Table of Contents

Native (Experimental)

KernSmith's own rasterizer backend -- a font rasterizer written entirely in C# inside this repository, with no native libraries and no third-party font code. Everything from SFNT table parsing to the scanline fill is KernSmith's own.

Important

This backend is experimental and not published to NuGet. RasterizerBackend.Native resolves only in builds that reference the KernSmith.Rasterizers.Native project directly (a source build) or in the KernSmith CLI, which ships it. In an app built against the released NuGet packages, RasterizerFactory.Create(RasterizerBackend.Native) throws "not registered". Use FreeType or StbTrueType for production work.

Platform: Cross-platform (net8.0, net10.0). No native binaries required.

Usage

The rasterizer auto-registers via [ModuleInitializer] -- referencing the project is sufficient. Select it in options:

var options = new FontGeneratorOptions
{
    Size = 32,
    Backend = RasterizerBackend.Native
};

var result = BmFont.Generate("path/to/font.ttf", options);

From the CLI:

kernsmith generate --font Roboto-Regular.ttf --size 32 --rasterizer native --output roboto

kernsmith list-rasterizers shows it alongside the other backends.

Capabilities

  • TrueType (glyf) outlines
  • TrueType Collections (.ttc) via face index
  • cmap formats 4 and 12 for character lookup
  • Anti-aliasing: Grayscale and None only
  • Super sampling (applied by the core pipeline)
  • Font and glyph metrics that track FreeType to within a pixel

Limitations

Everything below is either rejected with a clear error or simply unsupported:

  • CFF/OTF (PostScript) outlines -- rejected at load time with a RasterizationException. This is the one that bites: a .otf file will not render at all.
  • WOFF / WOFF2 -- not supported; supply raw TTF/TTC bytes
  • Hinting -- none, so small sizes are softer than FreeType or GDI output
  • SDF rendering -- not supported
  • Outline stroke -- not supported
  • Synthetic bold and italic -- not supported. Bold and Italic are silently ignored rather than rejected, so requesting them produces regular-weight glyphs. For a bitmap-level approximation, add BoldPostProcessor / ItalicPostProcessor to PostProcessors and leave Bold / Italic unset (the pipeline skips those post-processors when the matching option is set, on the assumption the backend handled it).
  • Variable fonts and color fonts (COLR/CPAL) -- not supported
  • System font loading by name -- not supported; load font bytes instead
  • Light and LCD anti-aliasing -- not supported

When to Use

Use Native when you are building KernSmith from source and want plain TrueType text rendered with no third-party dependencies whatsoever -- for example to audit the whole rasterization path, or to avoid pulling in a vendored C library. For shipping managed-only builds today, use StbTrueType: it is published, AOT-tested, and adds SDF plus synthetic bold/italic.

Edit this page