feat(native): Add MouseListener widget

4 files changed, 424 insertions, 0 deletions

diff --git a/native/src/widget.rs b/native/src/widget.rs
index 2b3ca7be..4eb3d1ba 100644
--- a/native/src/widget.rs
+++ b/native/src/widget.rs
@@ -17,6 +17,7 @@ pub mod column;
 pub mod container;
 pub mod helpers;
 pub mod image;
+pub mod mouse_listener;
 pub mod operation;
 pub mod pane_grid;
 pub mod pick_list;
@@ -51,6 +52,8 @@ pub use helpers::*;
 #[doc(no_inline)]
 pub use image::Image;
 #[doc(no_inline)]
+pub use mouse_listener::MouseListener;
+#[doc(no_inline)]
 pub use pane_grid::PaneGrid;
 #[doc(no_inline)]
 pub use pick_list::PickList;
diff --git a/native/src/widget/helpers.rs b/native/src/widget/helpers.rs
index b25e064d..88986d60 100644
--- a/native/src/widget/helpers.rs
+++ b/native/src/widget/helpers.rs
@@ -314,3 +314,13 @@ where
 {
     widget::Svg::new(handle)
 }
+
+/// A container intercepting mouse events.
+pub fn mouse_listener<'a, Message, Renderer>(
+    widget: impl Into<Element<'a, Message, Renderer>>,
+) -> widget::MouseListener<'a, Message, Renderer>
+where
+    Renderer: crate::Renderer,
+{
+    widget::MouseListener::new(widget)
+}
diff --git a/native/src/widget/mouse_listener.rs b/native/src/widget/mouse_listener.rs
new file mode 100644
index 00000000..0add7c71
--- /dev/null
+++ b/native/src/widget/mouse_listener.rs
@@ -0,0 +1,403 @@
+//! A container for capturing mouse events.
+
+use crate::event::{self, Event};
+use crate::layout;
+use crate::mouse;
+use crate::overlay;
+use crate::renderer;
+use crate::touch;
+use crate::widget::{tree, Operation, Tree};
+use crate::{
+    Clipboard, Element, Layout, Length, Point, Rectangle, Shell, Widget,
+};
+
+use std::u32;
+
+/// Emit messages on mouse events.
+#[allow(missing_debug_implementations)]
+pub struct MouseListener<'a, Message, Renderer> {
+    content: Element<'a, Message, Renderer>,
+
+    /// Sets the message to emit on a left mouse button press.
+    on_press: Option<Message>,
+
+    /// Sets the message to emit on a left mouse button release.
+    on_release: Option<Message>,
+
+    /// Sets the message to emit on a right mouse button press.
+    on_right_press: Option<Message>,
+
+    /// Sets the message to emit on a right mouse button release.
+    on_right_release: Option<Message>,
+
+    /// Sets the message to emit on a middle mouse button press.
+    on_middle_press: Option<Message>,
+
+    /// Sets the message to emit on a middle mouse button release.
+    on_middle_release: Option<Message>,
+
+    /// Sets the message to emit when the mouse enters the widget.
+    on_mouse_enter: Option<Message>,
+
+    /// Sets the messsage to emit when the mouse exits the widget.
+    on_mouse_exit: Option<Message>,
+}
+
+impl<'a, Message, Renderer> MouseListener<'a, Message, Renderer> {
+    /// The message to emit on a left button press.
+    #[must_use]
+    pub fn on_press(mut self, message: Message) -> Self {
+        self.on_press = Some(message);
+        self
+    }
+
+    /// The message to emit on a left button release.
+    #[must_use]
+    pub fn on_release(mut self, message: Message) -> Self {
+        self.on_release = Some(message);
+        self
+    }
+
+    /// The message to emit on a right button press.
+    #[must_use]
+    pub fn on_right_press(mut self, message: Message) -> Self {
+        self.on_right_press = Some(message);
+        self
+    }
+
+    /// The message to emit on a right button release.
+    #[must_use]
+    pub fn on_right_release(mut self, message: Message) -> Self {
+        self.on_right_release = Some(message);
+        self
+    }
+
+    /// The message to emit on a middle button press.
+    #[must_use]
+    pub fn on_middle_press(mut self, message: Message) -> Self {
+        self.on_middle_press = Some(message);
+        self
+    }
+
+    /// The message to emit on a middle button release.
+    #[must_use]
+    pub fn on_middle_release(mut self, message: Message) -> Self {
+        self.on_middle_release = Some(message);
+        self
+    }
+
+    /// The message to emit when the mouse enters the widget.
