Replace stateful widgets with new iced_pure API

native/src/widget/slider.rs

@@ -6,6 +6,7 @@ use crate::layout;
 use crate::mouse;
 use crate::renderer;
 use crate::touch;
+use crate::widget::tree::{self, Tree};
 use crate::{
     Background, Clipboard, Color, Element, Layout, Length, Point, Rectangle,
     Shell, Size, Widget,
@@ -29,15 +30,15 @@ pub use iced_style::slider::{Appearance, Handle, HandleShape, StyleSheet};
 /// # use iced_native::renderer::Null;
 /// #
 /// # type Slider<'a, T, Message> = slider::Slider<'a, T, Message, Null>;
+/// #
 /// #[derive(Clone)]
 /// pub enum Message {
 ///     SliderChanged(f32),
 /// }
 ///
-/// let state = &mut slider::State::new();
 /// let value = 50.0;
 ///
-/// Slider::new(state, 0.0..=100.0, value, Message::SliderChanged);
+/// Slider::new(0.0..=100.0, value, Message::SliderChanged);
 /// ```
 ///
 /// ![Slider drawn by Coffee's renderer](https://github.com/hecrj/coffee/blob/bda9818f823dfcb8a7ad0ff4940b4d4b387b5208/images/ui/slider.png?raw=true)
@@ -47,11 +48,10 @@ where
     Renderer: crate::Renderer,
     Renderer::Theme: StyleSheet,
 {
-    state: &'a mut State,
     range: RangeInclusive<T>,
     step: T,
     value: T,
-    on_change: Box<dyn Fn(T) -> Message>,
+    on_change: Box<dyn Fn(T) -> Message + 'a>,
     on_release: Option<Message>,
     width: Length,
     height: u16,
@@ -71,20 +71,14 @@ where
     /// Creates a new [`Slider`].
     ///
     /// It expects:
-    ///   * the local [`State`] of the [`Slider`]
     ///   * an inclusive range of possible values
     ///   * the current value of the [`Slider`]
     ///   * a function that will be called when the [`Slider`] is dragged.
     ///   It receives the new value of the [`Slider`] and must produce a
     ///   `Message`.
-    pub fn new<F>(
-        state: &'a mut State,
-        range: RangeInclusive<T>,
-        value: T,
-        on_change: F,
-    ) -> Self
+    pub fn new<F>(range: RangeInclusive<T>, value: T, on_change: F) -> Self
     where
-        F: 'static + Fn(T) -> Message,
+        F: 'a + Fn(T) -> Message,
     {
         let value = if value >= *range.start() {
             value
@@ -99,7 +93,6 @@ where
         };
 
         Slider {
-            state,
             value,
             range,
             step: T::from(1),
@@ -150,6 +143,120 @@ where
     }
 }
 
