Use Catalog approach for all widgets

core/src/widget/text.rs

@@ -18,6 +18,7 @@ pub use text::{LineHeight, Shaping};
 #[allow(missing_debug_implementations)]
 pub struct Text<'a, Theme, Renderer>
 where
+    Theme: Catalog,
     Renderer: text::Renderer,
 {
     content: Cow<'a, str>,
@@ -29,18 +30,16 @@ where
     vertical_alignment: alignment::Vertical,
     font: Option<Renderer::Font>,
     shaping: Shaping,
-    style: Style<'a, Theme>,
+    class: Theme::Class<'a>,
 }
 
 impl<'a, Theme, Renderer> Text<'a, Theme, Renderer>
 where
+    Theme: Catalog,
     Renderer: text::Renderer,
 {
     /// Create a new fragment of [`Text`] with the given contents.
-    pub fn new(content: impl Into<Cow<'a, str>>) -> Self
-    where
-        Theme: DefaultStyle + 'a,
-    {
+    pub fn new(content: impl Into<Cow<'a, str>>) -> Self {
         Text {
             content: content.into(),
             size: None,
@@ -51,7 +50,7 @@ where
             horizontal_alignment: alignment::Horizontal::Left,
             vertical_alignment: alignment::Vertical::Top,
             shaping: Shaping::Basic,
-            style: Box::new(Theme::default_style),
+            class: Theme::default(),
         }
     }
 
@@ -75,25 +74,6 @@ where
         self
     }
 
-    /// Sets the style of the [`Text`].
-    pub fn style(mut self, style: impl Fn(&Theme) -> Appearance + 'a) -> Self {
-        self.style = Box::new(style);
-        self
-    }
-
-    /// Sets the [`Color`] of the [`Text`].
-    pub fn color(self, color: impl Into<Color>) -> Self {
-        self.color_maybe(Some(color))
-    }
-
-    /// Sets the [`Color`] of the [`Text`], if `Some`.
-    pub fn color_maybe(mut self, color: Option<impl Into<Color>>) -> Self {
-        let color = color.map(Into::into);
-
-        self.style = Box::new(move |_theme| Appearance { color });
-        self
-    }
-
     /// Sets the width of the [`Text`] boundaries.
     pub fn width(mut self, width: impl Into<Length>) -> Self {
         self.width = width.into();
@@ -129,6 +109,42 @@ where
         self.shaping = shaping;
         self
     }
+
+    /// Sets the style of the [`Text`].
+    #[must_use]
+    pub fn style(mut self, style: impl Fn(&Theme) -> Style + 'a) -> Self
+    where
+        Theme::Class<'a>: From<StyleFn<'a, Theme>>,
+    {
+        self.class = (Box::new(style) as StyleFn<'a, Theme>).into();
+        self
+    }
+
+    /// Sets the [`Color`] of the [`Text`].
+    pub fn color(self, color: impl Into<Color>) -> Self
+    where
+        Theme::Class<'a>: From<StyleFn<'a, Theme>>,
+    {
+        self.color_maybe(Some(color))
+    }
+
+    /// Sets the [`Color`] of the [`Text`], if `Some`.
+    pub fn color_maybe(self, color: Option<impl Into<Color>>) -> Self
+    where
+        Theme::Class<'a>: From<StyleFn<'a, Theme>>,
+    {
+        let color = color.map(Into::into);
+
+        self.style(move |_theme| Style { color })
+    }
+
+    /// Sets the style class of the [`Text`].
+    #[cfg(feature = "advanced")]
+    #[must_use]
+    pub fn class(mut self, class: impl Into<Theme::Class<'a>>) -> Self {
+        self.class = class.into();
+        self
+    }
 }
 
