UOF Font Format

UOF is the uniOS runtime font format. It stores preprocessed bitmap font data (glyph atlas + metrics) for the userspace GUI library, so no desktop font parsing happens at runtime.

Identity

• Extension: .uof
• Magic: 0x4E464F55 (UOFN, little-endian)
• Version: 1
• Runtime users: libgui text rendering (apps, menubar, dock, window manager, terminal)

File Layout

typedef struct {
    uint32_t magic;         // 0x4E464F55
    uint16_t version;
    uint16_t flags;
    uint16_t pixel_size;
    uint16_t atlas_width;
    uint16_t atlas_height;
    int16_t  ascent;
    int16_t  descent;
    int16_t  line_gap;
    uint16_t glyph_count;
    uint16_t kerning_count;
    uint16_t fallback_index;
    uint32_t glyph_offset;
    uint32_t kerning_offset;
    uint32_t atlas_offset;
} UofHeader; // packed

The glyph table follows the header, then kerning pairs, then the 8-bit alpha atlas. Each glyph records its codepoint, atlas position, size, bearings, and advance. Loaders validate all offsets and counts against the file size.

Runtime Use

At startup the GUI picks a pixel size from the framebuffer dimensions (11-15, clamped to 11..18) and loads the nearest size of each family from /usr/share/fonts/:

Filenames follow <prefix>-<size>.uof. Each family applies a gamma boost through its alpha lookup table (UI 145, Title 100, Mono 175). When a font fails to load, a built-in 8x8 bitmap font takes over.

Generated font files are staged under:

/usr/share/fonts/

Generation

Font sources live under assets/fonts/. The conversion tool writes .uof files:

python3 tools/uof_convert.py

Generated binaries are committed; keep binaries and sources in sync in the same change. UOF is not a general desktop font format — it exists to avoid parsing full desktop font formats inside the GUI runtime.