**Ready for review. Examples migration progress: 100%.** # Objective - Implement https://github.com/bevyengine/bevy/discussions/15014 ## Solution This implements [cart's proposal](https://github.com/bevyengine/bevy/discussions/15014#discussioncomment-10574459) faithfully except for one change. I separated `TextSpan` from `TextSpan2d` because `TextSpan` needs to require the `GhostNode` component, which is a `bevy_ui` component only usable by UI. Extra changes: - Added `EntityCommands::commands_mut` that returns a mutable reference. This is a blocker for extension methods that return something other than `self`. Note that `sickle_ui`'s `UiBuilder::commands` returns a mutable reference for this reason. ## Testing - [x] Text examples all work. --- ## Showcase TODO: showcase-worthy ## Migration Guide TODO: very breaking ### Accessing text spans by index Text sections are now text sections on different entities in a hierarchy, Use the new `TextReader` and `TextWriter` system parameters to access spans by index. Before: ```rust fn refresh_text(mut query: Query<&mut Text, With<TimeText>>, time: Res<Time>) { let text = query.single_mut(); text.sections[1].value = format_time(time.elapsed()); } ``` After: ```rust fn refresh_text( query: Query<Entity, With<TimeText>>, mut writer: UiTextWriter, time: Res<Time> ) { let entity = query.single(); *writer.text(entity, 1) = format_time(time.elapsed()); } ``` ### Iterating text spans Text spans are now entities in a hierarchy, so the new `UiTextReader` and `UiTextWriter` system parameters provide ways to iterate that hierarchy. The `UiTextReader::iter` method will give you a normal iterator over spans, and `UiTextWriter::for_each` lets you visit each of the spans. --------- Co-authored-by: ickshonpe <david.curthoys@googlemail.com> Co-authored-by: Carter Anderson <mcanders1@gmail.com>
		
			
				
	
	
		
			84 lines
		
	
	
		
			2.9 KiB
		
	
	
	
		
			Rust
		
	
	
	
	
	
			
		
		
	
	
			84 lines
		
	
	
		
			2.9 KiB
		
	
	
	
		
			Rust
		
	
	
	
	
	
//! Demonstrates how to use transparency with UI.
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//! Shows two colored buttons with transparent text.
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use bevy::prelude::*;
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fn main() {
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    App::new()
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        .insert_resource(ClearColor(Color::BLACK))
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        .add_plugins(DefaultPlugins)
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        .add_systems(Startup, setup)
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        .run();
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}
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fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
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    commands.spawn(Camera2d);
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    let font_handle = asset_server.load("fonts/FiraSans-Bold.ttf");
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    commands
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        .spawn(NodeBundle {
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            style: Style {
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                width: Val::Percent(100.0),
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                height: Val::Percent(100.0),
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                align_items: AlignItems::Center,
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                justify_content: JustifyContent::SpaceAround,
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                ..default()
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            },
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            ..default()
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        })
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        .with_children(|parent| {
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            parent
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                .spawn(ButtonBundle {
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                    style: Style {
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                        width: Val::Px(150.0),
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                        height: Val::Px(65.0),
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                        justify_content: JustifyContent::Center,
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                        align_items: AlignItems::Center,
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                        ..default()
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                    },
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                    background_color: Color::srgb(0.1, 0.5, 0.1).into(),
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                    ..default()
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                })
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                .with_children(|parent| {
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                    parent.spawn((
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                        Text::new("Button 1"),
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                        TextStyle {
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                            font: font_handle.clone(),
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                            font_size: 33.0,
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                            // Alpha channel of the color controls transparency.
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                            color: Color::srgba(1.0, 1.0, 1.0, 0.2),
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                            ..default()
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                        },
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                    ));
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                });
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            // Button with a different color,
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            // to demonstrate the text looks different due to its transparency.
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            parent
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                .spawn(ButtonBundle {
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                    style: Style {
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                        width: Val::Px(150.0),
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                        height: Val::Px(65.0),
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                        justify_content: JustifyContent::Center,
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                        align_items: AlignItems::Center,
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                        ..default()
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                    },
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                    background_color: Color::srgb(0.5, 0.1, 0.5).into(),
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                    ..default()
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                })
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                .with_children(|parent| {
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                    parent.spawn((
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                        Text::new("Button 2"),
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                        TextStyle {
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                            font: font_handle.clone(),
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                            font_size: 33.0,
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                            // Alpha channel of the color controls transparency.
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                            color: Color::srgba(1.0, 1.0, 1.0, 0.2),
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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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