Merge branch 'master' into non-uniform-border-radius-for-quads

2 files changed, 583 insertions, 275 deletions

diff --git a/style/src/theme.rs b/style/src/theme.rs
index a253e990..d7ebb827 100644
--- a/style/src/theme.rs
+++ b/style/src/theme.rs
@@ -1,3 +1,4 @@
+//! Use the built-in theme and styles.
 pub mod palette;
 
 use self::palette::Extended;
@@ -19,20 +20,29 @@ use crate::text;
 use crate::text_input;
 use crate::toggler;
 
-use iced_core::{Background, Color};
+use iced_core::{Background, Color, Vector};
 
-#[derive(Debug, Clone, PartialEq)]
+use std::rc::Rc;
+
+/// A built-in theme.
+#[derive(Debug, Clone, PartialEq, Default)]
 pub enum Theme {
+    /// The built-in light variant.
+    #[default]
     Light,
+    /// The built-in dark variant.
     Dark,
+    /// A [`Theme`] that uses a [`Custom`] palette.
     Custom(Box<Custom>),
 }
 
 impl Theme {
+    /// Creates a new custom [`Theme`] from the given [`Palette`].
     pub fn custom(palette: Palette) -> Self {
         Self::Custom(Box::new(Custom::new(palette)))
     }
 
+    /// Returns the [`Palette`] of the [`Theme`].
     pub fn palette(&self) -> Palette {
         match self {
             Self::Light => Palette::LIGHT,
@@ -41,6 +51,7 @@ impl Theme {
         }
     }
 
+    /// Returns the [`palette::Extended`] of the [`Theme`].
     pub fn extended_palette(&self) -> &palette::Extended {
         match self {
             Self::Light => &palette::EXTENDED_LIGHT,
@@ -50,12 +61,7 @@ impl Theme {
     }
 }
 
-impl Default for Theme {
-    fn default() -> Self {
-        Self::Light
-    }
-}
-
+/// A [`Theme`] with a customized [`Palette`].
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub struct Custom {
     palette: Palette,
@@ -63,6 +69,7 @@ pub struct Custom {
 }
 
 impl Custom {
+    /// Creates a [`Custom`] theme from the given [`Palette`].
     pub fn new(palette: Palette) -> Self {
         Self {
             palette,
@@ -71,22 +78,20 @@ impl Custom {
     }
 }
 
-#[derive(Debug, Clone, Copy)]
+/// The style of an application.
+#[derive(Default)]
 pub enum Application {
+    /// The default style.
+    #[default]
     Default,
-    Custom(fn(Theme) -> application::Appearance),
-}
-
-impl Default for Application {
-    fn default() -> Self {
-        Self::Default
-    }
+    /// A custom style.
+    Custom(Box<dyn application::StyleSheet<Style = Theme>>),
 }
 
 impl application::StyleSheet for Theme {
     type Style = Application;
 
-    fn appearance(&self, style: Self::Style) -> application::Appearance {
+    fn appearance(&self, style: &Self::Style) -> application::Appearance {
         let palette = self.extended_palette();
 
         match style {
@@ -94,33 +99,49 @@ impl application::StyleSheet for Theme {
                 background_color: palette.background.base.color,
                 text_color: palette.background.base.text,
             },
-            Application::Custom(f) => f(self.clone()),
+            Application::Custom(custom) => custom.appearance(self),
         }
     }
 }
 
-/*
- * Button
- */
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+impl application::StyleSheet for fn(&Theme) -> application::Appearance {
+    type Style = Theme;
+
+    fn appearance(&self, style: &Self::Style) -> application::Appearance {
+        (self)(style)
+    }
+}
+
+impl From<fn(&Theme) -> application::Appearance> for Application {
+    fn from(f: fn(&Theme) -> application::Appearance) -> Self {
+        Self::Custom(Box::new(f))
+    }
+}
+
+/// The style of a button.
+#[derive(Default)]
 pub enum Button {
+    /// The primary style.
+    #[default]
     Primary,
+    /// The secondary style.
     Secondary,
+    /// The positive style.
     Positive,
+    /// The destructive style.
     Destructive,
+    /// The text style.
+    ///
+    /// Useful for links!
     Text,
-}
-
-impl Default for Button {
-    fn default() -> Self {
-        Self::Primary
-    }
+    /// A custom style.
+    Custom(Box<dyn button::StyleSheet<Style = Theme>>),
 }
 
 impl button::StyleSheet for Theme {
     type Style = Button;
 
-    fn active(&self, style: Self::Style) -> button::Appearance {
+    fn active(&self, style: &Self::Style) -> button::Appearance {
         let palette = self.extended_palette();
 
         let appearance = button::Appearance {
@@ -143,19 +164,25 @@ impl button::StyleSheet for Theme {
                 text_color: palette.background.base.text,
                 ..appearance
             },
+            Button::Custom(custom) => custom.active(self),
         }
     }
 
