Add context menu

src/mouse_area.rs

@@ -0,0 +1,330 @@
+//! A container for capturing mouse events.
+
+use cosmic::iced_core::{
+    event::{self, Event},
+    layout, mouse, overlay, renderer, touch,
+    widget::{tree, Operation, OperationOutputWrapper, Tree},
+    {Clipboard, Element, Layout, Length, Point, Rectangle, Shell, Widget},
+};
+
+/// Emit messages on mouse events.
+#[allow(missing_debug_implementations)]
+pub struct MouseArea<'a, Message, Renderer> {
+    content: Element<'a, Message, Renderer>,
+    on_drag: Option<Box<dyn Fn(Option<Point>) -> Message + 'a>>,
+    on_press: Option<Box<dyn Fn(Option<Point>) -> Message + 'a>>,
+    on_release: Option<Box<dyn Fn(Option<Point>) -> Message + 'a>>,
+    on_right_press: Option<Box<dyn Fn(Option<Point>) -> Message + 'a>>,
+    on_right_release: Option<Box<dyn Fn(Option<Point>) -> Message + 'a>>,
+    on_middle_press: Option<Box<dyn Fn(Option<Point>) -> Message + 'a>>,
+    on_middle_release: Option<Box<dyn Fn(Option<Point>) -> Message + 'a>>,
+}
+
+impl<'a, Message, Renderer> MouseArea<'a, Message, Renderer> {
+    /// The message to emit when a drag is initiated.
+    #[must_use]
+    pub fn on_drag(mut self, message: impl Fn(Option<Point>) -> Message + 'a) -> Self {
+        self.on_drag = Some(Box::new(message));
+        self
+    }
+
+    /// The message to emit on a left button press.
+    #[must_use]
+    pub fn on_press(mut self, message: impl Fn(Option<Point>) -> Message + 'a) -> Self {
+        self.on_press = Some(Box::new(message));
+        self
+    }
+
+    /// The message to emit on a left button release.
+    #[must_use]
+    pub fn on_release(mut self, message: impl Fn(Option<Point>) -> Message + 'a) -> Self {
+        self.on_release = Some(Box::new(message));
+        self
+    }
+
+    /// The message to emit on a right button press.
+    #[must_use]
+    pub fn on_right_press(mut self, message: impl Fn(Option<Point>) -> Message + 'a) -> Self {
+        self.on_right_press = Some(Box::new(message));
+        self
+    }
+
+    /// The message to emit on a right button release.
+    #[must_use]
+    pub fn on_right_release(mut self, message: impl Fn(Option<Point>) -> Message + 'a) -> Self {
+        self.on_right_release = Some(Box::new(message));
+        self
+    }
+
+    /// The message to emit on a middle button press.
+    #[must_use]
+    pub fn on_middle_press(mut self, message: impl Fn(Option<Point>) -> Message + 'a) -> Self {
+        self.on_middle_press = Some(Box::new(message));
+        self
+    }
+
+    /// The message to emit on a middle button release.
+    #[must_use]
+    pub fn on_middle_release(mut self, message: impl Fn(Option<Point>) -> Message + 'a) -> Self {
+        self.on_middle_release = Some(Box::new(message));
+        self
+    }
+}
+
+/// Local state of the [`MouseArea`].
+#[derive(Default)]
+struct State {
+    // TODO: Support on_mouse_enter and on_mouse_exit
+    drag_initiated: Option<Point>,
+}
+
+impl<'a, Message, Renderer> MouseArea<'a, Message, Renderer> {
+    /// Creates a [`MouseArea`] with the given content.
