Implement Slider in iced_pure

native/src/widget/slider.rs

@@ -143,6 +143,215 @@ where
     }
 }
 
+/// Processes an [`Event`] and updates the [`State`] of a [`Slider`]
+/// accordingly.
+pub fn update<Message, T>(
+    event: Event,
+    layout: Layout<'_>,
+    cursor_position: Point,
+    shell: &mut Shell<'_, Message>,
+    state: &mut State,
+    value: &mut T,
+    range: &RangeInclusive<T>,
+    step: T,
+    on_change: &dyn Fn(T) -> Message,
+    on_release: &Option<Message>,
+) -> event::Status
+where
+    T: Copy + Into<f64> + num_traits::FromPrimitive,
+    Message: Clone,
+{
+    let is_dragging = state.is_dragging;
+
+    let mut change = || {
+        let bounds = layout.bounds();
+        let new_value = if cursor_position.x <= bounds.x {
+            *range.start()
+        } else if cursor_position.x >= bounds.x + bounds.width {
+            *range.end()
+        } else {
+            let step = step.into();
+            let start = (*range.start()).into();
+            let end = (*range.end()).into();
+
+            let percent = f64::from(cursor_position.x - bounds.x)
+                / f64::from(bounds.width);
+
+            let steps = (percent * (end - start) / step).round();
+            let value = steps * step + start;
+
+            if let Some(value) = T::from_f64(value) {
+                value
+            } else {
+                return;
+            }
+        };
+
+        if ((*value).into() - new_value.into()).abs() > f64::EPSILON {
+            shell.publish((on_change)(new_value));
+
+            *value = new_value;
+        }
+    };
+
+    match event {
+        Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left))
+        | Event::Touch(touch::Event::FingerPressed { .. }) => {
+            if layout.bounds().contains(cursor_position) {
+                change();
+                state.is_dragging = true;
+
+                return event::Status::Captured;
+            }
+        }
+        Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Left))
+        | Event::Touch(touch::Event::FingerLifted { .. })
+        | Event::Touch(touch::Event::FingerLost { .. }) => {
+            if is_dragging {
+                if let Some(on_release) = on_release.clone() {
+                    shell.publish(on_release);
+                }
+                state.is_dragging = false;
+
+                return event::Status::Captured;
+            }
+        }
+        Event::Mouse(mouse::Event::CursorMoved { .. })
+        | Event::Touch(touch::Event::FingerMoved { .. }) => {
+            if is_dragging {
+                change();
+
+                return event::Status::Captured;
+            }
+        }
+        _ => {}
+    }
+
+    event::Status::Ignored
+}
+
+/// Draws a [`Slider`].
+pub fn draw<T>(
+    renderer: &mut impl crate::Renderer,
+    layout: Layout<'_>,
+    cursor_position: Point,
+    state: &State,
+    value: T,
+    range: &RangeInclusive<T>,
+    style_sheet: &dyn StyleSheet,
+) where
+    T: Into<f64> + Copy,
+{
+    let bounds = layout.bounds();
+    let is_mouse_over = bounds.contains(cursor_position);
+
+    let style = if state.is_dragging {
+        style_sheet.dragging()
+    } else if is_mouse_over {
+        style_sheet.hovered()
+    } else {
+        style_sheet.active()
+    };
+
+    let rail_y = bounds.y + (bounds.height / 2.0).round();
+
+    renderer.fill_quad(
+        renderer::Quad {
+            bounds: Rectangle {
+                x: bounds.x,
+                y: rail_y,
+                width: bounds.width,
+                height: 2.0,
+            },
+            border_radius: 0.0,
+            border_width: 0.0,
+            border_color: Color::TRANSPARENT,
+        },
+        style.rail_colors.0,
+    );
+
+    renderer.fill_quad(
+        renderer::Quad {
+            bounds: Rectangle {
+                x: bounds.x,
+                y: rail_y + 2.0,
+                width: bounds.width,
+                height: 2.0,
+            },
+            border_radius: 0.0,
+            border_width: 0.0,
+            border_color: Color::TRANSPARENT,
+        },
+        Background::Color(style.rail_colors.1),
+    );
+
+    let (handle_width, handle_height, handle_border_radius) = match style
+        .handle
+        .shape
+    {
+        HandleShape::Circle { radius } => (radius * 2.0, radius * 2.0, radius),
+        HandleShape::Rectangle {
+            width,
+            border_radius,
+        } => (f32::from(width), f32::from(bounds.height), border_radius),
+    };
+