+impl<'a, T, Message, Renderer> Widget<Message, Renderer>
+    for Slider<'a, T, Message, Renderer>
+where
+    T: Copy + Into<f64> + num_traits::FromPrimitive,
+    Message: Clone,
+    Renderer: crate::Renderer,
+    Renderer::Theme: StyleSheet,
+{
+    fn tag(&self) -> tree::Tag {
+        tree::Tag::of::<State>()
+    }
+
+    fn state(&self) -> tree::State {
+        tree::State::new(State::new())
+    }
+
+    fn width(&self) -> Length {
+        self.width
+    }
+
+    fn height(&self) -> Length {
+        Length::Shrink
+    }
+
+    fn layout(
+        &self,
+        _renderer: &Renderer,
+        limits: &layout::Limits,
+    ) -> layout::Node {
+        let limits =
+            limits.width(self.width).height(Length::Units(self.height));
+
+        let size = limits.resolve(Size::ZERO);
+
+        layout::Node::new(size)
+    }
+
+    fn on_event(
+        &mut self,
+        tree: &mut Tree,
+        event: Event,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        _renderer: &Renderer,
+        _clipboard: &mut dyn Clipboard,
+        shell: &mut Shell<'_, Message>,
+    ) -> event::Status {
+        update(
+            event,
+            layout,
+            cursor_position,
+            shell,
+            tree.state.downcast_mut::<State>(),
+            &mut self.value,
+            &self.range,
+            self.step,
+            self.on_change.as_ref(),
+            &self.on_release,
+        )
+    }
+
+    fn draw(
+        &self,
+        tree: &Tree,
+        renderer: &mut Renderer,
+        theme: &Renderer::Theme,
+        _style: &renderer::Style,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        _viewport: &Rectangle,
+    ) {
+        draw(
+            renderer,
+            layout,
+            cursor_position,
+            tree.state.downcast_ref::<State>(),
+            self.value,
+            &self.range,
+            theme,
+            self.style,
+        )
+    }
+
+    fn mouse_interaction(
+        &self,
+        tree: &Tree,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        _viewport: &Rectangle,
+        _renderer: &Renderer,
+    ) -> mouse::Interaction {
+        mouse_interaction(
+            layout,
+            cursor_position,
+            tree.state.downcast_ref::<State>(),
+        )
+    }
+}
+
+impl<'a, T, Message, Renderer> From<Slider<'a, T, Message, Renderer>>
+    for Element<'a, Message, Renderer>
+where
+    T: 'a + Copy + Into<f64> + num_traits::FromPrimitive,
+    Message: 'a + Clone,
+    Renderer: 'a + crate::Renderer,
+    Renderer::Theme: StyleSheet,
+{
+    fn from(
+        slider: Slider<'a, T, Message, Renderer>,
+    ) -> Element<'a, Message, Renderer> {
+        Element::new(slider)
+    }
+}
+
 /// Processes an [`Event`] and updates the [`State`] of a [`Slider`]
 /// accordingly.
 pub fn update<Message, T>(
@@ -366,102 +473,3 @@ impl State {
         State::default()
     }
 }
-
-impl<'a, T, Message, Renderer> Widget<Message, Renderer>
-    for Slider<'a, T, Message, Renderer>
-where
-    T: Copy + Into<f64> + num_traits::FromPrimitive,
-    Message: Clone,
-    Renderer: crate::Renderer,
-    Renderer::Theme: StyleSheet,
-{
-    fn width(&self) -> Length {
-        self.width
-    }
-
-    fn height(&self) -> Length {
-        Length::Shrink
-    }
-
-    fn layout(
-        &self,
-        _renderer: &Renderer,
-        limits: &layout::Limits,
-    ) -> layout::Node {
-        let limits =
-            limits.width(self.width).height(Length::Units(self.height));
-
-        let size = limits.resolve(Size::ZERO);
-
-        layout::Node::new(size)
-    }
-
-    fn on_event(
-        &mut self,
-        event: Event,
-        layout: Layout<'_>,
-        cursor_position: Point,
-        _renderer: &Renderer,
-        _clipboard: &mut dyn Clipboard,
-        shell: &mut Shell<'_, Message>,
-    ) -> event::Status {
-        update(
-            event,
-            layout,
-            cursor_position,
-            shell,
-            self.state,
-            &mut self.value,
-            &self.range,
-            self.step,
-            self.on_change.as_ref(),
-            &self.on_release,
-        )
-    }
-
-    fn draw(
-        &self,
-        renderer: &mut Renderer,
-        theme: &Renderer::Theme,
-        _style: &renderer::Style,
-        layout: Layout<'_>,
-        cursor_position: Point,
-        _viewport: &Rectangle,
-    ) {
-        draw(
-            renderer,
-            layout,
-            cursor_position,
-            self.state,
-            self.value,
-            &self.range,
-            theme,
-            self.style,
-        )
-    }
-
-    fn mouse_interaction(
-        &self,
-        layout: Layout<'_>,
-        cursor_position: Point,
-        _viewport: &Rectangle,
-        _renderer: &Renderer,
-    ) -> mouse::Interaction {
-        mouse_interaction(layout, cursor_position, self.state)
-    }
-}
-
-impl<'a, T, Message, Renderer> From<Slider<'a, T, Message, Renderer>>
-    for Element<'a, Message, Renderer>
-where
-    T: 'a + Copy + Into<f64> + num_traits::FromPrimitive,
-    Message: 'a + Clone,
-    Renderer: 'a + crate::Renderer,
-    Renderer::Theme: StyleSheet,
-{
-    fn from(
-        slider: Slider<'a, T, Message, Renderer>,
-    ) -> Element<'a, Message, Renderer> {
-        Element::new(slider)
-    }
-}