Project 9: Font Rendering with FreeType

A font rendering system using FreeType that rasterizes TrueType/OpenType fonts, with support for ligatures via HarfBuzz.

Quick Reference

Attribute Value
Primary Language C
Alternative Languages C++, Rust
Difficulty Level 3: Advanced (The Engineer)
Time Estimate 2-3 weeks
Knowledge Area Font Rendering / Graphics
Tooling Font Renderer
Prerequisites Basic graphics programming

What You Will Build

A font rendering system using FreeType that rasterizes TrueType/OpenType fonts, with support for ligatures via HarfBuzz.

Why It Matters

This project builds core skills that appear repeatedly in real-world systems and tooling.

Core Challenges

  • FreeType integration → Loading fonts, rasterizing glyphs
  • Glyph caching → Don’t re-rasterize the same character
  • Subpixel rendering → LCD antialiasing for sharpness
  • Unicode handling → Beyond ASCII, handling emoji
  • HarfBuzz for shaping → Ligatures, complex scripts

Key Concepts

  • FreeType Tutorial: FreeType 2 Tutorial
  • Text Rendering: “Computer Graphics from Scratch” Chapter 8 - Gabriel Gambetta
  • HarfBuzz: HarfBuzz Manual
  • Font Metrics: Understanding font metrics (ascender, descender, advance)

Real-World Outcome

$ ./font_render_demo --font="Fira Code" --size=14

[FONT] Loaded: Fira Code
[FONT] Has ligatures: Yes
[FONT] Glyph cache: 256 entries

Rendering: "Hello, World!"
  'H' (0x48) → glyph 43, advance 8px
  'e' (0x65) → glyph 72, advance 8px
  ...

Rendering with ligatures: "==> !="
  '=' '=' '>' → ligature glyph 512, advance 24px (3 chars)
  ' '
  '!' '=' → ligature glyph 489, advance 16px (2 chars)

Implementation Guide

  1. Reproduce the simplest happy-path scenario.
  2. Build the smallest working version of the core feature.
  3. Add input validation and error handling.
  4. Add instrumentation/logging to confirm behavior.
  5. Refactor into clean modules with tests.

Milestones

  • Milestone 1: Minimal working program that runs end-to-end.
  • Milestone 2: Correct outputs for typical inputs.
  • Milestone 3: Robust handling of edge cases.
  • Milestone 4: Clean structure and documented usage.

Validation Checklist

  • Output matches the real-world outcome example
  • Handles invalid inputs safely
  • Provides clear errors and exit codes
  • Repeatable results across runs

References

  • Main guide: TERMINAL_EMULATOR_DEEP_DIVE_PROJECTS.md
  • “Computer Graphics from Scratch” by Gabriel Gambetta