-    fn hovered(&self, style: Self::Style) -> button::Appearance {
-        let active = self.active(style);
+    fn hovered(&self, style: &Self::Style) -> button::Appearance {
         let palette = self.extended_palette();
 
+        if let Button::Custom(custom) = style {
+            return custom.hovered(self);
+        }
+
+        let active = self.active(style);
+
         let background = match style {
             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,
+            Button::Text | Button::Custom(_) => None,
         };
 
         button::Appearance {
@@ -163,23 +190,56 @@ impl button::StyleSheet for Theme {
             ..active
         }
     }
+
+    fn pressed(&self, style: &Self::Style) -> button::Appearance {
+        if let Button::Custom(custom) = style {
+            return custom.pressed(self);
+        }
+
+        button::Appearance {
+            shadow_offset: Vector::default(),
+            ..self.active(style)
+        }
+    }
+
+    fn disabled(&self, style: &Self::Style) -> button::Appearance {
+        if let Button::Custom(custom) = style {
+            return custom.disabled(self);
+        }
+
+        let active = self.active(style);
+
+        button::Appearance {
+            shadow_offset: Vector::default(),
+            background: active.background.map(|background| match background {
+                Background::Color(color) => Background::Color(Color {
+                    a: color.a * 0.5,
+                    ..color
+                }),
+            }),
+            text_color: Color {
+                a: active.text_color.a * 0.5,
+                ..active.text_color
+            },
+            ..active
+        }
+    }
 }
 
-/*
- * Checkbox
- */
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+/// The style of a checkbox.
+#[derive(Default)]
 pub enum Checkbox {
+    /// The primary style.
+    #[default]
     Primary,
+    /// The secondary style.
     Secondary,
+    /// The success style.
     Success,
+    /// The danger style.
     Danger,
-}
-
-impl Default for Checkbox {
-    fn default() -> Self {
-        Self::Primary
-    }
+    /// A custom style.
+    Custom(Box<dyn checkbox::StyleSheet<Style = Theme>>),
 }
 
 impl checkbox::StyleSheet for Theme {
@@ -187,7 +247,7 @@ impl checkbox::StyleSheet for Theme {
 
     fn active(
         &self,
-        style: Self::Style,
+        style: &Self::Style,
         is_checked: bool,
     ) -> checkbox::Appearance {
         let palette = self.extended_palette();
@@ -217,12 +277,13 @@ impl checkbox::StyleSheet for Theme {
                 palette.danger.base,
                 is_checked,
             ),
+            Checkbox::Custom(custom) => custom.active(self, is_checked),
         }
     }
 
     fn hovered(
         &self,
-        style: Self::Style,
+        style: &Self::Style,
         is_checked: bool,
     ) -> checkbox::Appearance {
         let palette = self.extended_palette();
@@ -252,6 +313,7 @@ impl checkbox::StyleSheet for Theme {
                 palette.danger.base,
                 is_checked,
             ),
+            Checkbox::Custom(custom) => custom.hovered(self, is_checked),
         }
     }
 }
@@ -276,32 +338,28 @@ fn checkbox_appearance(
     }
 }
 
-/*
- * Container
- */
-#[derive(Clone, Copy)]
+/// The style of a container.
+#[derive(Default)]
 pub enum Container {
+    /// No style.
+    #[default]
     Transparent,
+    /// A simple box.
     Box,
-    Custom(fn(&Theme) -> container::Appearance),
-}
-
-impl Default for Container {
-    fn default() -> Self {
-        Self::Transparent
-    }
+    /// A custom style.
+    Custom(Box<dyn container::StyleSheet<Style = Theme>>),
 }
 
 impl From<fn(&Theme) -> container::Appearance> for Container {
     fn from(f: fn(&Theme) -> container::Appearance) -> Self {
-        Self::Custom(f)
+        Self::Custom(Box::new(f))
     }
 }
 
 impl container::StyleSheet for Theme {
     type Style = Container;
 
-    fn appearance(&self, style: Self::Style) -> container::Appearance {
+    fn appearance(&self, style: &Self::Style) -> container::Appearance {
         match style {
             Container::Transparent => Default::default(),
             Container::Box => {
@@ -315,257 +373,389 @@ impl container::StyleSheet for Theme {
                     border_color: Color::TRANSPARENT,
                 }
             }
-            Container::Custom(f) => f(self),
+            Container::Custom(custom) => custom.appearance(self),
         }
     }
 }
 
-/*
- * Slider
- */
-impl slider::StyleSheet for Theme {
-    type Style = ();
+impl container::StyleSheet for fn(&Theme) -> container::Appearance {
+    type Style = Theme;
 
-    fn active(&self, _style: Self::Style) -> slider::Appearance {
-        let palette = self.extended_palette();
+    fn appearance(&self, style: &Self::Style) -> container::Appearance {
+        (self)(style)
+    }
+}
 
