| ## ttf-parser |
|  |
| [](https://crates.io/crates/ttf-parser) |
| [](https://docs.rs/ttf-parser) |
| [](https://www.rust-lang.org) |
|  |
| |
| A high-level, safe, zero-allocation TrueType font parser. |
| |
| Can be used as Rust and as C library. |
| |
| ### Features |
| |
| - A high-level API, for people who doesn't know how TrueType works internally. |
| Basically, no direct access to font tables. |
| - A [C API](./c-api). |
| - Zero heap allocations. |
| - Zero unsafe. |
| - Zero dependencies. |
| - `no_std`/WASM compatible. |
| - Fast. See the *Performance* section. |
| - Stateless. No mutable parsing methods. |
| - Simple and maintainable code (no magic numbers). |
| |
| ### Safety |
| |
| - The library must not panic. Any panic considered as a critical bug and should be reported. |
| - The library forbids the unsafe code. |
| - No heap allocations, so crash due to OOM is not possible. |
| - All recursive methods have a depth limit. |
| - Technically, should use less than 64KiB of stack in the worst case scenario. |
| - Most of arithmetic operations are checked. |
| - Most of numeric casts are checked. |
| |
| ### Alternatives |
| |
| It's very hard to compare different libraries, so we are using table-based comparison. |
| There are roughly three types of TrueType tables: |
| |
| - A table with a list of properties (like `head`, `OS/2`, etc.).<br/> |
| If a library tries to parse it at all then we mark it as supported. |
| - A table that contains a single type of data (`glyf`, `CFF` (kinda), `hmtx`, etc.).<br/> |
| Can only be supported or not. |
| - A table that contains multiple subtables (`cmap`, `kern`, `GPOS`, etc.).<br/> |
| Can be partially supported and we note which subtables are actually supported. |
| |
| | Feature/Library | ttf-parser | FreeType | stb_truetype | |
| | ----------------- | :--------------------: | :-----------------: | :----------------------------: | |
| | Memory safe | ✓ | | | |
| | Thread safe | ✓ | | ~ (mostly reentrant) | |
| | Zero allocation | ✓ | | | |
| | Variable fonts | ✓ | ✓ | | |
| | Rendering | -<sup>1</sup> | ✓ | ~ (very primitive) | |
| | `avar` table | ✓ | ✓ | | |
| | `bdat` table | | ✓ | | |
| | `bloc` table | | ✓ | | |
| | `CBDT` table | ✓ | ✓ | | |
| | `CBLC` table | ✓ | ✓ | | |
| | `CFF ` table | ✓ | ✓ | ~ (no `seac` support) | |
| | `CFF2` table | ✓ | ✓ | | |
| | `cmap` table | ~ (no 8) | ✓ | ~ (no 2,8,10,14; Unicode-only) | |
| | `EBDT` table | | ✓ | | |
| | `EBLC` table | | ✓ | | |
| | `fvar` table | ✓ | ✓ | | |
| | `gasp` table | | ✓ | | |
| | `GDEF` table | ~ | | | |
| | `glyf` table | ~<sup>2</sup> | ✓ | ~<sup>2</sup> | |
| | `GPOS` table | | | ~ (only 2) | |
| | `GSUB` table | | | | |
| | `gvar` table | ✓ | ✓ | | |
| | `head` table | ✓ | ✓ | ✓ | |
| | `hhea` table | ✓ | ✓ | ✓ | |
| | `hmtx` table | ✓ | ✓ | ✓ | |
| | `HVAR` table | ✓ | ✓ | | |
| | `kern` table | ~ (no AAT 1) | ~ (only 0) | ~ (only 0) | |
| | `maxp` table | ✓ | ✓ | ✓ | |
| | `MVAR` table | ✓ | ✓ | | |
| | `name` table | ✓ | ✓ | | |
| | `OS/2` table | ✓ | ✓ | | |
| | `post` table | ✓ | ✓ | | |
| | `sbix` table | ~ (PNG only) | ~ (PNG only) | | |
| | `SVG ` table | ✓ | | ✓ | |
| | `vhea` table | ✓ | ✓ | | |
| | `vmtx` table | ✓ | ✓ | | |
| | `VORG` table | ✓ | ✓ | | |
| | `VVAR` table | ✓ | ✓ | | |
| | Language | Rust + C API | C | C | |
| | Tested version | 0.10.0 | 2.10.4 | 1.24 | |
| | License | MIT / Apache-2.0 | FTL / GPLv2 | public domain | |
| |
| Legend: |
| |
| - ✓ - supported |
| - ~ - partial |
| - *nothing* - not supported |
| |
