bevy/examples/window/window_resizing.rs
Carter Anderson 015f2c69ca
Merge Style properties into Node. Use ComputedNode for computed properties. (#15975)
# Objective

Continue improving the user experience of our UI Node API in the
direction specified by [Bevy's Next Generation Scene / UI
System](https://github.com/bevyengine/bevy/discussions/14437)

## Solution

As specified in the document above, merge `Style` fields into `Node`,
and move "computed Node fields" into `ComputedNode` (I chose this name
over something like `ComputedNodeLayout` because it currently contains
more than just layout info. If we want to break this up / rename these
concepts, lets do that in a separate PR). `Style` has been removed.

This accomplishes a number of goals:

## Ergonomics wins

Specifying both `Node` and `Style` is now no longer required for
non-default styles

Before:
```rust
commands.spawn((
    Node::default(),
    Style {
        width:  Val::Px(100.),
        ..default()
    },
));
```

After:

```rust
commands.spawn(Node {
    width:  Val::Px(100.),
    ..default()
});
```

## Conceptual clarity

`Style` was never a comprehensive "style sheet". It only defined "core"
style properties that all `Nodes` shared. Any "styled property" that
couldn't fit that mold had to be in a separate component. A "real" style
system would style properties _across_ components (`Node`, `Button`,
etc). We have plans to build a true style system (see the doc linked
above).

By moving the `Style` fields to `Node`, we fully embrace `Node` as the
driving concept and remove the "style system" confusion.

## Next Steps

* Consider identifying and splitting out "style properties that aren't
core to Node". This should not happen for Bevy 0.15.

---

## Migration Guide

Move any fields set on `Style` into `Node` and replace all `Style`
component usage with `Node`.

Before:
```rust
commands.spawn((
    Node::default(),
    Style {
        width:  Val::Px(100.),
        ..default()
    },
));
```

After:

```rust
commands.spawn(Node {
    width:  Val::Px(100.),
    ..default()
});
```

For any usage of the "computed node properties" that used to live on
`Node`, use `ComputedNode` instead:

Before:
```rust
fn system(nodes: Query<&Node>) {
    for node in &nodes {
        let computed_size = node.size();
    }
}
```

After:
```rust
fn system(computed_nodes: Query<&ComputedNode>) {
    for computed_node in &computed_nodes {
        let computed_size = computed_node.size();
    }
}
```
2024-10-18 22:25:33 +00:00

83 lines
2.4 KiB
Rust

//! This example illustrates how to resize windows, and how to respond to a window being resized.
use bevy::{prelude::*, window::WindowResized};
fn main() {
App::new()
.insert_resource(ResolutionSettings {
large: Vec2::new(1920.0, 1080.0),
medium: Vec2::new(800.0, 600.0),
small: Vec2::new(640.0, 360.0),
})
.add_plugins(DefaultPlugins)
.add_systems(Startup, (setup_camera, setup_ui))
.add_systems(Update, (on_resize_system, toggle_resolution))
.run();
}
/// Marker component for the text that displays the current resolution.
#[derive(Component)]
struct ResolutionText;
/// Stores the various window-resolutions we can select between.
#[derive(Resource)]
struct ResolutionSettings {
large: Vec2,
medium: Vec2,
small: Vec2,
}
// Spawns the camera that draws UI
fn setup_camera(mut commands: Commands) {
commands.spawn(Camera2d);
}
// Spawns the UI
fn setup_ui(mut commands: Commands) {
// Node that fills entire background
commands
.spawn(Node {
width: Val::Percent(100.),
..default()
})
// Text where we display current resolution
.with_child((
Text::new("Resolution"),
TextFont {
font_size: 42.0,
..default()
},
ResolutionText,
));
}
/// This system shows how to request the window to a new resolution
fn toggle_resolution(
keys: Res<ButtonInput<KeyCode>>,
mut window: Single<&mut Window>,
resolution: Res<ResolutionSettings>,
) {
if keys.just_pressed(KeyCode::Digit1) {
let res = resolution.small;
window.resolution.set(res.x, res.y);
}
if keys.just_pressed(KeyCode::Digit2) {
let res = resolution.medium;
window.resolution.set(res.x, res.y);
}
if keys.just_pressed(KeyCode::Digit3) {
let res = resolution.large;
window.resolution.set(res.x, res.y);
}
}
/// This system shows how to respond to a window being resized.
/// Whenever the window is resized, the text will update with the new resolution.
fn on_resize_system(
mut text: Single<&mut Text, With<ResolutionText>>,
mut resize_reader: EventReader<WindowResized>,
) {
for e in resize_reader.read() {
// When resolution is being changed
text.0 = format!("{:.1} x {:.1}", e.width, e.height);
}
}