feat(Color): add whiteness & blackness

README.md

@@ -187,7 +187,7 @@ color.lab(); // "lab(97.14, -21.55, 94.48)"
 
 ### Color Channel
 
-You can use the `red`, `green`, `blue`, `alpha`, `hue`, `saturation`, `lightness`, `hsv_hue`, `hsv_saturation`, `hsv_value`, `luma`, `luminance`, `gray` method to extract the color channel.
+You can use the `red`, `green`, `blue`, `alpha`, `hue`, `saturation`, `lightness`, `whiteness`, `blackness`, `hsv_hue`, `hsv_saturation`, `hsv_value`, `luma`, `luminance`, `gray` method to extract the color channel.
 
 <details>
 <summary>For example</summary>
@@ -207,6 +207,9 @@ color.hue(); // 210.0
 color.saturation(); // 0.68
 color.lightness(); // 0.8039
 
+color.whiteness(); // 0.6706
+color.blackness(); // 0.0627
+
 color.hsv_hue(); // 210.0
 color.hsv_saturation(); // 0.2845
 color.hsv_value(); // 0.9373

src/color/color_channel.rs

@@ -47,6 +47,14 @@ impl Color {
     pub fn lightness(&self) -> f64 {
         self.vec_of(ColorSpace::HSL)[2]
     }
+    /// Returns the HWB whiteness of color as a number between 0.0 and 1.0.
+    pub fn whiteness(&self) -> f64 {
+        self.vec_of(ColorSpace::HWB)[1]
+    }
+    /// Returns the HWB blackness of color as a number between 0.0 and 1.0.
+    pub fn blackness(&self) -> f64 {
+        self.vec_of(ColorSpace::HWB)[2]
+    }
     /// Calculates the [luma](http://en.wikipedia.org/wiki/Luma_%28video%29) (perceptual brightness) of a color.
     pub fn luma(&self) -> f64 {
         let (r, g, b) = normalize_color(self.rgb);
@@ -85,7 +93,7 @@ impl Color {
 
 #[cfg(test)]
 mod tests {
-    use std::str::FromStr;
+    use std::{ str::FromStr, assert_eq };
     use crate::*;
 
     #[test]
@@ -97,6 +105,9 @@ mod tests {
         assert_eq!(color.blue(), 30);
         assert_eq!(color.alpha(), 0.8);
 
+        assert_eq!(color.whiteness(), 0.0392);
+        assert_eq!(color.blackness(), 0.8824);
+
         assert_eq!(color.luma(), 0.01);
         assert_eq!(color.luminance(), 0.07);
         assert_eq!(color.gray(), 18.15);
@@ -107,6 +118,9 @@ mod tests {
         assert_eq!(color.saturation(), 1.0);
         assert_eq!(color.lightness(), 0.5);
 
+        assert_eq!(color.whiteness(), 0.0);
+        assert_eq!(color.blackness(), 0.0);
+
         assert_eq!(color.luma(), 0.76);
         assert_eq!(color.luminance(), 0.82);
         assert_eq!(color.gray(), 187.8075);

src/conversion/hwb.rs

@@ -13,8 +13,8 @@ pub fn rgb2hwb(color: (f64, f64, f64)) -> (f64, f64, f64) {
     let hsl = hsl::rgb2hsl(color);
 
     let hue = round(hsl.0, 0);
-    let whiteness = round(min, 2);
-    let blackness = round(1.0 - max, 2);
+    let whiteness = round(min, 4);
+    let blackness = round(1.0 - max, 4);
 
     (hue, whiteness, blackness)
 }
@@ -43,12 +43,12 @@ mod tests {
     #[test]
     fn test_rgb2hwb() {
         assert_eq!(rgb2hwb((0.0, 255.0, 102.0)), (144.0, 0.0, 0.0));
-        assert_eq!(rgb2hwb((86.0, 59.0, 133.0)), (262.0, 0.23, 0.48));
+        assert_eq!(rgb2hwb((86.0, 59.0, 133.0)), (262.0, 0.2314, 0.4784));
     }
 
     #[test]
     fn test_hwb2rgb() {
         assert_eq!(hwb2rgb((144.0, 0.0, 0.0)), (0.0, 255.0, 102.0));
-        assert_eq!(hwb2rgb((262.0, 0.23, 0.48)), (86.0, 59.0, 133.0));
+        assert_eq!(hwb2rgb((262.0, 0.2314, 0.4784)), (86.0, 59.0, 133.0));
     }
 }

tests/color_channel.rs

@@ -12,6 +12,8 @@ fn test_color_channel() {
     assert_eq!(color.hue(), 210.0);
     assert_eq!(color.saturation(), 0.68);
     assert_eq!(color.lightness(), 0.8039);
+    assert_eq!(color.whiteness(), 0.6706);
+    assert_eq!(color.blackness(), 0.0627);
 
     assert_eq!(color.hsv_hue(), 210.0);
     assert_eq!(color.hsv_saturation(), 0.2845);