bevy/examples/ui/size_constraints.rs
Alice Cecile 336fddb101
Make default behavior for BackgroundColor and BorderColor more intuitive (#14017)
# Objective

In Bevy 0.13, `BackgroundColor` simply tinted the image of any
`UiImage`. This was confusing: in every other case (e.g. Text), this
added a solid square behind the element. #11165 changed this, but
removed `BackgroundColor` from `ImageBundle` to avoid confusion, since
the semantic meaning had changed.

However, this resulted in a serious UX downgrade / inconsistency, as
this behavior was no longer part of the bundle (unlike for `TextBundle`
or `NodeBundle`), leaving users with a relatively frustrating upgrade
path.

Additionally, adding both `BackgroundColor` and `UiImage` resulted in a
bizarre effect, where the background color was seemingly ignored as it
was covered by a solid white placeholder image.

Fixes #13969.

## Solution

Per @viridia's design:

> - if you don't specify a background color, it's transparent.
> - if you don't specify an image color, it's white (because it's a
multiplier).
> - if you don't specify an image, no image is drawn.
> - if you specify both a background color and an image color, they are
independent.
> - the background color is drawn behind the image (in whatever pixels
are transparent)

As laid out by @benfrankel, this involves:

1. Changing the default `UiImage` to use a transparent texture but a
pure white tint.
2. Adding `UiImage::solid_color` to quickly set placeholder images.
3. Changing the default `BorderColor` and `BackgroundColor` to
transparent.
4. Removing the default overrides for these values in the other assorted
UI bundles.
5. Adding `BackgroundColor` back to `ImageBundle` and `ButtonBundle`.
6. Adding a 1x1 `Image::transparent`, which can be accessed from
`Assets<Image>` via the `TRANSPARENT_IMAGE_HANDLE` constant.

Huge thanks to everyone who helped out with the design in the linked
issue and [the Discord
thread](https://discord.com/channels/691052431525675048/1255209923890118697/1255209999278280844):
this was very much a joint design.

@cart helped me figure out how to set the UiImage's default texture to a
transparent 1x1 image, which is a much nicer fix.

## Testing

I've checked the examples modified by this PR, and the `ui` example as
well just to be sure.

## Migration Guide

- `BackgroundColor` no longer tints the color of images in `ImageBundle`
or `ButtonBundle`. Set `UiImage::color` to tint images instead.
- The default texture for `UiImage` is now a transparent white square.
Use `UiImage::solid_color` to quickly draw debug images.
- The default value for `BackgroundColor` and `BorderColor` is now
transparent. Set the color to white manually to return to previous
behavior.
2024-06-25 21:50:41 +00:00

