oxitext-raster — Fontdue-based glyph rasterizer for OxiText

oxitext-raster is the rasterization stage of the OxiText pipeline: it turns glyph IDs and font bytes into oxitext_core::Bitmap coverage maps (and color, LCD, and SDF-ready output). The default backend wraps fontdue; optional backends add ab_glyph, swash (with TrueType hinting), SVG-in-OpenType rendering, and an oxifont backend. It also includes COLR/CPAL color compositing, CBDT/sbix raster-glyph extraction, glyph-outline extraction, full LCD subpixel rendering, sRGB gamma LUTs, FreeType-style stem darkening, quarter-pixel positioning, and SIMD-accelerated coverage/compositing primitives.

This crate is 100% Pure Rust and #![forbid(unsafe_code)]. The default fontdue path carries no C/C++ dependencies; png and ttf-parser are likewise Pure Rust. Optional features pull in wide (portable SIMD), swash, resvg/tiny-skia, and the oxifont parser. It consumes PositionedGlyph / Bitmap / RenderOutput from oxitext-core.

Installation

[dependencies]
oxitext-raster = "0.1.0"

With optional capabilities:

[dependencies]
# Portable SIMD primitives, swash hinting backend, and SVG-glyph rendering
oxitext-raster = { version = "0.1.0", features = ["simd", "swash-backend", "svg-backend"] }

Quick Start

Rasterize a single glyph to a greyscale bitmap

use oxitext_raster::FontdueRasterizer;
use std::sync::Arc;

let font_data: Arc<[u8]> = Arc::from(std::fs::read("font.ttf")?.as_slice());

let rasterizer = FontdueRasterizer::new();
let bitmap = rasterizer.raster(36, &font_data, 32.0)?; // glyph id 36 at 32px
println!("{}x{} coverage bitmap", bitmap.width, bitmap.height);
# Ok::<(), oxitext_core::OxiTextError>(())

Rasterize pre-laid-out glyphs

use oxitext_raster::{rasterize_positioned, RasterOptions};
use oxitext_core::PositionedGlyph;

let glyphs: Vec<PositionedGlyph> = Vec::new(); // produced by oxitext-layout
let options = RasterOptions::default();

let bitmaps = rasterize_positioned(&glyphs, &options);
assert_eq!(bitmaps.len(), glyphs.len()); // one Option<Bitmap> per glyph

API Overview

Top-level rasterizer and functions

Backends — backend module

Unified result — result module

Rasterization options — options module

Glyph caching — cache module

Subpixel positioning — subpixel module

Color glyphs — color and detect modules

Glyph outlines — outline module

LCD subpixel rendering — lcd module

Gamma and stem darkening — gamma, stem_darken modules

Hot-loop primitives — scalar, simd modules

scalar holds the reference implementations of accumulate_coverage, multiply_alpha_u8, coverage_f32_to_u8, and porter_duff_source_over_scalar. simd (feature simd) provides wide::f32x8-accelerated equivalents. The top-level dispatch functions select the SIMD path automatically when the feature is active.

Thread-local cache — tl_cache module

Optional backends

Feature Flags

Error variants

Fallible methods return Result<_, oxitext_core::OxiTextError> and use the OxiTextError::Raster(String) variant — e.g. a poisoned internal mutex or a fontdue parse failure. Many entry points (rasterize_positioned, FontdueRaster::rasterize) are infallible and return a (possibly zero-sized) bitmap rather than an error.

Cross-references

• oxitext — high-level façade combining all stages.
• oxitext-core — the shared Bitmap / RenderOutput / PositionedGlyph types.
• oxitext-shape — produces the glyphs that get rasterized.
• oxitext-layout — positions glyphs before rasterization.
• oxitext-sdf — consumes rasterize_for_sdf output to build signed-distance fields.

License

Apache-2.0 — COOLJAPAN OU (Team Kitasan)