| Notes: |
| |
| 1. While `ttf-parser` doesn't support rendering by itself, |
| there are mutliple rendering libraries on top of it: |
| [rusttype](https://gitlab.redox-os.org/redox-os/rusttype), |
| [ab-glyph](https://github.com/alexheretic/ab-glyph) |
| and [fontdue](https://github.com/mooman219/fontdue). |
| 2. Matching points are not supported. |
| |
| ### Performance |
| |
| TrueType fonts designed for fast querying, so most of the methods are very fast. |
| The main exception is glyph outlining. Glyphs can be stored using two different methods: |
| using [Glyph Data](https://docs.microsoft.com/en-us/typography/opentype/spec/glyf) format |
| and [Compact Font Format](http://wwwimages.adobe.com/content/dam/Adobe/en/devnet/font/pdfs/5176.CFF.pdf) (pdf). |
| The first one is fairly simple which makes it faster to process. |
| The second one is basically a tiny language with a stack-based VM, which makes it way harder to process. |
| |
| The [benchmark](./benches/outline/) tests how long it takes to outline all glyphs in the font. |
| |
| | Table/Library | ttf-parser | FreeType | stb_truetype | |
| | ------------- | -------------: | ---------: | -------------: | |
| | `glyf` | `0.895 ms` | `1.258 ms` | **`0.718 ms`** | |
| | `gvar` | **`3.504 ms`** | `4.369 ms` | - | |
| | `CFF` | **`1.365 ms`** | `6.104 ms` | `2.913 ms` | |
| | `CFF2` | **`1.982 ms`** | `7.024 ms` | - | |
| |
| **Note:** FreeType is surprisingly slow, so I'm worried that I've messed something up. |
| |
| And here are some methods benchmarks: |
| |
| ```text |
| test outline_glyph_276_from_cff2 ... bench: 778 ns/iter (+/- 15) |
| test from_data_otf_cff ... bench: 760 ns/iter (+/- 13) |
| test from_data_otf_cff2 ... bench: 709 ns/iter (+/- 25) |
| test outline_glyph_276_from_cff ... bench: 678 ns/iter (+/- 41) |
| test outline_glyph_276_from_glyf ... bench: 649 ns/iter (+/- 11) |
| test outline_glyph_8_from_cff2 ... bench: 476 ns/iter (+/- 14) |
| test from_data_ttf ... bench: 352 ns/iter (+/- 11) |
| test glyph_name_post_276 ... bench: 223 ns/iter (+/- 5) |
| test outline_glyph_8_from_cff ... bench: 261 ns/iter (+/- 13) |
| test outline_glyph_8_from_glyf ... bench: 281 ns/iter (+/- 5) |
| test family_name ... bench: 183 ns/iter (+/- 102) |
| test glyph_name_cff_276 ... bench: 109 ns/iter (+/- 1) |
| test glyph_index_u41 ... bench: 16 ns/iter (+/- 0) |
| test glyph_name_cff_8 ... bench: 7 ns/iter (+/- 0) |
| test glyph_name_post_8 ... bench: 2 ns/iter (+/- 0) |
| test subscript_metrics ... bench: 2 ns/iter (+/- 0) |
| test glyph_hor_advance ... bench: 2 ns/iter (+/- 0) |
| test glyph_hor_side_bearing ... bench: 2 ns/iter (+/- 0) |
| test glyph_name_8 ... bench: 1 ns/iter (+/- 0) |
| test ascender ... bench: 1 ns/iter (+/- 0) |
| test underline_metrics ... bench: 1 ns/iter (+/- 0) |
| test strikeout_metrics ... bench: 1 ns/iter (+/- 0) |
| test x_height ... bench: 1 ns/iter (+/- 0) |
| test units_per_em ... bench: 0.5 ns/iter (+/- 0) |
| test width ... bench: 0.2 ns/iter (+/- 0) |
| ``` |
| |
| ### License |
| |
| Licensed under either of |
| |
| - Apache License, Version 2.0 |
| ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0) |
| - MIT license |
| ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT) |
| |
| at your option. |
| |
| ### Contribution |
| |
| Unless you explicitly state otherwise, any contribution intentionally submitted |
| for inclusion in the work by you, as defined in the Apache-2.0 license, shall be |
| dual licensed as above, without any additional terms or conditions. |