+    let value = value.into() as f32;
+    let (range_start, range_end) = {
+        let (start, end) = range.clone().into_inner();
+
+        (start.into() as f32, end.into() as f32)
+    };
+
+    let handle_offset = if range_start >= range_end {
+        0.0
+    } else {
+        (bounds.width - handle_width) * (value - range_start)
+            / (range_end - range_start)
+    };
+
+    renderer.fill_quad(
+        renderer::Quad {
+            bounds: Rectangle {
+                x: bounds.x + handle_offset.round(),
+                y: rail_y - handle_height / 2.0,
+                width: handle_width,
+                height: handle_height,
+            },
+            border_radius: handle_border_radius,
+            border_width: style.handle.border_width,
+            border_color: style.handle.border_color,
+        },
+        style.handle.color,
+    );
+}
+
+/// Computes the current [`mouse::Interaction`] of a [`Slider`].
+pub fn mouse_interaction(
+    layout: Layout<'_>,
+    cursor_position: Point,
+    state: &State,
+) -> mouse::Interaction {
+    let bounds = layout.bounds();
+    let is_mouse_over = bounds.contains(cursor_position);
+
+    if state.is_dragging {
+        mouse::Interaction::Grabbing
+    } else if is_mouse_over {
+        mouse::Interaction::Grab
+    } else {
+        mouse::Interaction::default()
+    }
+}
+
+/// Hashes the layout of a [`Slider`].
+pub fn hash_layout(state: &mut Hasher, width: Length) {
+    struct Marker;
+    std::any::TypeId::of::<Marker>().hash(state);
+
+    width.hash(state);
+}
+
 /// The local state of a [`Slider`].
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
 pub struct State {
@@ -193,73 +402,18 @@ where
         _clipboard: &mut dyn Clipboard,
         shell: &mut Shell<'_, Message>,
     ) -> event::Status {
-        let is_dragging = self.state.is_dragging;
+        update(
-
+            event,
-        let mut change = || {
+            layout,
-            let bounds = layout.bounds();
+            cursor_position,
-            let new_value = if cursor_position.x <= bounds.x {
+            shell,
-                *self.range.start()
+            &mut self.state,
-            } else if cursor_position.x >= bounds.x + bounds.width {
+            &mut self.value,
-                *self.range.end()
+            &self.range,
-            } else {
+            self.step,
-                let step = self.step.into();
+            self.on_change.as_ref(),
-                let start = (*self.range.start()).into();
+            &self.on_release,
-                let end = (*self.range.end()).into();
+        )
-
-                let percent = f64::from(cursor_position.x - bounds.x)
-                    / f64::from(bounds.width);
-
-                let steps = (percent * (end - start) / step).round();
-                let value = steps * step + start;
-
-                if let Some(value) = T::from_f64(value) {
-                    value
-                } else {
-                    return;
-                }
-            };
-
-            if (self.value.into() - new_value.into()).abs() > f64::EPSILON {
-                shell.publish((self.on_change)(new_value));
-
-                self.value = new_value;
-            }
-        };
-
-        match event {
-            Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left))
-            | Event::Touch(touch::Event::FingerPressed { .. }) => {
-                if layout.bounds().contains(cursor_position) {
-                    change();
-                    self.state.is_dragging = true;
-
-                    return event::Status::Captured;
-                }
-            }
-            Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Left))
-            | Event::Touch(touch::Event::FingerLifted { .. })
-            | Event::Touch(touch::Event::FingerLost { .. }) => {
-                if is_dragging {
-                    if let Some(on_release) = self.on_release.clone() {
-                        shell.publish(on_release);
-                    }
-                    self.state.is_dragging = false;
-
-                    return event::Status::Captured;
-                }
-            }
-            Event::Mouse(mouse::Event::CursorMoved { .. })
-            | Event::Touch(touch::Event::FingerMoved { .. }) => {
-                if is_dragging {
-                    change();
-
-                    return event::Status::Captured;
-                }
-            }
-            _ => {}
-        }
-
-        event::Status::Ignored
     }
 
