//! This example illustrates the various features of Bevy UI.
use bevy::{
a11y::{
accesskit::{NodeBuilder, Role},
AccessibilityNode,
},
input::mouse::{MouseScrollUnit, MouseWheel},
prelude::*,
winit::WinitSettings,
};
fn main() {
App::new()
.add_plugins(DefaultPlugins)
// Only run the app when there is user input. This will significantly reduce CPU/GPU use.
.insert_resource(WinitSettings::desktop_app())
.add_startup_system(setup)
.add_system(mouse_scroll)
.run();
}
fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
// Camera
commands.spawn(Camera2dBundle::default());
// root node
commands
.spawn(NodeBundle {
style: Style {
size: Size::width(Val::Percent(100.0)),
justify_content: JustifyContent::SpaceBetween,
..default()
},
..default()
})
.with_children(|parent| {
// left vertical fill (border)
parent
.spawn(NodeBundle {
style: Style {
size: Size::width(Val::Px(200.0)),
border: UiRect::all(Val::Px(2.0)),
..default()
},
background_color: Color::rgb(0.65, 0.65, 0.65).into(),
..default()
})
.with_children(|parent| {
// left vertical fill (content)
parent
.spawn(NodeBundle {
style: Style {
size: Size::width(Val::Percent(100.0)),
..default()
},
background_color: Color::rgb(0.15, 0.15, 0.15).into(),
..default()
})
.with_children(|parent| {
// text
parent.spawn((
TextBundle::from_section(
"Text Example",
TextStyle {
font: asset_server.load("fonts/FiraSans-Bold.ttf"),
font_size: 30.0,
color: Color::WHITE,
},
)
.with_style(Style {
margin: UiRect::all(Val::Px(5.0)),
..default()
}),
// Because this is a distinct label widget and
// not button/list item text, this is necessary
// for accessibility to treat the text accordingly.
Label,
));
});
});
// right vertical fill
parent
.spawn(NodeBundle {
style: Style {
flex_direction: FlexDirection::Column,
justify_content: JustifyContent::Center,
align_items: AlignItems::Center,
size: Size::width(Val::Px(200.0)),
..default()
},
background_color: Color::rgb(0.15, 0.15, 0.15).into(),
..default()
})
.with_children(|parent| {
// Title
parent.spawn((
TextBundle::from_section(
"Scrolling list",
TextStyle {
font: asset_server.load("fonts/FiraSans-Bold.ttf"),
font_size: 25.,
color: Color::WHITE,
},
)
.with_style(Style {
size: Size::height(Val::Px(25.)),
..default()
}),
Label,
));
// List with hidden overflow
parent
.spawn(NodeBundle {
style: Style {
flex_direction: FlexDirection::Column,
align_self: AlignSelf::Stretch,
size: Size::height(Val::Percent(50.0)),
overflow: Overflow::Hidden,
..default()
},
background_color: Color::rgb(0.10, 0.10, 0.10).into(),
..default()
})
.with_children(|parent| {
// Moving panel
parent
.spawn((
NodeBundle {
style: Style {
flex_direction: FlexDirection::Column,
flex_grow: 1.0,
max_size: Size::UNDEFINED,
align_items: AlignItems::Center,
..default()
},
..default()
},
ScrollingList::default(),
AccessibilityNode(NodeBuilder::new(Role::List)),
))
.with_children(|parent| {
// List items
for i in 0..30 {
parent.spawn((
TextBundle::from_section(
format!("Item {i}"),
TextStyle {
font: asset_server
.load("fonts/FiraSans-Bold.ttf"),
font_size: 20.,
color: Color::WHITE,
},
)
.with_style(Style {
flex_shrink: 0.,
size: Size::new(Val::Undefined, Val::Px(20.)),
..default()
}),
Label,
AccessibilityNode(NodeBuilder::new(Role::ListItem)),
));
}
});
});
});
parent
.spawn(NodeBundle {
style: Style {
size: Size::new(Val::Px(200.0), Val::Px(200.0)),
position_type: PositionType::Absolute,
position: UiRect {
left: Val::Px(210.0),
bottom: Val::Px(10.0),
..default()
},
border: UiRect::all(Val::Px(20.0)),
..default()
},
background_color: Color::rgb(0.4, 0.4, 1.0).into(),
..default()
})
.with_children(|parent| {
parent.spawn(NodeBundle {
style: Style {
size: Size::new(Val::Percent(100.0), Val::Percent(100.0)),
..default()
},
background_color: Color::rgb(0.8, 0.8, 1.0).into(),
..default()
});
});
// render order test: reddest in the back, whitest in the front (flex center)
parent
.spawn(NodeBundle {
style: Style {
size: Size::new(Val::Percent(100.0), Val::Percent(100.0)),
position_type: PositionType::Absolute,
align_items: AlignItems::Center,
justify_content: JustifyContent::Center,
..default()
},
..default()
})
.with_children(|parent| {
parent
.spawn(NodeBundle {
style: Style {
size: Size::new(Val::Px(100.0), Val::Px(100.0)),
..default()
},
background_color: Color::rgb(1.0, 0.0, 0.0).into(),
..default()
})
.with_children(|parent| {
parent.spawn(NodeBundle {
style: Style {
// Take the size of the parent node.
