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::{Operation, Tree, tree};
8use crate::core::{
9    Clipboard, Element, Event, Layout, Length, Point, Rectangle, Shell, Size,
10    Vector, Widget,
11};
12
13/// Emit messages on mouse events.
14#[allow(missing_debug_implementations)]
15pub struct MouseArea<
16    'a,
17    Message,
18    Theme = crate::Theme,
19    Renderer = crate::Renderer,
20> {
21    content: Element<'a, Message, Theme, Renderer>,
22    on_press: Option<Message>,
23    on_release: Option<Message>,
24    on_double_click: Option<Message>,
25    on_right_press: Option<Message>,
26    on_right_release: Option<Message>,
27    on_middle_press: Option<Message>,
28    on_middle_release: Option<Message>,
29    on_scroll: Option<Box<dyn Fn(mouse::ScrollDelta) -> Message + 'a>>,
30    on_enter: Option<Message>,
31    on_move: Option<Box<dyn Fn(Point) -> Message + 'a>>,
32    on_exit: Option<Message>,
33    interaction: Option<mouse::Interaction>,
34}
35
36impl<'a, Message, Theme, Renderer> MouseArea<'a, Message, Theme, Renderer> {
37    /// The message to emit on a left button press.
38    #[must_use]
39    pub fn on_press(mut self, message: Message) -> Self {
40        self.on_press = Some(message);
41        self
42    }
43
44    /// The message to emit on a left button release.
45    #[must_use]
46    pub fn on_release(mut self, message: Message) -> Self {
47        self.on_release = Some(message);
48        self
49    }
50
51    /// The message to emit on a double click.
52    ///
53    /// If you use this with [`on_press`]/[`on_release`], those
54    /// event will be emit as normal.
55    ///
56    /// The events stream will be: on_press -> on_release -> on_press
57    /// -> on_double_click -> on_release -> on_press ...
58    ///
59    /// [`on_press`]: Self::on_press
60    /// [`on_release`]: Self::on_release
61    #[must_use]
62    pub fn on_double_click(mut self, message: Message) -> Self {
63        self.on_double_click = Some(message);
64        self
65    }
66
67    /// The message to emit on a right button press.
68    #[must_use]
69    pub fn on_right_press(mut self, message: Message) -> Self {
70        self.on_right_press = Some(message);
71        self
72    }
73
74    /// The message to emit on a right button release.
75    #[must_use]
76    pub fn on_right_release(mut self, message: Message) -> Self {
77        self.on_right_release = Some(message);
78        self
79    }
80
81    /// The message to emit on a middle button press.
82    #[must_use]
83    pub fn on_middle_press(mut self, message: Message) -> Self {
84        self.on_middle_press = Some(message);
85        self
86    }
87
88    /// The message to emit on a middle button release.
89    #[must_use]
90    pub fn on_middle_release(mut self, message: Message) -> Self {
91        self.on_middle_release = Some(message);
92        self
93    }
94
95    /// The message to emit when scroll wheel is used
96    #[must_use]
97    pub fn on_scroll(
98        mut self,
99        on_scroll: impl Fn(mouse::ScrollDelta) -> Message + 'a,
100    ) -> Self {
101        self.on_scroll = Some(Box::new(on_scroll));
102        self
103    }
104
105    /// The message to emit when the mouse enters the area.
106    #[must_use]
107    pub fn on_enter(mut self, message: Message) -> Self {
108        self.on_enter = Some(message);
109        self
110    }
111
112    /// The message to emit when the mouse moves in the area.
113    #[must_use]
114    pub fn on_move(mut self, on_move: impl Fn(Point) -> Message + 'a) -> Self {
115        self.on_move = Some(Box::new(on_move));
116        self
117    }
118
119    /// The message to emit when the mouse exits the area.
120    #[must_use]
121    pub fn on_exit(mut self, message: Message) -> Self {
122        self.on_exit = Some(message);
123        self
124    }
125
126    /// The [`mouse::Interaction`] to use when hovering the area.
127    #[must_use]
128    pub fn interaction(mut self, interaction: mouse::Interaction) -> Self {
129        self.interaction = Some(interaction);
130        self
131    }
132}
133
134/// Local state of the [`MouseArea`].
