feat(segmented-button): Configurable background and hover styling

src/widget/segmented_button/mod.rs

@@ -13,8 +13,16 @@ use iced::{
     event, mouse, touch, Background, Color, Element, Event, Length, Point, Rectangle, Size,
 };
 use iced_core::BorderRadius;
+use iced_native::widget::tree;
 use iced_native::{layout, renderer, widget::Tree, Clipboard, Layout, Shell, Widget};
 
+/// State that is maintained by the widget internally.
+#[derive(Default)]
+struct PrivateWidgetState {
+    /// The ID of the button that is being hovered. Defaults to null.
+    hovered: Key,
+}
+
 /// A linear set of options for choosing between.
 #[derive(Setters)]
 pub struct SegmentedButton<'a, Message, Renderer>
@@ -73,6 +81,14 @@ where
     Renderer::Theme: StyleSheet,
     Message: 'static + Clone,
 {
+    fn tag(&self) -> tree::Tag {
+        tree::Tag::of::<PrivateWidgetState>()
+    }
+
+    fn state(&self) -> tree::State {
+        tree::State::new(PrivateWidgetState::default())
+    }
+
     fn width(&self) -> Length {
         self.width
     }
@@ -101,7 +117,7 @@ where
 
     fn on_event(
         &mut self,
-        _tree: &mut Tree,
+        tree: &mut Tree,
         event: Event,
         layout: Layout<'_>,
         cursor_position: Point,
@@ -110,6 +126,7 @@ where
         shell: &mut Shell<'_, Message>,
     ) -> event::Status {
         let bounds = layout.bounds();
+        let state = tree.state.downcast_mut::<PrivateWidgetState>();
 
         if bounds.contains(cursor_position) {
             let button_width = bounds.width / self.state.buttons.len() as f32;
@@ -119,6 +136,9 @@ where
                 bounds.x += num as f32 * button_width;
 
                 if bounds.contains(cursor_position) {
+                    // Record that the mouse is hovering over this button.
+                    state.hovered = key;
+
                     if let Some(on_activate) = self.on_activate.as_ref() {
                         if let Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Left))
                         | Event::Touch(touch::Event::FingerLifted { .. }) = event
@@ -129,6 +149,8 @@ where
                     }
                 }
             }
+        } else {
+            state.hovered = Key::default();
         }
 
         event::Status::Ignored
@@ -151,7 +173,7 @@ where
 
     fn draw(
         &self,
-        _tree: &Tree,
+        tree: &Tree,
         renderer: &mut Renderer,
         theme: &<Renderer as iced_native::Renderer>::Theme,
         _style: &renderer::Style,
@@ -159,9 +181,23 @@ where
         _cursor_position: iced::Point,
         _viewport: &iced::Rectangle,
     ) {
+        let state = tree.state.downcast_ref::<PrivateWidgetState>();
         let appearance = theme.appearance(&self.style);
         let bounds = layout.bounds();
-        let button_width = bounds.width / self.state.buttons.len() as f32;
+        let button_amount = self.state.buttons.len();
+        let button_width = bounds.width / button_amount as f32;
+
+        if let Some(background) = appearance.background {
+            renderer.fill_quad(
+                renderer::Quad {
+                    bounds,
+                    border_radius: appearance.border_radius,
+                    border_width: appearance.border_width,
+                    border_color: appearance.border_color,
+                },
+                background,
+            );
+        }
 
         for (num, (key, content)) in self.state.buttons.iter().enumerate() {
             let mut bounds = bounds;
@@ -170,6 +206,8 @@ where
 
             let button_appearance = if self.state.active == key {
                 appearance.button_active
+            } else if state.hovered == key {
+                appearance.button_hover
             } else {
                 appearance.button_inactive
             };
@@ -182,7 +220,13 @@ where
                 renderer.fill_quad(
                     renderer::Quad {
                         bounds,
-                        border_radius: button_appearance.border_radius,
+                        border_radius: if num == 0 {
+                            button_appearance.border_radius_first
+                        } else if num + 1 == button_amount {
+                            button_appearance.border_radius_last
+                        } else {
+                            button_appearance.border_radius_middle
+                        },
                         border_width: 0.0,
                         border_color: Color::TRANSPARENT,
                     },

src/widget/segmented_button/style.rs

@@ -6,16 +6,23 @@ use iced_core::{Background, BorderRadius, Color};
 /// The appearance of a [`SegmentedButton`].
 #[derive(Clone, Copy)]
 pub struct Appearance {
+    pub background: Option<Background>,
+    pub border_color: Color,
+    pub border_radius: BorderRadius,
+    pub border_width: f32,
     pub button_active: ButtonAppearance,
     pub button_inactive: ButtonAppearance,
+    pub button_hover: ButtonAppearance,
 }
 
 /// The appearance of a button in the [`SegmentedButton`]
 #[derive(Clone, Copy)]
 pub struct ButtonAppearance {
     pub background: Option<Background>,
-    pub border_radius: BorderRadius,
     pub border_bottom: Option<(f32, Color)>,
+    pub border_radius_first: BorderRadius,
+    pub border_radius_middle: BorderRadius,
+    pub border_radius_last: BorderRadius,
     pub text_color: Color,
 }