OTFontFile2 0.1.0-alpha

OTFontFile2

OTFontFile2 is a modern OpenType parser/writer for .NET, focused on:

• high performance
• low allocation
• span-first table access

It supports both single-font sfnt (.ttf/.otf) and TTC collections (.ttc).

Quick Start

1) Open a font file

using OTFontFile2;

using var file = SfntFile.Open("font.ttf"); // or font.ttc
var font = file.GetFont(0);                 // first font in file/collection

2) Read common tables

using OTFontFile2.Tables;

if (font.TryGetHead(out var head))
{
    int unitsPerEm = head.UnitsPerEm;
}

if (font.TryGetMaxp(out var maxp))
{
    int glyphCount = maxp.NumGlyphs;
}

if (font.TryGetName(out var name))
{
    string? fullName = name.GetFullNameString();
}

3) Map Unicode to glyph id (cmap)

using OTFontFile2;

if (CmapUnicodeMap.TryCreate(font, out var map) &&
    map.TryMapCodePoint(0x4F60, out uint glyphId)) // U+4F60
{
    // glyphId
}

4) Repack/write font

using OTFontFile2;

using var inFile = SfntFile.Open("in.ttf");
var inFont = inFile.GetFont(0);

using var outStream = File.Create("out.ttf");
SfntWriter.Write(outStream, inFont);

Core API

SfntFile

• SfntFile.Open(path): open from disk.
• SfntFile.TryOpen(path, out file, out error): non-throwing open.
• SfntFile.FromMemory(memory): open from in-memory bytes.
• FontCount: number of fonts (1 for normal sfnt, >1 for TTC).
• GetFont(index): get SfntFont.

SfntFont

• TableCount: number of tables in this font.
• TryGetTable(tag, out record): table directory lookup.
• TryGetTableData(tag, out data, out record): raw bytes of a table.
• TryGetTableSlice(tag, out slice): zero-copy table slice.
• Generated helpers like TryGetHead, TryGetMaxp, TryGetName, TryGetCmap, TryGetGlyf, etc.

Table views

Most table structs in OTFontFile2.Tables expose:

• TryCreate(...)
• typed field properties (e.g. UnitsPerEm, NumGlyphs)
• helper methods for common read scenarios

Build New sfnt from table bytes

using OTFontFile2;

Tag.TryParse("head", out var headTag);
Tag.TryParse("cmap", out var cmapTag);

var builder = new SfntBuilder
{
    SfntVersion = 0x00010000
};

builder.SetTable(headTag, headBytes);
builder.SetTable(cmapTag, cmapBytes);

using var fs = File.Create("new.ttf");
builder.WriteTo(fs);

Notes

• API is span-based and optimized for low allocations.
• Current APIs are designed for safe table access; invalid font data usually returns false instead of throwing.
• Very large files (>2GB) are not supported by span-based offsets.