373f1eeb1e
# Objective Fix a few issues with some of the examples: * Root UI nodes have an implicit parent with `FlexDirection::Row` and `AlignItems::Stretch` set. Only a width constraint is needed to fill the viewport. Specifying ```height: Val::Percent(100.)``` is unnecessary and can cause confusing overflow behaviour. * The default for position and size constraint properties is `Val::Auto`. Setting `left: Val::Auto`, `max_height: Val::Auto`, etc does nothing. ## Solution Delete those lines. There should be no observable differences in the behaviours of any of the examples. Also changed a padding setting in the `flex_layout` example to use the `axes` helper function.
337 lines
15 KiB
Rust
337 lines
15 KiB
Rust
//! This example illustrates the various features of Bevy UI.
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use bevy::{
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a11y::{
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accesskit::{NodeBuilder, Role},
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AccessibilityNode,
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},
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input::mouse::{MouseScrollUnit, MouseWheel},
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prelude::*,
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winit::WinitSettings,
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};
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fn main() {
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App::new()
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.add_plugins(DefaultPlugins)
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// Only run the app when there is user input. This will significantly reduce CPU/GPU use.
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.insert_resource(WinitSettings::desktop_app())
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.add_systems(Startup, setup)
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.add_systems(Update, mouse_scroll)
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.run();
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}
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fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
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// Camera
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commands.spawn(Camera2dBundle::default());
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// root node
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commands
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.spawn(NodeBundle {
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style: Style {
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width: Val::Percent(100.0),
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justify_content: JustifyContent::SpaceBetween,
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..default()
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},
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..default()
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})
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.with_children(|parent| {
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// left vertical fill (border)
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parent
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.spawn(NodeBundle {
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style: Style {
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width: Val::Px(200.),
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border: UiRect::all(Val::Px(2.)),
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..default()
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},
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background_color: Color::rgb(0.65, 0.65, 0.65).into(),
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..default()
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})
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.with_children(|parent| {
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// left vertical fill (content)
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parent
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.spawn(NodeBundle {
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style: Style {
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width: Val::Percent(100.),
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..default()
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},
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background_color: Color::rgb(0.15, 0.15, 0.15).into(),
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..default()
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})
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.with_children(|parent| {
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// text
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parent.spawn((
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TextBundle::from_section(
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"Text Example",
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TextStyle {
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font: asset_server.load("fonts/FiraSans-Bold.ttf"),
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font_size: 30.0,
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color: Color::WHITE,
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},
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)
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.with_style(Style {
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margin: UiRect::all(Val::Px(5.)),
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..default()
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}),
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// Because this is a distinct label widget and
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// not button/list item text, this is necessary
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// for accessibility to treat the text accordingly.
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Label,
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));
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});
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});
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// right vertical fill
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parent
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.spawn(NodeBundle {
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style: Style {
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flex_direction: FlexDirection::Column,
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justify_content: JustifyContent::Center,
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align_items: AlignItems::Center,
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width: Val::Px(200.),
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..default()
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},
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background_color: Color::rgb(0.15, 0.15, 0.15).into(),
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..default()
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})
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.with_children(|parent| {
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// Title
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parent.spawn((
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TextBundle::from_section(
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"Scrolling list",
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TextStyle {
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font: asset_server.load("fonts/FiraSans-Bold.ttf"),
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font_size: 25.,
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color: Color::WHITE,
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},
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),
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Label,
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));
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// List with hidden overflow
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parent
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.spawn(NodeBundle {
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style: Style {
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flex_direction: FlexDirection::Column,
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align_self: AlignSelf::Stretch,
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height: Val::Percent(50.),
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overflow: Overflow::clip_y(),
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..default()
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},
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background_color: Color::rgb(0.10, 0.10, 0.10).into(),
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..default()
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})
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.with_children(|parent| {
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// Moving panel
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parent
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.spawn((
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NodeBundle {
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style: Style {
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flex_direction: FlexDirection::Column,
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align_items: AlignItems::Center,
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..default()
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},
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..default()
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},
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ScrollingList::default(),
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AccessibilityNode(NodeBuilder::new(Role::List)),
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))
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.with_children(|parent| {
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// List items
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for i in 0..30 {
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parent.spawn((
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TextBundle::from_section(
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format!("Item {i}"),
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TextStyle {
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font: asset_server
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.load("fonts/FiraSans-Bold.ttf"),
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font_size: 20.,
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color: Color::WHITE,
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},
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),
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Label,
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AccessibilityNode(NodeBuilder::new(Role::ListItem)),
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));
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}
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});
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});
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});
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parent
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.spawn(NodeBundle {
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style: Style {
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width: Val::Px(200.0),
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height: Val::Px(200.0),
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position_type: PositionType::Absolute,
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left: Val::Px(210.),
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bottom: Val::Px(10.),
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border: UiRect::all(Val::Px(20.)),
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..default()
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},
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border_color: Color::GREEN.into(),
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background_color: Color::rgb(0.4, 0.4, 1.).into(),
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..default()
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})
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.with_children(|parent| {
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parent.spawn(NodeBundle {
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style: Style {
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width: Val::Percent(100.0),
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height: Val::Percent(100.0),
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..default()
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},
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background_color: Color::rgb(0.8, 0.8, 1.).into(),
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..default()
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});
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});
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// render order test: reddest in the back, whitest in the front (flex center)
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parent
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.spawn(NodeBundle {
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style: Style {
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width: Val::Percent(100.0),
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height: Val::Percent(100.0),
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position_type: PositionType::Absolute,
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align_items: AlignItems::Center,
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justify_content: JustifyContent::Center,
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..default()
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},
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..default()
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})
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.with_children(|parent| {
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parent
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.spawn(NodeBundle {
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style: Style {
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width: Val::Px(100.0),
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height: Val::Px(100.0),
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..default()
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},
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background_color: Color::rgb(1.0, 0.0, 0.).into(),
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..default()
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})
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.with_children(|parent| {
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parent.spawn(NodeBundle {
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style: Style {
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// Take the size of the parent node.
