bevy/examples/ui/borders.rs
robtfm b641aa0ecf
separate border colors (#18682)
# Objective

allow specifying the left/top/right/bottom border colors separately for
ui elements

fixes #14773

## Solution

- change `BorderColor` to 
```rs
pub struct BorderColor {
    pub left: Color,
    pub top: Color,
    pub right: Color,
    pub bottom: Color,
}
```
- generate one ui node per distinct border color, set flags for the
active borders
- render only the active borders

i chose to do this rather than adding multiple colors to the
ExtractedUiNode in order to minimize the impact for the common case
where all border colors are the same.

## Testing

modified the `borders` example to use separate colors:


![image](https://github.com/user-attachments/assets/5d9a4492-429a-4ee1-9656-215511886164)

the behaviour is a bit weird but it mirrors html/css border behaviour.

---

## Migration:

To keep the existing behaviour, just change `BorderColor(color)` into
`BorderColor::all(color)`.

---------

Co-authored-by: ickshonpe <david.curthoys@googlemail.com>
2025-05-26 16:57:13 +00:00

257 lines
8.4 KiB
Rust

//! Example demonstrating bordered UI nodes
use bevy::{color::palettes::css::*, ecs::spawn::SpawnIter, prelude::*};
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_systems(Startup, setup)
.run();
}
fn setup(mut commands: Commands) {
commands.spawn(Camera2d);
// labels for the different border edges
let border_labels = [
"None",
"All",
"Left",
"Right",
"Top",
"Bottom",
"Horizontal",
"Vertical",
"Top Left",
"Bottom Left",
"Top Right",
"Bottom Right",
"Top Bottom Right",
"Top Bottom Left",
"Top Left Right",
"Bottom Left Right",
];
// all the different combinations of border edges
// these correspond to the labels above
let borders = [
UiRect::default(),
UiRect::all(Val::Px(10.)),
UiRect::left(Val::Px(10.)),
UiRect::right(Val::Px(10.)),
UiRect::top(Val::Px(10.)),
UiRect::bottom(Val::Px(10.)),
UiRect::horizontal(Val::Px(10.)),
UiRect::vertical(Val::Px(10.)),
UiRect {
left: Val::Px(20.),
top: Val::Px(10.),
..default()
},
UiRect {
left: Val::Px(10.),
bottom: Val::Px(20.),
..default()
},
UiRect {
right: Val::Px(20.),
top: Val::Px(10.),
..default()
},
UiRect {
right: Val::Px(10.),
bottom: Val::Px(10.),
..default()
},
UiRect {
right: Val::Px(10.),
top: Val::Px(20.),
bottom: Val::Px(10.),
..default()
},
UiRect {
left: Val::Px(10.),
top: Val::Px(10.),
bottom: Val::Px(10.),
..default()
},
UiRect {
left: Val::Px(20.),
right: Val::Px(10.),
top: Val::Px(10.),
..default()
},
UiRect {
left: Val::Px(10.),
right: Val::Px(10.),
bottom: Val::Px(20.),
..default()
},
];
let borders_examples = (
Node {
margin: UiRect::all(Val::Px(25.0)),
align_self: AlignSelf::Stretch,
justify_self: JustifySelf::Stretch,
flex_wrap: FlexWrap::Wrap,
justify_content: JustifyContent::FlexStart,
align_items: AlignItems::FlexStart,
align_content: AlignContent::FlexStart,
..default()
},
Children::spawn(SpawnIter(border_labels.into_iter().zip(borders).map(
|(label, border)| {
(
Node {
flex_direction: FlexDirection::Column,
align_items: AlignItems::Center,
..default()
},
children![
(
Node {
width: Val::Px(50.),
height: Val::Px(50.),
border,
margin: UiRect::all(Val::Px(20.)),
align_items: AlignItems::Center,
justify_content: JustifyContent::Center,
..default()
},
BackgroundColor(MAROON.into()),
BorderColor {
top: RED.into(),
bottom: YELLOW.into(),
left: GREEN.into(),
right: BLUE.into(),
},
Outline {
width: Val::Px(6.),
offset: Val::Px(6.),
color: Color::WHITE,
},
children![(
Node {
width: Val::Px(10.),
height: Val::Px(10.),
..default()
},
BackgroundColor(YELLOW.into()),
)]
),
(Text::new(label), TextFont::from_font_size(9.0))
],
)
},
))),
);
let non_zero = |x, y| x != Val::Px(0.) && y != Val::Px(0.);
let border_size = move |x, y| {
if non_zero(x, y) {
f32::MAX
} else {
0.
}
};
let borders_examples_rounded = (
Node {
margin: UiRect::all(Val::Px(25.0)),
align_self: AlignSelf::Stretch,
justify_self: JustifySelf::Stretch,
flex_wrap: FlexWrap::Wrap,
justify_content: JustifyContent::FlexStart,
align_items: AlignItems::FlexStart,
align_content: AlignContent::FlexStart,
..default()
},
Children::spawn(SpawnIter(border_labels.into_iter().zip(borders).map(
move |(label, border)| {
(
Node {
flex_direction: FlexDirection::Column,
align_items: AlignItems::Center,
..default()
},
children![
(
Node {
width: Val::Px(50.),
height: Val::Px(50.),
border,
margin: UiRect::all(Val::Px(20.)),
align_items: AlignItems::Center,
justify_content: JustifyContent::Center,
..default()
},
BackgroundColor(MAROON.into()),
BorderColor {
top: RED.into(),
bottom: YELLOW.into(),
left: GREEN.into(),
right: BLUE.into(),
},
BorderRadius::px(
border_size(border.left, border.top),
border_size(border.right, border.top),
border_size(border.right, border.bottom,),
border_size(border.left, border.bottom),
),
Outline {
width: Val::Px(6.),
offset: Val::Px(6.),
color: Color::WHITE,
},
children![(
Node {
width: Val::Px(10.),
height: Val::Px(10.),
..default()
},
BorderRadius::MAX,
BackgroundColor(YELLOW.into()),
)],
),
(Text::new(label), TextFont::from_font_size(9.0))
],
)
},
))),
);
commands.spawn((
Node {
margin: UiRect::all(Val::Px(25.0)),
flex_direction: FlexDirection::Column,
align_self: AlignSelf::Stretch,
justify_self: JustifySelf::Stretch,
flex_wrap: FlexWrap::Wrap,
justify_content: JustifyContent::FlexStart,
align_items: AlignItems::FlexStart,
align_content: AlignContent::FlexStart,
..default()
},
BackgroundColor(Color::srgb(0.25, 0.25, 0.25)),
children![
label("Borders"),
borders_examples,
label("Borders Rounded"),
borders_examples_rounded
],
));
}
// A label widget that accepts a &str and returns
// a Bundle that can be spawned
fn label(text: &str) -> impl Bundle {
(
Node {
margin: UiRect::all(Val::Px(25.0)),
..default()
},
children![(Text::new(text), TextFont::from_font_size(20.0))],
)
}