Create `iced_widget` subcrate and re-organize the whole codebase

1 files changed, 471 insertions, 0 deletions

diff --git a/widget/src/slider.rs b/widget/src/slider.rs
new file mode 100644
index 00000000..70a84fc6
--- /dev/null
+++ b/widget/src/slider.rs
@@ -0,0 +1,471 @@
+//! Display an interactive selector of a single value from a range of values.
+//!
+//! A [`Slider`] has some local [`State`].
+use crate::core::event::{self, Event};
+use crate::core::layout;
+use crate::core::mouse;
+use crate::core::renderer;
+use crate::core::touch;
+use crate::core::widget::tree::{self, Tree};
+use crate::core::{
+    Background, Clipboard, Color, Element, Layout, Length, Pixels, Point,
+    Rectangle, Shell, Size, Widget,
+};
+
+use std::ops::RangeInclusive;
+
+pub use iced_style::slider::{Appearance, Handle, HandleShape, 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
+/// ```
+/// # type Slider<'a, T, Message> =
+/// #     iced_widget::Slider<'a, Message, T, iced_widget::renderer::Renderer<iced_widget::style::Theme>>;
+/// #
+/// #[derive(Clone)]
+/// pub enum Message {
+///     SliderChanged(f32),
+/// }
+///
+/// let value = 50.0;
+///
+/// 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)
+#[allow(missing_debug_implementations)]
+pub struct Slider<'a, T, Message, Renderer = crate::Renderer>
+where
+    Renderer: crate::core::Renderer,
+    Renderer::Theme: StyleSheet,
+{
+    range: RangeInclusive<T>,
+    step: T,
+    value: T,
+    on_change: Box<dyn Fn(T) -> Message + 'a>,
+    on_release: Option<Message>,
+    width: Length,
+    height: f32,
+    style: <Renderer::Theme as StyleSheet>::Style,
+}
+
+impl<'a, T, Message, Renderer> Slider<'a, T, Message, Renderer>
+where
+    T: Copy + From<u8> + std::cmp::PartialOrd,
+    Message: Clone,
+    Renderer: crate::core::Renderer,
+    Renderer::Theme: StyleSheet,
+{
+    /// The default height of a [`Slider`].
+    pub const DEFAULT_HEIGHT: f32 = 22.0;
+
+    /// 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: 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: impl Into<Length>) -> Self {
+        self.width = width.into();
+        self
+    }
+
+    /// Sets the height of the [`Slider`].
+    pub fn height(mut self, height: impl Into<Pixels>) -> Self {
+        self.height = height.into().0;
+        self
+    }
+
+    /// Sets the style of the [`Slider`].
+    pub fn style(
+        mut self,
+        style: impl Into<<Renderer::Theme as StyleSheet>::Style>,
+    ) -> Self {
+        self.style = style.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, Renderer>
+where
+    T: Copy + Into<f64> + num_traits::FromPrimitive,
+    Message: Clone,
+    Renderer: crate::core::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(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::core::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>(
+    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, R>(
+    renderer: &mut R,
+    layout: Layout<'_>,
+    cursor_position: Point,
+    state: &State,
+    value: T,
+    range: &RangeInclusive<T>,
+    style_sheet: &dyn StyleSheet<Style = <R::Theme as StyleSheet>::Style>,
+    style: &<R::Theme as StyleSheet>::Style,
+) where
+    T: Into<f64> + Copy,
+    R: crate::core::Renderer,
+    R::Theme: StyleSheet,
+{
+    let bounds = layout.bounds();
+    let is_mouse_over = bounds.contains(cursor_position);
+
+    let style = if state.is_dragging {
+        style_sheet.dragging(style)
+    } else if is_mouse_over {
+        style_sheet.hovered(style)
+    } else {
+        style_sheet.active(style)
+    };
+
+    let rail_y = bounds.y + (bounds.height / 2.0).round();
+
+    renderer.fill_quad(
+        renderer::Quad {
+            bounds: Rectangle {
+                x: bounds.x,
+                y: rail_y - 1.0,
+                width: bounds.width,
+                height: 2.0,
+            },
+            border_radius: 0.0.into(),
+            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 + 1.0,
+                width: bounds.width,
+                height: 2.0,
+            },
+            border_radius: 0.0.into(),
+            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), 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.into(),
+            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()
+    }
+}
+
+/// The local state of a [`Slider`].
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
+pub struct State {
+    is_dragging: bool,
+}
+
+impl State {
+    /// Creates a new [`State`].
+    pub fn new() -> State {
+        State::default()
+    }
+}