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    Renderer: renderer::Renderer,
157    Message: Clone,
158    W: Widget<Message, Theme, Renderer>,
159{
160    fn tag(&self) -> tree::Tag {
161        tree::Tag::of::<State>()
162    }
163
164    fn state(&self) -> tree::State {
165        tree::State::new(State::default())
166    }
167
168    fn diff(&mut self, tree: &mut Tree) {
169        tree.diff_children(std::slice::from_mut(&mut self.content));
170    }
171
172    fn size(&self) -> Size<Length> {
173        self.content.size()
174    }
175
176    fn layout(&mut self, tree: &mut Tree, renderer: &Renderer, limits: &layout::Limits) {
177        self.content.layout(&mut tree.children[0], renderer, limits);
178
179        tree.size = tree.children[0].size;
180    }
181
182    fn operate(
183        &mut self,
184        tree: &mut Tree,
185        layout: Layout,
186        viewport: &Rectangle,
187        renderer: &Renderer,
188        operation: &mut dyn Operation,
189    ) {
190        self.content
191            .operate(&mut tree.children[0], layout, viewport, renderer, operation);
192    }
193
194    fn update(
195        &mut self,
196        tree: &mut Tree,
197        event: &Event,
198        layout: Layout,
199        cursor: mouse::Cursor,
200        renderer: &Renderer,
201        shell: &mut Shell<'_, Message>,
202        viewport: &Rectangle,
203    ) {
204        self.content.update(
205            &mut tree.children[0],
206            event,
207            layout,
208            cursor,
209            renderer,
210            shell,
211            viewport,
212        );
213
214        if shell.is_event_captured() {
215            return;
216        }
217
218        update(self, tree, event, layout, cursor, shell);
219    }
220
221    fn mouse_interaction(
222        &self,
223        tree: &Tree,
224        layout: Layout,
225        cursor: mouse::Cursor,
226        viewport: &Rectangle,
227        renderer: &Renderer,
228    ) -> mouse::Interaction {
229        let content_interaction =
230            self.content
231                .mouse_interaction(&tree.children[0], layout, cursor, viewport, renderer);
232
233        match (self.interaction, content_interaction) {
234            (Some(interaction), mouse::Interaction::None) if cursor.is_over(layout.bounds()) => {
235                interaction
236            }
237            _ => content_interaction,
238        }
239    }
240
241    fn draw(
242        &self,
243        tree: &Tree,
244        renderer: &mut Renderer,
245        theme: &Theme,
246        renderer_style: &renderer::Style,
247        layout: Layout,
248        cursor: mouse::Cursor,
249        viewport: &Rectangle,
250    ) {
251        self.content.draw(
252            &tree.children[0],
253            renderer,
254            theme,
255            renderer_style,
256            layout,
257            cursor,
258            viewport,
259        );
260    }
261
262    fn overlay<'b>(
263        &'b mut self,
264        tree: &'b mut Tree,
265        layout: Layout,
266        renderer: &Renderer,
267        viewport: &Rectangle,
268        translation: Vector,
269        window: Size,
270    ) -> Vec<overlay::Element<'b, Message, Theme, Renderer>> {
271        self.content.overlay(
272            &mut tree.children[0],
273            layout,
274            renderer,
275            viewport,
276            translation,
277            window,
278        )
279    }
280}
281
282/// Processes the given [`Event`] and updates the [`State`] of an [`MouseArea`]
283/// accordingly.
284fn update<Message: Clone, W>(
285    widget: &mut MouseArea<'_, Message, W>,
286    tree: &mut Tree,
287    event: &Event,
288    layout: Layout,
289    cursor: mouse::Cursor,
290    shell: &mut Shell<'_, Message>,
291) {
292    let state: &mut State = tree.state.downcast_mut();
293
294    let cursor_position = cursor.position();
295    let bounds = layout.bounds();
296
297    if state.cursor_position != cursor_position || state.bounds != bounds {
298        let was_hovered = state.is_hovered;
299
300        state.is_hovered = cursor.is_over(layout.bounds());
301        state.cursor_position = cursor_position;
302        state.bounds = bounds;
303
304        match (
305            widget.on_enter.as_ref(),
306            widget.on_move.as_ref(),
307            widget.on_exit.as_ref(),
308        ) {
309            (Some(on_enter), _, _) if state.is_hovered && !was_hovered => {
310                shell.publish(on_enter.clone());
311            }
312            (_, Some(on_move), _) if state.is_hovered => {
313                if let Some(position) = cursor.position_in(layout.bounds()) {
314                    shell.publish(on_move(position));
315                }
316            }
317            (_, _, Some(on_exit)) if !state.is_hovered && was_hovered => {
318                shell.publish(on_exit.clone());
319            }
320            _ => {}
321        }
322    }
323
324    if !cursor.is_over(layout.bounds()) {
325        return;
326    }
327
328    match event {
329        Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left))
330        | Event::Touch(touch::Event::FingerPressed { .. }) => {
331            if let Some(message) = widget.on_press.as_ref() {
332                shell.publish(message.clone());
333                shell.capture_event();
334            }
335
336            if let Some(position) = cursor_position
337                && let Some(message) = widget.on_double_click.as_ref()
338            {
339                let new_click =
340                    mouse::Click::new(position, mouse::Button::Left, state.previous_click);
341
342                if new_click.kind() == mouse::click::Kind::Double {
343                    shell.publish(message.clone());
344                }
345
346                state.previous_click = Some(new_click);
347
348                // Even if this is not a double click, but the press is nevertheless
349                // processed by us and should not be popup to parent widgets.
350                shell.capture_event();
351            }
352        }
353        Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Left))
354        | Event::Touch(touch::Event::FingerLifted { .. }) => {
355            if let Some(message) = widget.on_release.as_ref() {
356                shell.publish(message.clone());
357            }
358        }
359        Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Right)) => {
360            if let Some(message) = widget.on_right_press.as_ref() {
361                shell.publish(message.clone());
362                shell.capture_event();
363            }
364        }
365        Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Right)) => {
366            if let Some(message) = widget.on_right_release.as_ref() {
367                shell.publish(message.clone());
368            }
369        }
370        Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Middle)) => {
371            if let Some(message) = widget.on_middle_press.as_ref() {
372                shell.publish(message.clone());
373                shell.capture_event();
374            }
375        }
376        Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Middle)) => {
377            if let Some(message) = widget.on_middle_release.as_ref() {
378                shell.publish(message.clone());
379            }
380        }
381        Event::Mouse(mouse::Event::WheelScrolled { delta }) => {
382            if let Some(on_scroll) = widget.on_scroll.as_ref() {
383                shell.publish(on_scroll(*delta));
384                shell.capture_event();
385            }
386        }
387        _ => {}
388    }
389}
iced_widget/mouse_area.rs

iced_widget/
mouse_area.rs
