iced_widget/
button.rs

1//! Buttons allow your users to perform actions by pressing them.
2//!
3//! # Example
4//! ```no_run
5//! # mod iced { pub mod widget { pub use iced_widget::*; } pub use iced_widget::Renderer; pub use iced_widget::core::*; }
6//! # use iced::widget::Widget;
7//! # pub type State = ();
8//! use iced::widget::button;
9//!
10//! #[derive(Clone)]
11//! enum Message {
12//!     ButtonPressed,
13//! }
14//!
15//! fn view(state: &State) -> impl Widget<Message> {
16//!     button("Press me!").on_press(Message::ButtonPressed)
17//! }
18//! ```
19use crate::core::border::{self, Border};
20use crate::core::layout;
21use crate::core::mouse;
22use crate::core::overlay;
23use crate::core::renderer;
24use crate::core::theme::palette;
25use crate::core::touch;
26use crate::core::widget::tree::{self, Tree};
27use crate::core::widget::{Meta, Operation};
28use crate::core::window;
29use crate::core::{
30    Background, Color, Event, Layout, Length, Padding, Rectangle, Shadow, Shell, Size, Theme,
31    Vector, Widget,
32};
33
34/// A generic widget that produces a message when pressed.
35///
36/// # Example
37/// ```no_run
38/// # mod iced { pub mod widget { pub use iced_widget::*; } pub use iced_widget::Renderer; pub use iced_widget::core::*; }
39/// # use iced::widget::Widget;
40/// # pub type State = ();
41/// use iced::widget::button;
42///
43/// #[derive(Clone)]
44/// enum Message {
45///     ButtonPressed,
46/// }
47///
48/// fn view(state: &State) -> impl Widget<Message> {
49///     button("Press me!").on_press(Message::ButtonPressed)
50/// }
51/// ```
52///
53/// If a [`Button::on_press`] handler is not set, the resulting [`Button`] will
54/// be disabled:
55///
56/// ```no_run
57/// # mod iced { pub mod widget { pub use iced_widget::*; } pub use iced_widget::Renderer; pub use iced_widget::core::*; }
58/// # use iced::widget::Widget;
59/// # pub type State = ();
60/// use iced::widget::button;
61///
62/// #[derive(Clone)]
63/// enum Message {
64///     ButtonPressed,
65/// }
66///
67/// fn view(state: &State) -> impl Widget<Message> {
68///     button("I am disabled!")
69/// }
70/// ```
71pub struct Button<'a, Message, W = crate::Element<'a, Message>, Theme = crate::Theme>
72where
73    Theme: Catalog,
74{
75    content: W,
76    on_press: Option<OnPress<'a, Message>>,
77    width: Length,
78    height: Length,
79    padding: Padding,
80    clip: bool,
81    class: Theme::Class<'a>,
82    status: Option<Status>,
83}
84
85enum OnPress<'a, Message> {
86    Direct(Message),
87    Closure(Box<dyn Fn() -> Message + 'a>),
88}
89
90impl<Message: Clone> OnPress<'_, Message> {
91    fn get(&self) -> Message {
92        match self {
93            OnPress::Direct(message) => message.clone(),
94            OnPress::Closure(f) => f(),
95        }
96    }
97}
98
99impl<'a, Message, W, Theme> Button<'a, Message, W, Theme>
100where
101    Theme: Catalog,
102{
103    /// Creates a new [`Button`] with the given content.
104    pub fn new(content: W) -> Self {
105        Button {
106            content,
107            on_press: None,
108            width: Length::Fit,
109            height: Length::Fit,
110            padding: DEFAULT_PADDING,
111            clip: false,
112            class: Theme::default(),
113            status: None,
114        }
115    }
116
117    /// Sets the width of the [`Button`].
118    pub fn width(mut self, width: impl Into<Length>) -> Self {
119        self.width = width.into();
120        self
121    }
122
123    /// Sets the height of the [`Button`].
124    pub fn height(mut self, height: impl Into<Length>) -> Self {
125        self.height = height.into();
126        self
127    }
128
129    /// Sets the [`Padding`] of the [`Button`].
130    pub fn padding<P: Into<Padding>>(mut self, padding: P) -> Self {
131        self.padding = padding.into();
132        self
133    }
134
135    /// Sets the message that will be produced when the [`Button`] is pressed.
136    ///
137    /// Unless `on_press` is called, the [`Button`] will be disabled.
