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54 lines
1.5 KiB
Rust
54 lines
1.5 KiB
Rust
//! This example illustrates scrolling in Bevy UI.
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use games::*;
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fn main() {
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let mut app = App::new();
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app.add_plugins(BaseGamePlugin::default())
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.add_systems(Startup, setup);
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app.run();
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}
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const LINE_HEIGHT: f32 = 21.;
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fn setup(mut commands: Commands) {
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// Scrolling list
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commands
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.spawn((
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Node {
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flex_direction: FlexDirection::Column,
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// If height is not set, we need both align_self: Stetch and overflow: scroll()
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height: Val::Percent(50.0),
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// align_self: AlignSelf::Stretch,
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overflow: Overflow::scroll(),
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..default()
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},
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BackgroundColor(Color::srgb(0.10, 0.10, 0.10)),
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))
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.with_children(|parent| {
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// List items
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(0..250).for_each(|i| {
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parent.spawn(Text(format!("Item {i}")));
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});
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})
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.observe(scroll);
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}
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/// Updates the scroll position of scrollable nodes in response to mouse input
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pub fn scroll(
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trigger: Trigger<Pointer<Scroll>>,
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mut scrollers: Query<&mut ScrollPosition>,
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) {
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let Pointer { event: Scroll { unit, x, y, .. }, .. } = trigger.event();
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let (dx, dy) = match unit {
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MouseScrollUnit::Line => (x * LINE_HEIGHT, y * LINE_HEIGHT),
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MouseScrollUnit::Pixel => (x * 1., y * 1.),
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};
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if let Ok(mut pos) = scrollers.get_mut(trigger.target()) {
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pos.offset_x -= dx;
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pos.offset_y -= dy;
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}
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}
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