+    pub fn new(content: impl Into<Element<'a, Message, Renderer>>) -> Self {
+        MouseArea {
+            content: content.into(),
+            on_drag: None,
+            on_press: None,
+            on_release: None,
+            on_right_press: None,
+            on_right_release: None,
+            on_middle_press: None,
+            on_middle_release: None,
+        }
+    }
+}
+
+impl<'a, Message, Renderer> Widget<Message, Renderer> for MouseArea<'a, Message, Renderer>
+where
+    Renderer: renderer::Renderer,
+    Message: Clone,
+{
+    fn tag(&self) -> tree::Tag {
+        tree::Tag::of::<State>()
+    }
+
+    fn state(&self) -> tree::State {
+        tree::State::new(State::default())
+    }
+
+    fn children(&self) -> Vec<Tree> {
+        vec![Tree::new(&self.content)]
+    }
+
+    fn diff(&mut self, tree: &mut Tree) {
+        tree.diff_children(std::slice::from_mut(&mut self.content));
+    }
+
+    fn width(&self) -> Length {
+        self.content.as_widget().width()
+    }
+
+    fn height(&self) -> Length {
+        self.content.as_widget().height()
+    }
+
+    fn layout(
+        &self,
+        tree: &mut Tree,
+        renderer: &Renderer,
+        limits: &layout::Limits,
+    ) -> layout::Node {
+        self.content
+            .as_widget()
+            .layout(&mut tree.children[0], renderer, limits)
+    }
+
+    fn operate(
+        &self,
+        tree: &mut Tree,
+        layout: Layout<'_>,
+        renderer: &Renderer,
+        operation: &mut dyn Operation<OperationOutputWrapper<Message>>,
+    ) {
+        self.content
+            .as_widget()
+            .operate(&mut tree.children[0], layout, renderer, operation);
+    }
+
+    fn on_event(
+        &mut self,
+        tree: &mut Tree,
+        event: Event,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        renderer: &Renderer,
+        clipboard: &mut dyn Clipboard,
+        shell: &mut Shell<'_, Message>,
+        viewport: &Rectangle,
+    ) -> event::Status {
+        if let event::Status::Captured = self.content.as_widget_mut().on_event(
+            &mut tree.children[0],
+            event.clone(),
+            layout,
+            cursor,
+            renderer,
+            clipboard,
+            shell,
+            viewport,
+        ) {
+            return event::Status::Captured;
+        }
+
+        update(
+            self,
+            &event,
+            layout,
+            cursor,
+            shell,
+            tree.state.downcast_mut::<State>(),
+        )
+    }
+
+    fn mouse_interaction(
+        &self,
+        tree: &Tree,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        viewport: &Rectangle,
+        renderer: &Renderer,
+    ) -> mouse::Interaction {
+        self.content.as_widget().mouse_interaction(
+            &tree.children[0],
+            layout,
+            cursor,
+            viewport,
+            renderer,
+        )
+    }
+
+    fn draw(
+        &self,
+        tree: &Tree,
+        renderer: &mut Renderer,
+        theme: &Renderer::Theme,
+        renderer_style: &renderer::Style,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        viewport: &Rectangle,
+    ) {
+        self.content.as_widget().draw(
+            &tree.children[0],
+            renderer,
+            theme,
+            renderer_style,
+            layout,
+            cursor,
+            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, renderer)
+    }
+}
+
+impl<'a, Message, Renderer> From<MouseArea<'a, Message, Renderer>>
+    for Element<'a, Message, Renderer>
+where
+    Message: 'a + Clone,
+    Renderer: 'a + renderer::Renderer,
+{
+    fn from(area: MouseArea<'a, Message, Renderer>) -> Element<'a, Message, Renderer> {
+        Element::new(area)
+    }
+}
+
+/// Processes the given [`Event`] and updates the [`State`] of an [`MouseArea`]
+/// accordingly.
+fn update<Message: Clone, Renderer>(
+    widget: &mut MouseArea<'_, Message, Renderer>,
+    event: &Event,
+    layout: Layout<'_>,
+    cursor: mouse::Cursor,
+    shell: &mut Shell<'_, Message>,
+    state: &mut State,
+) -> event::Status {
+    if !cursor.is_over(layout.bounds()) {
+        return event::Status::Ignored;
+    }
+
+    if let Some(message) = widget.on_press.as_ref() {
+        if let Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left))
+        | Event::Touch(touch::Event::FingerPressed { .. }) = event
+        {
+            state.drag_initiated = cursor.position();
+            shell.publish(message(cursor.position_in(layout.bounds())));
+
+            return event::Status::Captured;
+        }
+    }
+
+    if let Some(message) = widget.on_release.as_ref() {
+        if let Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Left))
+        | Event::Touch(touch::Event::FingerLifted { .. }) = event
+        {
+            state.drag_initiated = None;
+            shell.publish(message(cursor.position_in(layout.bounds())));
+
+            return event::Status::Captured;
+        }
+    }
+
+    if let Some(message) = widget.on_right_press.as_ref() {
+        if let Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Right)) = event {
+            shell.publish(message(cursor.position_in(layout.bounds())));
+
+            return event::Status::Captured;
+        }
+    }
+
+    if let Some(message) = widget.on_right_release.as_ref() {
+        if let Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Right)) = event {
+            shell.publish(message(cursor.position_in(layout.bounds())));
+
+            return event::Status::Captured;
+        }
+    }
+
+    if let Some(message) = widget.on_middle_press.as_ref() {
+        if let Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Middle)) = event {
+            shell.publish(message(cursor.position_in(layout.bounds())));
+
+            return event::Status::Captured;
+        }
+    }
+
+    if let Some(message) = widget.on_middle_release.as_ref() {
+        if let Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Middle)) = event {
+            shell.publish(message(cursor.position_in(layout.bounds())));
+
+            return event::Status::Captured;
+        }
+    }
+
+    if state.drag_initiated.is_none() && widget.on_drag.is_some() {
+        if let Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left))
+        | Event::Touch(touch::Event::FingerPressed { .. }) = event
+        {
+            state.drag_initiated = cursor.position();
+        }
+    } else if let Some((message, drag_source)) = widget.on_drag.as_ref().zip(state.drag_initiated) {
+        if let Some(position) = cursor.position() {
+            if position.distance(drag_source) > 1.0 {
+                state.drag_initiated = None;
+                shell.publish(message(cursor.position_in(layout.bounds())));
+
+                return event::Status::Captured;
+            }
+        }
+    }
+
+    event::Status::Ignored
+}