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https://github.com/bevyengine/bevy
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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(); } } ```
347 lines
14 KiB
Rust
347 lines
14 KiB
Rust
//! This example illustrates the various features of Bevy UI.
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use bevy::{
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a11y::{
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accesskit::{NodeBuilder, Role},
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AccessibilityNode,
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},
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color::palettes::basic::LIME,
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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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// Only run the app when there is user input. This will significantly reduce CPU/GPU use.
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.insert_resource(WinitSettings::desktop_app())
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.add_systems(Startup, setup)
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.add_systems(Update, update_scroll_position);
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#[cfg(feature = "bevy_dev_tools")]
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{
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app.add_plugins(bevy::dev_tools::ui_debug_overlay::DebugUiPlugin)
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.add_systems(Update, toggle_overlay);
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}
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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, UiBoxShadowSamples(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(PickingBehavior::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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))
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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_dev_tools")]
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// Debug overlay text
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parent.spawn((
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Text::new("Press Space to enable 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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#[cfg(not(feature = "bevy_dev_tools"))]
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parent.spawn((
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Text::new("Try enabling feature \"bevy_dev_tools\"."),
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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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// 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.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(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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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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position_type: PositionType::Absolute,
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left: Val::Px(210.),
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bottom: Val::Px(10.),
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border: UiRect::all(Val::Px(20.)),
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..default()
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},
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BorderColor(LIME.into()),
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BackgroundColor(Color::srgb(0.4, 0.4, 1.)),
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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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width: Val::Percent(100.0),
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height: Val::Percent(100.0),
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..default()
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},
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BackgroundColor(Color::srgb(0.8, 0.8, 1.)),
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));
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});
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let shadow = BoxShadow {
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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::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(PickingBehavior::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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shadow,
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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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shadow,
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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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shadow,
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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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shadow,
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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 {
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color: Color::BLACK.with_alpha(0.3),
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..shadow
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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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UiImage::new(asset_server.load("branding/bevy_logo_dark_big.png")),
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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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});
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}
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#[cfg(feature = "bevy_dev_tools")]
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// The system that will enable/disable the debug outlines around the nodes
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fn toggle_overlay(
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input: Res<ButtonInput<KeyCode>>,
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mut options: ResMut<bevy::dev_tools::ui_debug_overlay::UiDebugOptions>,
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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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options.toggle();
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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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