# The design of FreeType 2

### Copyright 1998-2000 David Turner (david@freetype.org)
Copyright 2000 The FreeType Development Team (devel@freetype.org)

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# Introduction
This document provides details on the design and implementation of the FreeType 2 library. Its goal is to allow developers to better understand the way how FreeType 2 is organized, in order to let them extend, customize, and debug it. Before anything else, it is important to understand the purpose of this library, i.e., why it has been written: It allows client applications to access font files easily, wherever they could be stored, and as independently of the font format as possible. Easy retrieval of global font data most commonly found in normal font formats (i.e. global metrics, encoding/charmaps, etc.). It allows easy retrieval of individual glyph data (metrics, images, name, anything else). Access to font format-specific "features" whenever possible (e.g. SFNT tables, Multiple Masters, OpenType Layout tables, etc.). Its design has also severely been influenced by the following requirements: High portability. The library must be able to run on any kind of environment. This requirement introduces a few drastic choices that are part of FreeType 2's low-level system interface. Extendability. New features should be added with the least modifications in the library's code base. This requirement induces an extremely simple design where nearly all operations are provided by modules. Customization. It should be easy to build a version of the library that only contains the features needed by a specific project. This really is important when you need to integrate it in a font server for embedded graphics libraries. Compactness and efficiency. The primary target for this library are embedded systems with low cpu and memory resources. The rest of this document is divided in several sections. First, a few chapters will present the library's basic design as well as the objects/data managed internally by FreeType 2. A later section is then dedicated to library customization, relating such topics as system-specific interfaces, how to write your own module and how to tailor library initialization & compilation to your needs.
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