iced_widget/
mouse_area.rs

1//! A container for capturing mouse events.
2use crate::core::layout;
3use crate::core::mouse;
4use crate::core::overlay;
5use crate::core::renderer;
6use crate::core::touch;
7use crate::core::widget::{Meta, Operation, Tree, tree};
8use crate::core::{Event, Layout, Length, Point, Rectangle, Shell, Size, Vector, Widget};
9
10/// Emit messages on mouse events.
11pub struct MouseArea<'a, Message, W = crate::Element<'a, Message>> {
12    content: W,
13    on_press: Option<Message>,
14    on_release: Option<Message>,
15    on_double_click: Option<Message>,
16    on_right_press: Option<Message>,
17    on_right_release: Option<Message>,
18    on_middle_press: Option<Message>,
19    on_middle_release: Option<Message>,
20    on_scroll: Option<Box<dyn Fn(mouse::ScrollDelta) -> Message + 'a>>,
21    on_enter: Option<Message>,
22    on_move: Option<Box<dyn Fn(Point) -> Message + 'a>>,
23    on_exit: Option<Message>,
24    interaction: Option<mouse::Interaction>,
25}
26
27impl<'a, Message, W> MouseArea<'a, Message, W> {
28    /// The message to emit on a left button press.
29    #[must_use]
30    pub fn on_press(mut self, message: Message) -> Self {
31        self.on_press = Some(message);
32        self
33    }
34
35    /// The message to emit on a left button release.
36    #[must_use]
37    pub fn on_release(mut self, message: Message) -> Self {
38        self.on_release = Some(message);
39        self
40    }
41
42    /// The message to emit on a double click.
43    ///
44    /// If you use this with [`on_press`]/[`on_release`], those
45    /// event will be emit as normal.
46    ///
47    /// The events stream will be: on_press -> on_release -> on_press
48    /// -> on_double_click -> on_release -> on_press ...
49    ///
50    /// [`on_press`]: Self::on_press
51    /// [`on_release`]: Self::on_release
52    #[must_use]
53    pub fn on_double_click(mut self, message: Message) -> Self {
54        self.on_double_click = Some(message);
55        self
56    }
57
58    /// The message to emit on a right button press.
59    #[must_use]
60    pub fn on_right_press(mut self, message: Message) -> Self {
61        self.on_right_press = Some(message);
62        self
63    }
64
65    /// The message to emit on a right button release.
66    #[must_use]
67    pub fn on_right_release(mut self, message: Message) -> Self {
68        self.on_right_release = Some(message);
69        self
70    }
71
72    /// The message to emit on a middle button press.
73    #[must_use]
74    pub fn on_middle_press(mut self, message: Message) -> Self {
75        self.on_middle_press = Some(message);
76        self
77    }
78
79    /// The message to emit on a middle button release.
80    #[must_use]
81    pub fn on_middle_release(mut self, message: Message) -> Self {
82        self.on_middle_release = Some(message);
83        self
84    }
85
86    /// The message to emit when scroll wheel is used
87    #[must_use]
88    pub fn on_scroll(mut self, on_scroll: impl Fn(mouse::ScrollDelta) -> Message + 'a) -> Self {
89        self.on_scroll = Some(Box::new(on_scroll));
90        self
91    }
92
93    /// The message to emit when the mouse enters the area.
94    #[must_use]
95    pub fn on_enter(mut self, message: Message) -> Self {
96        self.on_enter = Some(message);
97        self
98    }
99
100    /// The message to emit when the mouse moves in the area.
101    #[must_use]
102    pub fn on_move(mut self, on_move: impl Fn(Point) -> Message + 'a) -> Self {
103        self.on_move = Some(Box::new(on_move));
104        self
105    }
106
107    /// The message to emit when the mouse exits the area.
108    #[must_use]
109    pub fn on_exit(mut self, message: Message) -> Self {
110        self.on_exit = Some(message);
111        self
112    }
113
114    /// The [`mouse::Interaction`] to use when hovering the area.