     fn draw(
@@ -270,90 +424,15 @@ where
         cursor_position: Point,
         _viewport: &Rectangle,
     ) {
-        let bounds = layout.bounds();
+        draw(
-        let is_mouse_over = bounds.contains(cursor_position);
+            renderer,
-
+            layout,
-        let style = if self.state.is_dragging {
+            cursor_position,
-            self.style_sheet.dragging()
+            &self.state,
-        } else if is_mouse_over {
+            self.value,
-            self.style_sheet.hovered()
+            &self.range,
-        } else {
+            self.style_sheet.as_ref(),
-            self.style_sheet.active()
+        )
-        };
-
-        let rail_y = bounds.y + (bounds.height / 2.0).round();
-
-        renderer.fill_quad(
-            renderer::Quad {
-                bounds: Rectangle {
-                    x: bounds.x,
-                    y: rail_y,
-                    width: bounds.width,
-                    height: 2.0,
-                },
-                border_radius: 0.0,
-                border_width: 0.0,
-                border_color: Color::TRANSPARENT,
-            },
-            style.rail_colors.0,
-        );
-
-        renderer.fill_quad(
-            renderer::Quad {
-                bounds: Rectangle {
-                    x: bounds.x,
-                    y: rail_y + 2.0,
-                    width: bounds.width,
-                    height: 2.0,
-                },
-                border_radius: 0.0,
-                border_width: 0.0,
-                border_color: Color::TRANSPARENT,
-            },
-            Background::Color(style.rail_colors.1),
-        );
-
-        let (handle_width, handle_height, handle_border_radius) = match style
-            .handle
-            .shape
-        {
-            HandleShape::Circle { radius } => {
-                (radius * 2.0, radius * 2.0, radius)
-            }
-            HandleShape::Rectangle {
-                width,
-                border_radius,
-            } => (f32::from(width), f32::from(bounds.height), border_radius),
-        };
-
-        let value = self.value.into() as f32;
-        let (range_start, range_end) = {
-            let (start, end) = self.range.clone().into_inner();
-
-            (start.into() as f32, end.into() as f32)
-        };
-
-        let handle_offset = if range_start >= range_end {
-            0.0
-        } else {
-            (bounds.width - handle_width) * (value - range_start)
-                / (range_end - range_start)
-        };
-
-        renderer.fill_quad(
-            renderer::Quad {
-                bounds: Rectangle {
-                    x: bounds.x + handle_offset.round(),
-                    y: rail_y - handle_height / 2.0,
-                    width: handle_width,
-                    height: handle_height,
-                },
-                border_radius: handle_border_radius,
-                border_width: style.handle.border_width,
-                border_color: style.handle.border_color,
-            },
-            style.handle.color,
-        );
     }
 
     fn mouse_interaction(
@@ -363,23 +442,11 @@ where
         _viewport: &Rectangle,
         _renderer: &Renderer,
     ) -> mouse::Interaction {
-        let bounds = layout.bounds();
+        mouse_interaction(layout, cursor_position, &self.state)
-        let is_mouse_over = bounds.contains(cursor_position);
-
-        if self.state.is_dragging {
-            mouse::Interaction::Grabbing
-        } else if is_mouse_over {
-            mouse::Interaction::Grab
-        } else {
-            mouse::Interaction::default()
-        }
     }
 
     fn hash_layout(&self, state: &mut Hasher) {
-        struct Marker;
+        hash_layout(state, self.width)
-        std::any::TypeId::of::<Marker>().hash(state);
-
-        self.width.hash(state);
     }
 }
 

