bevy/examples/ui/ui_texture_atlas_slice.rs

//! This example illustrates how to create buttons with their texture atlases sliced
//! and kept in proportion instead of being stretched by the button dimensions

use bevy::{
    color::palettes::css::{GOLD, ORANGE},
    prelude::*,
    ui::widget::NodeImageMode,
    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)
        .add_systems(Update, button_system)
        .run();
}

fn button_system(
    mut interaction_query: Query<
        (&Interaction, &Children, &mut UiImage),
        (Changed<Interaction>, With<Button>),
    >,
    mut text_query: Query<&mut Text>,
) {
    for (interaction, children, mut image) in &mut interaction_query {
        let mut text = text_query.get_mut(children[0]).unwrap();
        match *interaction {
            Interaction::Pressed => {
                **text = "Press".to_string();
                if let Some(atlas) = &mut image.texture_atlas {
                    atlas.index = (atlas.index + 1) % 30;
                }
                image.color = GOLD.into();
            }
            Interaction::Hovered => {
                **text = "Hover".to_string();
                image.color = ORANGE.into();
            }
            Interaction::None => {
                **text = "Button".to_string();
                image.color = Color::WHITE;
            }
        }
    }
}

fn setup(
    mut commands: Commands,
    asset_server: Res<AssetServer>,
    mut texture_atlases: ResMut<Assets<TextureAtlasLayout>>,
) {
    let texture_handle = asset_server.load("textures/fantasy_ui_borders/border_sheet.png");
    let atlas_layout =
        TextureAtlasLayout::from_grid(UVec2::new(50, 50), 6, 6, Some(UVec2::splat(2)), None);
    let atlas_layout_handle = texture_atlases.add(atlas_layout);

    let slicer = TextureSlicer {
        border: BorderRect::square(24.0),
        center_scale_mode: SliceScaleMode::Stretch,
        sides_scale_mode: SliceScaleMode::Stretch,
        max_corner_scale: 1.0,
    };
    // ui camera
    commands.spawn(Camera2d);
    commands
        .spawn(Node {
            width: Val::Percent(100.0),
            height: Val::Percent(100.0),
            align_items: AlignItems::Center,
            justify_content: JustifyContent::Center,
            ..default()
        })
        .with_children(|parent| {
            for (idx, [w, h]) in [
                (0, [150.0, 150.0]),
                (7, [300.0, 150.0]),
                (13, [150.0, 300.0]),
            ] {
                parent
                    .spawn((
                        Button,
                        UiImage::from_atlas_image(
                            texture_handle.clone(),
                            TextureAtlas {
                                index: idx,
                                layout: atlas_layout_handle.clone(),
                            },
                        )
                        .with_mode(NodeImageMode::Sliced(slicer.clone())),
                        Node {
                            width: Val::Px(w),
                            height: Val::Px(h),
                            // horizontally center child text
                            justify_content: JustifyContent::Center,
                            // vertically center child text
                            align_items: AlignItems::Center,
                            margin: UiRect::all(Val::Px(20.0)),
                            ..default()
                        },
                    ))
                    .with_children(|parent| {
                        parent.spawn((
                            Text::new("Button"),
                            TextFont {
                                font: asset_server.load("fonts/FiraSans-Bold.ttf"),
                                font_size: 33.0,
                                ..default()
                            },
                            TextColor(Color::srgb(0.9, 0.9, 0.9)),
                        ));
                    });
            }
        });
}