138    pub fn on_press(mut self, on_press: Message) -> Self {
139        self.on_press = Some(OnPress::Direct(on_press));
140        self
141    }
142
143    /// Sets the message that will be produced when the [`Button`] is pressed.
144    ///
145    /// This is analogous to [`Button::on_press`], but using a closure to produce
146    /// the message.
147    ///
148    /// This closure will only be called when the [`Button`] is actually pressed and,
149    /// therefore, this method is useful to reduce overhead if creating the resulting
150    /// message is slow.
151    pub fn on_press_with(mut self, on_press: impl Fn() -> Message + 'a) -> Self {
152        self.on_press = Some(OnPress::Closure(Box::new(on_press)));
153        self
154    }
155
156    /// Sets the message that will be produced when the [`Button`] is pressed,
157    /// if `Some`.
158    ///
159    /// If `None`, the [`Button`] will be disabled.
160    pub fn on_press_maybe(mut self, on_press: Option<Message>) -> Self {
161        self.on_press = on_press.map(OnPress::Direct);
162        self
163    }
164
165    /// Sets the message that will be produced when the [`Button`] is pressed,
166    /// if `Some`.
167    ///
168    /// This is analogous to [`Button::on_press`], but using a closure to produce
169    /// the message.
170    ///
171    /// This closure will only be called when the [`Button`] is actually pressed and,
172    /// therefore, this method is useful to reduce overhead if creating the resulting
173    /// message is slow.
174    ///
175    /// If `None`, the [`Button`] will be disabled.
176    pub fn on_press_maybe_with(mut self, on_press: Option<impl Fn() -> Message + 'a>) -> Self {
177        self.on_press = on_press.map(|on_press| OnPress::Closure(Box::new(on_press)));
178        self
179    }
180
181    /// Sets whether the contents of the [`Button`] should be clipped on
182    /// overflow.
183    pub fn clip(mut self, clip: bool) -> Self {
184        self.clip = clip;
185        self
186    }
187
188    /// Sets the style of the [`Button`].
189    #[must_use]
190    pub fn style(mut self, style: impl Fn(&Theme, Status) -> Style + 'a) -> Self
191    where
192        Theme::Class<'a>: From<StyleFn<'a, Theme>>,
193    {
194        self.class = (Box::new(style) as StyleFn<'a, Theme>).into();
195        self
196    }
197
198    /// Sets the style class of the [`Button`].
199    #[cfg(feature = "advanced")]
200    #[must_use]
201    pub fn class(mut self, class: impl Into<Theme::Class<'a>>) -> Self {
202        self.class = class.into();
203        self
204    }
205}
206
207#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
208struct State {
209    is_pressed: bool,
210}
211
212impl<'a, Message, W, Theme> Meta for Button<'a, Message, W, Theme> where Theme: Catalog {}
213
214impl<'a, Message, W, Theme, Renderer> Widget<Message, Theme, Renderer>
215    for Button<'a, Message, W, Theme>
216where
217    Message: 'a + Clone,
218    W: Widget<Message, Theme, Renderer>,
219    Renderer: 'a + crate::core::Renderer,
220    Theme: Catalog,
221{
222    fn tag(&self) -> tree::Tag {
223        tree::Tag::of::<State>()
224    }
225
226    fn state(&self) -> tree::State {
227        tree::State::new(State::default())
228    }
229
230    fn diff(&mut self, tree: &mut Tree) {
231        tree.diff_children(std::slice::from_mut(&mut self.content));
232
233        let size = self.content.size();
234        self.width = self.width.stack(size.width);
235        self.height = self.height.stack(size.height);
236    }
237
238    fn size(&self) -> Size<Length> {
239        Size {
240            width: self.width,
241            height: self.height,
242        }
243    }
244
245    fn layout(&mut self, tree: &mut Tree, renderer: &Renderer, limits: &layout::Limits) {
246        layout::padded(
247            tree,
248            limits,
249            self.width,
250            self.height,
251            self.padding,
252            |tree, limits| {
253                self.content.layout(tree, renderer, limits);
254
255                tree.size
256            },
257        );
258    }
259
260    fn operate(
261        &mut self,
262        tree: &mut Tree,
263        layout: Layout,
264        viewport: &Rectangle,
265        renderer: &Renderer,
266        operation: &mut dyn Operation,
267    ) {
268        operation.container(None, layout.bounds(), viewport);
269        operation.traverse(&mut |operation| {
270            let (layout, tree) = layout.iter_mut(&mut tree.children).next().unwrap();
271
272            self.content
273                .operate(tree, layout, viewport, renderer, operation);
274        });
275    }
276
277    fn update(
278        &mut self,
279        tree: &mut Tree,
280        event: &Event,
281        layout: Layout,
282        cursor: mouse::Cursor,
283        renderer: &Renderer,
284        shell: &mut Shell<'_, Message>,
285        viewport: &Rectangle,
286    ) {
287        let (content_layout, content_tree) = layout.iter_mut(&mut tree.children).next().unwrap();