size: Size::all(Val::Percent(100.)),
position_type: PositionType::Absolute,
position: UiRect {
left: Val::Px(20.0),
bottom: Val::Px(20.0),
..default()
},
..default()
},
background_color: Color::rgb(1.0, 0.3, 0.3).into(),
..default()
});
parent.spawn(NodeBundle {
style: Style {
size: Size::all(Val::Percent(100.)),
position_type: PositionType::Absolute,
position: UiRect {
left: Val::Px(40.0),
bottom: Val::Px(40.0),
..default()
},
..default()
},
background_color: Color::rgb(1.0, 0.5, 0.5).into(),
..default()
});
parent.spawn(NodeBundle {
style: Style {
size: Size::all(Val::Percent(100.)),
position_type: PositionType::Absolute,
position: UiRect {
left: Val::Px(60.0),
bottom: Val::Px(60.0),
..default()
},
..default()
},
background_color: Color::rgb(1.0, 0.7, 0.7).into(),
..default()
});
// alpha test
parent.spawn(NodeBundle {
style: Style {
size: Size::all(Val::Percent(100.)),
position_type: PositionType::Absolute,
position: UiRect {
left: Val::Px(80.0),
bottom: Val::Px(80.0),
..default()
},
..default()
},
background_color: Color::rgba(1.0, 0.9, 0.9, 0.4).into(),
..default()
});
});
});
// bevy logo (flex center)
parent
.spawn(NodeBundle {
style: Style {
size: Size::width(Val::Percent(100.)),
position_type: PositionType::Absolute,
justify_content: JustifyContent::Center,
align_items: AlignItems::FlexStart,
..default()
},
..default()
})
.with_children(|parent| {
// bevy logo (image)
parent
.spawn(ImageBundle {
style: Style {
size: Size::width(Val::Px(500.0)),
..default()
},
..default()
})
.with_children(|parent| {
// alt text
parent
.spawn(TextBundle::from_section("Bevy logo", TextStyle::default()));
});
});
});
}
#[derive(Component, Default)]
struct ScrollingList {
position: f32,
}
fn mouse_scroll(
mut mouse_wheel_events: EventReader<MouseWheel>,
mut query_list: Query<(&mut ScrollingList, &mut Style, &Children, &Node)>,
query_item: Query<&Node>,
) {
for mouse_wheel_event in mouse_wheel_events.iter() {
for (mut scrolling_list, mut style, children, uinode) in &mut query_list {
let items_height: f32 = children
.iter()
.map(|entity| query_item.get(*entity).unwrap().size().y)
.sum();
let panel_height = uinode.size().y;
let max_scroll = (items_height - panel_height).max(0.);
let dy = match mouse_wheel_event.unit {
MouseScrollUnit::Line => mouse_wheel_event.y * 20.,
MouseScrollUnit::Pixel => mouse_wheel_event.y,
};
scrolling_list.position += dy;
scrolling_list.position = scrolling_list.position.clamp(-max_scroll, 0.);
style.position.top = Val::Px(scrolling_list.position);
}
}
}
//! This example illustrates the various features of Bevy UI.
use ;