124 lines
4.9 KiB
Markdown
124 lines
4.9 KiB
Markdown
# Development status
|
|
|
|
This project is in a semi-abandoned state.
|
|
|
|
The port is complete. All tests are passing. But we're are a couple of years and thousands commits
|
|
behind harfbuzz.
|
|
|
|
Backporting takes a lot of time and I have barely any.
|
|
If you are interested in helping the project checkout
|
|
[docs/backporting.md](./docs/backporting.md).
|
|
|
|
---
|
|
|
|
# rustybuzz
|
|
|
|
[](https://crates.io/crates/rustybuzz)
|
|
[](https://docs.rs/rustybuzz)
|
|
|
|
`rustybuzz` is a complete [harfbuzz](https://github.com/harfbuzz/harfbuzz)'s
|
|
shaping algorithm port to Rust.
|
|
|
|
Matches `harfbuzz` v4.3.0
|
|
|
|
## Why?
|
|
|
|
Because you can add `rustybuzz = "*"` to your project and it just works.
|
|
No need for a C++ compiler. No need to configure anything. No need to link to system libraries.
|
|
|
|
## Conformance
|
|
|
|
rustybuzz passes 98% of harfbuzz tests (1764 to be more precise).
|
|
So it's mostly identical, but there are still some tiny edge-cases which
|
|
are not implemented yet or cannot be implemented at all.
|
|
|
|
Also, Apple layout is largely untested, because we cannot include Apple fonts for legal reasons.
|
|
harfbuzz uses macOS CI instances to test it, which is extremely painful
|
|
and we do not do this for now.
|
|
|
|
## Major changes
|
|
|
|
- Subsetting removed.
|
|
- TrueType parsing is completely handled by the
|
|
[ttf-parser](https://github.com/RazrFalcon/ttf-parser).
|
|
And while the parsing algorithm is very different, it's not better or worse, just different.
|
|
- Malformed fonts will cause an error. HarfBuzz uses fallback/dummy shaper in this case.
|
|
- No font size property. Shaping is always using UnitsPerEm. You should scale the result manually.
|
|
- Most of the TrueType and Unicode handling code was moved into separate crates.
|
|
- rustybuzz doesn't interact with any system libraries and must produce exactly the same
|
|
results on all OS'es and targets.
|
|
- `mort` table is not supported, since it's deprecated by Apple.
|
|
- No Arabic fallback shaper, since it requires subsetting.
|
|
- No `graphite` library support.
|
|
- No automated Apple layout testing for legal reasons. We just cannot include Apple fonts.
|
|
harfbuzz avoids this by running such tests only on CI, which is far from ideal.
|
|
|
|
## Performance
|
|
|
|
At the moment, performance isn't that great. We're 1.5-2x slower than harfbuzz.
|
|
Also, rustybuzz doesn't support shaping plan caching at the moment.
|
|
|
|
See [benches/README.md](./benches/README.md) for details.
|
|
|
|
## Notes about the port
|
|
|
|
rustybuzz is not a faithful port.
|
|
|
|
harfbuzz can roughly be split into 6 parts: shaping, subsetting, TrueType parsing,
|
|
Unicode routines, custom containers and utilities (harfbuzz doesn't use C++ std)
|
|
and glue for system/3rd party libraries. In the mean time, rustybuzz contains only shaping.
|
|
All of the TrueType parsing was moved to the [ttf-parser](https://github.com/RazrFalcon/ttf-parser).
|
|
Subsetting was removed. Unicode code was mostly moved to external crates.
|
|
We don't need custom containers because Rust's std is good enough.
|
|
And we do not use any non Rust libraries, so no glue code either.
|
|
|
|
In the end, we still have around 20 KLOC. While harfbuzz is around 80 KLOC.
|
|
|
|
## Lines of code
|
|
|
|
As mentioned above, rustybuzz has around 20 KLOC. But this is not strictly true,
|
|
because there are a lot of auto-generated data tables.
|
|
|
|
You can find the "real" code size using:
|
|
|
|
```sh
|
|
tokei --exclude unicode_norm.rs --exclude complex/vowel_constraints.rs \
|
|
--exclude '*_machine.rs' --exclude '*_table.rs' src
|
|
```
|
|
|
|
Which gives us around 13 KLOC, which is still a lot.
|
|
|
|
## Future work
|
|
|
|
Since the port is finished, there is not much to do other than syncing it with
|
|
a new harfbuzz releases.
|
|
But there are still a lot of room for performance optimizations and refactoring.
|
|
|
|
Also, despite the fact that harfbuzz has a vast test suite, there are still a lot of
|
|
things left to test.
|
|
|
|
## Safety
|
|
|
|
The library is completely safe.
|
|
|
|
We do have one `unsafe` to cast between two POD structures, which is perfectly safe.
|
|
But except that, there are no `unsafe` in this library and in most of its dependencies
|
|
(excluding `bytemuck`).
|
|
|
|
## Alternatives
|
|
|
|
- [harfbuzz_rs](https://crates.io/crates/harfbuzz_rs) - bindings to the actual harfbuzz library.
|
|
As of v2 doesn't expose subsetting and glyph outlining, which harfbuzz supports.
|
|
- [allsorts](https://github.com/yeslogic/allsorts) - shaper and subsetter.
|
|
As of v0.6 doesn't support variable fonts and
|
|
[Apple Advanced Typography](https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6AATIntro.html).
|
|
Relies on some unsafe code.
|
|
- [swash](https://github.com/dfrg/swash) - Supports variable fonts, text layout and rendering.
|
|
No subsetting. Relies on some unsafe code. As of v0.1.4 has zero tests.
|
|
|
|
## License
|
|
|
|
`rustybuzz` is licensed under the **MIT**.
|
|
|
|
`harfbuzz` is [licensed](https://github.com/harfbuzz/harfbuzz/blob/master/COPYING) under the **Old MIT**
|