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https://github.com/bevyengine/bevy
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# Objective UIs created for Bevy cannot currently be made accessible. This PR aims to address that. ## Solution Integrate AccessKit as a dependency, adding accessibility support to existing bevy_ui widgets. ## Changelog ### Added * Integrate with and expose [AccessKit](https://accesskit.dev) for platform accessibility. * Add `Label` for marking text specifically as a label for UI controls.
334 lines
15 KiB
Rust
334 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_startup_system(setup)
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.add_system(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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size: Size::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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size: Size::width(Val::Px(200.0)),
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border: UiRect::all(Val::Px(2.0)),
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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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size: Size::width(Val::Percent(100.0)),
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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(5.0)),
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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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size: Size::width(Val::Px(200.0)),
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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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.with_style(Style {
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size: Size::height(Val::Px(25.)),
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..default()
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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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size: Size::height(Val::Percent(50.0)),
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overflow: Overflow::Hidden,
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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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flex_grow: 1.0,
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max_size: Size::UNDEFINED,
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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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.with_style(Style {
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flex_shrink: 0.,
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size: Size::new(Val::Undefined, Val::Px(20.)),
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..default()
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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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size: Size::new(Val::Px(200.0), Val::Px(200.0)),
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position_type: PositionType::Absolute,
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position: UiRect {
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left: Val::Px(210.0),
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bottom: Val::Px(10.0),
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..default()
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},
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border: UiRect::all(Val::Px(20.0)),
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..default()
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},
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background_color: Color::rgb(0.4, 0.4, 1.0).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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size: Size::new(Val::Percent(100.0), 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, 1.0).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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size: Size::new(Val::Percent(100.0), 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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size: Size::new(Val::Px(100.0), 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, 0.0).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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size: Size::all(Val::Percent(100.)),
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position_type: PositionType::Absolute,
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position: UiRect {
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left: Val::Px(20.0),
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bottom: Val::Px(20.0),
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..default()
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},
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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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size: Size::all(Val::Percent(100.)),
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position_type: PositionType::Absolute,
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position: UiRect {
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left: Val::Px(40.0),
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bottom: Val::Px(40.0),
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..default()
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},
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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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size: Size::all(Val::Percent(100.)),
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position_type: PositionType::Absolute,
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position: UiRect {
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left: Val::Px(60.0),
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bottom: Val::Px(60.0),
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..default()
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},
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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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size: Size::all(Val::Percent(100.)),
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position_type: PositionType::Absolute,
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position: UiRect {
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left: Val::Px(80.0),
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bottom: Val::Px(80.0),
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..default()
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},
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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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size: Size::width(Val::Percent(100.)),
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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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parent
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.spawn(ImageBundle {
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style: Style {
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size: Size::width(Val::Px(500.0)),
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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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// alt text
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parent
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.spawn(TextBundle::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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#[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, &Children, &Node)>,
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query_item: 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, children, uinode) in &mut query_list {
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let items_height: f32 = children
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.iter()
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.map(|entity| query_item.get(*entity).unwrap().size().y)
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.sum();
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let panel_height = uinode.size().y;
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let max_scroll = (items_height - panel_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.position.top = Val::Px(scrolling_list.position);
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}
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}
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}
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