# Objective
Currently text is recomputed unnecessarily on any changes to its color,
which is extremely expensive.
## Solution
Split up `TextStyle` into two separate components `TextFont` and
`TextColor`.
## Testing
I added this system to `many_buttons`:
```rust
fn set_text_colors_changed(mut colors: Query<&mut TextColor>) {
    for mut text_color in colors.iter_mut() {
        text_color.set_changed();
    }
}
```
reports ~4fps on main, ~50fps with this PR.
## Migration Guide
`TextStyle` has been renamed to `TextFont` and its `color` field has
been moved to a separate component named `TextColor` which newtypes
`Color`.
		
	
			
		
			
				
	
	
		
			118 lines
		
	
	
		
			4.2 KiB
		
	
	
	
		
			Rust
		
	
	
	
	
	
			
		
		
	
	
			118 lines
		
	
	
		
			4.2 KiB
		
	
	
	
		
			Rust
		
	
	
	
	
	
//! This example illustrates how to create buttons with their texture atlases sliced
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//! and kept in proportion instead of being stretched by the button dimensions
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use bevy::{
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    color::palettes::css::{GOLD, ORANGE},
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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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    App::new()
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        .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, button_system)
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        .run();
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}
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fn button_system(
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    mut interaction_query: Query<
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        (&Interaction, &mut TextureAtlas, &Children, &mut UiImage),
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        (Changed<Interaction>, With<Button>),
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    >,
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    mut text_query: Query<&mut Text>,
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) {
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    for (interaction, mut atlas, children, mut image) in &mut interaction_query {
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        let mut text = text_query.get_mut(children[0]).unwrap();
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        match *interaction {
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            Interaction::Pressed => {
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                **text = "Press".to_string();
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                atlas.index = (atlas.index + 1) % 30;
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                image.color = GOLD.into();
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            }
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            Interaction::Hovered => {
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                **text = "Hover".to_string();
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                image.color = ORANGE.into();
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            }
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            Interaction::None => {
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                **text = "Button".to_string();
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                image.color = Color::WHITE;
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            }
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        }
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    }
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}
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fn setup(
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    mut commands: Commands,
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    asset_server: Res<AssetServer>,
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    mut texture_atlases: ResMut<Assets<TextureAtlasLayout>>,
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) {
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    let texture_handle = asset_server.load("textures/fantasy_ui_borders/border_sheet.png");
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    let atlas_layout =
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        TextureAtlasLayout::from_grid(UVec2::new(50, 50), 6, 6, Some(UVec2::splat(2)), None);
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    let atlas_layout_handle = texture_atlases.add(atlas_layout);
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    let slicer = TextureSlicer {
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        border: BorderRect::square(24.0),
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        center_scale_mode: SliceScaleMode::Stretch,
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        sides_scale_mode: SliceScaleMode::Stretch,
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        max_corner_scale: 1.0,
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    };
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    // ui camera
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    commands.spawn(Camera2d);
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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::Center,
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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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            for (idx, [w, h]) in [
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                (0, [150.0, 150.0]),
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                (7, [300.0, 150.0]),
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                (13, [150.0, 300.0]),
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            ] {
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                parent
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                    .spawn((
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                        ButtonBundle {
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                            style: Style {
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                                width: Val::Px(w),
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                                height: Val::Px(h),
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                                // horizontally center child text
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                                justify_content: JustifyContent::Center,
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                                // vertically center child text
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                                align_items: AlignItems::Center,
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                                margin: UiRect::all(Val::Px(20.0)),
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                                ..default()
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                            },
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                            image: texture_handle.clone().into(),
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                            ..default()
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                        },
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                        ImageScaleMode::Sliced(slicer.clone()),
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                        TextureAtlas {
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                            index: idx,
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                            layout: atlas_layout_handle.clone(),
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                        },
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                    ))
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                    .with_children(|parent| {
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                        parent.spawn((
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                            Text::new("Button"),
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                            TextFont {
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                                font: asset_server.load("fonts/FiraSans-Bold.ttf"),
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                                font_size: 33.0,
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                                ..default()
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                            },
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                            TextColor(Color::srgb(0.9, 0.9, 0.9)),
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                        ));
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                    });
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            }
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        });
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}
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