-        let handle = slider::Handle {
-            shape: slider::HandleShape::Rectangle {
-                width: 8,
-                border_radius: 4.0,
-            },
-            color: Color::WHITE,
-            border_color: Color::WHITE,
-            border_width: 1.0,
-        };
+/// The style of a slider.
+#[derive(Default)]
+pub enum Slider {
+    /// The default style.
+    #[default]
+    Default,
+    /// A custom style.
+    Custom(Box<dyn slider::StyleSheet<Style = Theme>>),
+}
 
-        slider::Appearance {
-            rail_colors: (palette.primary.base.color, Color::TRANSPARENT),
-            handle: slider::Handle {
-                color: palette.background.base.color,
-                border_color: palette.primary.base.color,
-                ..handle
-            },
+impl slider::StyleSheet for Theme {
+    type Style = Slider;
+
+    fn active(&self, style: &Self::Style) -> slider::Appearance {
+        match style {
+            Slider::Default => {
+                let palette = self.extended_palette();
+
+                let handle = slider::Handle {
+                    shape: slider::HandleShape::Rectangle {
+                        width: 8,
+                        border_radius: 4.0,
+                    },
+                    color: Color::WHITE,
+                    border_color: Color::WHITE,
+                    border_width: 1.0,
+                };
+
+                slider::Appearance {
+                    rail_colors: (
+                        palette.primary.base.color,
+                        Color::TRANSPARENT,
+                    ),
+                    handle: slider::Handle {
+                        color: palette.background.base.color,
+                        border_color: palette.primary.base.color,
+                        ..handle
+                    },
+                }
+            }
+            Slider::Custom(custom) => custom.active(self),
         }
     }
 
-    fn hovered(&self, style: Self::Style) -> slider::Appearance {
-        let active = self.active(style);
-        let palette = self.extended_palette();
+    fn hovered(&self, style: &Self::Style) -> slider::Appearance {
+        match style {
+            Slider::Default => {
+                let active = self.active(style);
+                let palette = self.extended_palette();
 
-        slider::Appearance {
-            handle: slider::Handle {
-                color: palette.primary.weak.color,
-                ..active.handle
-            },
-            ..active
+                slider::Appearance {
+                    handle: slider::Handle {
+                        color: palette.primary.weak.color,
+                        ..active.handle
+                    },
+                    ..active
+                }
+            }
+            Slider::Custom(custom) => custom.hovered(self),
         }
     }
 
-    fn dragging(&self, style: Self::Style) -> slider::Appearance {
-        let active = self.active(style);
-        let palette = self.extended_palette();
+    fn dragging(&self, style: &Self::Style) -> slider::Appearance {
+        match style {
+            Slider::Default => {
+                let active = self.active(style);
+                let palette = self.extended_palette();
 
-        slider::Appearance {
-            handle: slider::Handle {
-                color: palette.primary.base.color,
-                ..active.handle
-            },
-            ..active
+                slider::Appearance {
+                    handle: slider::Handle {
+                        color: palette.primary.base.color,
+                        ..active.handle
+                    },
+                    ..active
+                }
+            }
+            Slider::Custom(custom) => custom.dragging(self),
         }
     }
 }
 
-/*
- * Menu
- */
+/// The style of a menu.
+#[derive(Clone, Default)]
+pub enum Menu {
+    /// The default style.
+    #[default]
+    Default,
+    /// A custom style.
+    Custom(Rc<dyn menu::StyleSheet<Style = Theme>>),
+}
+
 impl menu::StyleSheet for Theme {
-    type Style = ();
+    type Style = Menu;
 
-    fn appearance(&self, _style: Self::Style) -> menu::Appearance {
-        let palette = self.extended_palette();
+    fn appearance(&self, style: &Self::Style) -> menu::Appearance {
+        match style {
+            Menu::Default => {
+                let palette = self.extended_palette();
 
-        menu::Appearance {
-            text_color: palette.background.weak.text,
-            background: palette.background.weak.color.into(),
-            border_width: 1.0,
-            border_radius: 0.0,
-            border_color: palette.background.strong.color,
-            selected_text_color: palette.primary.strong.text,
-            selected_background: palette.primary.strong.color.into(),
+                menu::Appearance {
+                    text_color: palette.background.weak.text,
+                    background: palette.background.weak.color.into(),
+                    border_width: 1.0,
+                    border_radius: 0.0,
+                    border_color: palette.background.strong.color,
+                    selected_text_color: palette.primary.strong.text,
+                    selected_background: palette.primary.strong.color.into(),
+                }
+            }
+            Menu::Custom(custom) => custom.appearance(self),
+        }
+    }
+}
+
+impl From<PickList> for Menu {
+    fn from(pick_list: PickList) -> Self {
+        match pick_list {
+            PickList::Default => Self::Default,
+            PickList::Custom(_, menu) => Self::Custom(menu),
         }
     }
 }
 