pure/Cargo.toml

@@ -6,3 +6,4 @@ edition = "2021"
 [dependencies]
 iced_native = { version = "0.4", path = "../native" }
 iced_style = { version = "0.3", path = "../style" }
+num-traits = "0.2"

pure/src/widget.rs

@@ -7,6 +7,7 @@ mod container;
 mod element;
 mod row;
 mod scrollable;
+mod slider;
 mod text;
 mod text_input;
 mod tree;
@@ -19,6 +20,7 @@ pub use element::Element;
 pub use image::Image;
 pub use row::Row;
 pub use scrollable::Scrollable;
+pub use slider::Slider;
 pub use text::Text;
 pub use text_input::TextInput;
 pub use tree::Tree;
@@ -36,8 +38,6 @@ pub trait Widget<Message, Renderer> {
 
     fn state(&self) -> Box<dyn Any>;
 
-    fn diff(&self, tree: &mut Tree);
-
     fn children_state(&self) -> Vec<Tree>;
 
     fn width(&self) -> Length;
@@ -62,6 +62,8 @@ pub trait Widget<Message, Renderer> {
         viewport: &Rectangle,
     );
 
+    fn diff(&self, _tree: &mut Tree) {}
+
     fn mouse_interaction(
         &self,
         _state: &Tree,
@@ -149,6 +151,19 @@ where
     TextInput::new(placeholder, value, on_change)
 }
 
+pub fn slider<'a, Message, Renderer, T>(
+    range: std::ops::RangeInclusive<T>,
+    value: T,
+    on_change: impl Fn(T) -> Message + 'a,
+) -> Slider<'a, T, Message>
+where
+    Message: Clone,
+    Renderer: iced_native::Renderer,
+    T: Copy + From<u8> + std::cmp::PartialOrd,
+{
+    Slider::new(range, value, on_change)
+}
+
 pub fn image<Handle>(handle: Handle) -> Image<Handle> {
     Image::new(handle)
 }

