bevy/examples/ui/overflow_clip_margin.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

94 lines
3.9 KiB
Rust

//! Simple example demonstrating the `OverflowClipMargin` style property.
use bevy::{color::palettes::css::*, 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)
.run();
}
fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
commands.spawn(Camera2d);
let image = asset_server.load("branding/icon.png");
commands
.spawn((
Node {
width: Val::Percent(100.),
height: Val::Percent(100.),
align_items: AlignItems::Center,
justify_content: JustifyContent::Center,
row_gap: Val::Px(40.),
flex_direction: FlexDirection::Column,
..default()
},
BackgroundColor(ANTIQUE_WHITE.into()),
))
.with_children(|parent| {
for overflow_clip_margin in [
OverflowClipMargin::border_box().with_margin(25.),
OverflowClipMargin::border_box(),
OverflowClipMargin::padding_box(),
OverflowClipMargin::content_box(),
] {
parent
.spawn(Node {
flex_direction: FlexDirection::Row,
column_gap: Val::Px(20.),
..default()
})
.with_children(|parent| {
parent
.spawn((
Node {
padding: UiRect::all(Val::Px(10.)),
margin: UiRect::bottom(Val::Px(25.)),
..default()
},
BackgroundColor(Color::srgb(0.25, 0.25, 0.25)),
))
.with_child(Text(format!("{overflow_clip_margin:#?}")));
parent
.spawn((
Node {
margin: UiRect::top(Val::Px(10.)),
width: Val::Px(100.),
height: Val::Px(100.),
padding: UiRect::all(Val::Px(20.)),
border: UiRect::all(Val::Px(5.)),
overflow: Overflow::clip(),
overflow_clip_margin,
..default()
},
BackgroundColor(GRAY.into()),
BorderColor(Color::BLACK),
))
.with_children(|parent| {
parent
.spawn((
Node {
min_width: Val::Px(50.),
min_height: Val::Px(50.),
..default()
},
BackgroundColor(LIGHT_CYAN.into()),
))
.with_child((
UiImage::new(image.clone()),
Node {
min_width: Val::Px(100.),
min_height: Val::Px(100.),
..default()
},
));
});
});
}
});
}