115    #[must_use]
116    pub fn interaction(mut self, interaction: mouse::Interaction) -> Self {
117        self.interaction = Some(interaction);
118        self
119    }
120}
121
122/// Local state of the [`MouseArea`].
123#[derive(Default)]
124struct State {
125    is_hovered: bool,
126    bounds: Rectangle,
127    cursor_position: Option<Point>,
128    previous_click: Option<mouse::Click>,
129}
130
131impl<'a, Message, W> MouseArea<'a, Message, W> {
132    /// Creates a [`MouseArea`] with the given content.
133    pub fn new(content: W) -> Self {
134        MouseArea {
135            content,
136            on_press: None,
137            on_release: None,
138            on_double_click: None,
139            on_right_press: None,
140            on_right_release: None,
141            on_middle_press: None,
142            on_middle_release: None,
143            on_scroll: None,
144            on_enter: None,
145            on_move: None,
146            on_exit: None,
147            interaction: None,
148        }
149    }
150}
151
152impl<Message, W> Meta for MouseArea<'_, Message, W> {}
153
154impl<Message, W, Theme, Renderer> Widget<Message, Theme, Renderer> for MouseArea<'_, Message, W>
155where
156    Message: Clone,
157    W: Widget<Message, Theme, Renderer>,
158{
159    fn tag(&self) -> tree::Tag {
160        tree::Tag::of::<State>()
161    }
162
163    fn state(&self) -> tree::State {
164        tree::State::new(State::default())
165    }
166
167    fn diff(&mut self, tree: &mut Tree) {
168        tree.diff_children(std::slice::from_mut(&mut self.content));
169    }
170
171    fn size(&self) -> Size<Length> {
172        self.content.size()
173    }
174
175    fn layout(&mut self, tree: &mut Tree, renderer: &Renderer, limits: &layout::Limits) {
176        self.content.layout(&mut tree.children[0], renderer, limits);
177
178        tree.size = tree.children[0].size;
179    }
180
181    fn operate(
182        &mut self,
183        tree: &mut Tree,
184        layout: Layout,
185        viewport: &Rectangle,
186        renderer: &Renderer,
187        operation: &mut dyn Operation,
188    ) {
189        self.content
190            .operate(&mut tree.children[0], layout, viewport, renderer, operation);
191    }
192
193    fn update(
194        &mut self,
195        tree: &mut Tree,
196        event: &Event,
197        layout: Layout,
198        cursor: mouse::Cursor,
199        renderer: &Renderer,
200        shell: &mut Shell<'_, Message>,
201        viewport: &Rectangle,
202    ) {
203        self.content.update(
204            &mut tree.children[0],
205            event,
206            layout,
207            cursor,
208            renderer,
209            shell,
210            viewport,
211        );
212
213        if shell.is_event_captured() {
214            return;
215        }
216
217        update(self, tree, event, layout, cursor, shell);
218    }
219
220    fn mouse_interaction(
221        &self,
222        tree: &Tree,
223        layout: Layout,
224        cursor: mouse::Cursor,
225        viewport: &Rectangle,
226        renderer: &Renderer,
227    ) -> mouse::Interaction {
228        let content_interaction =
229            self.content
230                .mouse_interaction(&tree.children[0], layout, cursor, viewport, renderer);
231
232        match (self.interaction, content_interaction) {
233            (Some(interaction), mouse::Interaction::None) if cursor.is_over(layout.bounds()) => {
234                interaction
235            }
236            _ => content_interaction,
237        }
238    }
239
240    fn draw(
241        &self,
242        tree: &Tree,
243        renderer: &mut Renderer,
244        theme: &Theme,
245        renderer_style: &renderer::Style,
246        layout: Layout,
247        cursor: mouse::Cursor,
248        viewport: &Rectangle,
249    ) {
250        self.content.draw(
251            &tree.children[0],
252            renderer,
253            theme,
254            renderer_style,
255            layout,
256            cursor,
257            viewport,
258        );
259    }
260
261    fn overlay<'b>(
262        &'b mut self,
263        tree: &'b mut Tree,
264        layout: Layout,
265        renderer: &Renderer,
266        viewport: &Rectangle,
267        translation: Vector,
268        window: Size,
269    ) -> Vec<overlay::Element<'b, Message, Theme, Renderer>> {
270        self.content.overlay(
271            &mut tree.children[0],
272            layout,
273            renderer,
274            viewport,
275            translation,
276            window,
277        )
278    }
279}
280
281/// Processes the given [`Event`] and updates the [`State`] of an [`MouseArea`]
282/// accordingly.
