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| content="David Turner"> |
| <title>The Design of FreeType 2 - Introduction</title> |
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| The Design of FreeType 2 |
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| <h1> |
| Introduction |
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| <p>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.</p> |
| |
| <p>Before anything else, it is important to understand the |
| <em>purpose</em> of this library, i.e., why it has been written:</p> |
| |
| <ul> |
| <li> |
| <p>It allows client applications to <em>access font files easily</em>, |
| wherever they could be stored, and as independently of the font format |
| as possible.</p> |
| </li> |
| <li> |
| <p>Easy <em>retrieval of global font data</em> most commonly found in |
| normal font formats (i.e. global metrics, encoding/charmaps, |
| etc.).</p> |
| </li> |
| <li> |
| <p>It allows easy <em>retrieval of individual glyph data</em> |
| (metrics, images, name, anything else).</p> |
| </li> |
| <li> |
| <p><em>Access to font format-specific "features"</em> whenever |
| possible (e.g. SFNT tables, Multiple Masters, OpenType Layout tables, |
| etc.).</p> |
| </li> |
| </ul> |
| |
| <p>Its design has also severely been influenced by the following |
| requirements:</p> |
| |
| <ul> |
| <li> |
| <p><em>High portability</em>. 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.</p> |
| </li> |
| <li> |
| <p><em>Extendability</em>. 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.</p> |
| </li> |
| <li> |
| <p><em>Customization</b>. 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.</p> |
| </li> |
| <li> |
| <p><em>Compactness</em> and <em>efficiency</em>. The primary target |
| for this library are embedded systems with low cpu and memory |
| resources.</p> |
| </li> |
| </ul> |
| |
| <p>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.</p> |
| |
| <p>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.</p> |
| |
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