+    #[must_use]
+    pub fn on_mouse_enter(mut self, message: Message) -> Self {
+        self.on_mouse_enter = Some(message);
+        self
+    }
+
+    /// The messsage to emit when the mouse exits the widget.
+    #[must_use]
+    pub fn on_mouse_exit(mut self, message: Message) -> Self {
+        self.on_mouse_exit = Some(message);
+        self
+    }
+}
+
+/// Local state of the [`MouseListener`].
+#[derive(Default)]
+struct State {
+    hovered: bool,
+}
+
+impl<'a, Message, Renderer> MouseListener<'a, Message, Renderer> {
+    /// Creates an empty [`MouseListener`].
+    pub fn new(content: impl Into<Element<'a, Message, Renderer>>) -> Self {
+        MouseListener {
+            content: content.into(),
+            on_press: None,
+            on_release: None,
+            on_right_press: None,
+            on_right_release: None,
+            on_middle_press: None,
+            on_middle_release: None,
+            on_mouse_enter: None,
+            on_mouse_exit: None,
+        }
+    }
+}
+
+impl<'a, Message, Renderer> Widget<Message, Renderer>
+    for MouseListener<'a, Message, Renderer>
+where
+    Renderer: crate::Renderer,
+    Message: Clone,
+{
+    fn children(&self) -> Vec<Tree> {
+        vec![Tree::new(&self.content)]
+    }
+
+    fn diff(&self, tree: &mut Tree) {
+        tree.diff_children(std::slice::from_ref(&self.content));
+    }
+
+    fn width(&self) -> Length {
+        self.content.as_widget().width()
+    }
+
+    fn height(&self) -> Length {
+        self.content.as_widget().height()
+    }
+
+    fn layout(
+        &self,
+        renderer: &Renderer,
+        limits: &layout::Limits,
+    ) -> layout::Node {
+        layout(
+            renderer,
+            limits,
+            Widget::<Message, Renderer>::width(self),
+            Widget::<Message, Renderer>::height(self),
+            u32::MAX,
+            u32::MAX,
+            |renderer, limits| {
+                self.content.as_widget().layout(renderer, limits)
+            },
+        )
+    }
+
+    fn operate(
+        &self,
+        tree: &mut Tree,
+        layout: Layout<'_>,
+        renderer: &Renderer,
+        operation: &mut dyn Operation<Message>,
+    ) {
+        operation.container(None, &mut |operation| {
+            self.content.as_widget().operate(
+                &mut tree.children[0],
+                layout.children().next().unwrap(),
+                renderer,
+                operation,
+            );
+        });
+    }
+
+    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 {
+        if let event::Status::Captured = self.content.as_widget_mut().on_event(
+            &mut tree.children[0],
+            event.clone(),
+            layout.children().next().unwrap(),
+            cursor_position,
+            renderer,
+            clipboard,
+            shell,
+        ) {
+            return event::Status::Captured;
+        }
+
+        update(
+            self,
+            &event,
+            layout,
+            cursor_position,
+            shell,
+            tree.state.downcast_mut::<State>(),
+        )
+    }
+
+    fn mouse_interaction(
+        &self,
+        tree: &Tree,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        viewport: &Rectangle,
+        renderer: &Renderer,
+    ) -> mouse::Interaction {
+        self.content.as_widget().mouse_interaction(
+            &tree.children[0],
+            layout.children().next().unwrap(),
+            cursor_position,
+            viewport,
+            renderer,
+        )
+    }
+
+    fn draw(
+        &self,
+        tree: &Tree,
+        renderer: &mut Renderer,
+        theme: &Renderer::Theme,
+        renderer_style: &renderer::Style,
+        layout: Layout<'_>,
+        cursor_position: Point,
+        viewport: &Rectangle,
+    ) {
+        self.content.as_widget().draw(
+            &tree.children[0],
+            renderer,
+            theme,
+            renderer_style,
+            layout.children().next().unwrap(),
+            cursor_position,
+            viewport,
+        );
+    }
+
+    fn overlay<'b>(
+        &'b mut self,
+        tree: &'b mut Tree,
+        layout: Layout<'_>,
+        renderer: &Renderer,
+    ) -> Option<overlay::Element<'b, Message, Renderer>> {
+        self.content.as_widget_mut().overlay(
+            &mut tree.children[0],
+            layout.children().next().unwrap(),
+            renderer,
+        )
+    }
+
+    fn tag(&self) -> tree::Tag {
+        tree::Tag::of::<State>()
+    }
+
+    fn state(&self) -> tree::State {
+        tree::State::new(State::default())
+    }
+}
+
+impl<'a, Message, Renderer> From<MouseListener<'a, Message, Renderer>>
+    for Element<'a, Message, Renderer>
+where
+    Message: 'a + Clone,
+    Renderer: 'a + crate::Renderer,
+{
+    fn from(
+        listener: MouseListener<'a, Message, Renderer>,
+    ) -> Element<'a, Message, Renderer> {
+        Element::new(listener)
+    }
+}
+
+/// Processes the given [`Event`] and updates the [`State`] of an [`MouseListener`]
+/// accordingly.
