FreeType Glyph Conventions

This document presents the core conventions used within the FreeType library to manage font and glyph data. It is a must-read for all developers who need to understand digital typography, especially if you want to use the FreeType 2 library in your projects.

I. Basic Typographic Concepts

• 1. Font files, format and information
• 2. Character images and mappings
• 3. Character and font metrics

II. Glyph Outlines

• 1. Pixels, points and device resolutions
• 2. Vectorial representation
• 3. Hinting and bitmap rendering

III. Glyph Metrics

• 1. Baseline, pens and layouts
• 2. Typographic metrics and bounding boxes
• 3. Bearings and advances
• 4. The effects of grid-fitting
• 5. Text widths and bounding box

IV. Kerning

• 1. Kerning pairs
• 2. Applying kerning

V. Text Processing

• 1. Writing simple text strings
• 2. Sub-pixel positioning
• 3. Simple kerning
• 4. Right-to-left layouts
• 5. Vertical layouts

VI. FreeType Outlines

• 1. FreeType outline description and structure
• 2. Bounding and control box computations
• 3. Coordinates, scaling, and grid-fitting

VII. FreeType Bitmaps

• 1. Vectorial versus pixel coordinates
• 2. The FT_Bitmap descriptor
• 3. Converting outlines into bitmaps and pixmaps