283fn update<Message: Clone, W>(
284    widget: &mut MouseArea<'_, Message, W>,
285    tree: &mut Tree,
286    event: &Event,
287    layout: Layout,
288    cursor: mouse::Cursor,
289    shell: &mut Shell<'_, Message>,
290) {
291    let state: &mut State = tree.state.downcast_mut();
292
293    let cursor_position = cursor.position();
294    let bounds = layout.bounds();
295
296    if state.cursor_position != cursor_position || state.bounds != bounds {
297        let was_hovered = state.is_hovered;
298
299        state.is_hovered = cursor.is_over(layout.bounds());
300        state.cursor_position = cursor_position;
301        state.bounds = bounds;
302
303        match (
304            widget.on_enter.as_ref(),
305            widget.on_move.as_ref(),
306            widget.on_exit.as_ref(),
307        ) {
308            (Some(on_enter), _, _) if state.is_hovered && !was_hovered => {
309                shell.publish(on_enter.clone());
310            }
311            (_, Some(on_move), _) if state.is_hovered => {
312                if let Some(position) = cursor.position_in(layout.bounds()) {
313                    shell.publish(on_move(position));
314                }
315            }
316            (_, _, Some(on_exit)) if !state.is_hovered && was_hovered => {
317                shell.publish(on_exit.clone());
318            }
319            _ => {}
320        }
321    }
322
323    if !cursor.is_over(layout.bounds()) {
324        return;
325    }
326
327    match event {
328        Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left))
329        | Event::Touch(touch::Event::FingerPressed { .. }) => {
330            if let Some(message) = widget.on_press.as_ref() {
331                shell.publish(message.clone());
332                shell.capture_event();
333            }
334
335            if let Some(position) = cursor_position
336                && let Some(message) = widget.on_double_click.as_ref()
337            {
338                let new_click =
339                    mouse::Click::new(position, mouse::Button::Left, state.previous_click);
340
341                if new_click.kind() == mouse::click::Kind::Double {
342                    shell.publish(message.clone());
343                }
344
345                state.previous_click = Some(new_click);
346
347                // Even if this is not a double click, but the press is nevertheless
348                // processed by us and should not be popup to parent widgets.
349                shell.capture_event();
350            }
351        }
352        Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Left))
353        | Event::Touch(touch::Event::FingerLifted { .. }) => {
354            if let Some(message) = widget.on_release.as_ref() {
355                shell.publish(message.clone());
356            }
357        }
358        Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Right)) => {
359            if let Some(message) = widget.on_right_press.as_ref() {
360                shell.publish(message.clone());
361                shell.capture_event();
362            }
363        }
364        Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Right)) => {
365            if let Some(message) = widget.on_right_release.as_ref() {
366                shell.publish(message.clone());
367            }
368        }
369        Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Middle)) => {
370            if let Some(message) = widget.on_middle_press.as_ref() {
371                shell.publish(message.clone());
372                shell.capture_event();
373            }
374        }
375        Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Middle)) => {
376            if let Some(message) = widget.on_middle_release.as_ref() {
377                shell.publish(message.clone());
378            }
379        }
380        Event::Mouse(mouse::Event::WheelScrolled { delta }) => {
381            if let Some(on_scroll) = widget.on_scroll.as_ref() {
382                shell.publish(on_scroll(*delta));
383                shell.capture_event();
384            }
385        }
386        _ => {}
387    }
388}
iced_widget/mouse_area.rs

iced_widget/
mouse_area.rs
