text-typeset

Turns rich text documents into GPU-ready glyph quads.

Typesetting crate for the text-document ecosystem. Takes a rich text document model (styled paragraphs, tables, lists, frames) and produces positioned glyph quads, decoration rectangles, and a glyph atlas texture that any GPU framework can render in a few draw calls.

text-document (model) --> text-typeset (shaping + layout) --> framework adapter (rendering)

Features

• Text shaping via rustybuzz (Rust port of HarfBuzz) with OpenType feature support
• Font management via fontdb with CSS-spec font matching, generic family mapping, and glyph fallback
• Glyph rasterization via swash with color emoji support (COLR/CBDT)
• Glyph atlas backed by etagere shelf packing with auto-grow and LRU eviction
• Paragraph layout with line breaking (unicode-linebreak, UAX #14), four alignment modes (left, right, center, justify), and first-line indent
• BiDi text analysis via unicode-bidi with per-run directional shaping
• Tables with column width distribution, cell layout, borders, and cell backgrounds
• Lists with marker rendering (bullet, decimal, alpha, roman) at configurable indent levels
• Frames with inline, float-left, float-right, and absolute positioning
• Text decorations: underline, strikeout, overline (from font metrics)
• Letter spacing and word spacing
• Hit testing: screen coordinates to document position with region detection (text, margin, link, image)
• Cursor display with caret rendering, blink support, multi-cursor, and selection painting with full-width line highlighting
• Scrolling: ensure_caret_visible, scroll_to_position, viewport culling
• Incremental relayout: update a single block without re-laying-out the entire document
• Content width modes: auto (follows viewport) or fixed (for page-like WYSIWYG layout)

Framework-agnostic output

text-typeset produces a RenderFrame containing:

• Glyph quads ([screen_rect, atlas_rect, color]) drawn as textured rectangles from the atlas
• Image quads (position + resource name) for inline images loaded by the adapter
• Decoration rects (underline, strikeout, selection, cursor, table borders, backgrounds)
• Atlas texture (RGBA, updated incrementally)

The rendering contract is thin: "draw N sub-rects from a texture + M colored rects." Any framework that supports textured quads can serve as a backend: Godot (draw_texture_rect_region), Qt (QPainter::drawImage), wgpu, egui, iced.

Quick start

use text_typeset::Typesetter;
use text_document::TextDocument;

// Set up the typesetter
let mut typesetter = Typesetter::new();
let font = typesetter.register_font(include_bytes!("fonts/NotoSans.ttf"));
typesetter.set_default_font(font, 16.0);
typesetter.set_viewport(800.0, 600.0);

// Load a document
let doc = TextDocument::new();
doc.set_plain_text("Hello, world!").unwrap();

// Layout and render
typesetter.layout_full(&doc.snapshot_flow());
let frame = typesetter.render();

// frame.glyphs    -> glyph quads to draw
// frame.atlas_pixels -> RGBA texture data
// frame.decorations  -> cursor, selection, underlines

Content width

By default, text wraps at the viewport width (web/editor style). For page-like layout:

// Fixed width: text wraps at 600px regardless of viewport size
typesetter.set_content_width(600.0);

// Back to auto: text reflows when viewport resizes
typesetter.set_content_width_auto();

Dependencies

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE)
• MIT license (LICENSE-MIT)

at your option.