bevy/examples/ui/button.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

96 lines
3.3 KiB
Rust

//! This example illustrates how to create a button that changes color and text based on its
//! interaction state.
use bevy::{color::palettes::basic::*, prelude::*, 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, button_system)
.run();
}
const NORMAL_BUTTON: Color = Color::srgb(0.15, 0.15, 0.15);
const HOVERED_BUTTON: Color = Color::srgb(0.25, 0.25, 0.25);
const PRESSED_BUTTON: Color = Color::srgb(0.35, 0.75, 0.35);
fn button_system(
mut interaction_query: Query<
(
&Interaction,
&mut BackgroundColor,
&mut BorderColor,
&Children,
),
(Changed<Interaction>, With<Button>),
>,
mut text_query: Query<&mut Text>,
) {
for (interaction, mut color, mut border_color, children) in &mut interaction_query {
let mut text = text_query.get_mut(children[0]).unwrap();
match *interaction {
Interaction::Pressed => {
**text = "Press".to_string();
*color = PRESSED_BUTTON.into();
border_color.0 = RED.into();
}
Interaction::Hovered => {
**text = "Hover".to_string();
*color = HOVERED_BUTTON.into();
border_color.0 = Color::WHITE;
}
Interaction::None => {
**text = "Button".to_string();
*color = NORMAL_BUTTON.into();
border_color.0 = Color::BLACK;
}
}
}
}
fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
// ui camera
commands.spawn(Camera2d);
commands
.spawn(NodeBundle {
style: Style {
width: Val::Percent(100.0),
height: Val::Percent(100.0),
align_items: AlignItems::Center,
justify_content: JustifyContent::Center,
..default()
},
..default()
})
.with_children(|parent| {
parent
.spawn(ButtonBundle {
style: Style {
width: Val::Px(150.0),
height: Val::Px(65.0),
border: UiRect::all(Val::Px(5.0)),
// horizontally center child text
justify_content: JustifyContent::Center,
// vertically center child text
align_items: AlignItems::Center,
..default()
},
border_color: BorderColor(Color::BLACK),
border_radius: BorderRadius::MAX,
background_color: NORMAL_BUTTON.into(),
..default()
})
.with_child((
Text::new("Button"),
TextStyle {
font: asset_server.load("fonts/FiraSans-Bold.ttf"),
font_size: 33.0,
color: Color::srgb(0.9, 0.9, 0.9),
..default()
},
));
});
}