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width: Val::Percent(100.0),
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height: Val::Percent(100.0),
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position_type: PositionType::Absolute,
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left: Val::Px(20.),
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bottom: Val::Px(20.),
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..default()
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},
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background_color: Color::rgb(1.0, 0.3, 0.3).into(),
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..default()
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});
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parent.spawn(NodeBundle {
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style: Style {
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width: Val::Percent(100.0),
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height: Val::Percent(100.0),
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position_type: PositionType::Absolute,
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left: Val::Px(40.),
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bottom: Val::Px(40.),
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..default()
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},
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background_color: Color::rgb(1.0, 0.5, 0.5).into(),
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..default()
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});
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parent.spawn(NodeBundle {
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style: Style {
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width: Val::Percent(100.0),
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height: Val::Percent(100.0),
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position_type: PositionType::Absolute,
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left: Val::Px(60.),
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bottom: Val::Px(60.),
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..default()
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},
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background_color: Color::rgb(1.0, 0.7, 0.7).into(),
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..default()
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});
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// alpha test
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parent.spawn(NodeBundle {
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style: Style {
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width: Val::Percent(100.0),
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height: Val::Percent(100.0),
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position_type: PositionType::Absolute,
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left: Val::Px(80.),
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bottom: Val::Px(80.),
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..default()
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},
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background_color: Color::rgba(1.0, 0.9, 0.9, 0.4).into(),
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..default()
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});
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});
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});
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// bevy logo (flex center)
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parent
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.spawn(NodeBundle {
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style: Style {
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width: Val::Percent(100.0),
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position_type: PositionType::Absolute,
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justify_content: JustifyContent::Center,
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align_items: AlignItems::FlexStart,
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..default()
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},
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..default()
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})
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.with_children(|parent| {
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// bevy logo (image)
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// A `NodeBundle` is used to display the logo the image as an `ImageBundle` can't automatically
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// size itself with a child node present.
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parent
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.spawn((
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NodeBundle {
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style: Style {
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width: Val::Px(500.0),
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height: Val::Px(125.0),
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margin: UiRect::top(Val::VMin(5.)),
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..default()
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},
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// a `NodeBundle` is transparent by default, so to see the image we have to its color to `WHITE`
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background_color: Color::WHITE.into(),
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..default()
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},
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UiImage::new(asset_server.load("branding/bevy_logo_dark_big.png")),
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))
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.with_children(|parent| {
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// alt text
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// This UI node takes up no space in the layout and the `Text` component is used by the accessibility module
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// and is not rendered.
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parent.spawn((
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NodeBundle {
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style: Style {
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display: Display::None,
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..Default::default()
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},
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..Default::default()
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},
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Text::from_section("Bevy logo", TextStyle::default()),
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));
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});
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});
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});
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}
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#[derive(Component, Default)]
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struct ScrollingList {
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position: f32,
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}
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fn mouse_scroll(
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mut mouse_wheel_events: EventReader<MouseWheel>,
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mut query_list: Query<(&mut ScrollingList, &mut Style, &Parent, &Node)>,
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query_node: Query<&Node>,
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) {
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for mouse_wheel_event in mouse_wheel_events.iter() {
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for (mut scrolling_list, mut style, parent, list_node) in &mut query_list {
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let items_height = list_node.size().y;
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let container_height = query_node.get(parent.get()).unwrap().size().y;
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let max_scroll = (items_height - container_height).max(0.);
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let dy = match mouse_wheel_event.unit {
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MouseScrollUnit::Line => mouse_wheel_event.y * 20.,
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MouseScrollUnit::Pixel => mouse_wheel_event.y,
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};
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scrolling_list.position += dy;
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scrolling_list.position = scrolling_list.position.clamp(-max_scroll, 0.);
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style.top = Val::Px(scrolling_list.position);
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}
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}
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}
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