# 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`.
		
	
			
		
			
				
	
	
		
			84 lines
		
	
	
		
			2.9 KiB
		
	
	
	
		
			Rust
		
	
	
	
	
	
			
		
		
	
	
			84 lines
		
	
	
		
			2.9 KiB
		
	
	
	
		
			Rust
		
	
	
	
	
	
//! This example illustrates how to use `TextureAtlases` within ui
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use bevy::{color::palettes::css::*, prelude::*, winit::WinitSettings};
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fn main() {
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    App::new()
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        .add_plugins(DefaultPlugins.set(
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            // This sets image filtering to nearest
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            // This is done to prevent textures with low resolution (e.g. pixel art) from being blurred
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            // by linear filtering.
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            ImagePlugin::default_nearest(),
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        ))
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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, increment_atlas_index)
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        .run();
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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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    // Camera
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    commands.spawn(Camera2d);
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    let text_font = TextFont::default();
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    let texture_handle = asset_server.load("textures/rpg/chars/gabe/gabe-idle-run.png");
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    let texture_atlas = TextureAtlasLayout::from_grid(UVec2::splat(24), 7, 1, None, None);
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    let texture_atlas_handle = texture_atlases.add(texture_atlas);
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    // root node
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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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                flex_direction: FlexDirection::Column,
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                justify_content: JustifyContent::Center,
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                align_items: AlignItems::Center,
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                row_gap: Val::Px(text_font.font_size * 2.),
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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.spawn((
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                ImageBundle {
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                    style: Style {
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                        width: Val::Px(256.),
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                        height: Val::Px(256.),
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                        ..default()
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                    },
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                    image: UiImage::new(texture_handle),
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                    background_color: BackgroundColor(ANTIQUE_WHITE.into()),
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                    ..default()
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                },
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                TextureAtlas::from(texture_atlas_handle),
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                Outline::new(Val::Px(8.0), Val::ZERO, CRIMSON.into()),
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            ));
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            parent
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                .spawn((Text::new("press "), text_font.clone()))
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                .with_child((
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                    TextSpan::new("space"),
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                    TextColor(YELLOW.into()),
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                    text_font.clone(),
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                ))
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                .with_child((TextSpan::new(" to advance frames"), text_font));
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        });
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}
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fn increment_atlas_index(
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    mut atlas_images: Query<&mut TextureAtlas>,
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    keyboard: Res<ButtonInput<KeyCode>>,
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) {
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    if keyboard.just_pressed(KeyCode::Space) {
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        for mut atlas_image in &mut atlas_images {
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            atlas_image.index = (atlas_image.index + 1) % 6;
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        }
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    }
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}
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