397 lines
14 KiB
Rust

//! Demonstrates how the to use the size constraints to control the size of a UI node.
use bevy::{color::palettes::css::*, prelude::*};
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_event::<ButtonActivatedEvent>()
.add_systems(Startup, setup)
.add_systems(Update, (update_buttons, update_radio_buttons_colors))
.run();
}
const ACTIVE_BORDER_COLOR: Color = Color::Srgba(ANTIQUE_WHITE);
const INACTIVE_BORDER_COLOR: Color = Color::BLACK;
const ACTIVE_INNER_COLOR: Color = Color::WHITE;
const INACTIVE_INNER_COLOR: Color = Color::Srgba(NAVY);
const ACTIVE_TEXT_COLOR: Color = Color::BLACK;
const HOVERED_TEXT_COLOR: Color = Color::WHITE;
const UNHOVERED_TEXT_COLOR: Color = Color::srgb(0.5, 0.5, 0.5);
#[derive(Component)]
struct Bar;
#[derive(Copy, Clone, Debug, Component, PartialEq)]
enum Constraint {
FlexBasis,
Width,
MinWidth,
MaxWidth,
}
#[derive(Copy, Clone, Component)]
struct ButtonValue(Val);
#[derive(Event)]
struct ButtonActivatedEvent(Entity);
fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
// ui camera
commands.spawn(Camera2dBundle::default());
let text_style = TextStyle {
font: asset_server.load("fonts/FiraSans-Bold.ttf"),
font_size: 40.0,
color: Color::srgb(0.9, 0.9, 0.9),
};
commands
.spawn(NodeBundle {
style: Style {
width: Val::Percent(100.0),
height: Val::Percent(100.0),
justify_content: JustifyContent::Center,
align_items: AlignItems::Center,
..Default::default()
},
background_color: Color::BLACK.into(),
..Default::default()
})
.with_children(|parent| {
parent
.spawn(NodeBundle {
style: Style {
flex_direction: FlexDirection::Column,
align_items: AlignItems::Center,
justify_content: JustifyContent::Center,
..Default::default()
},
..Default::default()
})
.with_children(|parent| {
parent.spawn(
TextBundle::from_section("Size Constraints Example", text_style.clone())
.with_style(Style {
margin: UiRect::bottom(Val::Px(25.)),
..Default::default()
}),
);
spawn_bar(parent);
parent
.spawn(NodeBundle {
style: Style {
flex_direction: FlexDirection::Column,
align_items: AlignItems::Stretch,
padding: UiRect::all(Val::Px(10.)),
margin: UiRect::top(Val::Px(50.)),
..Default::default()
},
background_color: YELLOW.into(),
..Default::default()
})
.with_children(|parent| {
for constraint in [
Constraint::MinWidth,
Constraint::FlexBasis,
Constraint::Width,
Constraint::MaxWidth,
] {
spawn_button_row(parent, constraint, text_style.clone());
}
});
});
});
}
fn spawn_bar(parent: &mut ChildBuilder) {
parent
.spawn(NodeBundle {
style: Style {
flex_basis: Val::Percent(100.0),
align_self: AlignSelf::Stretch,
padding: UiRect::all(Val::Px(10.)),
..Default::default()
},
background_color: YELLOW.into(),
..Default::default()
})
.with_children(|parent| {
parent
.spawn(NodeBundle {
style: Style {
align_items: AlignItems::Stretch,
width: Val::Percent(100.),
height: Val::Px(100.),
padding: UiRect::all(Val::Px(4.)),
..Default::default()
},
background_color: Color::BLACK.into(),
..Default::default()
})
.with_children(|parent| {
parent.spawn((
NodeBundle {
style: Style {
..Default::default()
},
background_color: Color::WHITE.into(),
..Default::default()
},
Bar,
));
});
});
}
fn spawn_button_row(parent: &mut ChildBuilder, constraint: Constraint, text_style: TextStyle) {
let label = match constraint {
Constraint::FlexBasis => "flex_basis",
Constraint::Width => "size",
Constraint::MinWidth => "min_size",
Constraint::MaxWidth => "max_size",
};
parent
.spawn(NodeBundle {
style: Style {
flex_direction: FlexDirection::Column,
padding: UiRect::all(Val::Px(2.)),
align_items: AlignItems::Stretch,
..Default::default()
},
background_color: Color::BLACK.into(),
..Default::default()
})
.with_children(|parent| {
parent
.spawn(NodeBundle {
style: Style {
flex_direction: FlexDirection::Row,
justify_content: JustifyContent::End,
padding: UiRect::all(Val::Px(2.)),
..Default::default()
},
..Default::default()
})
.with_children(|parent| {
// spawn row label
parent
.spawn(NodeBundle {
style: Style {
min_width: Val::Px(200.),
max_width: Val::Px(200.),
justify_content: JustifyContent::Center,
align_items: AlignItems::Center,
..Default::default()
},
..Default::default()
})
.with_children(|parent| {
parent.spawn(TextBundle {
