Add Color trait

showbits-common/src/color.rs

@@ -0,0 +1,11 @@
+use palette::Srgb;
+
+pub trait Color: Copy {
+    /// Convert to an sRGB color.
+    ///
+    /// Useful for debugging or dithering.
+    fn to_srgb(self) -> Srgb;
+
+    /// Combine two colors by putting one "over" the other.
+    fn over(self, below: Self) -> Self;
+}