Function text_system 

pub fn text_system(
    textures: ResMut<'_, Assets<Image>>,
    fonts: Res<'_, Assets<Font>>,
    texture_atlases: ResMut<'_, Assets<TextureAtlasLayout>>,
    font_atlas_sets: ResMut<'_, FontAtlasSets>,
    text_pipeline: ResMut<'_, TextPipeline>,
    text_query: Query<'_, '_, (Entity, Ref<'_, ComputedNode>, &TextLayout, &mut TextLayoutInfo, &mut TextNodeFlags, &mut ComputedTextBlock)>,
    text_reader: TextReader<'_, '_, Text>,
    font_system: ResMut<'_, CosmicFontSystem>,
    swash_cache: ResMut<'_, SwashCache>,
)

Updates the layout and size information for a UI text node on changes to the size value of its Node component, or when the needs_recompute field of TextNodeFlags is set to true. This information is computed by the TextPipeline and then stored in TextLayoutInfo.

World Resources

ResMut<Assets<Image>> – This system only adds new Image assets. It does not modify or observe existing ones. The exception is when adding new glyphs to a bevy_text::FontAtlas.