-/*
- * Pick List
- */
+/// The style of a pick list.
+#[derive(Clone, Default)]
+pub enum PickList {
+    /// The default style.
+    #[default]
+    Default,
+    /// A custom style.
+    Custom(
+        Rc<dyn pick_list::StyleSheet<Style = Theme>>,
+        Rc<dyn menu::StyleSheet<Style = Theme>>,
+    ),
+}
+
 impl pick_list::StyleSheet for Theme {
-    type Style = ();
+    type Style = PickList;
 
-    fn active(&self, _style: ()) -> pick_list::Appearance {
-        let palette = self.extended_palette();
+    fn active(&self, style: &Self::Style) -> pick_list::Appearance {
+        match style {
+            PickList::Default => {
+                let palette = self.extended_palette();
 
-        pick_list::Appearance {
-            text_color: palette.background.weak.text,
-            background: palette.background.weak.color.into(),
-            placeholder_color: palette.background.strong.color,
-            border_radius: 2.0,
-            border_width: 1.0,
-            border_color: palette.background.strong.color,
-            icon_size: 0.7,
+                pick_list::Appearance {
+                    text_color: palette.background.weak.text,
+                    background: palette.background.weak.color.into(),
+                    placeholder_color: palette.background.strong.color,
+                    border_radius: 2.0,
+                    border_width: 1.0,
+                    border_color: palette.background.strong.color,
+                    icon_size: 0.7,
+                }
+            }
+            PickList::Custom(custom, _) => custom.active(self),
         }
     }
 
-    fn hovered(&self, _style: ()) -> pick_list::Appearance {
-        let palette = self.extended_palette();
+    fn hovered(&self, style: &Self::Style) -> pick_list::Appearance {
+        match style {
+            PickList::Default => {
+                let palette = self.extended_palette();
 
-        pick_list::Appearance {
-            text_color: palette.background.weak.text,
-            background: palette.background.weak.color.into(),
-            placeholder_color: palette.background.strong.color,
-            border_radius: 2.0,
-            border_width: 1.0,
-            border_color: palette.primary.strong.color,
-            icon_size: 0.7,
+                pick_list::Appearance {
+                    text_color: palette.background.weak.text,
+                    background: palette.background.weak.color.into(),
+                    placeholder_color: palette.background.strong.color,
+                    border_radius: 2.0,
+                    border_width: 1.0,
+                    border_color: palette.primary.strong.color,
+                    icon_size: 0.7,
+                }
+            }
+            PickList::Custom(custom, _) => custom.active(self),
         }
     }
 }
 
-/*
- * Radio
- */
+/// The style of a radio button.
+#[derive(Default)]
+pub enum Radio {
+    /// The default style.
+    #[default]
+    Default,
+    /// A custom style.
+    Custom(Box<dyn radio::StyleSheet<Style = Theme>>),
+}
+
 impl radio::StyleSheet for Theme {
-    type Style = ();
+    type Style = Radio;
 
     fn active(
         &self,
-        _style: Self::Style,
-        _is_selected: bool,
+        style: &Self::Style,
+        is_selected: bool,
     ) -> radio::Appearance {
-        let palette = self.extended_palette();
+        match style {
+            Radio::Default => {
+                let palette = self.extended_palette();
 
-        radio::Appearance {
-            background: Color::TRANSPARENT.into(),
-            dot_color: palette.primary.strong.color,
-            border_width: 1.0,
-            border_color: palette.primary.strong.color,
-            text_color: None,
+                radio::Appearance {
+                    background: Color::TRANSPARENT.into(),
+                    dot_color: palette.primary.strong.color,
+                    border_width: 1.0,
+                    border_color: palette.primary.strong.color,
+                    text_color: None,
+                }
+            }
+            Radio::Custom(custom) => custom.active(self, is_selected),
         }
     }
 
     fn hovered(
         &self,
-        style: Self::Style,
+        style: &Self::Style,
         is_selected: bool,
     ) -> radio::Appearance {
-        let active = self.active(style, is_selected);
-        let palette = self.extended_palette();
+        match style {
+            Radio::Default => {
+                let active = self.active(style, is_selected);
+                let palette = self.extended_palette();
 
-        radio::Appearance {
-            dot_color: palette.primary.strong.color,
-            background: palette.primary.weak.color.into(),
-            ..active
+                radio::Appearance {
+                    dot_color: palette.primary.strong.color,
+                    background: palette.primary.weak.color.into(),
+                    ..active
+                }
+            }
+            Radio::Custom(custom) => custom.hovered(self, is_selected),
         }
     }
 }
 
-/*
- * Toggler
- */
+/// The style of a toggler.
+#[derive(Default)]
+pub enum Toggler {
+    /// The default style.
+    #[default]
+    Default,
+    /// A custom style.
+    Custom(Box<dyn toggler::StyleSheet<Style = Theme>>),
+}
+
 impl toggler::StyleSheet for Theme {
-    type Style = ();
+    type Style = Toggler;
 
     fn active(
         &self,
-        _style: Self::Style,
+        style: &Self::Style,
         is_active: bool,
     ) -> toggler::Appearance {
-        let palette = self.extended_palette();
+        match style {
+            Toggler::Default => {
+                let palette = self.extended_palette();
 
