bevy/examples/ui/text.rs
ira 9f906fdc8b Improve ergonomics and reduce boilerplate around creating text elements. (#5343)
# Objective

Creating UI elements is very boilerplate-y with lots of indentation.
This PR aims to reduce boilerplate around creating text elements.

## Changelog

* Renamed `Text::with_section` to `from_section`.
  It no longer takes a `TextAlignment` as argument, as the vast majority of cases left it `Default::default()`.
* Added `Text::from_sections` which creates a `Text` from a list of `TextSections`.
  Reduces line-count and reduces indentation by one level.
* Added `Text::with_alignment`.
  A builder style method for setting the `TextAlignment` of a `Text`.
* Added `TextSection::new`.
  Does not reduce line count, but reduces character count and made it easier to read. No more `.to_string()` calls!
* Added `TextSection::from_style` which creates an empty `TextSection` with a style.
  No more empty strings! Reduces indentation.
* Added `TextAlignment::CENTER` and friends.
* Added methods to `TextBundle`. `from_section`, `from_sections`, `with_text_alignment` and `with_style`.

## Note for reviewers.
Because of the nature of these changes I recommend setting diff view to 'split'.
~~Look for the book icon~~ cog in the top-left of the Files changed tab.

Have fun reviewing ❤️
<sup> >:D </sup>

## Migration Guide

`Text::with_section` was renamed to `from_section` and no longer takes a `TextAlignment` as argument.
Use `with_alignment` to set the alignment instead.

Co-authored-by: devil-ira <justthecooldude@gmail.com>
2022-07-20 14:14:29 +00:00

109 lines
3.7 KiB
Rust

//! This example illustrates how to create UI text and update it in a system.
//!
//! It displays the current FPS in the top left corner, as well as text that changes color
//! in the bottom right. For text within a scene, please see the text2d example.
use bevy::{
diagnostic::{Diagnostics, FrameTimeDiagnosticsPlugin},
prelude::*,
};
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_plugin(FrameTimeDiagnosticsPlugin::default())
.add_startup_system(setup)
.add_system(text_update_system)
.add_system(text_color_system)
.run();
}
// A unit struct to help identify the FPS UI component, since there may be many Text components
#[derive(Component)]
struct FpsText;
// A unit struct to help identify the color-changing Text component
#[derive(Component)]
struct ColorText;
fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
// UI camera
commands.spawn_bundle(Camera2dBundle::default());
// Text with one section
commands
.spawn_bundle(
// Create a TextBundle that has a Text with a single section.
TextBundle::from_section(
// Accepts a `String` or any type that converts into a `String`, such as `&str`
"hello\nbevy!",
TextStyle {
font: asset_server.load("fonts/FiraSans-Bold.ttf"),
font_size: 100.0,
color: Color::WHITE,
},
) // Set the alignment of the Text
.with_text_alignment(TextAlignment::TOP_CENTER)
// Set the style of the TextBundle itself.
.with_style(Style {
align_self: AlignSelf::FlexEnd,
position_type: PositionType::Absolute,
position: UiRect {
bottom: Val::Px(5.0),
right: Val::Px(15.0),
..default()
},
..default()
}),
)
.insert(ColorText);
// Text with multiple sections
commands
.spawn_bundle(
// Create a TextBundle that has a Text with a list of sections.
TextBundle::from_sections([
TextSection::new(
"FPS: ",
TextStyle {
font: asset_server.load("fonts/FiraSans-Bold.ttf"),
font_size: 60.0,
color: Color::WHITE,
},
),
TextSection::from_style(TextStyle {
font: asset_server.load("fonts/FiraMono-Medium.ttf"),
font_size: 60.0,
color: Color::GOLD,
}),
])
.with_style(Style {
align_self: AlignSelf::FlexEnd,
..default()
}),
)
.insert(FpsText);
}
fn text_color_system(time: Res<Time>, mut query: Query<&mut Text, With<ColorText>>) {
for mut text in &mut query {
let seconds = time.seconds_since_startup() as f32;
// Update the color of the first and only section.
text.sections[0].style.color = Color::Rgba {
red: (1.25 * seconds).sin() / 2.0 + 0.5,
green: (0.75 * seconds).sin() / 2.0 + 0.5,
blue: (0.50 * seconds).sin() / 2.0 + 0.5,
alpha: 1.0,
};
}
}
fn text_update_system(diagnostics: Res<Diagnostics>, mut query: Query<&mut Text, With<FpsText>>) {
for mut text in &mut query {
if let Some(fps) = diagnostics.get(FrameTimeDiagnosticsPlugin::FPS) {
if let Some(average) = fps.average() {
// Update the value of the second section
text.sections[1].value = format!("{average:.2}");
}
}
}
}