# Objective PR #17225 allowed for sprite picking to be opt-in. After some discussion, it was agreed that `PickingBehavior` should be used to opt-in to sprite picking behavior for entities. This leads to `PickingBehavior` having two purposes: mark an entity for use in a backend, and describe how it should be picked. Discussion led to the name `Pickable`making more sense (also: this is what the component was named before upstreaming). A follow-up pass will be made after this PR to unify backends. ## Solution Replace all instances of `PickingBehavior` and `picking_behavior` with `Pickable` and `pickable`, respectively. ## Testing CI ## Migration Guide Change all instances of `PickingBehavior` to `Pickable`.
		
			
				
	
	
		
			360 lines
		
	
	
		
			18 KiB
		
	
	
	
		
			Rust
		
	
	
	
	
	
			
		
		
	
	
			360 lines
		
	
	
		
			18 KiB
		
	
	
	
		
			Rust
		
	
	
	
	
	
//! This example illustrates scrolling in Bevy UI.
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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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    input::mouse::{MouseScrollUnit, MouseWheel},
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    picking::hover::HoverMap,
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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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    let mut app = App::new();
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    app.add_plugins(DefaultPlugins)
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        .insert_resource(WinitSettings::desktop_app())
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        .add_systems(Startup, setup)
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        .add_systems(Update, update_scroll_position);
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    app.run();
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}
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const FONT_SIZE: f32 = 20.;
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const LINE_HEIGHT: f32 = 21.;
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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));
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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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            flex_direction: FlexDirection::Column,
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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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            // horizontal scroll example
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            parent
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                .spawn(Node {
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                    width: Val::Percent(100.),
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                    flex_direction: FlexDirection::Column,
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                    ..default()
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                })
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                .with_children(|parent| {
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                    // header
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                    parent.spawn((
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                        Text::new("Horizontally Scrolling list (Ctrl + Mousewheel)"),
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                        TextFont {
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                            font: asset_server.load("fonts/FiraSans-Bold.ttf"),
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                            font_size: FONT_SIZE,
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                            ..default()
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                        },
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                        Label,
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                    ));
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                    // horizontal scroll container
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                    parent
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                        .spawn((
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                            Node {
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                                width: Val::Percent(80.),
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                                margin: UiRect::all(Val::Px(10.)),
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                                flex_direction: FlexDirection::Row,
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                                overflow: Overflow::scroll_x(), // n.b.
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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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                            for i in 0..100 {
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                                parent.spawn((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(Node {
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                                    min_width: Val::Px(200.),
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                                    align_content: AlignContent::Center,
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                                    ..default()
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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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                                .observe(|
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                                    trigger: Trigger<Pointer<Pressed>>,
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                                    mut commands: Commands
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                                | {
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                                    if trigger.event().button == PointerButton::Primary {
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                                        commands.entity(trigger.target()).despawn_recursive();
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                                    }
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                                });
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                            }
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                        });
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                });
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            // container for all other examples
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            parent
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                .spawn(Node {
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                    width: Val::Percent(100.),
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                    height: Val::Percent(100.),
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                    flex_direction: FlexDirection::Row,
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                    justify_content: JustifyContent::SpaceBetween,
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                    ..default()
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                })
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                .with_children(|parent| {
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                    // vertical scroll example
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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("Vertically 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: FONT_SIZE,
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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(), // n.b.
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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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                                    // List items
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                                    for i in 0..25 {
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                                        parent
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                                            .spawn(Node {
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                                                min_height: Val::Px(LINE_HEIGHT),
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                                                max_height: Val::Px(LINE_HEIGHT),
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                                                ..default()
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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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                                            .with_children(|parent| {
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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(
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                                                            Role::ListItem,
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                                                        )),
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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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                    // Bidirectional scroll example
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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("Bidirectionally 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: FONT_SIZE,
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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(), // n.b.
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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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                                    // Rows in each column
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                                    for oi in 0..10 {
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                                        parent
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                                            .spawn(Node {
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                                                flex_direction: FlexDirection::Row,
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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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                                                // Elements in each row
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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 {}", (oi * 25) + i)),
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                                                            TextFont {
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                                                                font: asset_server.load(
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                                                                    "fonts/FiraSans-Bold.ttf",
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                                                                ),
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                                                                ..default()
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                                                            },
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                                                            Label,
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                                                            AccessibilityNode(Accessible::new(
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                                                                Role::ListItem,
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                                                            )),
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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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                        });
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                    // Nested scrolls example
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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("Nested Scrolling Lists"),
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                                TextFont {
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                                    font: asset_server.load("fonts/FiraSans-Bold.ttf"),
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                                    font_size: FONT_SIZE,
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                                    ..default()
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                                },
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                                Label,
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                            ));
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                            // Outer, horizontal scrolling container
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                            parent
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                                .spawn((
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                                    Node {
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                                        column_gap: Val::Px(20.),
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                                        flex_direction: FlexDirection::Row,
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                                        align_self: AlignSelf::Stretch,
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                                        height: Val::Percent(50.),
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                                        overflow: Overflow::scroll_x(), // n.b.
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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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                                    // Inner, scrolling columns
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                                    for oi in 0..30 {
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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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                                                    overflow: Overflow::scroll_y(),
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                                                    ..default()
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                                                },
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                                                BackgroundColor(Color::srgb(0.05, 0.05, 0.05)),
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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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                                            .with_children(|parent| {
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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 {}", (oi * 25) + i)),
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                                                            TextFont {
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                                                                font: asset_server.load(
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                                                                    "fonts/FiraSans-Bold.ttf",
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                                                                ),
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                                                                ..default()
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                                                            },
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                                                            Label,
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                                                            AccessibilityNode(Accessible::new(
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                                                                Role::ListItem,
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                                                            )),
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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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                        });
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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 => (
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                mouse_wheel_event.x * LINE_HEIGHT,
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                mouse_wheel_event.y * LINE_HEIGHT,
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            ),
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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::ControlLeft)
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            || keyboard_input.pressed(KeyCode::ControlRight)
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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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