+fn update<Message: Clone, Renderer>(
+    widget: &mut MouseListener<'_, Message, Renderer>,
+    event: &Event,
+    layout: Layout<'_>,
+    cursor_position: Point,
+    shell: &mut Shell<'_, Message>,
+    state: &mut State,
+) -> event::Status {
+    let hovered = state.hovered;
+
+    if !layout.bounds().contains(cursor_position) {
+        if hovered {
+            state.hovered = false;
+            if let Some(message) = widget.on_mouse_exit.clone() {
+                shell.publish(message);
+                return event::Status::Captured;
+            }
+        }
+
+        return event::Status::Ignored;
+    }
+
+    state.hovered = true;
+
+    if !hovered {
+        if let Some(message) = widget.on_mouse_enter.clone() {
+            shell.publish(message);
+            return event::Status::Captured;
+        }
+    }
+
+    if let Some(message) = widget.on_press.clone() {
+        if let Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left))
+        | Event::Touch(touch::Event::FingerPressed { .. }) = event
+        {
+            shell.publish(message);
+            return event::Status::Captured;
+        }
+    }
+
+    if let Some(message) = widget.on_release.clone() {
+        if let Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Left))
+        | Event::Touch(touch::Event::FingerLifted { .. }) = event
+        {
+            shell.publish(message);
+            return event::Status::Captured;
+        }
+    }
+
+    if let Some(message) = widget.on_right_press.clone() {
+        if let Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Right)) =
+            event
+        {
+            shell.publish(message);
+            return event::Status::Captured;
+        }
+    }
+
+    if let Some(message) = widget.on_right_release.clone() {
+        if let Event::Mouse(mouse::Event::ButtonReleased(
+            mouse::Button::Right,
+        )) = event
+        {
+            shell.publish(message);
+            return event::Status::Captured;
+        }
+    }
+
+    if let Some(message) = widget.on_middle_press.clone() {
+        if let Event::Mouse(mouse::Event::ButtonPressed(
+            mouse::Button::Middle,
+        )) = event
+        {
+            shell.publish(message);
+            return event::Status::Captured;
+        }
+    }
+
+    if let Some(message) = widget.on_middle_release.clone() {
+        if let Event::Mouse(mouse::Event::ButtonReleased(
+            mouse::Button::Middle,
+        )) = event
+        {
+            shell.publish(message);
+            return event::Status::Captured;
+        }
+    }
+
+    event::Status::Ignored
+}
+
+/// Computes the layout of a [`MouseListener`].
+pub fn layout<Renderer>(
+    renderer: &Renderer,
+    limits: &layout::Limits,
+    width: Length,
+    height: Length,
+    max_height: u32,
+    max_width: u32,
+    layout_content: impl FnOnce(&Renderer, &layout::Limits) -> layout::Node,
+) -> layout::Node {
+    let limits = limits
+        .loose()
+        .max_height(max_height)
+        .max_width(max_width)
+        .width(width)
+        .height(height);
+
+    let content = layout_content(renderer, &limits);
+    let size = limits.resolve(content.size());
+
+    layout::Node::with_children(size, vec![content])
+}
diff --git a/src/widget.rs b/src/widget.rs
index c0ac716f..15b34ffa 100644
--- a/src/widget.rs
+++ b/src/widget.rs
@@ -47,6 +47,14 @@ pub mod container {
         iced_native::widget::Container<'a, Message, Renderer>;
 }
 
+pub mod mouse_listener {
+    //! Intercept mouse events on a widget.
+
+    /// A container intercepting mouse events.
+    pub type MouseListener<'a, Message, Renderer = crate::Renderer> =
+        iced_native::widget::MouseListener<'a, Message, Renderer>;
+}
+
 pub mod pane_grid {
     //! Let your users split regions of your application and organize layout dynamically.
     //!