Provide red/green/blue/alpha getters for Rust and C++ Color

And fix up the C++ class docs.

api/sixtyfps-cpp/include/sixtyfps_color.h

@@ -16,10 +16,15 @@ LICENSE END */
 
 namespace sixtyfps {
 
+/// Color represents a color in the SixtyFPS run-time, represented using 8-bit channels for
+/// red, green, blue and the alpha (opacity).
 class Color
 {
 public:
+    /// Default constructs a new color that is entirely transparent.
     Color() { inner.red = inner.green = inner.blue = inner.alpha = 0; }
+
+    /// Construct a color from an integer encoded as `0xAARRGGBB`
     static Color from_argb_encoded(uint32_t argb_encoded)
     {
         Color col;
@@ -30,18 +35,35 @@ public:
         return col;
     }
 
+    /// Returns `(alpha, red, green, blue)` encoded as uint32_t.
     uint32_t as_argb_encoded() const
     {
         return (uint32_t(inner.red) << 16) | (uint32_t(inner.green) << 8) | uint32_t(inner.blue)
                 | (uint32_t(inner.alpha) << 24);
     }
 
+    /// Returns the red channel of the color as u8 in the range 0..255.
+    uint8_t red() const { return inner.red; }
+
+    /// Returns the green channel of the color as u8 in the range 0..255.
+    uint8_t green() const { return inner.green; }
+
+    /// Returns the blue channel of the color as u8 in the range 0..255.
+    uint8_t blue() const { return inner.blue; }
+
+    /// Returns the alpha channel of the color as u8 in the range 0..255.
+    uint8_t alpha() const { return inner.alpha; }
+
+    /// Returns true if \a lhs has the same values for the individual color channels as \rhs; false
+    /// otherwise.
     friend bool operator==(const Color &lhs, const Color &rhs)
     {
         return lhs.inner.red == rhs.inner.red && lhs.inner.green == rhs.inner.green
                 && lhs.inner.blue == rhs.inner.blue && lhs.inner.alpha == rhs.inner.alpha;
     }
 
+    /// Returns true if \a lhs has any different values for the individual color channels as \rhs;
+    /// false otherwise.
     friend bool operator!=(const Color &lhs, const Color &rhs) { return !(lhs == rhs); }
 
 private:

sixtyfps_runtime/corelib/graphics.rs

@@ -124,6 +124,26 @@ impl Color {
             | (self.blue as u32)
             | ((self.alpha as u32) << 24)
     }
+
+    /// Returns the red channel of the color as u8 in the range 0..255.
+    pub fn red(self) -> u8 {
+        self.red
+    }
+
+    /// Returns the green channel of the color as u8 in the range 0..255.
+    pub fn green(self) -> u8 {
+        self.green
+    }
+
+    /// Returns the blue channel of the color as u8 in the range 0..255.
+    pub fn blue(self) -> u8 {
+        self.blue
+    }
+
+    /// Returns the alpha channel of the color as u8 in the range 0..255.
+    pub fn alpha(self) -> u8 {
+        self.alpha
+    }
 }
 
 impl InterpolatedPropertyValue for Color {