = rgb.red;
-  Scalar G = rgb.green;
-  Scalar B = rgb.blue;
-
-  Scalar v = 0.0;
-  Scalar x = 0.0;
-  Scalar f = 0.0;
-
-  int64_t i = 0;
-
-  x = fmin(R, G);
-  x = fmin(x, B);
-
-  v = fmax(R, G);
-  v = fmax(v, B);
-
-  if (v == x) {
-    return ColorHSB(0.0, 0.0, v, rgb.alpha);
-  }
-
-  f = (R == x) ? G - B : ((G == x) ? B - R : R - G);
-  i = (R == x) ? 3 : ((G == x) ? 5 : 1);
-
-  return ColorHSB(((i - f / (v - x)) / 6.0), (v - x) / v, v, rgb.alpha);
-}
-
-Color ColorHSB::ToRGBA() const {
-  Scalar h = hue * 6.0;
-  Scalar s = saturation;
-  Scalar v = brightness;
-
-  Scalar m = 0.0;
-  Scalar n = 0.0;
-  Scalar f = 0.0;
-
-  int64_t i = 0;
-
-  if (h == 0) {
-    h = 0.01;
-  }
-
-  if (h == 0.0) {
-    return Color(v, v, v, alpha);
-  }
-
-  i = static_cast<int64_t>(floor(h));
-
-  f = h - i;
-
-  if (!(i & 1)) {
-    f = 1 - f;
-  }
-
-  m = v * (1 - s);
-  n = v * (1 - s * f);
-
-  switch (i) {
-    case 6:
-    case 0:
-      return Color(v, n, m, alpha);
-    case 1:
-      return Color(n, v, m, alpha);
-    case 2:
-      return Color(m, v, n, alpha);
-    case 3:
-      return Color(m, n, v, alpha);
-    case 4:
-      return Color(n, m, v, alpha);
-    case 5:
-      return Color(v, m, n, alpha);
-  }
-  return Color(0, 0, 0, alpha);
-}
-
-Color::Color(const ColorHSB& hsbColor) : Color(hsbColor.ToRGBA()) {}
-
 Color::Color(const Vector4& value)
     : red(value.x), green(value.y), blue(value.z), alpha(value.w) {}
 

engine/src/flutter/impeller/geometry/color.h

@@ -49,7 +49,6 @@
 
 namespace impeller {
 
-struct ColorHSB;
 struct Vector4;
 
 enum class YUVColorSpace { kBT601LimitedRange, kBT601FullRange };
@@ -144,8 +143,6 @@ struct Color {
 
   constexpr Color() {}
 
-  explicit Color(const ColorHSB& hsbColor);
-
   explicit Color(const Vector4& value);
 
   constexpr Color(Scalar r, Scalar g, Scalar b, Scalar a)
@@ -920,38 +917,6 @@ constexpr inline Color operator/(T value, const Color& c) {
 
 std::string ColorToString(const Color& color);
 
-/**
- *  Represents a color by its constituent hue, saturation, brightness and alpha
- */
-struct ColorHSB {
-  /**
-   *  The hue of the color (0 to 1)
-   */
-  Scalar hue;
-
-  /**
-   *  The saturation of the color (0 to 1)
-   */
-  Scalar saturation;
-
-  /**
-   *  The brightness of the color (0 to 1)
-   */
-  Scalar brightness;
-
-  /**
-   *  The alpha of the color (0 to 1)
-   */
-  Scalar alpha;
-
-  constexpr ColorHSB(Scalar h, Scalar s, Scalar b, Scalar a)
-      : hue(h), saturation(s), brightness(b), alpha(a) {}
-
-  static ColorHSB FromRGB(Color rgb);
-
-  Color ToRGBA() const;
-};
-
 static_assert(sizeof(Color) == 4 * sizeof(Scalar));
 
 }  // namespace impeller