Color improvements

CHANGELOG.md

@@ -10,6 +10,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `Default` implementation for `ui::widget::slider::State`.
 - `Default`, `Clone`, `Copy`, `PartialEq`, and `Eq` implementations for
   `ui::widget::button::State`.
+- `Color::RED`, `Color::GREEN`, `Color::BLUE` constants.
+- `Color::from_rgb_u32`: Constructs a `Color` from `0xRRGGBB`.
 
 ### Changed
 - `Mesh::stroke` now takes an `f32` as `line_width` instead of a `u16`.

src/graphics/color.rs

@@ -31,10 +31,42 @@ impl Color {
         a: 1.0,
     };
 
+    /// Red color.
+    pub const RED: Self = Self {
+        r: 1.0,
+        g: 0.0,
+        b: 0.0,
+        a: 1.0,
+    };
+
+    /// Green color.
+    pub const GREEN: Self = Self {
+        r: 0.0,
+        g: 1.0,
+        b: 0.0,
+        a: 1.0,
+    };
+
+    /// Blue color.
+    pub const BLUE: Self = Self {
+        r: 0.0,
+        g: 0.0,
+        b: 1.0,
+        a: 1.0,
+    };
+
     /// Creates a new [`Color`] from components in the [0, 1.0] range.
     ///
     /// [`Color`]: struct.Color.html
     pub fn new(r: f32, g: f32, b: f32, a: f32) -> Color {
+        debug_assert!(r >= 0.0, "Color values should be in the [0, 1.0] range");
+        debug_assert!(r <= 1.0, "Color values should be in the [0, 1.0] range");
+        debug_assert!(g >= 0.0, "Color values should be in the [0, 1.0] range");
+        debug_assert!(g <= 1.0, "Color values should be in the [0, 1.0] range");
+        debug_assert!(b >= 0.0, "Color values should be in the [0, 1.0] range");
+        debug_assert!(b <= 1.0, "Color values should be in the [0, 1.0] range");
+        debug_assert!(a >= 0.0, "Color values should be in the [0, 1.0] range");
+        debug_assert!(a <= 1.0, "Color values should be in the [0, 1.0] range");
         Color { r, g, b, a }
     }
 
@@ -50,6 +82,20 @@ impl Color {
         }
     }
 
+    /// Creates a new [`Color`] from its RGB representation (0xRRGGBB).
+    ///
+    /// [`Color`]: struct.Color.html
+    pub fn from_rgb_u32(color: u32) -> Color {
+        debug_assert!(
+            color <= 0xFFFFFF,
+            "Color contains value higher than 0xFFFFFF"
+        );
+        let r = ((color & 0xFF0000) >> 16) as u8;
+        let g = ((color & 0x00FF00) >> 8) as u8;
+        let b = ((color & 0x0000FF) >> 0) as u8;
+        Color::from_rgb(r, g, b)
+    }
+
     /// Returns the [`Color`] components in the [0, 255] range.
     ///
     /// [`Color`]: struct.Color.html