bevy/crates/bevy_ui/src/widget/text.rs

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use crate::{CalculatedSize, Node};
use bevy_asset::{Assets, Handle};
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use bevy_core::FloatOrd;
use bevy_ecs::{Changed, Local, Query, Res, ResMut};
use bevy_math::Size;
use bevy_render::{
draw::{Draw, DrawContext, Drawable},
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prelude::Msaa,
renderer::{AssetRenderResourceBindings, RenderResourceBindings},
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texture::Texture,
};
use bevy_sprite::TextureAtlas;
use bevy_text::{DrawableText, Font, FontAtlasSet, TextStyle};
use bevy_transform::prelude::GlobalTransform;
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use bevy_utils::HashSet;
#[derive(Default)]
pub struct QueuedTextGlyphs {
glyphs: HashSet<(Handle<Font>, FloatOrd, char)>,
}
#[derive(Default, Clone)]
pub struct Text {
pub value: String,
pub font: Handle<Font>,
pub style: TextStyle,
}
pub fn text_system(
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mut queued_text_glyphs: Local<QueuedTextGlyphs>,
mut textures: ResMut<Assets<Texture>>,
fonts: Res<Assets<Font>>,
mut font_atlas_sets: ResMut<Assets<FontAtlasSet>>,
mut texture_atlases: ResMut<Assets<TextureAtlas>>,
mut query: Query<(Changed<Text>, &mut CalculatedSize)>,
) {
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// add queued glyphs to atlases
if !queued_text_glyphs.glyphs.is_empty() {
let mut glyphs_to_queue = Vec::new();
println!("queue {}", queued_text_glyphs.glyphs.len());
for (font_handle, FloatOrd(font_size), character) in queued_text_glyphs.glyphs.drain() {
let font_atlases = font_atlas_sets
.get_or_insert_with(Handle::from_id(font_handle.id), || {
FontAtlasSet::new(font_handle)
});
// try adding the glyph to an atlas. if it fails, re-queue
if let Ok(char_str) = std::str::from_utf8(&[character as u8]) {
if font_atlases
.add_glyphs_to_atlas(
&fonts,
&mut texture_atlases,
&mut textures,
font_size,
char_str,
)
.is_none()
{
glyphs_to_queue.push((font_handle, FloatOrd(font_size), character));
}
}
}
queued_text_glyphs.glyphs.extend(glyphs_to_queue);
}
for (text, mut calculated_size) in &mut query.iter() {
let font_atlases = font_atlas_sets
.get_or_insert_with(Handle::from_id(text.font.id), || {
FontAtlasSet::new(text.font)
});
// TODO: this call results in one or more TextureAtlases, whose render resources are created in the RENDER_GRAPH_SYSTEMS
// stage. That logic runs _before_ the DRAW stage, which means we cant call add_glyphs_to_atlas in the draw stage
// without our render resources being a frame behind. Therefore glyph atlasing either needs its own system or the TextureAtlas
// resource generation needs to happen AFTER the render graph systems. maybe draw systems should execute within the
// render graph so ordering like this can be taken into account? Maybe the RENDER_GRAPH_SYSTEMS stage should be removed entirely
// in favor of node.update()? Regardless, in the immediate short term the current approach is fine.
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if let Some(width) = font_atlases.add_glyphs_to_atlas(
&fonts,
&mut texture_atlases,
&mut textures,
text.style.font_size,
&text.value,
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) {
calculated_size.size = Size::new(width, text.style.font_size);
} else {
for character in text.value.chars() {
queued_text_glyphs.glyphs.insert((
text.font,
FloatOrd(text.style.font_size),
character,
));
}
}
}
}
#[allow(clippy::too_many_arguments)]
pub fn draw_text_system(
mut draw_context: DrawContext,
fonts: Res<Assets<Font>>,
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msaa: Res<Msaa>,
font_atlas_sets: Res<Assets<FontAtlasSet>>,
texture_atlases: Res<Assets<TextureAtlas>>,
mut render_resource_bindings: ResMut<RenderResourceBindings>,
mut asset_render_resource_bindings: ResMut<AssetRenderResourceBindings>,
mut query: Query<(&mut Draw, &Text, &Node, &GlobalTransform)>,
) {
for (mut draw, text, node, global_transform) in &mut query.iter() {
if let Some(font) = fonts.get(&text.font) {
let position = global_transform.translation() - (node.size / 2.0).extend(0.0);
let mut drawable_text = DrawableText {
font,
font_atlas_set: font_atlas_sets
.get(&text.font.as_handle::<FontAtlasSet>())
.unwrap(),
texture_atlases: &texture_atlases,
render_resource_bindings: &mut render_resource_bindings,
asset_render_resource_bindings: &mut asset_render_resource_bindings,
position,
msaa: &msaa,
style: &text.style,
text: &text.value,
container_size: node.size,
};
drawable_text.draw(&mut draw, &mut draw_context).unwrap();
}
}
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}