336fddb101
# 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.
82 lines
2.9 KiB
Rust
82 lines
2.9 KiB
Rust
//! Demonstrates how to use transparency with UI.
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//! Shows two colored buttons with transparent text.
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use bevy::prelude::*;
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fn main() {
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App::new()
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.insert_resource(ClearColor(Color::BLACK))
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.add_plugins(DefaultPlugins)
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.add_systems(Startup, setup)
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.run();
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}
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fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
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commands.spawn(Camera2dBundle::default());
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let font_handle = asset_server.load("fonts/FiraSans-Bold.ttf");
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commands
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.spawn(NodeBundle {
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style: Style {
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width: Val::Percent(100.0),
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height: Val::Percent(100.0),
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align_items: AlignItems::Center,
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justify_content: JustifyContent::SpaceAround,
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..default()
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},
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..default()
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})
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.with_children(|parent| {
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parent
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.spawn(ButtonBundle {
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style: Style {
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width: Val::Px(150.0),
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height: Val::Px(65.0),
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justify_content: JustifyContent::Center,
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align_items: AlignItems::Center,
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..default()
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},
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background_color: Color::srgb(0.1, 0.5, 0.1).into(),
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..default()
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})
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.with_children(|parent| {
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parent.spawn(TextBundle::from_section(
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"Button 1",
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TextStyle {
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font: font_handle.clone(),
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font_size: 40.0,
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// Alpha channel of the color controls transparency.
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color: Color::srgba(1.0, 1.0, 1.0, 0.2),
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},
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));
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});
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// Button with a different color,
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// to demonstrate the text looks different due to its transparency.
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parent
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.spawn(ButtonBundle {
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style: Style {
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width: Val::Px(150.0),
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height: Val::Px(65.0),
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justify_content: JustifyContent::Center,
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align_items: AlignItems::Center,
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..default()
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},
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background_color: Color::srgb(0.5, 0.1, 0.5).into(),
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..default()
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})
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.with_children(|parent| {
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parent.spawn(TextBundle::from_section(
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"Button 2",
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TextStyle {
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font: font_handle.clone(),
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font_size: 40.0,
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// Alpha channel of the color controls transparency.
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color: Color::srgba(1.0, 1.0, 1.0, 0.2),
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},
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));
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});
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});
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}
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