135#[derive(Default)]
136struct State {
137    is_hovered: bool,
138    bounds: Rectangle,
139    cursor_position: Option<Point>,
140    previous_click: Option<mouse::Click>,
141}
142
143impl<'a, Message, Theme, Renderer> MouseArea<'a, Message, Theme, Renderer> {
144    /// Creates a [`MouseArea`] with the given content.
145    pub fn new(
146        content: impl Into<Element<'a, Message, Theme, Renderer>>,
147    ) -> Self {
148        MouseArea {
149            content: content.into(),
150            on_press: None,
151            on_release: None,
152            on_double_click: None,
153            on_right_press: None,
154            on_right_release: None,
155            on_middle_press: None,
156            on_middle_release: None,
157            on_scroll: None,
158            on_enter: None,
159            on_move: None,
160            on_exit: None,
161            interaction: None,
162        }
163    }
164}
165
166impl<Message, Theme, Renderer> Widget<Message, Theme, Renderer>
167    for MouseArea<'_, Message, Theme, Renderer>
168where
169    Renderer: renderer::Renderer,
170    Message: Clone,
171{
172    fn tag(&self) -> tree::Tag {
173        tree::Tag::of::<State>()
174    }
175
176    fn state(&self) -> tree::State {
177        tree::State::new(State::default())
178    }
179
180    fn children(&self) -> Vec<Tree> {
181        vec![Tree::new(&self.content)]
182    }
183
184    fn diff(&self, tree: &mut Tree) {
185        tree.diff_children(std::slice::from_ref(&self.content));
186    }
187
188    fn size(&self) -> Size<Length> {
189        self.content.as_widget().size()
190    }
191
192    fn layout(
193        &self,
194        tree: &mut Tree,
195        renderer: &Renderer,
196        limits: &layout::Limits,
197    ) -> layout::Node {
198        self.content
199            .as_widget()
200            .layout(&mut tree.children[0], renderer, limits)
201    }
202
203    fn operate(
204        &self,
205        tree: &mut Tree,
206        layout: Layout<'_>,
207        renderer: &Renderer,
208        operation: &mut dyn Operation,
209    ) {
210        self.content.as_widget().operate(
211            &mut tree.children[0],
212            layout,
213            renderer,
214            operation,
215        );
216    }
217
218    fn update(
219        &mut self,
220        tree: &mut Tree,
221        event: &Event,
222        layout: Layout<'_>,
223        cursor: mouse::Cursor,
224        renderer: &Renderer,
225        clipboard: &mut dyn Clipboard,
226        shell: &mut Shell<'_, Message>,
227        viewport: &Rectangle,
228    ) {
229        self.content.as_widget_mut().update(
230            &mut tree.children[0],
231            event,
232            layout,
233            cursor,
234            renderer,
235            clipboard,
236            shell,
237            viewport,
238        );
239
240        if shell.is_event_captured() {
241            return;
242        }
243
244        update(self, tree, event, layout, cursor, shell);
245    }
246
247    fn mouse_interaction(
248        &self,
249        tree: &Tree,
250        layout: Layout<'_>,
251        cursor: mouse::Cursor,
252        viewport: &Rectangle,
253        renderer: &Renderer,
254    ) -> mouse::Interaction {
255        let content_interaction = self.content.as_widget().mouse_interaction(
256            &tree.children[0],
257            layout,
258            cursor,
259            viewport,
260            renderer,
261        );
262
263        match (self.interaction, content_interaction) {
264            (Some(interaction), mouse::Interaction::None)
265                if cursor.is_over(layout.bounds()) =>
266            {
267                interaction
268            }
269            _ => content_interaction,
270        }
271    }
272
273    fn draw(
274        &self,
275        tree: &Tree,
276        renderer: &mut Renderer,
277        theme: &Theme,
278        renderer_style: &renderer::Style,
279        layout: Layout<'_>,
280        cursor: mouse::Cursor,
281        viewport: &Rectangle,
282    ) {
283        self.content.as_widget().draw(
284            &tree.children[0],
285            renderer,
286            theme,
287            renderer_style,
288            layout,
289            cursor,
290            viewport,
291        );
292    }
293
294    fn overlay<'b>(
295        &'b mut self,
296        tree: &'b mut Tree,
297        layout: Layout<'b>,
298        renderer: &Renderer,
299        viewport: &Rectangle,
300        translation: Vector,
301    ) -> Option<overlay::Element<'b, Message, Theme, Renderer>> {
302        self.content.as_widget_mut().overlay(
303            &mut tree.children[0],
304            layout,
305            renderer,
306            viewport,
307            translation,
308        )
309    }
310}
311
312impl<'a, Message, Theme, Renderer> From<MouseArea<'a, Message, Theme, Renderer>>
313    for Element<'a, Message, Theme, Renderer>
314where
315    Message: 'a + Clone,
316    Theme: 'a,
317    Renderer: 'a + renderer::Renderer,
318{
319    fn from(
320        area: MouseArea<'a, Message, Theme, Renderer>,
321    ) -> Element<'a, Message, Theme, Renderer> {
322        Element::new(area)
323    }
324}
325
326/// Processes the given [`Event`] and updates the [`State`] of an [`MouseArea`]
327/// accordingly.
