015f2c69ca
# Objective Continue improving the user experience of our UI Node API in the direction specified by [Bevy's Next Generation Scene / UI System](https://github.com/bevyengine/bevy/discussions/14437) ## Solution As specified in the document above, merge `Style` fields into `Node`, and move "computed Node fields" into `ComputedNode` (I chose this name over something like `ComputedNodeLayout` because it currently contains more than just layout info. If we want to break this up / rename these concepts, lets do that in a separate PR). `Style` has been removed. This accomplishes a number of goals: ## Ergonomics wins Specifying both `Node` and `Style` is now no longer required for non-default styles Before: ```rust commands.spawn(( Node::default(), Style { width: Val::Px(100.), ..default() }, )); ``` After: ```rust commands.spawn(Node { width: Val::Px(100.), ..default() }); ``` ## Conceptual clarity `Style` was never a comprehensive "style sheet". It only defined "core" style properties that all `Nodes` shared. Any "styled property" that couldn't fit that mold had to be in a separate component. A "real" style system would style properties _across_ components (`Node`, `Button`, etc). We have plans to build a true style system (see the doc linked above). By moving the `Style` fields to `Node`, we fully embrace `Node` as the driving concept and remove the "style system" confusion. ## Next Steps * Consider identifying and splitting out "style properties that aren't core to Node". This should not happen for Bevy 0.15. --- ## Migration Guide Move any fields set on `Style` into `Node` and replace all `Style` component usage with `Node`. Before: ```rust commands.spawn(( Node::default(), Style { width: Val::Px(100.), ..default() }, )); ``` After: ```rust commands.spawn(Node { width: Val::Px(100.), ..default() }); ``` For any usage of the "computed node properties" that used to live on `Node`, use `ComputedNode` instead: Before: ```rust fn system(nodes: Query<&Node>) { for node in &nodes { let computed_size = node.size(); } } ``` After: ```rust fn system(computed_nodes: Query<&ComputedNode>) { for computed_node in &computed_nodes { let computed_size = computed_node.size(); } } ```
362 lines
18 KiB
Rust
362 lines
18 KiB
Rust
//! This example illustrates scrolling in 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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picking::focus::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(PickingBehavior::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(NodeBuilder::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(PickingBehavior {
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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<Down>>,
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mut commands: Commands
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if trigger.event().button == PointerButton::Primary {
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commands.entity(trigger.entity()).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(PickingBehavior {
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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(NodeBuilder::new(
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Role::ListItem,
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)),
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))
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.insert(PickingBehavior {
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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(PickingBehavior::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(NodeBuilder::new(
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Role::ListItem,
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)),
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))
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.insert(PickingBehavior {
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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(PickingBehavior {
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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(NodeBuilder::new(
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Role::ListItem,
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)),
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))
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.insert(PickingBehavior {
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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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