bevy/examples/ui/ui.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

360 lines
15 KiB
Rust

//! This example illustrates the various features of Bevy UI.
use bevy::{
a11y::{
accesskit::{NodeBuilder, Role},
AccessibilityNode,
},
color::palettes::basic::LIME,
input::mouse::{MouseScrollUnit, MouseWheel},
picking::focus::HoverMap,
prelude::*,
winit::WinitSettings,
};
fn main() {
let mut app = App::new();
app.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, update_scroll_position);
#[cfg(feature = "bevy_dev_tools")]
{
app.add_plugins(bevy::dev_tools::ui_debug_overlay::DebugUiPlugin)
.add_systems(Update, toggle_overlay);
}
app.run();
}
fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
// Camera
commands.spawn((Camera2d, IsDefaultUiCamera));
// root node
commands
.spawn(NodeBundle {
style: Style {
width: Val::Percent(100.0),
height: Val::Percent(100.0),
justify_content: JustifyContent::SpaceBetween,
..default()
},
..default()
})
.insert(PickingBehavior::IGNORE)
.with_children(|parent| {
// left vertical fill (border)
parent
.spawn(NodeBundle {
style: Style {
width: Val::Px(200.),
border: UiRect::all(Val::Px(2.)),
..default()
},
background_color: Color::srgb(0.65, 0.65, 0.65).into(),
..default()
})
.with_children(|parent| {
// left vertical fill (content)
parent
.spawn(NodeBundle {
style: Style {
width: Val::Percent(100.),
flex_direction: FlexDirection::Column,
padding: UiRect::all(Val::Px(5.)),
row_gap: Val::Px(5.),
..default()
},
background_color: Color::srgb(0.15, 0.15, 0.15).into(),
..default()
})
.with_children(|parent| {
// text
parent.spawn((
Text::new("Text Example"),
TextStyle {
font: asset_server.load("fonts/FiraSans-Bold.ttf"),
font_size: 25.0,
..default()
},
// Because this is a distinct label widget and
// not button/list item text, this is necessary
// for accessibility to treat the text accordingly.
Label,
));
#[cfg(feature = "bevy_dev_tools")]
// Debug overlay text
parent.spawn((
Text::new("Press Space to enable debug outlines."),
TextStyle {
font: asset_server.load("fonts/FiraSans-Bold.ttf"),
..default()
},
Label,
));
#[cfg(not(feature = "bevy_dev_tools"))]
parent.spawn((
Text::new("Try enabling feature \"bevy_dev_tools\"."),
TextStyle {
font: asset_server.load("fonts/FiraSans-Bold.ttf"),
..default()
},
Label,
));
});
});
// right vertical fill
parent
.spawn(NodeBundle {
style: Style {
flex_direction: FlexDirection::Column,
justify_content: JustifyContent::Center,
align_items: AlignItems::Center,
width: Val::Px(200.),
..default()
},
..default()
})
.with_children(|parent| {
// Title
parent.spawn((
Text::new("Scrolling list"),
TextStyle {
font: asset_server.load("fonts/FiraSans-Bold.ttf"),
font_size: 21.,
..default()
},
Label,
));
// Scrolling list
parent
.spawn(NodeBundle {
style: Style {
flex_direction: FlexDirection::Column,
align_self: AlignSelf::Stretch,
height: Val::Percent(50.),
overflow: Overflow::scroll_y(),
..default()
},
background_color: Color::srgb(0.10, 0.10, 0.10).into(),
..default()
})
.with_children(|parent| {
// List items
for i in 0..25 {
parent
.spawn((
Text(format!("Item {i}")),
TextStyle {
font: asset_server.load("fonts/FiraSans-Bold.ttf"),
..default()
},
Label,
AccessibilityNode(NodeBuilder::new(Role::ListItem)),
))
.insert(PickingBehavior {
should_block_lower: false,
..default()
});
}
});
});
parent
.spawn(NodeBundle {
style: Style {
width: Val::Px(200.0),
height: Val::Px(200.0),
position_type: PositionType::Absolute,
left: Val::Px(210.),
bottom: Val::Px(10.),
border: UiRect::all(Val::Px(20.)),
..default()
},
border_color: LIME.into(),
background_color: Color::srgb(0.4, 0.4, 1.).into(),
..default()
})
.with_children(|parent| {
parent.spawn(NodeBundle {
style: Style {
width: Val::Percent(100.0),
height: Val::Percent(100.0),
..default()
},
background_color: Color::srgb(0.8, 0.8, 1.).into(),
..default()
});
});
// render order test: reddest in the back, whitest in the front (flex center)
parent
.spawn(NodeBundle {
style: Style {
width: Val::Percent(100.0),
height: Val::Percent(100.0),
position_type: PositionType::Absolute,
align_items: AlignItems::Center,
justify_content: JustifyContent::Center,
..default()
},
..default()
})
.insert(PickingBehavior::IGNORE)
.with_children(|parent| {
parent
.spawn(NodeBundle {
style: Style {
width: Val::Px(100.0),
height: Val::Px(100.0),
..default()
},
background_color: Color::srgb(1.0, 0.0, 0.).into(),
..default()
})
.with_children(|parent| {
parent.spawn(NodeBundle {
style: Style {
// Take the size of the parent node.
