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https://github.com/bevyengine/bevy
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015f2c69ca
# 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(); } } ```
206 lines
9.4 KiB
Rust
206 lines
9.4 KiB
Rust
//! Demonstrates how CSS Grid layout can be used to lay items out in a 2D grid
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use bevy::{color::palettes::css::*, prelude::*};
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fn main() {
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App::new()
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.add_plugins(DefaultPlugins.set(WindowPlugin {
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primary_window: Some(Window {
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resolution: [800., 600.].into(),
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title: "Bevy CSS Grid Layout Example".to_string(),
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..default()
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}),
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..default()
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}))
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.add_systems(Startup, spawn_layout)
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.run();
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}
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fn spawn_layout(mut commands: Commands, asset_server: Res<AssetServer>) {
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let font = asset_server.load("fonts/FiraSans-Bold.ttf");
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commands.spawn(Camera2d);
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// Top-level grid (app frame)
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commands
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.spawn((
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Node {
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// Use the CSS Grid algorithm for laying out this node
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display: Display::Grid,
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// Make node fill the entirety of its parent (in this case the window)
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width: Val::Percent(100.0),
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height: Val::Percent(100.0),
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// Set the grid to have 2 columns with sizes [min-content, minmax(0, 1fr)]
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// - The first column will size to the size of its contents
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// - The second column will take up the remaining available space
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grid_template_columns: vec![GridTrack::min_content(), GridTrack::flex(1.0)],
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// Set the grid to have 3 rows with sizes [auto, minmax(0, 1fr), 20px]
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// - The first row will size to the size of its contents
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// - The second row take up remaining available space (after rows 1 and 3 have both been sized)
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// - The third row will be exactly 20px high
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grid_template_rows: vec![
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GridTrack::auto(),
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GridTrack::flex(1.0),
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GridTrack::px(20.),
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],
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..default()
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},
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BackgroundColor(Color::WHITE),
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))
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.with_children(|builder| {
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// Header
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builder
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.spawn(
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Node {
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display: Display::Grid,
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// Make this node span two grid columns so that it takes up the entire top tow
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grid_column: GridPlacement::span(2),
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padding: UiRect::all(Val::Px(6.0)),
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..default()
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},
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)
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.with_children(|builder| {
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spawn_nested_text_bundle(builder, font.clone(), "Bevy CSS Grid Layout Example");
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});
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// Main content grid (auto placed in row 2, column 1)
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builder
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.spawn((
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Node {
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// Make the height of the node fill its parent
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height: Val::Percent(100.0),
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// Make the grid have a 1:1 aspect ratio meaning it will scale as an exact square
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// As the height is set explicitly, this means the width will adjust to match the height
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aspect_ratio: Some(1.0),
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// Use grid layout for this node
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display: Display::Grid,
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// Add 24px of padding around the grid
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padding: UiRect::all(Val::Px(24.0)),
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// Set the grid to have 4 columns all with sizes minmax(0, 1fr)
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// This creates 4 exactly evenly sized columns
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grid_template_columns: RepeatedGridTrack::flex(4, 1.0),
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// Set the grid to have 4 rows all with sizes minmax(0, 1fr)
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// This creates 4 exactly evenly sized rows
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grid_template_rows: RepeatedGridTrack::flex(4, 1.0),
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// Set a 12px gap/gutter between rows and columns
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row_gap: Val::Px(12.0),
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column_gap: Val::Px(12.0),
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..default()
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},
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BackgroundColor(Color::srgb(0.25, 0.25, 0.25)),
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))
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.with_children(|builder| {
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// Note there is no need to specify the position for each grid item. Grid items that are
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// not given an explicit position will be automatically positioned into the next available
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// grid cell. The order in which this is performed can be controlled using the grid_auto_flow
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// style property.
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item_rect(builder, ORANGE);
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item_rect(builder, BISQUE);
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item_rect(builder, BLUE);
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item_rect(builder, CRIMSON);
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item_rect(builder, AQUA);
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item_rect(builder, ORANGE_RED);
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item_rect(builder, DARK_GREEN);
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item_rect(builder, FUCHSIA);
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item_rect(builder, TEAL);
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item_rect(builder, ALICE_BLUE);
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item_rect(builder, CRIMSON);
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item_rect(builder, ANTIQUE_WHITE);
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item_rect(builder, YELLOW);
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item_rect(builder, DEEP_PINK);
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item_rect(builder, YELLOW_GREEN);
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item_rect(builder, SALMON);
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});
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// Right side bar (auto placed in row 2, column 2)
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builder
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.spawn((
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Node {
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display: Display::Grid,
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// Align content towards the start (top) in the vertical axis
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align_items: AlignItems::Start,
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// Align content towards the center in the horizontal axis
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justify_items: JustifyItems::Center,
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// Add 10px padding
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padding: UiRect::all(Val::Px(10.)),
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// Add an fr track to take up all the available space at the bottom of the column so that the text nodes
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// can be top-aligned. Normally you'd use flexbox for this, but this is the CSS Grid example so we're using grid.
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grid_template_rows: vec![GridTrack::auto(), GridTrack::auto(), GridTrack::fr(1.0)],
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// Add a 10px gap between rows
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row_gap: Val::Px(10.),
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..default()
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},
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BackgroundColor(BLACK.into()),
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))
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.with_children(|builder| {
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builder.spawn((Text::new("Sidebar"),
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TextFont {
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font: font.clone(),
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..default()
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},
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));
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builder.spawn((Text::new("A paragraph of text which ought to wrap nicely. A paragraph of text which ought to wrap nicely. A paragraph of text which ought to wrap nicely. A paragraph of text which ought to wrap nicely. A paragraph of text which ought to wrap nicely. A paragraph of text which ought to wrap nicely. A paragraph of text which ought to wrap nicely."),
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TextFont {
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font: font.clone(),
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font_size: 13.0,
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..default()
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},
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));
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builder.spawn(Node::default());
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});
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// Footer / status bar
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builder.spawn((
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Node {
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// Make this node span two grid column so that it takes up the entire bottom row
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grid_column: GridPlacement::span(2),
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..default()
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},
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BackgroundColor(WHITE.into()),
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));
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// Modal (absolutely positioned on top of content - currently hidden: to view it, change its visibility)
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builder.spawn((
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Node {
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position_type: PositionType::Absolute,
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margin: UiRect {
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top: Val::Px(100.),
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bottom: Val::Auto,
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left: Val::Auto,
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right: Val::Auto,
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},
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width: Val::Percent(60.),
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height: Val::Px(300.),
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max_width: Val::Px(600.),
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..default()
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},
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Visibility::Hidden,
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BackgroundColor(Color::WHITE.with_alpha(0.8)),
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));
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});
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}
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/// Create a coloured rectangle node. The node has size as it is assumed that it will be
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/// spawned as a child of a Grid container with `AlignItems::Stretch` and `JustifyItems::Stretch`
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/// which will allow it to take its size from the size of the grid area it occupies.
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fn item_rect(builder: &mut ChildBuilder, color: Srgba) {
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builder
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.spawn((
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Node {
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display: Display::Grid,
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padding: UiRect::all(Val::Px(3.0)),
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..default()
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},
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BackgroundColor(BLACK.into()),
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))
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.with_children(|builder| {
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builder.spawn((Node::default(), BackgroundColor(color.into())));
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});
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}
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fn spawn_nested_text_bundle(builder: &mut ChildBuilder, font: Handle<Font>, text: &str) {
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builder.spawn((
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Text::new(text),
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TextFont { font, ..default() },
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TextColor::BLACK,
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));
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}
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