62 lines
2.3 KiB
Markdown
62 lines
2.3 KiB
Markdown
# fontdb
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[](https://crates.io/crates/fontdb)
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[](https://docs.rs/fontdb)
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[](https://www.rust-lang.org)
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`fontdb` is a simple, in-memory font database with CSS-like queries.
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## Features
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- The database can load fonts from files, directories and raw data (`Vec<u8>`).
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- The database can match a font using CSS-like queries. See `Database::query`.
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- The database can try to load system fonts.
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Currently, this is implemented by scanning predefined directories.
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The library does not interact with the system API.
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- Provides a unique ID for each font face.
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## Non-goals
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- Advanced font properties querying.<br>
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The database provides only storage and matching capabilities.
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For font properties querying you can use [ttf-parser].
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- A font fallback mechanism.<br>
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This library can be used to implement a font fallback mechanism, but it doesn't implement one.
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- Application's global database.<br>
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The database doesn't use `static`, therefore it's up to the caller where it should be stored.
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- Font types support other than TrueType.
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## Font vs Face
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A font is a collection of font faces. Therefore, a font face is a subset of a font.
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A simple font (\*.ttf/\*.otf) usually contains a single font face,
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but a font collection (\*.ttc) can contain multiple font faces.
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`fontdb` stores and matches font faces, not fonts.
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Therefore, after loading a font collection with 5 faces (for example), the database will be
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populated with 5 `FaceInfo` objects, all of which will be pointing to the same file or binary data.
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## Performance
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The database performance is largely limited by the storage itself.
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We are using [ttf-parser], so the parsing should not be a bottleneck.
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For example, on Mac Book Pro 14 with M1 Pro, it takes just ~24ms to load 1361 font faces.
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## Safety
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The library relies on memory-mapped files, which is inherently unsafe.
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But since we do not keep the files open it should be perfectly safe.
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If you would like to use a persistent memory mapping of the font files,
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then you can use the unsafe `Database::make_shared_face_data` function.
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## License
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MIT
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[ttf-parser]: https://github.com/RazrFalcon/ttf-parser
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