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<h1><a href="http://freetype.org/index.html">FreeType</a> Design</h1>
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<h2>Introduction</h2>
<p>This document provides details on the design and
implementation of the FreeType 2 library. Its goal
is to help developers better understand 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,
font variations, 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 or services.</p>
</li>
<li>
<p><em>Customization</em>. 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 into a font
server for embedded graphics libraries, say.</p>
</li>
<li>
<p><em>Compactness</em> and <em>efficiency</em>. The
primary target for this library originally were
embedded systems with low CPU and memory resources.
Today, however, memory constraints are much less
strict, and the focus of development shifted to
support as much font features as possible.</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 and data managed internally
by FreeType 2.</p>
<p>It is intended to eventually add sections that cover
library customization, relating to topics as
system-specific interfaces, how to write your own modules
or services and how to tailor library initialization and
compilation to your needs. Those sections are not written
yet, however.</p>
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<p>Last update: 13-Feb-2018</p>
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