egui/widgets/
radio_button.rs

1use crate::{
2    Atom, AtomLayout, Atoms, Id, IntoAtoms, NumExt as _, Response, Sense, Ui, Vec2, Widget,
3    WidgetInfo, WidgetType, epaint,
4};
5
6/// One out of several alternatives, either selected or not.
7///
8/// Usually you'd use [`Ui::radio_value`] or [`Ui::radio`] instead.
9///
10/// ```
11/// # egui::__run_test_ui(|ui| {
12/// #[derive(PartialEq)]
13/// enum Enum { First, Second, Third }
14/// let mut my_enum = Enum::First;
15///
16/// ui.radio_value(&mut my_enum, Enum::First, "First");
17///
18/// // is equivalent to:
19///
20/// if ui.add(egui::RadioButton::new(my_enum == Enum::First, "First")).clicked() {
21///     my_enum = Enum::First
22/// }
23/// # });
24/// ```
25#[must_use = "You should put this widget in a ui with `ui.add(widget);`"]
26pub struct RadioButton<'a> {
27    checked: bool,
28    atoms: Atoms<'a>,
29}
30
31impl<'a> RadioButton<'a> {
32    pub fn new(checked: bool, atoms: impl IntoAtoms<'a>) -> Self {
33        Self {
34            checked,
35            atoms: atoms.into_atoms(),
36        }
37    }
38}
39
40impl Widget for RadioButton<'_> {
41    fn ui(self, ui: &mut Ui) -> Response {
42        let Self { checked, mut atoms } = self;
43
44        let spacing = &ui.spacing();
45        let icon_width = spacing.icon_width;
46
47        let mut min_size = Vec2::splat(spacing.interact_size.y);
48        min_size.y = min_size.y.at_least(icon_width);
49
50        // In order to center the checkbox based on min_size we set the icon height to at least min_size.y
51        let mut icon_size = Vec2::splat(icon_width);
52        icon_size.y = icon_size.y.at_least(min_size.y);
53        let rect_id = Id::new("egui::radio_button");
54        atoms.push_left(Atom::custom(rect_id, icon_size));
55
56        let text = atoms.text().map(String::from);
57
58        let mut prepared = AtomLayout::new(atoms)
59            .sense(Sense::click())
60            .min_size(min_size)
61            .allocate(ui);
62
63        prepared.response.widget_info(|| {
64            WidgetInfo::selected(
65                WidgetType::RadioButton,
66                ui.is_enabled(),
67                checked,
68                text.as_deref().unwrap_or(""),
69            )
70        });
71
72        if ui.is_rect_visible(prepared.response.rect) {
73            // let visuals = ui.style().interact_selectable(&response, checked); // too colorful
74            let visuals = *ui.style().interact(&prepared.response);
75
76            prepared.fallback_text_color = visuals.text_color();
77            let response = prepared.paint(ui);
78
79            if let Some(rect) = response.rect(rect_id) {
80                let (small_icon_rect, big_icon_rect) = ui.spacing().icon_rectangles(rect);
81
82                let painter = ui.painter();
83
84                painter.add(epaint::CircleShape {
85                    center: big_icon_rect.center(),
86                    radius: big_icon_rect.width() / 2.0 + visuals.expansion,
87                    fill: visuals.bg_fill,
88                    stroke: visuals.bg_stroke,
89                });
90
91                if checked {
92                    painter.add(epaint::CircleShape {
93                        center: small_icon_rect.center(),
94                        radius: small_icon_rect.width() / 3.0,
95                        fill: visuals.fg_stroke.color, // Intentional to use stroke and not fill
96                        // fill: ui.visuals().selection.stroke.color, // too much color
97                        stroke: Default::default(),
98                    });
99                }
100            }
101            response.response
102        } else {
103            prepared.response
104        }
105    }
106}
egui/widgets/radio_button.rs

egui/widgets/
radio_button.rs
