# 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`.
		
	
			
		
			
				
	
	
		
			115 lines
		
	
	
		
			3.5 KiB
		
	
	
	
		
			Rust
		
	
	
	
	
	
			
		
		
	
	
			115 lines
		
	
	
		
			3.5 KiB
		
	
	
	
		
			Rust
		
	
	
	
	
	
//! This example illustrates how to override the window scale factor imposed by the
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//! operating system.
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use bevy::{prelude::*, window::WindowResolution};
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#[derive(Component)]
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struct CustomText;
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fn main() {
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    App::new()
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        .add_plugins(DefaultPlugins.set(WindowPlugin {
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            primary_window: Some(Window {
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                resolution: WindowResolution::new(500., 300.).with_scale_factor_override(1.0),
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                ..default()
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            }),
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            ..default()
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        }))
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        .add_systems(Startup, setup)
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        .add_systems(
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            Update,
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            (display_override, toggle_override, change_scale_factor),
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        )
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        .run();
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}
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fn setup(mut commands: Commands) {
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    // camera
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    commands.spawn(Camera2d);
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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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                justify_content: JustifyContent::SpaceBetween,
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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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            // left vertical fill (border)
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            parent
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                .spawn(NodeBundle {
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                    style: Style {
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                        width: Val::Px(300.0),
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                        height: Val::Percent(100.0),
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                        border: UiRect::all(Val::Px(2.0)),
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                        ..default()
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                    },
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                    background_color: Color::srgb(0.65, 0.65, 0.65).into(),
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                    ..default()
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                })
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                .with_child((
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                    CustomText,
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                    Text::new("Example text"),
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                    TextFont {
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                        font_size: 25.0,
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                        ..default()
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                    },
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                    Style {
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                        align_self: AlignSelf::FlexEnd,
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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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/// Set the title of the window to the current override
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fn display_override(
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    mut windows: Query<&mut Window>,
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    mut custom_text: Query<&mut Text, With<CustomText>>,
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) {
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    let mut window = windows.single_mut();
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    let text = format!(
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        "Scale factor: {:.1} {}",
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        window.scale_factor(),
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        if window.resolution.scale_factor_override().is_some() {
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            "(overridden)"
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        } else {
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            "(default)"
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        }
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    );
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    window.title.clone_from(&text);
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    **custom_text.single_mut() = text;
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}
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/// This system toggles scale factor overrides when enter is pressed
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fn toggle_override(input: Res<ButtonInput<KeyCode>>, mut windows: Query<&mut Window>) {
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    let mut window = windows.single_mut();
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    if input.just_pressed(KeyCode::Enter) {
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        let scale_factor_override = window.resolution.scale_factor_override();
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        window
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            .resolution
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            .set_scale_factor_override(scale_factor_override.xor(Some(1.0)));
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    }
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}
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/// This system changes the scale factor override when up or down is pressed
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fn change_scale_factor(input: Res<ButtonInput<KeyCode>>, mut windows: Query<&mut Window>) {
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    let mut window = windows.single_mut();
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    let scale_factor_override = window.resolution.scale_factor_override();
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    if input.just_pressed(KeyCode::ArrowUp) {
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        window
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            .resolution
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            .set_scale_factor_override(scale_factor_override.map(|n| n + 1.0));
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    } else if input.just_pressed(KeyCode::ArrowDown) {
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        window
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            .resolution
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            .set_scale_factor_override(scale_factor_override.map(|n| (n - 1.0).max(1.0)));
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    }
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}
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