pure/src/widget/slider.rs

@@ -0,0 +1,253 @@
+//! Display an interactive selector of a single value from a range of values.
+//!
+//! A [`Slider`] has some local [`State`].
+use crate::{Element, Tree, Widget};
+
+use iced_native::event::{self, Event};
+use iced_native::layout;
+use iced_native::mouse;
+use iced_native::renderer;
+use iced_native::widget::slider;
+use iced_native::{
+    Clipboard, Hasher, Layout, Length, Point, Rectangle, Shell, Size,
+};
+
+use std::any::{self, Any};
+use std::ops::RangeInclusive;
+
+pub use iced_style::slider::{Handle, HandleShape, Style, StyleSheet};
+
+/// An horizontal bar and a handle that selects a single value from a range of
+/// values.
+///
+/// A [`Slider`] will try to fill the horizontal space of its container.
+///
+/// The [`Slider`] range of numeric values is generic and its step size defaults
+/// to 1 unit.
+///
+/// # Example
+/// ```
+/// # use iced_native::widget::slider::{self, Slider};
+/// #
+/// #[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 drawn by Coffee's renderer](https://github.com/hecrj/coffee/blob/bda9818f823dfcb8a7ad0ff4940b4d4b387b5208/images/ui/slider.png?raw=true)
+#[allow(missing_debug_implementations)]
+pub struct Slider<'a, T, Message> {
+    range: RangeInclusive<T>,
+    step: T,
+    value: T,
+    on_change: Box<dyn Fn(T) -> Message + 'a>,
+    on_release: Option<Message>,
+    width: Length,
+    height: u16,
+    style_sheet: Box<dyn StyleSheet + 'a>,
+}
+
+impl<'a, T, Message> Slider<'a, T, Message>
+where
+    T: Copy + From<u8> + std::cmp::PartialOrd,
+    Message: Clone,
+{
+    /// The default height of a [`Slider`].
+    pub const DEFAULT_HEIGHT: u16 = 22;
+
+    /// Creates a new [`Slider`].
+    ///
+    /// It expects:
+    ///   * 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>(range: RangeInclusive<T>, value: T, on_change: F) -> Self
+    where
+        F: 'a + Fn(T) -> Message,
+    {
+        let value = if value >= *range.start() {
+            value
+        } else {
+            *range.start()
+        };
+
+        let value = if value <= *range.end() {
+            value
+        } else {
+            *range.end()
+        };
+
+        Slider {
+            value,
+            range,
+            step: T::from(1),
+            on_change: Box::new(on_change),
+            on_release: None,
+            width: Length::Fill,
+            height: Self::DEFAULT_HEIGHT,
+            style_sheet: Default::default(),
+        }
+    }
+
+    /// Sets the release message of the [`Slider`].
+    /// This is called when the mouse is released from the slider.
+    ///
+    /// Typically, the user's interaction with the slider is finished when this message is produced.
+    /// This is useful if you need to spawn a long-running task from the slider's result, where
+    /// the default on_change message could create too many events.
+    pub fn on_release(mut self, on_release: Message) -> Self {
+        self.on_release = Some(on_release);
+        self
+    }
+
+    /// Sets the width of the [`Slider`].
+    pub fn width(mut self, width: Length) -> Self {
+        self.width = width;
+        self
+    }
+
+    /// Sets the height of the [`Slider`].
+    pub fn height(mut self, height: u16) -> Self {
+        self.height = height;
+        self
+    }
+
+    /// Sets the style of the [`Slider`].
+    pub fn style(
+        mut self,
+        style_sheet: impl Into<Box<dyn StyleSheet + 'a>>,
+    ) -> Self {
+        self.style_sheet = style_sheet.into();
+        self
+    }
+
+    /// Sets the step size of the [`Slider`].
+    pub fn step(mut self, step: T) -> Self {
+        self.step = step;
+        self
+    }
+}
+
+impl<'a, T, Message, Renderer> Widget<Message, Renderer>
+    for Slider<'a, T, Message>
+where
+    T: Copy + Into<f64> + num_traits::FromPrimitive,
+    Message: Clone,
+    Renderer: iced_native::Renderer,
+{
+    fn tag(&self) -> any::TypeId {
+        any::TypeId::of::<slider::State>()
+    }
+
+    fn state(&self) -> Box<dyn Any> {
+        Box::new(slider::State::new())
+    }
+
+    fn children_state(&self) -> Vec<Tree> {
+        Vec::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 {
+        slider::update(
+            event,
+            layout,
+            cursor_position,
+            shell,
+            tree.state.downcast_mut::<slider::State>(),
+            &mut self.value,
+            &self.range,
+            self.step,
+            self.on_change.as_ref(),
+            &self.on_release,
+        )
+    }
+
+    fn draw(
+        &self,
+        tree: &Tree,
+        renderer: &mut Renderer,
+        _style: &renderer::Style,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        _viewport: &Rectangle,
+    ) {
+        slider::draw(
+            renderer,
+            layout,
+            cursor_position,
+            tree.state.downcast_ref::<slider::State>(),
+            self.value,
+            &self.range,
+            self.style_sheet.as_ref(),
+        )
+    }
+
+    fn mouse_interaction(
+        &self,
+        tree: &Tree,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        _viewport: &Rectangle,
+        _renderer: &Renderer,
+    ) -> mouse::Interaction {
+        slider::mouse_interaction(
+            layout,
+            cursor_position,
+            tree.state.downcast_ref::<slider::State>(),
+        )
+    }
+
+    fn hash_layout(&self, state: &mut Hasher) {
+        slider::hash_layout(state, self.width)
+    }
+}
+
+impl<'a, T, Message, Renderer> From<Slider<'a, T, Message>>
+    for Element<'a, Message, Renderer>
+where
+    T: 'a + Copy + Into<f64> + num_traits::FromPrimitive,
+    Message: 'a + Clone,
+    Renderer: 'a + iced_native::Renderer,
+{
+    fn from(slider: Slider<'a, T, Message>) -> Element<'a, Message, Renderer> {
+        Element::new(slider)
+    }
+}