harfbuzz VS Cap'n Proto

For C/C++ projects that use meson as the build system, there is an excellent way to manage dependencies:

https://mesonbuild.com/Wrapdb-projects.html

https://mesonbuild.com/Wrap-dependency-system-manual.html

meson will download and build the libraries automatically and give you a variable which you pass as a regular dependency into the built target:

https://github.com/qemu/qemu/tree/005ad32358f12fe9313a4a0191...

https://github.com/harfbuzz/harfbuzz/tree/main/subprojects

https://github.com/harfbuzz/harfbuzz/blob/37457412b3212463c5...

Or, if you're using proper operating systems, they're managed by the usual package manager, just like everything else.

If you sympathize with the travails of people working on text rendering in applications, please consider supporting (among other projects):

1. The LibreOffice project (libreoffice.org), the free office application suite. This is where the rubber hits the road and developers deal with the extreme complexities of everything regarding text - shaping, styling, multi-object interaction, multi-language, you name it. And - they/we absolutely need donations to manage a project with > 200 million users: https://www.libreoffice.org/donate

2. harfbuzz (https://harfbuzz.github.io), and specifically Behdad Esfahood the main contributor. Although, TBH, I've not quite figured out whether you can donate to that or to him. At least star the project on GitHub I guess.

As for text, it depends very heavily on what exactly you need. Simple ASCII text and bitmap fonts? Just do it yourself or get a .bdf parser. Simple Latin/Cyrillic-like writing with ok-looking vector fonts (ttfs)? stb_truetype has all you need. Font hinting, subpixel rendering? You use freetype. More complex writing like Arabic? You will have to do shaping as well, say with HarfBuzz. Need right-to-left or unidirectional text? Hypenation? Go for platform APIs if you can (DirectWrite om Windows, CoreText on Mac).

Gold standard? Even though serious bugs are not fixed [1] because "the code is too fragile to touch at this point"? Looks like Android uses HarfBuzz, if so it can't be that bad.

[1] https://github.com/harfbuzz/harfbuzz/issues/2814

The linked libraries are not even close to solving limited subsets of problems solved by FreeType or HarfBuzz. No test is needed if they do not even have a working implementation of particular requisites: Do they work on heterogeneous layouts, directions, languages, locales, scripts, symbols and composites, extensions, variations, legacy, missing, partial or corrupted instructions, standards interpretations, platforms, output devices, nonstandard point structures and grids?

They do not. What they solve is almost a toy problem compared to the size, scope and breadth of these libraries.

Just because some project is implemented in Rust does not make it comparable never mind superior by default.

There is a world out there and it is not homogeneous format and standards-compliant Latin fonts in English LTR text in linear disposition with some generic rectangular subpixel rendering on a regular rectangular grid.

I warmly welcome you to browse closed issues of FreeType [1] and also the closed issues of HarfBuzz [2]. If you feel inspired please do also look into mailing lists and discussion pages related to the development, building, tracking and patching of packages of these projects in any of the numerous places it is used.

The only argument Rust people have is in relation WASM but if you insist in targeting WASM why not fork FreeType, strip it to the strict subset of features your application needs and target it?

Why do it in the first place? Why reinvent the wheel?

As such I will restate my view: I see no gain in using any of these subpar libraries.

[1] https://gitlab.freedesktop.org/freetype/freetype/-/issues/?s...

[2] https://github.com/harfbuzz/harfbuzz/issues?q=is%3Aclosed

Yeah I pretty much only use my own alternate container implementations (from KJ[0]), which avoid these footguns, but the result is everyone complains our project is written in Kenton-Language rather than C++ and there's no Stack Overflow for it and we can't hire engineers who know how to write it... oops.

[0] https://github.com/capnproto/capnproto/blob/v2/kjdoc/tour.md

- may massively reduce the latency involved.

Those sharing Cap'n Proto-encoded data may have particular interest. Cap'n Proto (https://capnproto.org) is fantastic at its core task - in-place serialization with zero-copy - and we wanted to make the IPC (inter-process communication) involving capnp-serialized messages be zero-copy, end-to-end.

That said, we paid equal attention to other varieties of payload; it's not limited to capnp-encoded messages. For example there is painless (<-- I hope!) zero-copy transmission of arbitrary combinations of STL-compliant native C++ data structures.

To help determine whether Flow-IPC is relevant to you we wrote an intro blog post. It works through an example, summarizes the available features, and has some performance results. https://www.linode.com/blog/open-source/flow-ipc-introductio...

Of course there's nothing wrong with going straight to the GitHub link and getting into the README and docs.

Currently Flow-IPC is for Linux. (macOS/ARM64 and Windows support could follow soon, depending on demand/contributions.)

FWIW, my C++ toolkit library, KJ, does the same thing.[0]

But presumably you could still write a condition predicate which looks at things which aren't actually part of the mutex-wrapped structure? Or does is the Rust type system able to enforce that the callback can only consider the mutex-wrapped value and values that are constant over the lifetime of the wait? (You need the latter e.g. if you are waiting for the mutex-wrapped value to compare equal to some local variable...)

[0] https://github.com/capnproto/capnproto/blob/e6ad6f919aeb381b...

The second one is to encode data in such a way that you can read it and operate on it directly from the buffer. You write data in a layout that is the same, or easily transformed as types in memory. To do that you usually need to encode with a known schema, only Sized types to efficiently compute fields locations as offsets in the buffer, and you usually represent pointers as offset into the encode. You can look at capnproto protocol for instance https://capnproto.org/

Worked well for Cap'n Proto (the cerealization protocol)! https://capnproto.org/

With all due respect, you read completely wrong.

* The very first use case for which Cap'n Proto was designed was to be the protocol that Sandstorm.io used to talk between sandbox and supervisor -- an explicitly adversarial security scenario.

* The documentation explicitly calls out how implementations should manage resource exhaustion problems like deep recursion depth (stack overflow risk).

* The implementation has been fuzz-tested multiple ways, including as part of Google's oss-fuzz.

* When there are security bugs, I issue advisories like this:

https://github.com/capnproto/capnproto/tree/v2/security-advi...

* The primary aim of the entire project is to be a Capability-Based Security RPC protocol.

I like how they use capability-based security [0] and use Cap'n Proto protocol. This is another technology that is slow to get broad adoption, but has many things going for when compared to e.g. Protocol Buffers (Cap'n Proto is created by the primary author of Protobuf v2, Kenton Varda).

[0] https://sandstorm.io/how-it-works#capabilities

[1] https://capnproto.org

Related but not Rust-specific: FlatBuffers, Cap'n Proto.