bevy/examples/ui/relative_cursor_position.rs
UkoeHB c2c19e5ae4
Text rework (#15591)
**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>
2024-10-09 18:35:36 +00:00

92 lines
3 KiB
Rust

//! Showcases the [`RelativeCursorPosition`] component, used to check the position of the cursor relative to a UI node.
use bevy::{
prelude::*, render::camera::Viewport, ui::RelativeCursorPosition, winit::WinitSettings,
};
fn main() {
App::new()
.add_plugins(DefaultPlugins)
// Only run the app when there is user input. This will significantly reduce CPU/GPU use.
.insert_resource(WinitSettings::desktop_app())
.add_systems(Startup, setup)
.add_systems(Update, relative_cursor_position_system)
.run();
}
fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
commands.spawn((
Camera2d,
Camera {
// Cursor position will take the viewport offset into account
viewport: Some(Viewport {
physical_position: [200, 100].into(),
physical_size: [600, 600].into(),
..default()
}),
..default()
},
));
commands
.spawn(NodeBundle {
style: Style {
width: Val::Percent(100.),
height: Val::Percent(100.0),
align_items: AlignItems::Center,
justify_content: JustifyContent::Center,
flex_direction: FlexDirection::Column,
..default()
},
..default()
})
.with_children(|parent| {
parent
.spawn(NodeBundle {
style: Style {
width: Val::Px(250.),
height: Val::Px(250.),
margin: UiRect::bottom(Val::Px(15.)),
..default()
},
background_color: Color::srgb(235., 35., 12.).into(),
..default()
})
.insert(RelativeCursorPosition::default());
parent.spawn((
Text::new("(0.0, 0.0)"),
TextStyle {
font: asset_server.load("fonts/FiraSans-Bold.ttf"),
font_size: 33.0,
color: Color::srgb(0.9, 0.9, 0.9),
..default()
},
));
});
}
/// This systems polls the relative cursor position and displays its value in a text component.
fn relative_cursor_position_system(
relative_cursor_position_query: Query<&RelativeCursorPosition>,
mut output_query: Query<(&mut Text, &mut TextStyle)>,
) {
let relative_cursor_position = relative_cursor_position_query.single();
let (mut output, mut style) = output_query.single_mut();
**output = if let Some(relative_cursor_position) = relative_cursor_position.normalized {
format!(
"({:.1}, {:.1})",
relative_cursor_position.x, relative_cursor_position.y
)
} else {
"unknown".to_string()
};
style.color = if relative_cursor_position.mouse_over() {
Color::srgb(0.1, 0.9, 0.1)
} else {
Color::srgb(0.9, 0.1, 0.1)
};
}