328fn update<Message: Clone, Theme, Renderer>(
329    widget: &mut MouseArea<'_, Message, Theme, Renderer>,
330    tree: &mut Tree,
331    event: &Event,
332    layout: Layout<'_>,
333    cursor: mouse::Cursor,
334    shell: &mut Shell<'_, Message>,
335) {
336    let state: &mut State = tree.state.downcast_mut();
337
338    let cursor_position = cursor.position();
339    let bounds = layout.bounds();
340
341    if state.cursor_position != cursor_position || state.bounds != bounds {
342        let was_hovered = state.is_hovered;
343
344        state.is_hovered = cursor.is_over(layout.bounds());
345        state.cursor_position = cursor_position;
346        state.bounds = bounds;
347
348        match (
349            widget.on_enter.as_ref(),
350            widget.on_move.as_ref(),
351            widget.on_exit.as_ref(),
352        ) {
353            (Some(on_enter), _, _) if state.is_hovered && !was_hovered => {
354                shell.publish(on_enter.clone());
355            }
356            (_, Some(on_move), _) if state.is_hovered => {
357                if let Some(position) = cursor.position_in(layout.bounds()) {
358                    shell.publish(on_move(position));
359                }
360            }
361            (_, _, Some(on_exit)) if !state.is_hovered && was_hovered => {
362                shell.publish(on_exit.clone());
363            }
364            _ => {}
365        }
366    }
367
368    if !cursor.is_over(layout.bounds()) {
369        return;
370    }
371
372    match event {
373        Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left))
374        | Event::Touch(touch::Event::FingerPressed { .. }) => {
375            if let Some(message) = widget.on_press.as_ref() {
376                shell.publish(message.clone());
377                shell.capture_event();
378            }
379
380            if let Some(position) = cursor_position {
381                if let Some(message) = widget.on_double_click.as_ref() {
382                    let new_click = mouse::Click::new(
383                        position,
384                        mouse::Button::Left,
385                        state.previous_click,
386                    );
387
388                    if new_click.kind() == mouse::click::Kind::Double {
389                        shell.publish(message.clone());
390                    }
391
392                    state.previous_click = Some(new_click);
393
394                    // Even if this is not a double click, but the press is nevertheless
395                    // processed by us and should not be popup to parent widgets.
396                    shell.capture_event();
397                }
398            }
399        }
400        Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Left))
401        | Event::Touch(touch::Event::FingerLifted { .. }) => {
402            if let Some(message) = widget.on_release.as_ref() {
403                shell.publish(message.clone());
404            }
405        }
406        Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Right)) => {
407            if let Some(message) = widget.on_right_press.as_ref() {
408                shell.publish(message.clone());
409                shell.capture_event();
410            }
411        }
412        Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Right)) => {
413            if let Some(message) = widget.on_right_release.as_ref() {
414                shell.publish(message.clone());
415            }
416        }
417        Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Middle)) => {
418            if let Some(message) = widget.on_middle_press.as_ref() {
419                shell.publish(message.clone());
420                shell.capture_event();
421            }
422        }
423        Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Middle)) => {
424            if let Some(message) = widget.on_middle_release.as_ref() {
425                shell.publish(message.clone());
426            }
427        }
428        Event::Mouse(mouse::Event::WheelScrolled { delta }) => {
429            if let Some(on_scroll) = widget.on_scroll.as_ref() {
430                shell.publish(on_scroll(*delta));
431                shell.capture_event();
432            }
433        }
434        _ => {}
435    }
436}
iced_widget/mouse_area.rs

iced_widget/
mouse_area.rs