text: Text::from_section(label.to_string(), text_style.clone()),
..Default::default()
});
});
// spawn row buttons
parent
.spawn(NodeBundle {
..Default::default()
})
.with_children(|parent| {
spawn_button(
parent,
constraint,
ButtonValue(Val::Auto),
"Auto".to_string(),
text_style.clone(),
true,
);
for percent in [0., 25., 50., 75., 100., 125.] {
spawn_button(
parent,
constraint,
ButtonValue(Val::Percent(percent)),
format!("{percent}%"),
text_style.clone(),
false,
);
}
});
});
});
}
fn spawn_button(
parent: &mut ChildBuilder,
constraint: Constraint,
action: ButtonValue,
label: String,
text_style: TextStyle,
active: bool,
) {
parent
.spawn((
ButtonBundle {
style: Style {
align_items: AlignItems::Center,
justify_content: JustifyContent::Center,
border: UiRect::all(Val::Px(2.)),
margin: UiRect::horizontal(Val::Px(2.)),
..Default::default()
},
background_color: if active {
ACTIVE_BORDER_COLOR
} else {
INACTIVE_BORDER_COLOR
}
.into(),
..Default::default()
},
constraint,
action,
))
.with_children(|parent| {
parent
.spawn(NodeBundle {
style: Style {
width: Val::Px(100.),
justify_content: JustifyContent::Center,
..Default::default()
},
background_color: if active {
ACTIVE_INNER_COLOR
} else {
INACTIVE_INNER_COLOR
}
.into(),
..Default::default()
})
.with_children(|parent| {
parent.spawn(TextBundle {
text: Text::from_section(
label,
TextStyle {
color: if active {
ACTIVE_TEXT_COLOR
} else {
UNHOVERED_TEXT_COLOR
},
..text_style
},
)
.with_justify(JustifyText::Center),
..Default::default()
});
});
});
}
fn update_buttons(
mut button_query: Query<
(Entity, &Interaction, &Constraint, &ButtonValue),
Changed<Interaction>,
>,
mut bar_query: Query<&mut Style, With<Bar>>,
mut text_query: Query<&mut Text>,
children_query: Query<&Children>,
mut button_activated_event: EventWriter<ButtonActivatedEvent>,
) {
let mut style = bar_query.single_mut();
for (button_id, interaction, constraint, value) in button_query.iter_mut() {
match interaction {
Interaction::Pressed => {
button_activated_event.send(ButtonActivatedEvent(button_id));
match constraint {
Constraint::FlexBasis => {
style.flex_basis = value.0;
}
Constraint::Width => {
style.width = value.0;
}
Constraint::MinWidth => {
style.min_width = value.0;
}
Constraint::MaxWidth => {
style.max_width = value.0;
}
}
}
Interaction::Hovered => {
if let Ok(children) = children_query.get(button_id) {
for &child in children {
if let Ok(grand_children) = children_query.get(child) {
for &grandchild in grand_children {
if let Ok(mut text) = text_query.get_mut(grandchild) {
if text.sections[0].style.color != ACTIVE_TEXT_COLOR {
text.sections[0].style.color = HOVERED_TEXT_COLOR;
}
}
}
}
}
}
}
Interaction::None => {
if let Ok(children) = children_query.get(button_id) {
for &child in children {
if let Ok(grand_children) = children_query.get(child) {
for &grandchild in grand_children {
if let Ok(mut text) = text_query.get_mut(grandchild) {
if text.sections[0].style.color != ACTIVE_TEXT_COLOR {
text.sections[0].style.color = UNHOVERED_TEXT_COLOR;
}
}
}
}
}
}
}
}
}
}
fn update_radio_buttons_colors(
mut event_reader: EventReader<ButtonActivatedEvent>,
button_query: Query<(Entity, &Constraint, &Interaction)>,
mut image_query: Query<&mut UiImage>,
mut color_query: Query<&mut BackgroundColor>,
mut text_query: Query<&mut Text>,
children_query: Query<&Children>,
) {
for &ButtonActivatedEvent(button_id) in event_reader.read() {
let (_, target_constraint, _) = button_query.get(button_id).unwrap();
for (id, constraint, interaction) in button_query.iter() {
if target_constraint == constraint {
let (border_color, inner_color, text_color) = if id == button_id {
(ACTIVE_BORDER_COLOR, ACTIVE_INNER_COLOR, ACTIVE_TEXT_COLOR)
} else {
(
INACTIVE_BORDER_COLOR,
INACTIVE_INNER_COLOR,
if matches!(interaction, Interaction::Hovered) {
HOVERED_TEXT_COLOR
} else {
UNHOVERED_TEXT_COLOR
},
)
};
image_query.get_mut(id).unwrap().color = border_color;
for &child in children_query.get(id).into_iter().flatten() {
color_query.get_mut(child).unwrap().0 = inner_color;
for &grandchild in children_query.get(child).into_iter().flatten() {
if let Ok(mut text) = text_query.get_mut(grandchild) {
text.sections[0].style.color = text_color;
}
}
}
}
}
}
}