 /// The internal state of a [`Text`] widget.
@@ -138,6 +154,7 @@ pub struct State<P: Paragraph>(P);
 impl<'a, Message, Theme, Renderer> Widget<Message, Theme, Renderer>
     for Text<'a, Theme, Renderer>
 where
+    Theme: Catalog,
     Renderer: text::Renderer,
 {
     fn tag(&self) -> tree::Tag {
@@ -182,15 +199,15 @@ where
         tree: &Tree,
         renderer: &mut Renderer,
         theme: &Theme,
-        style: &renderer::Style,
+        defaults: &renderer::Style,
         layout: Layout<'_>,
         _cursor_position: mouse::Cursor,
         viewport: &Rectangle,
     ) {
         let state = tree.state.downcast_ref::<State<Renderer::Paragraph>>();
-        let appearance = (self.style)(theme);
+        let style = theme.style(&self.class);
 
-        draw(renderer, style, layout, state, appearance, viewport);
+        draw(renderer, defaults, layout, state, style, viewport);
     }
 }
 
@@ -250,7 +267,7 @@ pub fn draw<Renderer>(
     style: &renderer::Style,
     layout: Layout<'_>,
     state: &State<Renderer::Paragraph>,
-    appearance: Appearance,
+    appearance: Style,
     viewport: &Rectangle,
 ) where
     Renderer: text::Renderer,
@@ -281,7 +298,7 @@ pub fn draw<Renderer>(
 impl<'a, Message, Theme, Renderer> From<Text<'a, Theme, Renderer>>
     for Element<'a, Message, Theme, Renderer>
 where
-    Theme: 'a,
+    Theme: Catalog + 'a,
     Renderer: text::Renderer + 'a,
 {
     fn from(
@@ -293,7 +310,7 @@ where
 
 impl<'a, Theme, Renderer> From<&'a str> for Text<'a, Theme, Renderer>
 where
-    Theme: DefaultStyle + 'a,
+    Theme: Catalog + 'a,
     Renderer: text::Renderer,
 {
     fn from(content: &'a str) -> Self {
@@ -304,7 +321,7 @@ where
 impl<'a, Message, Theme, Renderer> From<&'a str>
     for Element<'a, Message, Theme, Renderer>
 where
-    Theme: DefaultStyle + 'a,
+    Theme: Catalog + 'a,
     Renderer: text::Renderer + 'a,
 {
     fn from(content: &'a str) -> Self {
@@ -314,30 +331,38 @@ where
 
 /// The appearance of some text.
 #[derive(Debug, Clone, Copy, Default)]
-pub struct Appearance {
+pub struct Style {
     /// The [`Color`] of the text.
     ///
     /// The default, `None`, means using the inherited color.
     pub color: Option<Color>,
 }
 
-/// The style of some [`Text`].
-pub type Style<'a, Theme> = Box<dyn Fn(&Theme) -> Appearance + 'a>;
+/// The theme catalog of a [`Text`].
+pub trait Catalog: Sized {
+    /// The item class of this [`Catalog`].
+    type Class<'a>;
 
-/// The default style of some [`Text`].
-pub trait DefaultStyle {
-    /// Returns the default style of some [`Text`].
-    fn default_style(&self) -> Appearance;
+    /// The default class produced by this [`Catalog`].
+    fn default<'a>() -> Self::Class<'a>;
+
+    /// The [`Style`] of a class with the given status.
+    fn style(&self, item: &Self::Class<'_>) -> Style;
 }
 
-impl DefaultStyle for Theme {
-    fn default_style(&self) -> Appearance {
-        Appearance::default()
+/// A styling function for a [`Text`].
+///
+/// This is just a boxed closure: `Fn(&Theme, Status) -> Style`.
+pub type StyleFn<'a, Theme> = Box<dyn Fn(&Theme) -> Style + 'a>;
+
+impl Catalog for Theme {
+    type Class<'a> = StyleFn<'a, Self>;
+
+    fn default<'a>() -> Self::Class<'a> {
+        Box::new(|_theme| Style::default())
     }
-}
 