-        toggler::Appearance {
-            background: if is_active {
-                palette.primary.strong.color
-            } else {
-                palette.background.strong.color
-            },
-            background_border: None,
-            foreground: if is_active {
-                palette.primary.strong.text
-            } else {
-                palette.background.base.color
-            },
-            foreground_border: None,
+                toggler::Appearance {
+                    background: if is_active {
+                        palette.primary.strong.color
+                    } else {
+                        palette.background.strong.color
+                    },
+                    background_border: None,
+                    foreground: if is_active {
+                        palette.primary.strong.text
+                    } else {
+                        palette.background.base.color
+                    },
+                    foreground_border: None,
+                }
+            }
+            Toggler::Custom(custom) => custom.active(self, is_active),
         }
     }
 
     fn hovered(
         &self,
-        style: Self::Style,
+        style: &Self::Style,
         is_active: bool,
     ) -> toggler::Appearance {
-        let palette = self.extended_palette();
+        match style {
+            Toggler::Default => {
+                let palette = self.extended_palette();
 
-        toggler::Appearance {
-            foreground: if is_active {
-                Color {
-                    a: 0.5,
-                    ..palette.primary.strong.text
+                toggler::Appearance {
+                    foreground: if is_active {
+                        Color {
+                            a: 0.5,
+                            ..palette.primary.strong.text
+                        }
+                    } else {
+                        palette.background.weak.color
+                    },
+                    ..self.active(style, is_active)
                 }
-            } else {
-                palette.background.weak.color
-            },
-            ..self.active(style, is_active)
+            }
+            Toggler::Custom(custom) => custom.hovered(self, is_active),
         }
     }
 }
 
-/*
- * Pane Grid
- */
+/// The style of a pane grid.
+#[derive(Default)]
+pub enum PaneGrid {
+    /// The default style.
+    #[default]
+    Default,
+    /// A custom style.
+    Custom(Box<dyn pane_grid::StyleSheet<Style = Theme>>),
+}
+
 impl pane_grid::StyleSheet for Theme {
-    type Style = ();
+    type Style = PaneGrid;
 
-    fn picked_split(&self, _style: Self::Style) -> Option<pane_grid::Line> {
-        let palette = self.extended_palette();
+    fn picked_split(&self, style: &Self::Style) -> Option<pane_grid::Line> {
+        match style {
+            PaneGrid::Default => {
+                let palette = self.extended_palette();
 
-        Some(pane_grid::Line {
-            color: palette.primary.strong.color,
-            width: 2.0,
-        })
+                Some(pane_grid::Line {
+                    color: palette.primary.strong.color,
+                    width: 2.0,
+                })
+            }
+            PaneGrid::Custom(custom) => custom.picked_split(self),
+        }
     }
 
-    fn hovered_split(&self, _style: Self::Style) -> Option<pane_grid::Line> {
-        let palette = self.extended_palette();
+    fn hovered_split(&self, style: &Self::Style) -> Option<pane_grid::Line> {
+        match style {
+            PaneGrid::Default => {
+                let palette = self.extended_palette();
 
-        Some(pane_grid::Line {
-            color: palette.primary.base.color,
-            width: 2.0,
-        })
+                Some(pane_grid::Line {
+                    color: palette.primary.base.color,
+                    width: 2.0,
+                })
+            }
+            PaneGrid::Custom(custom) => custom.hovered_split(self),
+        }
     }
 }
 
-/*
- * Progress Bar
- */
-#[derive(Clone, Copy)]
+/// The style of a progress bar.
+#[derive(Default)]
 pub enum ProgressBar {
+    /// The primary style.
+    #[default]
     Primary,
+    /// The success style.
     Success,
+    /// The danger style.
     Danger,
-    Custom(fn(&Theme) -> progress_bar::Appearance),
+    /// A custom style.
+    Custom(Box<dyn progress_bar::StyleSheet<Style = Theme>>),
 }
 
-impl Default for ProgressBar {
-    fn default() -> Self {
-        Self::Primary
+impl From<fn(&Theme) -> progress_bar::Appearance> for ProgressBar {
+    fn from(f: fn(&Theme) -> progress_bar::Appearance) -> Self {
+        Self::Custom(Box::new(f))
     }
 }
 
 impl progress_bar::StyleSheet for Theme {
     type Style = ProgressBar;
 
