Introduce specific types for each `palette::Extended` field

We will have more control over color calculations for each semantic purpose this way.

2 files changed, 131 insertions, 62 deletions

diff --git a/style/src/theme.rs b/style/src/theme.rs
index df67f594..c9fae3c2 100644
--- a/style/src/theme.rs
+++ b/style/src/theme.rs
@@ -40,13 +40,13 @@ impl application::StyleSheet for Theme {
     fn background_color(&self) -> Color {
         let palette = self.extended_palette();
 
-        palette.background.base
+        palette.background.base.color
     }
 
     fn text_color(&self) -> Color {
         let palette = self.extended_palette();
 
-        palette.background.text
+        palette.background.base.text
     }
 }
 
@@ -76,29 +76,19 @@ impl button::StyleSheet for Theme {
             ..button::Appearance::default()
         };
 
+        let from_pair = |pair: palette::Pair| button::Appearance {
+            background: Some(pair.color.into()),
+            text_color: pair.text,
+            ..appearance
+        };
+
         match style {
-            Button::Primary => button::Appearance {
-                background: Some(palette.primary.strong.into()),
-                text_color: palette.primary.text,
-                ..appearance
-            },
-            Button::Secondary => button::Appearance {
-                background: Some(palette.background.weak.into()),
-                text_color: palette.background.text,
-                ..appearance
-            },
-            Button::Positive => button::Appearance {
-                background: Some(palette.success.base.into()),
-                text_color: palette.success.text,
-                ..appearance
-            },
-            Button::Destructive => button::Appearance {
-                background: Some(palette.danger.base.into()),
-                text_color: palette.danger.text,
-                ..appearance
-            },
+            Button::Primary => from_pair(palette.primary.strong),
+            Button::Secondary => from_pair(palette.secondary.base),
+            Button::Positive => from_pair(palette.success.base),
+            Button::Destructive => from_pair(palette.danger.base),
             Button::Text => button::Appearance {
-                text_color: palette.background.text,
+                text_color: palette.background.base.text,
                 ..appearance
             },
         }
@@ -109,10 +99,10 @@ impl button::StyleSheet for Theme {
         let palette = self.extended_palette();
 
         let background = match style {
-            Button::Primary => Some(palette.primary.base),
-            Button::Secondary => Some(palette.background.strong),
-            Button::Positive => Some(palette.success.strong),
-            Button::Destructive => Some(palette.danger.strong),
+            Button::Primary => Some(palette.primary.base.color),
+            Button::Secondary => Some(palette.background.strong.color),
+            Button::Positive => Some(palette.success.strong.color),
+            Button::Destructive => Some(palette.danger.strong.color),
             Button::Text => None,
         };
 
@@ -140,10 +130,10 @@ impl slider::StyleSheet for Theme {
         };
 
         slider::Appearance {
-            rail_colors: (palette.primary.base, palette.background.base),
+            rail_colors: (palette.primary.base.color, Color::TRANSPARENT),
             handle: slider::Handle {
-                color: palette.background.base,
-                border_color: palette.primary.base,
+                color: palette.background.base.color,
+                border_color: palette.primary.base.color,
                 ..handle
             },
         }
@@ -155,7 +145,7 @@ impl slider::StyleSheet for Theme {
 
         slider::Appearance {
             handle: slider::Handle {
-                color: palette.primary.weak,
+                color: palette.primary.weak.color,
                 ..active.handle
             },
             ..active
@@ -168,7 +158,7 @@ impl slider::StyleSheet for Theme {
 
         slider::Appearance {
             handle: slider::Handle {
-                color: palette.primary.base,
+                color: palette.primary.base.color,
                 ..active.handle
             },
             ..active
diff --git a/style/src/theme/palette.rs b/style/src/theme/palette.rs
index acc147ed..3d1ca097 100644
--- a/style/src/theme/palette.rs
+++ b/style/src/theme/palette.rs
@@ -60,9 +60,10 @@ impl Palette {
 
 pub struct Extended {
     pub background: Background,
-    pub primary: Group,
-    pub success: Group,
-    pub danger: Group,
+    pub primary: Primary,
+    pub secondary: Secondary,
+    pub success: Success,
+    pub danger: Danger,
 }
 
 lazy_static! {
@@ -75,17 +76,18 @@ impl Extended {
     pub fn generate(palette: Palette) -> Self {
         Self {
             background: Background::new(palette.background, palette.text),
-            primary: Group::new(
+            primary: Primary::generate(
                 palette.primary,
                 palette.background,
                 palette.text,
             ),
-            success: Group::new(
+            secondary: Secondary::generate(palette.background, palette.text),
+            success: Success::generate(
                 palette.success,
                 palette.background,
                 palette.text,
             ),
-            danger: Group::new(
+            danger: Danger::generate(
                 palette.danger,
                 palette.background,
                 palette.text,
@@ -94,44 +96,113 @@ impl Extended {
     }
 }
 