width: Val::Percent(100.0),
height: Val::Percent(100.0),
position_type: PositionType::Absolute,
left: Val::Px(20.),
bottom: Val::Px(20.),
..default()
},
background_color: Color::srgb(1.0, 0.3, 0.3).into(),
..default()
});
parent.spawn(NodeBundle {
style: Style {
width: Val::Percent(100.0),
height: Val::Percent(100.0),
position_type: PositionType::Absolute,
left: Val::Px(40.),
bottom: Val::Px(40.),
..default()
},
background_color: Color::srgb(1.0, 0.5, 0.5).into(),
..default()
});
parent.spawn(NodeBundle {
style: Style {
width: Val::Percent(100.0),
height: Val::Percent(100.0),
position_type: PositionType::Absolute,
left: Val::Px(60.),
bottom: Val::Px(60.),
..default()
},
background_color: Color::srgb(1.0, 0.7, 0.7).into(),
..default()
});
// alpha test
parent.spawn(NodeBundle {
style: Style {
width: Val::Percent(100.0),
height: Val::Percent(100.0),
position_type: PositionType::Absolute,
left: Val::Px(80.),
bottom: Val::Px(80.),
..default()
},
background_color: Color::srgba(1.0, 0.9, 0.9, 0.4).into(),
..default()
});
});
});
// bevy logo (flex center)
parent
.spawn(NodeBundle {
style: Style {
width: Val::Percent(100.0),
position_type: PositionType::Absolute,
justify_content: JustifyContent::Center,
align_items: AlignItems::FlexStart,
..default()
},
..default()
})
.with_children(|parent| {
// bevy logo (image)
// A `NodeBundle` is used to display the logo the image as an `ImageBundle` can't automatically
// size itself with a child node present.
parent
.spawn((
NodeBundle {
style: Style {
width: Val::Px(500.0),
height: Val::Px(125.0),
margin: UiRect::top(Val::VMin(5.)),
..default()
},
..default()
},
UiImage::new(asset_server.load("branding/bevy_logo_dark_big.png")),
))
.with_children(|parent| {
// alt text
// This UI node takes up no space in the layout and the `Text` component is used by the accessibility module
// and is not rendered.
parent.spawn((
NodeBundle {
style: Style {
display: Display::None,
..Default::default()
},
..Default::default()
},
Text::new("Bevy logo"),
));
});
});
});
}
#[cfg(feature = "bevy_dev_tools")]
// The system that will enable/disable the debug outlines around the nodes
fn toggle_overlay(
input: Res<ButtonInput<KeyCode>>,
mut options: ResMut<bevy::dev_tools::ui_debug_overlay::UiDebugOptions>,
) {
info_once!("The debug outlines are enabled, press Space to turn them on/off");
if input.just_pressed(KeyCode::Space) {
// The toggle method will enable the debug_overlay if disabled and disable if enabled
options.toggle();
}
}
/// Updates the scroll position of scrollable nodes in response to mouse input
pub fn update_scroll_position(
mut mouse_wheel_events: EventReader<MouseWheel>,
hover_map: Res<HoverMap>,
mut scrolled_node_query: Query<&mut ScrollPosition>,
keyboard_input: Res<ButtonInput<KeyCode>>,
) {
for mouse_wheel_event in mouse_wheel_events.read() {
let (mut dx, mut dy) = match mouse_wheel_event.unit {
MouseScrollUnit::Line => (mouse_wheel_event.x * 20., mouse_wheel_event.y * 20.),
MouseScrollUnit::Pixel => (mouse_wheel_event.x, mouse_wheel_event.y),
};
if keyboard_input.pressed(KeyCode::ShiftLeft) || keyboard_input.pressed(KeyCode::ShiftRight)
{
std::mem::swap(&mut dx, &mut dy);
}
for (_pointer, pointer_map) in hover_map.iter() {
for (entity, _hit) in pointer_map.iter() {
if let Ok(mut scroll_position) = scrolled_node_query.get_mut(*entity) {
scroll_position.offset_x -= dx;
scroll_position.offset_y -= dy;
}
}
}
}
}