-    fn appearance(&self, style: Self::Style) -> progress_bar::Appearance {
+    fn appearance(&self, style: &Self::Style) -> progress_bar::Appearance {
+        if let ProgressBar::Custom(custom) = style {
+            return custom.appearance(self);
+        }
+
         let palette = self.extended_palette();
 
         let from_palette = |bar: Color| progress_bar::Appearance {
@@ -578,30 +768,39 @@ impl progress_bar::StyleSheet for Theme {
             ProgressBar::Primary => from_palette(palette.primary.base.color),
             ProgressBar::Success => from_palette(palette.success.base.color),
             ProgressBar::Danger => from_palette(palette.danger.base.color),
-            ProgressBar::Custom(f) => f(self),
+            ProgressBar::Custom(custom) => custom.appearance(self),
         }
     }
 }
 
-/*
- * Rule
- */
-#[derive(Clone, Copy)]
+impl progress_bar::StyleSheet for fn(&Theme) -> progress_bar::Appearance {
+    type Style = Theme;
+
+    fn appearance(&self, style: &Self::Style) -> progress_bar::Appearance {
+        (self)(style)
+    }
+}
+
+/// The style of a rule.
+#[derive(Default)]
 pub enum Rule {
+    /// The default style.
+    #[default]
     Default,
-    Custom(fn(&Theme) -> rule::Appearance),
+    /// A custom style.
+    Custom(Box<dyn rule::StyleSheet<Style = Theme>>),
 }
 
-impl Default for Rule {
-    fn default() -> Self {
-        Self::Default
+impl From<fn(&Theme) -> rule::Appearance> for Rule {
+    fn from(f: fn(&Theme) -> rule::Appearance) -> Self {
+        Self::Custom(Box::new(f))
     }
 }
 
 impl rule::StyleSheet for Theme {
     type Style = Rule;
 
-    fn style(&self, style: Self::Style) -> rule::Appearance {
+    fn appearance(&self, style: &Self::Style) -> rule::Appearance {
         let palette = self.extended_palette();
 
         match style {
@@ -611,66 +810,92 @@ impl rule::StyleSheet for Theme {
                 radius: 0.0,
                 fill_mode: rule::FillMode::Full,
             },
-            Rule::Custom(f) => f(self),
+            Rule::Custom(custom) => custom.appearance(self),
         }
     }
 }
 
-/*
- * Scrollable
- */
+impl rule::StyleSheet for fn(&Theme) -> rule::Appearance {
+    type Style = Theme;
+
+    fn appearance(&self, style: &Self::Style) -> rule::Appearance {
+        (self)(style)
+    }
+}
+
+/// The style of a scrollable.
+#[derive(Default)]
+pub enum Scrollable {
+    /// The default style.
+    #[default]
+    Default,
+    /// A custom style.
+    Custom(Box<dyn scrollable::StyleSheet<Style = Theme>>),
+}
+
 impl scrollable::StyleSheet for Theme {
-    type Style = ();
+    type Style = Scrollable;
 
-    fn active(&self, _style: Self::Style) -> scrollable::Scrollbar {
-        let palette = self.extended_palette();
+    fn active(&self, style: &Self::Style) -> scrollable::Scrollbar {
+        match style {
+            Scrollable::Default => {
+                let palette = self.extended_palette();
 
-        scrollable::Scrollbar {
-            background: palette.background.weak.color.into(),
-            border_radius: 2.0,
-            border_width: 0.0,
-            border_color: Color::TRANSPARENT,
-            scroller: scrollable::Scroller {
-                color: palette.background.strong.color,
-                border_radius: 2.0,
-                border_width: 0.0,
-                border_color: Color::TRANSPARENT,
-            },
+                scrollable::Scrollbar {
+                    background: palette.background.weak.color.into(),
+                    border_radius: 2.0,
+                    border_width: 0.0,
+                    border_color: Color::TRANSPARENT,
+                    scroller: scrollable::Scroller {
+                        color: palette.background.strong.color,
+                        border_radius: 2.0,
+                        border_width: 0.0,
+                        border_color: Color::TRANSPARENT,
+                    },
+                }
+            }
+            Scrollable::Custom(custom) => custom.active(self),
         }
     }
 
-    fn hovered(&self, _style: Self::Style) -> scrollable::Scrollbar {
-        let palette = self.extended_palette();
+    fn hovered(&self, style: &Self::Style) -> scrollable::Scrollbar {
+        match style {
+            Scrollable::Default => {
+                let palette = self.extended_palette();
 
-        scrollable::Scrollbar {
-            background: palette.background.weak.color.into(),
-            border_radius: 2.0,
-            border_width: 0.0,
-            border_color: Color::TRANSPARENT,
-            scroller: scrollable::Scroller {
-                color: palette.primary.strong.color,
-                border_radius: 2.0,
-                border_width: 0.0,
-                border_color: Color::TRANSPARENT,
-            },
+                scrollable::Scrollbar {
+                    background: palette.background.weak.color.into(),
+                    border_radius: 2.0,
+                    border_width: 0.0,
+                    border_color: Color::TRANSPARENT,
+                    scroller: scrollable::Scroller {
+                        color: palette.primary.strong.color,
+                        border_radius: 2.0,
+                        border_width: 0.0,
+                        border_color: Color::TRANSPARENT,
+                    },
+                }
+            }
+            Scrollable::Custom(custom) => custom.hovered(self),
+        }
+    }
+
+    fn dragging(&self, style: &Self::Style) -> scrollable::Scrollbar {
+        match style {
+            Scrollable::Default => self.hovered(style),
+            Scrollable::Custom(custom) => custom.dragging(self),
         }
     }
 }
 
