Auto merge of #53 - sidred:hwb, r=Ogeon

Add hwb color

Added support for HWB color model.

Added tests, implemented Alpha, ApproxEq, FromColor and IntoColor traits and added to color enum.

closes #32

src/convert.rs

@@ -1,6 +1,6 @@
 use num::Float;
 
-use {Alpha, Rgb, Luma, Xyz, Yxy, Lab, Lch, Hsv, Hsl, Color};
+use {Alpha, Rgb, Luma, Xyz, Yxy, Lab, Lch, Hsv, Hwb, Hsl, Color};
 
 ///FromColor provides conversion between the colors.
 ///
@@ -46,6 +46,11 @@ pub trait FromColor<T>: Sized
         Self::from_rgb(inp.into_rgb())
     }
 
+    ///Convert from HWB color space
+    fn from_hwb(inp: Hwb<T>) -> Self {
+        Self::from_hsv(inp.into_hsv())
+    }
+
     ///Convert from Luma
     fn from_luma(inp: Luma<T>) -> Self {
         Self::from_xyz(inp.into_xyz())
@@ -95,6 +100,11 @@ pub trait IntoColor<T>: Sized
         Hsv::from_rgb(self.into_rgb())
     }
 
+    ///Convert into HWB color space
+    fn into_hwb(self) -> Hwb<T> {
+        Hwb::from_hsv(self.into_hsv())
+    }
+
     ///Convert into Luma
     fn into_luma(self) -> Luma<T> {
         Luma::from_xyz(self.into_xyz())
@@ -163,6 +173,7 @@ macro_rules! impl_from_trait {
                     Color::Lch(c) => c.$into_fn(),
                     Color::Hsv(c) => c.$into_fn(),
                     Color::Hsl(c) => c.$into_fn(),
+                    Color::Hwb(c) => c.$into_fn(),
                 }
             }
         }
@@ -218,14 +229,16 @@ impl_into_color!(Lch,from_lch);
 impl_into_color!(Rgb,from_rgb);
 impl_into_color!(Hsl,from_hsl);
 impl_into_color!(Hsv,from_hsv);
+impl_into_color!(Hwb,from_hwb);
 impl_into_color!(Luma,from_luma);
 
 
-impl_from_trait!((Xyz,into_xyz) => {Yxy, Lab, Lch, Rgb, Hsl, Hsv, Luma});
-impl_from_trait!((Yxy,into_yxy) => {Xyz, Lab, Lch, Rgb, Hsl, Hsv, Luma});
-impl_from_trait!((Lab,into_lab) => {Xyz, Yxy, Lch, Rgb, Hsl, Hsv, Luma});
-impl_from_trait!((Lch,into_lch) => {Xyz, Yxy, Lab, Rgb, Hsl, Hsv, Luma});
-impl_from_trait!((Rgb,into_rgb) => {Xyz, Yxy, Lab, Lch, Hsl, Hsv, Luma});
-impl_from_trait!((Hsl,into_hsl) => {Xyz, Yxy, Lab, Lch, Rgb, Hsv, Luma});
-impl_from_trait!((Hsv,into_hsv) => {Xyz, Yxy, Lab, Lch, Rgb, Hsl, Luma});
-impl_from_trait!((Luma,into_luma) => {Xyz, Yxy, Lab, Lch, Rgb, Hsl, Hsv});
+impl_from_trait!((Xyz,into_xyz) => {Yxy, Lab, Lch, Rgb, Hsl, Hsv, Hwb, Luma});
+impl_from_trait!((Yxy,into_yxy) => {Xyz, Lab, Lch, Rgb, Hsl, Hsv, Hwb, Luma});
+impl_from_trait!((Lab,into_lab) => {Xyz, Yxy, Lch, Rgb, Hsl, Hsv, Hwb, Luma});
+impl_from_trait!((Lch,into_lch) => {Xyz, Yxy, Lab, Rgb, Hsl, Hsv, Hwb, Luma});
+impl_from_trait!((Rgb,into_rgb) => {Xyz, Yxy, Lab, Lch, Hsl, Hsv, Hwb, Luma});
+impl_from_trait!((Hsl,into_hsl) => {Xyz, Yxy, Lab, Lch, Rgb, Hsv, Hwb, Luma});
+impl_from_trait!((Hsv,into_hsv) => {Xyz, Yxy, Lab, Lch, Rgb, Hsl, Hwb, Luma});
+impl_from_trait!((Hwb,into_hwb) => {Xyz, Yxy, Lab, Lch, Rgb, Hsl, Hsv, Luma});
+impl_from_trait!((Luma,into_luma) => {Xyz, Yxy, Lab, Lch, Rgb, Hsl, Hsv, Hwb});

src/equality.rs

@@ -1,7 +1,7 @@
 use num::Float;
 use approx::ApproxEq;
 
-use {Xyz, Yxy, Lab, Lch, Rgb, Hsl, Hsv , Luma, LabHue, RgbHue, flt};
+use {Xyz, Yxy, Lab, Lch, Rgb, Hsl, Hsv, Hwb, Luma, LabHue, RgbHue, flt};
 
 macro_rules! impl_eq {
     (  $self_ty: ident , [$($element: ident),+]) => {
@@ -44,6 +44,7 @@ impl_eq!( Luma, [luma] );
 impl_eq!( Lch, [l, chroma] );
 impl_eq!( Hsl, [hue, saturation, lightness] );
 impl_eq!( Hsv, [hue, saturation, value] );
+impl_eq!( Hwb, [hue, whiteness, blackness] );
 
 // For hues diffence is calculated and compared to zero. However due to the way floating point's
 // work this is not so simple

src/hsv.rs

@@ -2,7 +2,7 @@ use num::Float;
 
 use std::ops::{Add, Sub};
 
-use {Alpha, Rgb, Xyz, Hsl, Limited, Mix, Shade, GetHue, Hue, Saturate, RgbHue, FromColor, clamp, flt};
+use {Alpha, Rgb, Xyz, Hsl, Hwb, Limited, Mix, Shade, GetHue, Hue, Saturate, RgbHue, FromColor, clamp, flt};
 
 ///Linear HSV with an alpha component. See the [`Hsva` implementation in `Alpha`](struct.Alpha.html#Hsva).
 pub type Hsva<T = f32> = Alpha<Hsv<T>, T>;
@@ -125,6 +125,21 @@ impl<T: Float> FromColor<T> for Hsv<T> {
         hsv
     }
 
+    fn from_hwb(hwb: Hwb<T>) -> Self {
+        let inv = T::one() - hwb.blackness;
+        // avoid divide by zero
+        let s = if inv.is_normal() {
+            T::one() - ( hwb.whiteness / inv )
+        } else {
+            T::zero()
+        };
+        Hsv {
+            hue: hwb.hue,
+            saturation: s,
+            value: inv,
+        }
+    }
+
 }
 
 impl<T: Float> Limited for Hsv<T> {