bevy_text 0.18.1

Provides text functionality for Bevy Engine
Documentation 
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use crate::{Font, FontAtlas, FontSmoothing, TextFont};
use bevy_asset::{AssetEvent, AssetId};
use bevy_derive::{Deref, DerefMut};
use bevy_ecs::{message::MessageReader, resource::Resource, system::ResMut};
use bevy_platform::collections::HashMap;

/// Identifies the font atlases for a particular font in [`FontAtlasSet`]
///
/// Allows an `f32` font size to be used as a key in a `HashMap`, by its binary representation.
#[derive(Debug, Hash, PartialEq, Eq, Clone, Copy)]
pub struct FontAtlasKey(pub AssetId<Font>, pub u32, pub FontSmoothing);

impl From<&TextFont> for FontAtlasKey {
    fn from(font: &TextFont) -> Self {
        FontAtlasKey(
            font.font.id(),
            font.font_size.to_bits(),
            font.font_smoothing,
        )
    }
}

/// Set of rasterized fonts stored in [`FontAtlas`]es.
#[derive(Debug, Default, Resource, Deref, DerefMut)]
pub struct FontAtlasSet(HashMap<FontAtlasKey, Vec<FontAtlas>>);

impl FontAtlasSet {
    /// Checks whether the given subpixel-offset glyph is contained in any of the [`FontAtlas`]es for the font identified by the given [`FontAtlasKey`].
    pub fn has_glyph(&self, cache_key: cosmic_text::CacheKey, font_key: &FontAtlasKey) -> bool {
        self.get(font_key)
            .is_some_and(|font_atlas| font_atlas.iter().any(|atlas| atlas.has_glyph(cache_key)))
    }
}

/// A system that automatically frees unused texture atlases when a font asset is removed.
pub fn free_unused_font_atlases_system(
    mut font_atlas_sets: ResMut<FontAtlasSet>,
    mut font_events: MessageReader<AssetEvent<Font>>,
) {
    for event in font_events.read() {
        if let AssetEvent::Removed { id } = event {
            font_atlas_sets.retain(|key, _| key.0 != *id);
        }
    }
}