bf20c630a8
# Objective Allowing drawing of UI nodes with a gradient instead of a flat color. ## Solution The are three gradient structs corresponding to the three types of gradients supported: `LinearGradient`, `ConicGradient` and `RadialGradient`. These are then wrapped in a `Gradient` enum discriminator which has `Linear`, `Conic` and `Radial` variants. Each gradient type consists of the geometric properties for that gradient and a list of color stops. Color stops consist of a color, a position or angle and an optional hint. If no position is specified for a stop, it's evenly spaced between the previous and following stops. Color stop positions are absolute, if you specify a list of stops: ```vec   Conic gradients can be used to draw simple pie charts like in CSS: 
458 lines
20 KiB
Rust
458 lines
20 KiB
Rust
//! This example illustrates the various features of Bevy UI.
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use std::f32::consts::PI;
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use accesskit::{Node as Accessible, Role};
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use bevy::{
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a11y::AccessibilityNode,
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color::palettes::{
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basic::LIME,
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css::{DARK_GRAY, NAVY},
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},
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input::mouse::{MouseScrollUnit, MouseWheel},
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picking::hover::HoverMap,
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prelude::*,
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ui::widget::NodeImageMode,
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};
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fn main() {
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let mut app = App::new();
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app.add_plugins(DefaultPlugins)
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.add_systems(Startup, setup)
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.add_systems(Update, update_scroll_position);
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#[cfg(feature = "bevy_ui_debug")]
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app.add_systems(Update, toggle_debug_overlay);
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app.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((Camera2d, IsDefaultUiCamera, BoxShadowSamples(6)));
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// root node
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commands
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.spawn(Node {
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width: Val::Percent(100.0),
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height: 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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.insert(Pickable::IGNORE)
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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((
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Node {
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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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BackgroundColor(Color::srgb(0.65, 0.65, 0.65)),
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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((
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Node {
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width: Val::Percent(100.),
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flex_direction: FlexDirection::Column,
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padding: UiRect::all(Val::Px(5.)),
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row_gap: Val::Px(5.),
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..default()
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},
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BackgroundColor(Color::srgb(0.15, 0.15, 0.15)),
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Visibility::Visible,
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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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Text::new("Text Example"),
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TextFont {
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font: asset_server.load("fonts/FiraSans-Bold.ttf"),
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font_size: 25.0,
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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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#[cfg(feature = "bevy_ui_debug")]
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{
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// Debug overlay text
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parent.spawn((
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Text::new("Press Space to toggle debug outlines."),
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TextFont {
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font: asset_server.load("fonts/FiraSans-Bold.ttf"),
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..default()
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},
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Label,
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));
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parent.spawn((
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Text::new("V: toggle UI root's visibility"),
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TextFont {
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font: asset_server.load("fonts/FiraSans-Bold.ttf"),
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font_size: 12.,
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..default()
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},
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Label,
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));
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parent.spawn((
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Text::new("S: toggle outlines for hidden nodes"),
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TextFont {
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font: asset_server.load("fonts/FiraSans-Bold.ttf"),
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font_size: 12.,
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..default()
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},
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Label,
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));
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parent.spawn((
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Text::new("C: toggle outlines for clipped nodes"),
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TextFont {
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font: asset_server.load("fonts/FiraSans-Bold.ttf"),
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font_size: 12.,
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..default()
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},
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Label,
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));
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}
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#[cfg(not(feature = "bevy_ui_debug"))]
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parent.spawn((
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Text::new("Try enabling feature \"bevy_ui_debug\"."),
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TextFont {
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font: asset_server.load("fonts/FiraSans-Bold.ttf"),
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..default()
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},
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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(Node {
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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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.with_children(|parent| {
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// Title
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parent.spawn((
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Text::new("Scrolling list"),
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TextFont {
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font: asset_server.load("fonts/FiraSans-Bold.ttf"),
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font_size: 21.,
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..default()
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},
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Label,
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));
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// Scrolling list
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parent
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.spawn((
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Node {
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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::scroll_y(),
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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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parent
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.spawn((
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Node {
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flex_direction: FlexDirection::Column,
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..Default::default()
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},
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BackgroundGradient::from(LinearGradient::to_bottom(vec![
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ColorStop::auto(NAVY),
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ColorStop::auto(Color::BLACK),
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])),
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Pickable {
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should_block_lower: false,
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..Default::default()
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},
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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..25 {
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parent
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.spawn((
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Text(format!("Item {i}")),
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TextFont {
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font: asset_server
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.load("fonts/FiraSans-Bold.ttf"),
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..default()
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},
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Label,
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AccessibilityNode(Accessible::new(Role::ListItem)),
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))
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.insert(Pickable {
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should_block_lower: false,
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..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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parent
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.spawn(Node {
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left: Val::Px(210.),
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bottom: Val::Px(10.),
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position_type: PositionType::Absolute,
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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((
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Node {
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width: Val::Px(200.0),
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height: Val::Px(200.0),
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border: UiRect::all(Val::Px(20.)),
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flex_direction: FlexDirection::Column,
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justify_content: JustifyContent::Center,
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..default()
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},
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BorderColor(LIME.into()),
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BackgroundColor(Color::srgb(0.8, 0.8, 1.)),
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))
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.with_children(|parent| {
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parent.spawn((