288
289        self.content.update(
290            content_tree,
291            event,
292            content_layout,
293            cursor,
294            renderer,
295            shell,
296            viewport,
297        );
298
299        if shell.is_event_captured() {
300            return;
301        }
302
303        match event {
304            Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left))
305            | Event::Touch(touch::Event::FingerPressed { .. })
306                if self.on_press.is_some() =>
307            {
308                let bounds = layout.bounds();
309
310                if cursor.is_over(bounds) {
311                    let state = tree.state.downcast_mut::<State>();
312
313                    state.is_pressed = true;
314
315                    shell.capture_event();
316                }
317            }
318            Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Left))
319            | Event::Touch(touch::Event::FingerLifted { .. }) => {
320                if let Some(on_press) = &self.on_press {
321                    let state = tree.state.downcast_mut::<State>();
322
323                    if state.is_pressed {
324                        state.is_pressed = false;
325
326                        let bounds = layout.bounds();
327
328                        if cursor.is_over(bounds) {
329                            shell.publish(on_press.get());
330                        }
331
332                        shell.capture_event();
333                    }
334                }
335            }
336            Event::Touch(touch::Event::FingerLost { .. }) => {
337                let state = tree.state.downcast_mut::<State>();
338
339                state.is_pressed = false;
340            }
341            _ => {}
342        }
343
344        let current_status = if self.on_press.is_none() {
345            Status::Disabled
346        } else if cursor.is_over(layout.bounds()) {
347            let state = tree.state.downcast_ref::<State>();
348
349            if state.is_pressed {
350                Status::Pressed
351            } else {
352                Status::Hovered
353            }
354        } else {
355            Status::Active
356        };
357
358        if let Event::Window(window::Event::RedrawRequested(_now)) = event {
359            self.status = Some(current_status);
360        } else if self.status.is_some_and(|status| status != current_status) {
361            shell.request_redraw();
362        }
363    }
364
365    fn draw(
366        &self,
367        tree: &Tree,
368        renderer: &mut Renderer,
369        theme: &Theme,
370        _style: &renderer::Style,
371        layout: Layout,
372        cursor: mouse::Cursor,
373        viewport: &Rectangle,
374    ) {
375        let bounds = layout.bounds();
376        let (layout, tree) = layout.iter(&tree.children).next().unwrap();
377        let style = theme.style(&self.class, self.status.unwrap_or(Status::Disabled));
378
379        if style.background.is_some() || style.border.width > 0.0 || style.shadow.color.a > 0.0 {
380            renderer.fill_quad(
381                renderer::Quad {
382                    bounds,
383                    border: style.border,
384                    shadow: style.shadow,
385                    snap: style.snap,
386                },
387                style
388                    .background
389                    .unwrap_or(Background::Color(Color::TRANSPARENT)),
390            );
391        }
392
393        let viewport = if self.clip {
394            bounds.intersection(viewport).unwrap_or(*viewport)
395        } else {
396            *viewport
397        };
398
399        self.content.draw(
400            tree,
401            renderer,
402            theme,
403            &renderer::Style {
404                text_color: style.text_color,
405            },
406            layout,
407            cursor,
408            &viewport,
409        );
410    }
411
412    fn mouse_interaction(
413        &self,
414        _tree: &Tree,
415        layout: Layout,
416        cursor: mouse::Cursor,
417        _viewport: &Rectangle,
418        _renderer: &Renderer,
419    ) -> mouse::Interaction {
420        let is_mouse_over = cursor.is_over(layout.bounds());
421
422        if is_mouse_over && self.on_press.is_some() {
423            mouse::Interaction::Pointer
424        } else {
425            mouse::Interaction::default()
426        }
427    }
428
429    fn overlay<'b>(
430        &'b mut self,
431        tree: &'b mut Tree,
432        layout: Layout,
433        renderer: &Renderer,
434        viewport: &Rectangle,
435        translation: Vector,
436        window: Size,
437    ) -> Vec<overlay::Element<'b, Message, Theme, Renderer>> {
438        let (layout, tree) = layout.iter_mut(&mut tree.children).next().unwrap();
439
440        self.content
441            .overlay(tree, layout, renderer, viewport, translation, window)
442    }
443}
444
445/// The default [`Padding`] of a [`Button`].