-impl DefaultStyle for Color {
-    fn default_style(&self) -> Appearance {
-        Appearance { color: Some(*self) }
+    fn style(&self, class: &Self::Class<'_>) -> Style {
+        class(self)
     }
 }

examples/component/src/main.rs

@@ -73,10 +73,7 @@ mod numeric_input {
 
     impl<Message, Theme> Component<Message, Theme> for NumericInput<Message>
     where
-        Theme: text::DefaultStyle
-            + button::Catalog
-            + text_input::DefaultStyle
-            + 'static,
+        Theme: text::Catalog + button::Catalog + text_input::Catalog + 'static,
     {
         type State = ();
         type Event = Event;
@@ -151,10 +148,7 @@ mod numeric_input {
     impl<'a, Message, Theme> From<NumericInput<Message>>
         for Element<'a, Message, Theme>
     where
-        Theme: text::DefaultStyle
-            + button::Catalog
-            + text_input::DefaultStyle
-            + 'static,
+        Theme: text::Catalog + button::Catalog + text_input::Catalog + 'static,
         Message: 'a,
     {
         fn from(numeric_input: NumericInput<Message>) -> Self {

examples/gradient/src/main.rs

@@ -60,7 +60,7 @@ impl Gradient {
         } = *self;
 
         let gradient_box = container(horizontal_space())
-            .style(move |_theme, _status| {
+            .style(move |_theme| {
                 let gradient = gradient::Linear::new(angle)
                     .add_stop(0.0, start)
                     .add_stop(1.0, end);

examples/layout/src/main.rs

@@ -81,10 +81,10 @@ impl Layout {
         } else {
             self.example.view()
         })
-        .style(|theme, _status| {
+        .style(|theme| {
             let palette = theme.extended_palette();
 
-            container::Appearance::default()
+            container::Style::default()
                 .with_border(palette.background.strong.color, 4.0)
         })
         .padding(4)
@@ -245,10 +245,10 @@ fn application<'a>() -> Element<'a, Message> {
         .padding(10)
         .align_items(Alignment::Center),
     )
-    .style(|theme, _status| {
+    .style(|theme| {
         let palette = theme.extended_palette();
 
-        container::Appearance::default()
+        container::Style::default()
             .with_border(palette.background.strong.color, 1)
     });
 

examples/pane_grid/src/main.rs

@@ -338,39 +338,30 @@ mod style {
     use iced::widget::container;
     use iced::{Border, Theme};
 
-    pub fn title_bar_active(
-        theme: &Theme,
-        _status: container::Status,
-    ) -> container::Appearance {
+    pub fn title_bar_active(theme: &Theme) -> container::Style {
         let palette = theme.extended_palette();
 
-        container::Appearance {
+        container::Style {
             text_color: Some(palette.background.strong.text),
             background: Some(palette.background.strong.color.into()),
             ..Default::default()
         }
     }
 
-    pub fn title_bar_focused(
-        theme: &Theme,
-        _status: container::Status,
-    ) -> container::Appearance {
+    pub fn title_bar_focused(theme: &Theme) -> container::Style {
         let palette = theme.extended_palette();
 
-        container::Appearance {
+        container::Style {
             text_color: Some(palette.primary.strong.text),
             background: Some(palette.primary.strong.color.into()),
             ..Default::default()
         }
     }
 
-    pub fn pane_active(
-        theme: &Theme,
-        _status: container::Status,
-    ) -> container::Appearance {
+    pub fn pane_active(theme: &Theme) -> container::Style {
         let palette = theme.extended_palette();
 
-        container::Appearance {
+        container::Style {
             background: Some(palette.background.weak.color.into()),
             border: Border {
                 width: 2.0,
@@ -381,13 +372,10 @@ mod style {
         }
     }
 
-    pub fn pane_focused(
-        theme: &Theme,
-        _status: container::Status,
-    ) -> container::Appearance {
+    pub fn pane_focused(theme: &Theme) -> container::Style {
         let palette = theme.extended_palette();
 
-        container::Appearance {
+        container::Style {
             background: Some(palette.background.weak.color.into()),
             border: Border {
                 width: 2.0,

examples/scrollable/src/main.rs

@@ -341,8 +341,8 @@ impl Default for ScrollableDemo {
     }
 }
 
-fn progress_bar_custom_style(theme: &Theme) -> progress_bar::Appearance {
-    progress_bar::Appearance {
+fn progress_bar_custom_style(theme: &Theme) -> progress_bar::Style {
+    progress_bar::Style {
         background: theme.extended_palette().background.strong.color.into(),
         bar: Color::from_rgb8(250, 85, 134).into(),
         border: Border::default(),