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ImageNode::new(asset_server.load("branding/bevy_logo_light.png")),
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// Uses the transform to rotate the logo image by 45 degrees
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Transform::from_rotation(Quat::from_rotation_z(0.25 * PI)),
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BorderRadius::all(Val::Px(10.)),
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Outline {
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width: Val::Px(2.),
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offset: Val::Px(4.),
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color: DARK_GRAY.into(),
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},
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));
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});
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});
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let shadow_style = ShadowStyle {
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color: Color::BLACK.with_alpha(0.5),
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blur_radius: Val::Px(2.),
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x_offset: Val::Px(10.),
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y_offset: Val::Px(10.),
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..default()
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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(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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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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.insert(Pickable::IGNORE)
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.with_children(|parent| {
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parent
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.spawn((
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Node {
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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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BackgroundColor(Color::srgb(1.0, 0.0, 0.)),
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BoxShadow::from(shadow_style),
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))
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.with_children(|parent| {
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parent.spawn((
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Node {
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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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BackgroundColor(Color::srgb(1.0, 0.3, 0.3)),
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BoxShadow::from(shadow_style),
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));
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parent.spawn((
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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(40.),
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bottom: Val::Px(40.),
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..default()
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},
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BackgroundColor(Color::srgb(1.0, 0.5, 0.5)),
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BoxShadow::from(shadow_style),
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));
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parent.spawn((
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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(60.),
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bottom: Val::Px(60.),
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..default()
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},
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BackgroundColor(Color::srgb(0.0, 0.7, 0.7)),
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BoxShadow::from(shadow_style),
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));
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// alpha test
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parent.spawn((
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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(80.),
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bottom: Val::Px(80.),
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..default()
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},
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BackgroundColor(Color::srgba(1.0, 0.9, 0.9, 0.4)),
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BoxShadow::from(ShadowStyle {
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color: Color::BLACK.with_alpha(0.3),
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..shadow_style
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}),
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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(Node {
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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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.with_children(|parent| {
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// bevy logo (image)
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parent
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.spawn((
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ImageNode::new(asset_server.load("branding/bevy_logo_dark_big.png"))
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.with_mode(NodeImageMode::Stretch),
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Node {
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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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))
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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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Node {
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display: Display::None,
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..default()
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},
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Text::new("Bevy logo"),
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));
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});
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});
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// four bevy icons demonstrating image flipping
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parent
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.spawn(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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justify_content: JustifyContent::Center,
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align_items: AlignItems::FlexEnd,
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column_gap: Val::Px(10.),
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padding: UiRect::all(Val::Px(10.)),
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..default()
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})
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.insert(Pickable::IGNORE)
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.with_children(|parent| {
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for (flip_x, flip_y) in
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[(false, false), (false, true), (true, true), (true, false)]
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{
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parent.spawn((
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ImageNode {
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image: asset_server.load("branding/icon.png"),
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flip_x,
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flip_y,
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..default()
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},
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Node {
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// The height will be chosen automatically to preserve the image's aspect ratio
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width: Val::Px(75.),
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..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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}
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#[cfg(feature = "bevy_ui_debug")]
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// The system that will enable/disable the debug outlines around the nodes
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fn toggle_debug_overlay(
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input: Res<ButtonInput<KeyCode>>,
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mut debug_options: ResMut<UiDebugOptions>,
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mut root_node_query: Query<&mut Visibility, (With<Node>, Without<ChildOf>)>,
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) {
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info_once!("The debug outlines are enabled, press Space to turn them on/off");
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if input.just_pressed(KeyCode::Space) {
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// The toggle method will enable the debug overlay if disabled and disable if enabled
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debug_options.toggle();
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}
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if input.just_pressed(KeyCode::KeyS) {
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// Toggle debug outlines for nodes with `ViewVisibility` set to false.
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debug_options.show_hidden = !debug_options.show_hidden;
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}
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if input.just_pressed(KeyCode::KeyC) {
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// Toggle outlines for clipped UI nodes.
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debug_options.show_clipped = !debug_options.show_clipped;
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}
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if input.just_pressed(KeyCode::KeyV) {
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for mut visibility in root_node_query.iter_mut() {
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// Toggle the UI root node's visibility
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visibility.toggle_inherited_hidden();
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}
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}
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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 update_scroll_position(
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mut mouse_wheel_events: EventReader<MouseWheel>,
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hover_map: Res<HoverMap>,
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mut scrolled_node_query: Query<&mut ScrollPosition>,
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keyboard_input: Res<ButtonInput<KeyCode>>,
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) {
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for mouse_wheel_event in mouse_wheel_events.read() {
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let (mut dx, mut dy) = match mouse_wheel_event.unit {
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MouseScrollUnit::Line => (mouse_wheel_event.x * 20., mouse_wheel_event.y * 20.),
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MouseScrollUnit::Pixel => (mouse_wheel_event.x, mouse_wheel_event.y),
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};
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if keyboard_input.pressed(KeyCode::ShiftLeft) || keyboard_input.pressed(KeyCode::ShiftRight)
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{
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std::mem::swap(&mut dx, &mut dy);
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}
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for (_pointer, pointer_map) in hover_map.iter() {
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for (entity, _hit) in pointer_map.iter() {
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if let Ok(mut scroll_position) = scrolled_node_query.get_mut(*entity) {
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scroll_position.offset_x -= dx;
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scroll_position.offset_y -= dy;
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}
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}
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}
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}
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}
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