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//! This example illustrates the various features of Bevy UI.
use bevy::{
input::mouse::{MouseScrollUnit, MouseWheel},
prelude::*,
winit::WinitSettings,
};
use bevy_ui_style_builder::prelude::*;
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(
node()
.width(Val::Percent(100.))
.height(Val::Percent(100.))
.justify_content_space_between(),
)
.with_children(|parent| {
// left vertical fill (border)
parent
.spawn(
node()
.width(Val::Px(200.))
.height(Val::Percent(100.))
.border(Breadth::Px(2.))
.background_color(Color::rgb(0.65, 0.65, 0.65)),
)
.with_children(|parent| {
// left vertical fill (content)
parent
.spawn(
node()
.width(Val::Px(196.))
.height(Val::Percent(100.))
.background_color(Color::rgb(0.15, 0.15, 0.15)),
)
.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,
},
)
.margin(Val::Px(5.)),
);
});
});
// right vertical fill
parent
.spawn(
node()
.column()
.justify_content_center()
.align_items_center()
.size(Size::new(Val::Px(200.0), Val::Percent(100.0)))
.background_color(Color::rgb(0.15, 0.15, 0.15)),
)
.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::new(Val::Undefined, Val::Px(25.)))),
);
// List with hidden overflow
parent
.spawn(
node()
.column()
.size(Size::new(Val::Percent(100.0), Val::Percent(50.0)))
.hide_overflow()
.background_color(Color::rgb(0.10, 0.10, 0.10)),
)
.with_children(|parent| {
// Moving panel
parent
.spawn((
node().column().grow(1.0).max_size(Size::UNDEFINED),
ScrollingList::default(),
))
.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,
},
)
.shrink(0.)
.height(Val::Px(20.))
.margin(UiRect::horizontal(Val::Auto)),
);
}
});
});
});
parent
.spawn(
node()
.size(Size::new(Val::Px(200.0), Val::Px(200.0)))
.absolute()
.left(Val::Px(210.0))
.bottom(Val::Px(10.0))
.border(Breadth::Px(20.0))
.background_color(Color::rgb(0.4, 0.4, 1.0)),
)
.with_children(|parent| {
parent.spawn(
node()
.size(Size::new(Val::Percent(100.0), Val::Percent(100.0)))
.background_color(Color::rgb(0.8, 0.8, 1.0)),
);
});
// render order test: reddest in the back, whitest in the front (flex center)
parent
.spawn(
node()
.width(Val::Percent(100.0))
.height(Val::Percent(100.0))
.absolute()
.align_items_center()
.justify_content_center(),
)
.with_children(|parent| {
parent
.spawn(
node()
.size_all( Val::Px(100.0))
.background_color(Color::rgb(1.0, 0.0, 0.0)),
)
.with_children(|parent| {
parent.spawn(
node()
.size_all(Val::Px(100.0))
.absolute()
.left(Val::Px(20.0))
.bottom(Val::Px(20.0))
.background_color(Color::rgb(1.0, 0.3, 0.3)),
);
parent.spawn(
node()
.size_all( Val::Px(100.0))
.absolute()
.left(Val::Px(40.0))
.bottom(Val::Px(40.0))
.background_color(Color::rgb(1.0, 0.5, 0.5))
);
parent.spawn(
node()
.size_all( Val::Px(100.0))
.absolute()
.left(Val::Px(60.0))
.bottom(Val::Px(60.0))
.background_color(Color::rgb(1.0, 0.7, 0.7)),
);
// alpha test
parent.spawn(
node()
.size_all(Val::Px(100.0))
.absolute()
.left(Val::Px(80.0))
.bottom(Val::Px(80.0))
.background_color(Color::rgba(1.0, 0.9, 0.9, 0.4)),
);
});
// bevy logo (flex center)
parent
.spawn(
node()
.size(Size::new(Val::Percent(100.0), Val::Percent(100.0)))
.absolute()
.justify_content_center()
.align_items_start(),
)
.with_children(|parent| {
// bevy logo (image)
parent.spawn(
ImageBundle {
image: asset_server
.load("branding/bevy_logo_dark_big.png")
.into(),
..default()
}
.size(Size::new(Val::Px(500.0), Val::Auto)),
);
});
});
});
}
#[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);
}
}
}