Removing magic numbers from color generator

src/draw.rs

@@ -121,20 +121,49 @@ impl<T: fmt::Display> fmt::Display for Background<T> {
 
 /// A type that can generate distinct 8-bit colors.
 pub struct ColorGenerator {
- state: [u16; 3],
+ state: [u16; Self::MAX_AMOUNT_STATES],
  min_brightness: f32,
 }
 
 impl Default for ColorGenerator {
- fn default() -> Self { Self::from_state([30000, 15000, 35000], 0.5) }
+ fn default() -> Self {
+ Self::from_state(
+ [
+ Self::DEFAULT_MIN_COLOR,
+ Self::DEFAULT_COLOR_STEP,
+ Self::DEFAULT_MAX_COLOR,
+ ],
+ Self::DEFAULT_BRIGHTNESS,
+ )
+ }
 }
 
 impl ColorGenerator {
+ /// the minimal possible brightness value
+ pub const MIN_BRIGHTNESS_VALUE: f32 = 0.0;
+
+ /// the maximal possible brightness value
+ pub const MAX_BRIGHTNESS_VALUE: f32 = 1.0;
+
+ /// the default brightness
+ pub const DEFAULT_BRIGHTNESS: f32 = 0.5;
+
+ const MAX_AMOUNT_STATES: usize = 3;
+
+ const DEFAULT_MIN_COLOR: u16 = 30_000;
+ const DEFAULT_COLOR_STEP: u16 = 15_000;
+ const DEFAULT_MAX_COLOR: u16 = 35_000;
+
  /// Create a new [`ColorGenerator`] with the given pre-chosen state.
  ///
  /// The minimum brightness can be used to control the colour brightness (0.0 - 1.0). The default is 0.5.
- pub fn from_state(state: [u16; 3], min_brightness: f32) -> Self {
- Self { state, min_brightness: min_brightness.max(0.0).min(1.0) }
+ pub fn from_state(state: [u16; Self::MAX_AMOUNT_STATES], min_brightness: f32) -> Self {
+ Self {
+ state,
+ min_brightness: min_brightness
+ .max(Self::MIN_BRIGHTNESS_VALUE)
+ .min(Self::MAX_BRIGHTNESS_VALUE),
+ }
  }
 
  /// Create a new [`ColorGenerator`] with the default state.
@@ -144,13 +173,23 @@ impl ColorGenerator {
 
  /// Generate the next colour in the sequence.
  pub fn next(&mut self) -> Color {
- for i in 0..3 {
+ for i in 0..Self::MAX_AMOUNT_STATES {
  // magic constant, one of only two that have this property!
  self.state[i] = (self.state[i] as usize).wrapping_add(40503 * (i * 4 + 1130)) as u16;
  }
- Color::Fixed(16
- + ((self.state[2] as f32 / 65535.0 * (1.0 - self.min_brightness) + self.min_brightness) * 5.0
- + (self.state[1] as f32 / 65535.0 * (1.0 - self.min_brightness) + self.min_brightness) * 30.0
- + (self.state[0] as f32 / 65535.0 * (1.0 - self.min_brightness) + self.min_brightness) * 180.0) as u8)
+ Color::Fixed(
+ 16 + ((self.state[2] as f32 / 65535.0
+ * (Self::MAX_BRIGHTNESS_VALUE - self.min_brightness)
+ + self.min_brightness)
+ * 5.0
+ + (self.state[1] as f32 / 65535.0
+ * (Self::MAX_BRIGHTNESS_VALUE - self.min_brightness)
+ + self.min_brightness)
+ * 30.0
+ + (self.state[0] as f32 / 65535.0
+ * (Self::MAX_BRIGHTNESS_VALUE - self.min_brightness)
+ + self.min_brightness)
+ * 180.0) as u8,
+ )
  }
 }