-/*
- * Text
- */
-#[derive(Clone, Copy)]
+/// The style of text.
+#[derive(Clone, Copy, Default)]
 pub enum Text {
+    /// The default style.
+    #[default]
     Default,
+    /// Colored text.
     Color(Color),
-    Custom(fn(&Theme) -> text::Appearance),
-}
-
-impl Default for Text {
-    fn default() -> Self {
-        Self::Default
-    }
 }
 
 impl From<Color> for Text {
@@ -686,18 +911,28 @@ impl text::StyleSheet for Theme {
         match style {
             Text::Default => Default::default(),
             Text::Color(c) => text::Appearance { color: Some(c) },
-            Text::Custom(f) => f(self),
         }
     }
 }
 
-/*
- * Text Input
- */
+/// The style of a text input.
+#[derive(Default)]
+pub enum TextInput {
+    /// The default style.
+    #[default]
+    Default,
+    /// A custom style.
+    Custom(Box<dyn text_input::StyleSheet<Style = Theme>>),
+}
+
 impl text_input::StyleSheet for Theme {
-    type Style = ();
+    type Style = TextInput;
+
+    fn active(&self, style: &Self::Style) -> text_input::Appearance {
+        if let TextInput::Custom(custom) = style {
+            return custom.active(self);
+        }
 
-    fn active(&self, _style: Self::Style) -> text_input::Appearance {
         let palette = self.extended_palette();
 
         text_input::Appearance {
@@ -708,7 +943,11 @@ impl text_input::StyleSheet for Theme {
         }
     }
 
-    fn hovered(&self, _style: Self::Style) -> text_input::Appearance {
+    fn hovered(&self, style: &Self::Style) -> text_input::Appearance {
+        if let TextInput::Custom(custom) = style {
+            return custom.hovered(self);
+        }
+
         let palette = self.extended_palette();
 
         text_input::Appearance {
@@ -719,7 +958,11 @@ impl text_input::StyleSheet for Theme {
         }
     }
 
-    fn focused(&self, _style: Self::Style) -> text_input::Appearance {
+    fn focused(&self, style: &Self::Style) -> text_input::Appearance {
+        if let TextInput::Custom(custom) = style {
+            return custom.focused(self);
+        }
+
         let palette = self.extended_palette();
 
         text_input::Appearance {
@@ -730,19 +973,31 @@ impl text_input::StyleSheet for Theme {
         }
     }
 
-    fn placeholder_color(&self, _style: Self::Style) -> Color {
+    fn placeholder_color(&self, style: &Self::Style) -> Color {
+        if let TextInput::Custom(custom) = style {
+            return custom.placeholder_color(self);
+        }
+
         let palette = self.extended_palette();
 
         palette.background.strong.color
     }
 
-    fn value_color(&self, _style: Self::Style) -> Color {
+    fn value_color(&self, style: &Self::Style) -> Color {
+        if let TextInput::Custom(custom) = style {
+            return custom.value_color(self);
+        }
+
         let palette = self.extended_palette();
 
         palette.background.base.text
     }
 
-    fn selection_color(&self, _style: Self::Style) -> Color {
+    fn selection_color(&self, style: &Self::Style) -> Color {
+        if let TextInput::Custom(custom) = style {
+            return custom.selection_color(self);
+        }
+
         let palette = self.extended_palette();
 
         palette.primary.weak.color
diff --git a/style/src/theme/palette.rs b/style/src/theme/palette.rs
index b3a10d28..0f15494b 100644
--- a/style/src/theme/palette.rs
+++ b/style/src/theme/palette.rs
@@ -1,18 +1,26 @@
+//! Define the colors of a theme.
 use iced_core::Color;
 
 use once_cell::sync::Lazy;
 use palette::{FromColor, Hsl, Mix, RelativeContrast, Srgb};
 
+/// A color palette.
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub struct Palette {
+    /// The background [`Color`] of the [`Palette`].
     pub background: Color,
+    /// The text [`Color`] of the [`Palette`].
     pub text: Color,
+    /// The primary [`Color`] of the [`Palette`].
     pub primary: Color,
+    /// The success [`Color`] of the [`Palette`].
     pub success: Color,
+    /// The danger [`Color`] of the [`Palette`].
     pub danger: Color,
 }
 
 impl Palette {
+    /// The built-in light variant of a [`Palette`].
     pub const LIGHT: Self = Self {
         background: Color::WHITE,
         text: Color::BLACK,
@@ -33,6 +41,7 @@ impl Palette {
         ),
     };
 
