5b29402cc8
# Objective
This idea came up in the context of a hypothetical "text sections as
entities" where text sections are children of a text bundle.
```rust
commands
.spawn(TextBundle::default())
.with_children(|parent} {
parent.spawn(TextSection::from("Hello"));
});
```
This is a bit cumbersome (but powerful and probably the way things are
headed). [`bsn!`](https://github.com/bevyengine/bevy/discussions/14437)
will eventually make this nicer, but in the mean time, this might
improve ergonomics for the common case where there is only one
`TextSection`.
## Solution
Add a `with_child` method to the `BuildChildren` trait that spawns a
single bundle and adds it as a child to the entity.
```rust
commands
.spawn(TextBundle::default())
.with_child(TextSection::from("Hello"));
```
## Testing
I added some tests, and modified the `button` example to use the new
method.
If any potential co-authors want to improve the tests, that would be
great.
## Alternatives
- Some sort of macro. See
https://github.com/tigregalis/bevy_spans_ent/blob/main/examples/macro.rs#L20.
I don't love this, personally, and it would probably be obsoleted by
`bsn!`.
- Wait for `bsn!`
- Add `with_children_batch` that takes an `Into<Iterator>` of bundles.
```rust
with_children_batch(vec![TextSection::from("Hello")])
```
This is maybe not as useful as it sounds -- it only works with
homogeneous bundles, so no marker components or styles.
- If this doesn't seem valuable, doing nothing is cool with me.
96 lines
3.3 KiB
Rust
96 lines
3.3 KiB
Rust
//! This example illustrates how to create a button that changes color and text based on its
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//! interaction state.
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use bevy::{color::palettes::basic::*, prelude::*, winit::WinitSettings};
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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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const NORMAL_BUTTON: Color = Color::srgb(0.15, 0.15, 0.15);
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const HOVERED_BUTTON: Color = Color::srgb(0.25, 0.25, 0.25);
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const PRESSED_BUTTON: Color = Color::srgb(0.35, 0.75, 0.35);
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fn button_system(
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mut interaction_query: Query<
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(
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&Interaction,
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&mut BackgroundColor,
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&mut BorderColor,
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&Children,
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),
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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 color, mut border_color, children) 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.sections[0].value = "Press".to_string();
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*color = PRESSED_BUTTON.into();
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border_color.0 = RED.into();
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}
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Interaction::Hovered => {
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text.sections[0].value = "Hover".to_string();
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*color = HOVERED_BUTTON.into();
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border_color.0 = Color::WHITE;
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}
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Interaction::None => {
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text.sections[0].value = "Button".to_string();
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*color = NORMAL_BUTTON.into();
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border_color.0 = Color::BLACK;
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}
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}
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}
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}
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fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
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// ui camera
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commands.spawn(Camera2dBundle::default());
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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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parent
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.spawn(ButtonBundle {
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style: Style {
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width: Val::Px(150.0),
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height: Val::Px(65.0),
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border: UiRect::all(Val::Px(5.0)),
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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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..default()
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},
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border_color: BorderColor(Color::BLACK),
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border_radius: BorderRadius::MAX,
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background_color: NORMAL_BUTTON.into(),
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..default()
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})
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.with_child(TextBundle::from_section(
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"Button",
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TextStyle {
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font: asset_server.load("fonts/FiraSans-Bold.ttf"),
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font_size: 40.0,
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color: 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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