-pub struct Background {
-    pub base: Color,
-    pub weak: Color,
-    pub strong: Color,
+#[derive(Debug, Clone, Copy)]
+pub struct Pair {
+    pub color: Color,
     pub text: Color,
 }
 
+impl Pair {
+    pub fn new(color: Color, text: Color) -> Self {
+        Self {
+            color,
+            text: readable(color, text),
+        }
+    }
+}
+
+pub struct Background {
+    pub base: Pair,
+    pub weak: Pair,
+    pub strong: Pair,
+}
+
 impl Background {
     pub fn new(base: Color, text: Color) -> Self {
+        let weak = mix(base, text, 0.15);
+        let strong = mix(base, text, 0.25);
+
         Self {
-            base,
-            weak: mix(base, text, 0.15),
-            strong: mix(base, text, 0.25),
-            text,
+            base: Pair::new(base, text),
+            weak: Pair::new(weak, text),
+            strong: Pair::new(strong, text),
         }
     }
 }
 
-pub struct Group {
-    pub base: Color,
-    pub weak: Color,
-    pub strong: Color,
-    pub text: Color,
+pub struct Primary {
+    pub base: Pair,
+    pub weak: Pair,
+    pub strong: Pair,
+}
+
+impl Primary {
+    pub fn generate(base: Color, background: Color, text: Color) -> Self {
+        let weak = mix(base, background, 0.4);
+        let strong = deviate(base, 0.1);
+
+        Self {
+            base: Pair::new(base, text),
+            weak: Pair::new(weak, text),
+            strong: Pair::new(strong, text),
+        }
+    }
 }
 
-impl Group {
-    pub fn new(base: Color, background: Color, text: Color) -> Self {
-        let strong = if is_dark(base) {
-            lighten(base, 0.1)
-        } else {
-            darken(base, 0.1)
-        };
+pub struct Secondary {
+    pub base: Pair,
+    pub weak: Pair,
+    pub strong: Pair,
+}
+
+impl Secondary {
+    pub fn generate(base: Color, text: Color) -> Self {
+        let base = mix(base, text, 0.2);
+        let weak = mix(base, text, 0.1);
+        let strong = mix(base, text, 0.3);
 
         Self {
-            base,
-            weak: mix(base, background, 0.4),
-            strong,
-            text: readable(strong, text),
+            base: Pair::new(base, text),
+            weak: Pair::new(weak, text),
+            strong: Pair::new(strong, text),
+        }
+    }
+}
+
+pub struct Success {
+    pub base: Pair,
+    pub weak: Pair,
+    pub strong: Pair,
+}
+
+impl Success {
+    pub fn generate(base: Color, background: Color, text: Color) -> Self {
+        let weak = mix(base, background, 0.4);
+        let strong = deviate(base, 0.1);
+
+        Self {
+            base: Pair::new(base, text),
+            weak: Pair::new(weak, text),
+            strong: Pair::new(strong, text),
+        }
+    }
+}
+
+pub struct Danger {
+    pub base: Pair,
+    pub weak: Pair,
+    pub strong: Pair,
+}
+
+impl Danger {
+    pub fn generate(base: Color, background: Color, text: Color) -> Self {
+        let weak = mix(base, background, 0.4);
+        let strong = deviate(base, 0.1);
+
+        Self {
+            base: Pair::new(base, text),
+            weak: Pair::new(weak, text),
+            strong: Pair::new(strong, text),
         }
     }
 }
@@ -174,6 +245,14 @@ fn lighten(color: Color, amount: f32) -> Color {
     from_hsl(hsl)
 }
 
+fn deviate(color: Color, amount: f32) -> Color {
+    if is_dark(color) {
+        lighten(color, amount)
+    } else {
+        darken(color, amount)
+    }
+}
+
 fn mix(a: Color, b: Color, factor: f32) -> Color {
     let a_lin = Srgb::from(a).into_linear();
     let b_lin = Srgb::from(b).into_linear();