446pub const DEFAULT_PADDING: Padding = Padding {
447    top: 5.0,
448    bottom: 5.0,
449    right: 10.0,
450    left: 10.0,
451};
452
453/// The possible status of a [`Button`].
454#[derive(Debug, Clone, Copy, PartialEq, Eq)]
455pub enum Status {
456    /// The [`Button`] can be pressed.
457    Active,
458    /// The [`Button`] can be pressed and it is being hovered.
459    Hovered,
460    /// The [`Button`] is being pressed.
461    Pressed,
462    /// The [`Button`] cannot be pressed.
463    Disabled,
464}
465
466/// The style of a button.
467///
468/// If not specified with [`Button::style`]
469/// the theme will provide the style.
470#[derive(Debug, Clone, Copy, PartialEq)]
471pub struct Style {
472    /// The [`Background`] of the button.
473    pub background: Option<Background>,
474    /// The text [`Color`] of the button.
475    pub text_color: Color,
476    /// The [`Border`] of the button.
477    pub border: Border,
478    /// The [`Shadow`] of the button.
479    pub shadow: Shadow,
480    /// Whether the button should be snapped to the pixel grid.
481    pub snap: bool,
482}
483
484impl Style {
485    /// Updates the [`Style`] with the given [`Background`].
486    pub fn with_background(self, background: impl Into<Background>) -> Self {
487        Self {
488            background: Some(background.into()),
489            ..self
490        }
491    }
492}
493
494impl Default for Style {
495    fn default() -> Self {
496        Self {
497            background: None,
498            text_color: Color::BLACK,
499            border: Border::default(),
500            shadow: Shadow::default(),
501            snap: renderer::CRISP,
502        }
503    }
504}
505
506/// The theme catalog of a [`Button`].
507///
508/// All themes that can be used with [`Button`]
509/// must implement this trait.
510///
511/// # Example
512/// ```no_run
513/// # use iced_widget::core::{Color, Background};
514/// # use iced_widget::button::{Catalog, Status, Style};
515/// # struct MyTheme;
516/// #[derive(Debug, Default)]
517/// pub enum ButtonClass {
518///     #[default]
519///     Primary,
520///     Secondary,
521///     Danger
522/// }
523///
524/// impl Catalog for MyTheme {
525///     type Class<'a> = ButtonClass;
526///     fn default<'a>() -> Self::Class<'a> {
527///         ButtonClass::default()
528///     }
529///
530///     fn style(&self, class: &Self::Class<'_>, status: Status) -> Style {
531///         let mut style = Style::default();
532///
533///         match class {
534///             ButtonClass::Primary => {
535///                 style.background = Some(Background::Color(Color::from_rgb(0.529, 0.808, 0.921)));
536///             },
537///             ButtonClass::Secondary => {
538///                 style.background = Some(Background::Color(Color::WHITE));
539///             },
540///             ButtonClass::Danger => {
541///                 style.background = Some(Background::Color(Color::from_rgb(0.941, 0.502, 0.502)));
542///             },
543///         }
544///
545///         style
546///     }
547/// }
548/// ```
549///
550/// Although, in order to use [`Button::style`]
551/// with `MyTheme`, [`Catalog::Class`] must implement
552/// `From<StyleFn<'_, MyTheme>>`.
553pub trait Catalog {
554    /// The item class of the [`Catalog`].
555    type Class<'a>;
556
557    /// The default class produced by the [`Catalog`].
558    fn default<'a>() -> Self::Class<'a>;
559
560    /// The [`Style`] of a class with the given status.
561    fn style(&self, class: &Self::Class<'_>, status: Status) -> Style;
562}
563
564/// A styling function for a [`Button`].
565pub type StyleFn<'a, Theme> = Box<dyn Fn(&Theme, Status) -> Style + 'a>;
566
567impl Catalog for Theme {
568    type Class<'a> = StyleFn<'a, Self>;
569
570    fn default<'a>() -> Self::Class<'a> {
571        Box::new(primary)
572    }
573
574    fn style(&self, class: &Self::Class<'_>, status: Status) -> Style {
575        class(self, status)
576    }
577}
578
579/// A primary button; denoting a main action.