+    /// The built-in dark variant of a [`Palette`].
     pub const DARK: Self = Self {
         background: Color::from_rgb(
             0x20 as f32 / 255.0,
@@ -58,21 +67,31 @@ impl Palette {
     };
 }
 
+/// An extended set of colors generated from a [`Palette`].
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub struct Extended {
+    /// The set of background colors.
     pub background: Background,
+    /// The set of primary colors.
     pub primary: Primary,
+    /// The set of secondary colors.
     pub secondary: Secondary,
+    /// The set of success colors.
     pub success: Success,
+    /// The set of danger colors.
     pub danger: Danger,
 }
 
+/// The built-in light variant of an [`Extended`] palette.
 pub static EXTENDED_LIGHT: Lazy<Extended> =
     Lazy::new(|| Extended::generate(Palette::LIGHT));
+
+/// The built-in dark variant of an [`Extended`] palette.
 pub static EXTENDED_DARK: Lazy<Extended> =
     Lazy::new(|| Extended::generate(Palette::DARK));
 
 impl Extended {
+    /// Generates an [`Extended`] palette from a simple [`Palette`].
     pub fn generate(palette: Palette) -> Self {
         Self {
             background: Background::new(palette.background, palette.text),
@@ -96,13 +115,22 @@ impl Extended {
     }
 }
 
+/// A pair of background and text colors.
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub struct Pair {
+    /// The background color.
     pub color: Color,
+
+    /// The text color.
+    ///
+    /// It's guaranteed to be readable on top of the background [`color`].
+    ///
+    /// [`color`]: Self::color
     pub text: Color,
 }
 
 impl Pair {
+    /// Creates a new [`Pair`] from a background [`Color`] and some text [`Color`].
     pub fn new(color: Color, text: Color) -> Self {
         Self {
             color,
@@ -111,14 +139,19 @@ impl Pair {
     }
 }
 
+/// A set of background colors.
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub struct Background {
+    /// The base background color.
     pub base: Pair,
+    /// A weaker version of the base background color.
     pub weak: Pair,
+    /// A stronger version of the base background color.
     pub strong: Pair,
 }
 
 impl Background {
+    /// Generates a set of [`Background`] colors from the base and text colors.
     pub fn new(base: Color, text: Color) -> Self {
         let weak = mix(base, text, 0.15);
         let strong = mix(base, text, 0.40);
@@ -131,14 +164,19 @@ impl Background {
     }
 }
 
+/// A set of primary colors.
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub struct Primary {
+    /// The base primary color.
     pub base: Pair,
+    /// A weaker version of the base primary color.
     pub weak: Pair,
+    /// A stronger version of the base primary color.
     pub strong: Pair,
 }
 
 impl Primary {
+    /// Generates a set of [`Primary`] colors from the base, background, and text colors.
     pub fn generate(base: Color, background: Color, text: Color) -> Self {
         let weak = mix(base, background, 0.4);
         let strong = deviate(base, 0.1);
@@ -151,14 +189,19 @@ impl Primary {
     }
 }
 
+/// A set of secondary colors.
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub struct Secondary {
+    /// The base secondary color.
     pub base: Pair,
+    /// A weaker version of the base secondary color.
     pub weak: Pair,
+    /// A stronger version of the base secondary color.
     pub strong: Pair,
 }
 
 impl Secondary {
+    /// Generates a set of [`Secondary`] colors from the base and text colors.
     pub fn generate(base: Color, text: Color) -> Self {
         let base = mix(base, text, 0.2);
         let weak = mix(base, text, 0.1);
@@ -172,14 +215,19 @@ impl Secondary {
     }
 }
 
+/// A set of success colors.
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub struct Success {
+    /// The base success color.
     pub base: Pair,
+    /// A weaker version of the base success color.
     pub weak: Pair,
+    /// A stronger version of the base success color.
     pub strong: Pair,
 }
 
 impl Success {
+    /// Generates a set of [`Success`] colors from the base, background, and text colors.
     pub fn generate(base: Color, background: Color, text: Color) -> Self {
         let weak = mix(base, background, 0.4);
         let strong = deviate(base, 0.1);
@@ -192,14 +240,19 @@ impl Success {
     }
 }
 
+/// A set of danger colors.
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub struct Danger {
+    /// The base danger color.
     pub base: Pair,
+    /// A weaker version of the base danger color.
     pub weak: Pair,
+    /// A stronger version of the base danger color.
     pub strong: Pair,
 }
 
 impl Danger {
+    /// Generates a set of [`Danger`] colors from the base, background, and text colors.
     pub fn generate(base: Color, background: Color, text: Color) -> Self {
         let weak = mix(base, background, 0.4);
         let strong = deviate(base, 0.1);