fontdb is a simple, in-memory font database with CSS-like queries.
Vec<u8>).Database::query.System fonts loading.
This library is intentionally doesn't load system fonts.
This is a very complex feature and should be handled by the caller or other libraries.
Font properties querying.
The database provides only storage and matching capabilities.
For font properties querying you can use [ttf-parser].
A font fallback mechanism.
This library can be used to implement a font fallback mechanism, but it doesn't implement it.
Application's global database.
The database doesn't use static, therefore it's up to the caller where it should be stored.
Font types support other than TrueType.
A font is a collection of font faces. Therefore, a font face is a subset of a font. A simple font (*.ttf/*.otf) usually contains a single font face, but a font collection (*.ttc) can contain multiple font faces.
fontdb stores and matches font faces, not fonts.
Therefore, after loading a font collection with 5 faces (for example), the database will be populated
with 5 FaceInfo objects, all of which will be pointing to the same file or binary data.
The database performance is largely limited by the storage itself. We are using [ttf-parser], so the parsing should not be a bottleneck.
On my machine with Samsung SSD 860 and Gentoo Linux, it takes ~20ms to load 1906 font faces (most of them are from Google Noto collection) with a hot disk cache and ~860ms with a cold one.
The library relies on memory-mapped files, which is inherently unsafe. But we do not keep such files open forever. Instead, we are memory-mapping files only when needed.
MIT