580pub fn primary(theme: &Theme, status: Status) -> Style {
581    let palette = theme.palette();
582    let base = styled(palette.primary.base);
583
584    match status {
585        Status::Active | Status::Pressed => base,
586        Status::Hovered => Style {
587            background: Some(Background::Color(palette.primary.strong.color)),
588            ..base
589        },
590        Status::Disabled => disabled(base),
591    }
592}
593
594/// A secondary button; denoting a complementary action.
595pub fn secondary(theme: &Theme, status: Status) -> Style {
596    let palette = theme.palette();
597    let base = styled(palette.secondary.base);
598
599    match status {
600        Status::Active | Status::Pressed => base,
601        Status::Hovered => Style {
602            background: Some(Background::Color(palette.secondary.strong.color)),
603            ..base
604        },
605        Status::Disabled => disabled(base),
606    }
607}
608
609/// A success button; denoting a good outcome.
610pub fn success(theme: &Theme, status: Status) -> Style {
611    let palette = theme.palette();
612    let base = styled(palette.success.base);
613
614    match status {
615        Status::Active | Status::Pressed => base,
616        Status::Hovered => Style {
617            background: Some(Background::Color(palette.success.strong.color)),
618            ..base
619        },
620        Status::Disabled => disabled(base),
621    }
622}
623
624/// A warning button; denoting a risky action.
625pub fn warning(theme: &Theme, status: Status) -> Style {
626    let palette = theme.palette();
627    let base = styled(palette.warning.base);
628
629    match status {
630        Status::Active | Status::Pressed => base,
631        Status::Hovered => Style {
632            background: Some(Background::Color(palette.warning.strong.color)),
633            ..base
634        },
635        Status::Disabled => disabled(base),
636    }
637}
638
639/// A danger button; denoting a destructive action.
640pub fn danger(theme: &Theme, status: Status) -> Style {
641    let palette = theme.palette();
642    let base = styled(palette.danger.base);
643
644    match status {
645        Status::Active | Status::Pressed => base,
646        Status::Hovered => Style {
647            background: Some(Background::Color(palette.danger.strong.color)),
648            ..base
649        },
650        Status::Disabled => disabled(base),
651    }
652}
653
654/// A text button; useful for links.
655pub fn text(theme: &Theme, status: Status) -> Style {
656    let palette = theme.palette();
657
658    let base = Style {
659        text_color: palette.background.base.text,
660        ..Style::default()
661    };
662
663    match status {
664        Status::Active | Status::Pressed => base,
665        Status::Hovered => Style {
666            text_color: palette.background.base.text.scale_alpha(0.8),
667            ..base
668        },
669        Status::Disabled => disabled(base),
670    }
671}
672
673/// A button using background shades.
674pub fn background(theme: &Theme, status: Status) -> Style {
675    let palette = theme.palette();
676    let base = styled(palette.background.base);
677
678    match status {
679        Status::Active => base,
680        Status::Pressed => Style {
681            background: Some(Background::Color(palette.background.strong.color)),
682            ..base
683        },
684        Status::Hovered => Style {
685            background: Some(Background::Color(palette.background.weak.color)),
686            ..base
687        },
688        Status::Disabled => disabled(base),
689    }
690}
691
692/// A subtle button using weak background shades.
693pub fn subtle(theme: &Theme, status: Status) -> Style {
694    let palette = theme.palette();
695    let base = styled(palette.background.weakest);
696
697    match status {
698        Status::Active => base,
699        Status::Pressed => Style {
700            background: Some(Background::Color(palette.background.strong.color)),
701            ..base
702        },
703        Status::Hovered => Style {
704            background: Some(Background::Color(palette.background.weaker.color)),
705            ..base
706        },
707        Status::Disabled => disabled(base),
708    }
709}
710
711fn styled(pair: palette::Pair) -> Style {
712    Style {
713        background: Some(Background::Color(pair.color)),
714        text_color: pair.text,
715        border: border::rounded(2),
716        ..Style::default()
717    }
718}
719
720fn disabled(style: Style) -> Style {
721    Style {
722        background: style
723            .background
724            .map(|background| background.scale_alpha(0.5)),
725        text_color: style.text_color.scale_alpha(0.5),
726        ..style
727    }
728}
iced_widget/button.rs

iced_widget/
button.rs
