docs/bevy/examples/ui/text/system_fonts.rs 3.6 K · 96 lines · raw · history

1 //! This example displays a scrollable list of all available system fonts.
2 //! Demonstrates querying system fonts via `FontCx`.
3
4 use bevy::{
5 diagnostic::FrameTimeDiagnosticsPlugin, input::mouse::MouseScrollUnit, prelude::*, text::FontCx,
6 };
7
8 fn main() {
9 let mut app = App::new();
10 app.add_plugins((DefaultPlugins, FrameTimeDiagnosticsPlugin::default()))
11 .add_systems(Startup, setup);
12
13 app.run();
14 }
15
16 fn setup(mut commands: Commands, mut font_system: ResMut<FontCx>) {
17 let mut families: Vec<String> = font_system
18 .context
19 .collection
20 .family_names()
21 .map(ToOwned::to_owned)
22 .collect();
23 families.sort_unstable();
24 families.dedup();
25 let family_count = families.len();
26
27 commands.spawn(Camera2d);
28
29 commands
30 .spawn((
31 Node {
32 flex_direction: FlexDirection::Column,
33 width: percent(100),
34 height: percent(100),
35 align_items: AlignItems::Center,
36 row_gap: px(10.),
37 ..default()
38 },
39 BackgroundColor(Color::srgb(0.1, 0.1, 0.1)),
40 ))
41 .with_children(move |builder| {
42 builder.spawn(Text::new(format!(
43 "Total available fonts: {}",
44 family_count,
45 )));
46
47 builder
48 .spawn(Node {
49 flex_direction: FlexDirection::Column,
50 row_gap: px(6),
51 overflow: Overflow::scroll_y(),
52 align_items: AlignItems::Stretch,
53 ..default()
54 })
55 .with_children(|builder| {
56 for family in families {
57 let font = FontSource::Family(family.clone().into());
58 builder.spawn((
59 Node {
60 display: Display::Grid,
61 grid_template_columns: vec![
62 GridTrack::flex(1.),
63 GridTrack::flex(1.),
64 ],
65 padding: px(6).all(),
66 column_gap: px(50.),
67 ..default()
68 },
69 BackgroundColor(Color::srgb(0.2, 0.2, 0.25)),
70 children![
71 (
72 Text::new(&family),
73 TextFont { font, ..default() },
74 TextLayout::no_wrap()
75 ),
76 (Text::new(family), TextLayout::no_wrap()),
77 ],
78 ));
79 }
80 })
81 .observe(
82 |on_scroll: On<PointerScroll>,
83 mut query: Query<(&mut ScrollPosition, &ComputedNode)>| {
84 if let Ok((mut scroll_position, node)) = query.get_mut(on_scroll.entity) {
85 let dy = match on_scroll.unit {
86 MouseScrollUnit::Line => on_scroll.y * 20.,
87 MouseScrollUnit::Pixel => on_scroll.y,
88 };
89 let range = (node.content_size.y - node.size.y).max(0.)
90 * node.inverse_scale_factor;
91 scroll_position.y = (scroll_position.y - dy).clamp(0., range);
92 }
93 },
94 );
95 });
96 }