Crate read_fonts

Reading OpenType tables

This crate provides memory safe zero-allocation parsing of font files. It is unopinionated, and attempts to provide raw access to the underlying font data as it is described in the OpenType specification.

This crate is intended for use by other parts of a font stack, such as a shaping engine or a glyph rasterizer.

In addition to raw data access, this crate may also provide reference implementations of algorithms for interpreting that data, where such an implementation is required for the data to be useful. For instance, we provide functions for mapping codepoints to glyph identifiers using the cmap table, or for decoding entries in the name table.

For higher level/more ergonomic access to font data, you may want to look into using skrifa instead.

Structure & codegen

The root tables module contains a submodule for each supported table, and that submodule contains items for each table, record, flagset or enum described in the relevant portion of the spec.

The majority of the code in the tables module is auto-generated. For more information on our use of codegen, see the codegen tour.

Related projects

• write-fonts is a companion crate for creating/modifying font files
• skrifa provides access to glyph outlines and metadata (in the same vein as freetype)

Example

use read_fonts::{FontRef, TableProvider};
let font_bytes = std::fs::read(path_to_my_font_file).unwrap();
// Single fonts only. for font collections (.ttc) use FontRef::from_index
let font = FontRef::new(&font_bytes).expect("failed to read font data");
let head = font.head().expect("missing 'head' table");
let maxp = font.maxp().expect("missing 'maxp' table");

println!("font version {} containing {} glyphs", head.font_revision(), maxp.num_glyphs());

Re-exports

pub extern crate font_types as types;

Modules

array

Custom array types

collectionsstd

Data structures useful for font work.

tables

The various font tables

Structs

ArrayOfNullableOffsets

An array of nullable offsets that can be resolved on access.

ArrayOfOffsets

An array of offsets that can be resolved on access.

CollectionRef

Reference to the content of a font collection file.

FontData

A reference to raw binary font data.

FontRef

Reference to an in-memory font.

TableRecord

Record for a table in a font.

TableRef

Typed access to raw table data.

Enums

FileRef

Reference to the content of a font or font collection file.

ReadError

An error that occurs when reading font data

Traits

ComputeSize

A type that can compute its size at runtime, based on some input.

FontRead

A type that can be read from raw table data.

FontReadWithArgs

A trait for types that require external data in order to be constructed.

MinByteRange

Return the minimum range of the table bytes

Offset

Any offset type.

ReadArgs

A trait for a type that needs additional arguments to be read.

ResolveNullableOffset

A helper trait providing a ‘resolve’ method for nullable offset types

ResolveOffset

A helper trait providing a ‘resolve’ method for offset types

TableProvider

An interface for accessing tables from a font (or font-like object)

TopLevelTable

A table that has an associated tag.

VarSize

A trait for types that have variable length.

Type Aliases

TTCHeader

TTC Header

TableDirectory

The OpenType Table Directory