## 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.
Supports [TrueType](https://docs.microsoft.com/en-us/typography/truetype/),
[OpenType](https://docs.microsoft.com/en-us/typography/opentype/spec/)
and [AAT](https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6AATIntro.html)
fonts.
Can be used as Rust and as C library.
### Features
- A high-level API for most common properties, hiding all parsing and data resolving logic.
- A low-level, but safe API to access TrueType tables data.
- Highly configurable. You can disable most of the features, reducing binary size.
You can also parse TrueType tables separately, without loading the whole font/face.
- Zero heap allocations.
- Zero unsafe.
- Zero dependencies.
- `no_std`/WASM compatible.
- A basic [C API](./c-api).
- Fast.
- Stateless. All parsing methods are immutable.
- 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 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.).
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.).
Can only be supported or not.
- A table that contains multiple subtables (`cmap`, `kern`, `GPOS`, etc.).
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 | -1 | ✓ | ~ (very primitive) |
| `ankr` table | ✓ | | |
| `avar` table | ✓ | ✓ | |
| `bdat` table | | ✓ | |
| `bloc` table | | ✓ | |
| `CBDT` table | ✓ | ✓ | |
| `CBLC` table | ✓ | ✓ | |
| `COLR` table | | ✓ | |
| `CPAL` table | | ✓ | |
| `CFF ` table | ✓ | ✓ | ~ (no `seac` support) |
| `CFF2` table | ✓ | ✓ | |
| `cmap` table | ~ (no 8) | ✓ | ~ (no 2,8,10,14; Unicode-only) |
| `EBDT` table | | ✓ | |
| `EBLC` table | | ✓ | |
| `feat` table | ✓ | | |
| `fvar` table | ✓ | ✓ | |
| `gasp` table | | ✓ | |
| `GDEF` table | ~ | | |
| `glyf` table | ~2 | ✓ | ~2 |
| `GPOS` table | ✓ | | ~ (only 2) |
| `GSUB` table | ✓ | | |
| `gvar` table | ✓ | ✓ | |
| `head` table | ✓ | ✓ | ✓ |
| `hhea` table | ✓ | ✓ | ✓ |
| `hmtx` table | ✓ | ✓ | ✓ |
| `HVAR` table | ✓ | ✓ | |
| `kern` table | ✓ | ~ (only 0) | ~ (only 0) |
| `kerx` table | ✓ | | |
| `maxp` table | ✓ | ✓ | ✓ |
| `morx` table | ✓ | | |
| `MVAR` table | ✓ | ✓ | |
| `name` table | ✓ | ✓ | |
| `OS/2` table | ✓ | ✓ | |
| `post` table | ✓ | ✓ | |
| `sbix` table | ~ (PNG only) | ~ (PNG only) | |
| `SVG ` table | ✓ | ✓ | ✓ |
| `trak` table | ✓ | | |
| `vhea` table | ✓ | ✓ | |
| `vmtx` table | ✓ | ✓ | |
| `VORG` table | ✓ | ✓ | |
| `VVAR` table | ✓ | ✓ | |
| Language | Rust + C API | C | C |
| Tested version | 0.15.0 | 2.12.0 | 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 multiple 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 Format](https://docs.microsoft.com/en-us/typography/opentype/spec/glyf)
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 a font.
x86 (AMD 3700X)
| Table/Library | ttf-parser | FreeType | stb_truetype |
| ------------- | -------------: | ---------: | -------------: |
| `glyf` | `0.901 ms` | `1.171 ms` | **`0.675 ms`** |
| `gvar` | **`2.972 ms`** | `4.132 ms` | - |
| `CFF` | **`1.197 ms`** | `5.647 ms` | `2.813 ms` |
| `CFF2` | **`1.968 ms`** | `6.392 ms` | - |
ARM (Apple M1)
| Table/Library | ttf-parser | FreeType | stb_truetype |
| ------------- | -------------: | ---------: | -------------: |
| `glyf` | **`0.550 ms`** | `0.854 ms` | `0.703 ms` |
| `gvar` | **`2.270 ms`** | `4.594 ms` | - |
| `CFF` | **`1.054 ms`** | `5.223 ms` | `3.262 ms` |
| `CFF2` | **`1.765 ms`** | `5.995 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: 867 ns/iter (+/- 15)
test from_data_otf_cff ... bench: 968 ns/iter (+/- 13)
test from_data_otf_cff2 ... bench: 887 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: 534 ns/iter (+/- 14)
test from_data_ttf ... bench: 467 ns/iter (+/- 11)
test glyph_name_post_276 ... bench: 223 ns/iter (+/- 5)
test outline_glyph_8_from_cff ... bench: 315 ns/iter (+/- 13)
test outline_glyph_8_from_glyf ... bench: 291 ns/iter (+/- 5)
test family_name ... bench: 183 ns/iter (+/- 102)
test glyph_name_cff_276 ... bench: 62 ns/iter (+/- 1)
test glyph_index_u41 ... bench: 16 ns/iter (+/- 0)
test glyph_name_cff_8 ... bench: 5 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.