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

105 lines
3.3 KiB
Rust

//! This example illustrates how to override the window scale factor imposed by the
//! operating system.
use bevy::{prelude::*, window::WindowResolution};
#[derive(Component)]
struct CustomText;
fn main() {
App::new()
.add_plugins(DefaultPlugins.set(WindowPlugin {
primary_window: Some(Window {
resolution: WindowResolution::new(500., 300.).with_scale_factor_override(1.0),
..default()
}),
..default()
}))
.add_systems(Startup, setup)
.add_systems(
Update,
(display_override, toggle_override, change_scale_factor),
)
.run();
}
fn setup(mut commands: Commands) {
// camera
commands.spawn(Camera2d);
// root node
commands
.spawn(Node {
width: Val::Percent(100.0),
height: Val::Percent(100.0),
justify_content: JustifyContent::SpaceBetween,
..default()
})
.with_children(|parent| {
// left vertical fill (border)
parent
.spawn((
Node {
width: Val::Px(300.0),
height: Val::Percent(100.0),
border: UiRect::all(Val::Px(2.0)),
..default()
},
BackgroundColor(Color::srgb(0.65, 0.65, 0.65)),
))
.with_child((
CustomText,
Text::new("Example text"),
TextFont {
font_size: 25.0,
..default()
},
Node {
align_self: AlignSelf::FlexEnd,
..default()
},
));
});
}
/// Set the title of the window to the current override
fn display_override(
mut window: Single<&mut Window>,
mut custom_text: Single<&mut Text, With<CustomText>>,
) {
let text = format!(
"Scale factor: {:.1} {}",
window.scale_factor(),
if window.resolution.scale_factor_override().is_some() {
"(overridden)"
} else {
"(default)"
}
);
window.title.clone_from(&text);
custom_text.0 = text;
}
/// This system toggles scale factor overrides when enter is pressed
fn toggle_override(input: Res<ButtonInput<KeyCode>>, mut window: Single<&mut Window>) {
if input.just_pressed(KeyCode::Enter) {
let scale_factor_override = window.resolution.scale_factor_override();
window
.resolution
.set_scale_factor_override(scale_factor_override.xor(Some(1.0)));
}
}
/// This system changes the scale factor override when up or down is pressed
fn change_scale_factor(input: Res<ButtonInput<KeyCode>>, mut window: Single<&mut Window>) {
let scale_factor_override = window.resolution.scale_factor_override();
if input.just_pressed(KeyCode::ArrowUp) {
window
.resolution
.set_scale_factor_override(scale_factor_override.map(|n| n + 1.0));
} else if input.just_pressed(KeyCode::ArrowDown) {
window
.resolution
.set_scale_factor_override(scale_factor_override.map(|n| (n - 1.0).max(1.0)));
}
}