forked from minhngoc25a/freetype2
353 lines
13 KiB
HTML
353 lines
13 KiB
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<head>
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<title>FreeType 2 Introduction</title>
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link="#0000EF"
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vlink="#51188E"
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alink="#FF0000">
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<font size=1>http://www.freetype.org</font><p>
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<center>
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<a href="freetype.html">
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<img src="image/freetype.jpg" width=550 height=105 alt="The FreeType Project" border=0></a>
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<h1>An Introduction to FreeType 2</h1>
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</center>
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<center><table width=750 cellspacing=10 cellpadding=30><tr><td>
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<hr><p>
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DOCUMENT INDEX:<br>
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<ul>
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<li><a href="#what">What is FreeType 2 ?</a>
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<li><a href="#features">Features</a>
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<li><a href="#requirements">Requirements</a>
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<li><a href="#patents">Patents issues</a>
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</ul><p>
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<hr><p>
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<table width="100%" cellspacing=5><tr bgcolor="#CCCCEE"><td>
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<h2 align=center><a name="what">What is FreeType 2 ?</h2>
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</td></tr><tr><td>
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<p>The FreeType project is a team of volunteers who develop free, portable
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and high-quality software solutions for digital typography. We specifically
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target embedded systems and focus on bringing small, efficient and
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ubiquitous products.</p>
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<p>the FreeType 2 library is our new software font engine. It has been
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designed to provide the following important features:</p>
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<ul>
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<li><p>
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<b>A universal and simple API to manage font files:</b><br>
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<ul>
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<p>The FreeType 2 API is simple and easy to use. It supports both
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bitmapped and scalable fonts and is well-suited to manage font
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files of all formats. Unlike other font libraries, FreeType 2
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returns and manages outline font data (images & metrics).</p>
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</ul>
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</p></li>
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<li><p>
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<b>Support for several font formats through loadable modules:</b><br>
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<ul>
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<p>FreeType 2 uses <em>"font drivers"</em>. Each driver is a loadable
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module used to support one specific font format. Each driver can also
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provide specific extensions used to access format-specific features of
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the font.</p>
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</ul>
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</p></li>
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<li><p>
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<b>High-quality anti-aliasing:</b><br>
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<ul>
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<p>FreeType 2 produces etremely smooth outlines at small sizes, with its new
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anti-aliasing renderer, which produces bitmaps with 256-levels of gray.
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It uses a new algorithm that has been specifically designed to render
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small complex shapes (like glyphs) at high speed. Indeed, it's even
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faster than the monochrome renderer for small character sizes (under
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20 pixels) !!
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</p>
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</ul>
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<li><b>High portability & performance:</b><br>
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<ul>
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<p>The FreeType 2 source code is written in ANSI C and runs on any
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platform with a compliant compiler. Client applications can
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provide their own memory manager or input stream to the library
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(which means that font files can come from any place: disk,
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memory, compressed file, network, etc..).
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</p>
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</ul>
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</ul>
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<p>Note that <em>the beta of FreeType 2 is available <b>now</b></em>. For more
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info, check our <a href="download.html">Download page</a> or see the source
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and its diffs through our <a href="cgi-bin/cvsweb.cgi">CVS Web interface</a>.
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</p>
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</ul>
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</td></tr></table>
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<table width="100%" cellspacing=5><tr bgcolor="#CCCCEE"><td>
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<h2 align=center><a name="features">Features</h2>
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</td></tr><tr><td>
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<h3>Supported font formats</h3>
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<p>FreeType 2 readily supports the following font formats:</p>
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<ul>
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<li>TrueType files (.ttf) and collections (.ttc)</li>
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<li>Type 1 font files both in ASCII (.pfa) or binary (.pfb) format</li>
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<li>Type 1 Multiple Master fonts. The FreeType 2 API also provides
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routines to manage design instances easily</li>
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<li>Type 1 CID-keyed fonts</li>
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<li>OpenType/CFF (.otf) fonts</li>
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<li>CFF/Type 2 fonts</li>
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<li>Adobe CEF fonts (.cef), used to embed fonts in SVG documents
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with the Adobe SVG viewer plugin.</li>
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<li>Windows FNT/FON bitmap fonts</li>
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</ul>
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<p>Note that Apple's TrueType GX fonts are supported as normal TTFs,
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(the advanced tables are ignored).</p>
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<p>Besides, it's possible to add support for new font formats by providing
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a specific <em>font driver</em> module. Modules can be added either at
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build time (when recompiling the library), or at <em>run-time</em>;
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this allows, for example, applications to register their own
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font driver to support program-specific formats.</p>
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<h3>Patent-free automatic hinter</h3>
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<p>TrueType fonts are normally renderered (hinted) with the help of a
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specific bytecode where the behaviour of a few opcodes is patented by
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Apple. We're currently in contact with Apple to discuss the importance
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of such patents and their use in open source projects like FreeType.
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</p>
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<p>In the meantime, we have developped our own alternative technology that
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is capable of automatically hinting scalable glyph images. It is
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now part of the FreeType 2 source tree as the "autohint" module,
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and is used to hint glyphs when the bytecode interpreter is disabled
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(through a configuration macro when building the engine). Note that
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the auto-hinter is also used to handle glyphs in other formats like
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CFF and Type 1.</p>
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<p>The auto-hinter provides pretty good results (in some cases, it even
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significantly improves the output of poorly hinted fonts) but we'll
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continue to improve it with each new release of FreeType to achieve
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the highest possible quality.</p>
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<h3>Modular design:</h3>
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<p>The design of FreeType 2 is extremely modular as most features are
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supported through optional modules. This means it's easily possible to
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only compile the features you need. As each module is between
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10 and 20 Kb in size, it's possible to build a bare-bones
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font engine that supports anti-aliasing in about 30 Kb !!</p>
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<p>Configuration is performed by modifications of only two header
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files (one to select global features, another one to select modules)
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and don't need tweaking of source code. Note that it is however
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possible to provide your own implementation of certain components.</p>
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<p>For example, when building on Unix, the engine will automatically
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use memory-mapped files when available on the target platform,
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thus significantly increasing font file i/o.</p>
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<p>Due to its very flexible design, it is possible to add, remove and
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upgrade modules at run-time.</p>
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<h3>Advanced glyph management</h3>
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<p>The API comes with a standard extension used to extract individual
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glyph images from font files. These images can be bitmaps, scalable
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bezier outlines or even anything else. (e.g. bi-color or metafont
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glyphs, as long as they're supported by a module).</p>
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<p>Each scalable glyph image can be transformed, measured and
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rendered into a monochrome or anti-aliased bitmaps easily
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through a uniform interface.
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This allows client applications to easily cache glyphs or
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perform text rendering effects with minimal difficulty
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(look at the FreeType 2 Tutorial to see how to render
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rotated text with very few lines of code).
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</p>
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<h3>Advanced font access</h3>
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<p>The FreeType 2 API is useful to retrieve advanced information from
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various fonts:</p>
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<ul>
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<li>vertical metrics are available whenever found in the font file</li>
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<li>kerning distances are available when found in the font file. It
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is also possible to "attach" a given additional file to a given
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font face. This is useful to load kerning distances from an
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.afm file into a Type 1 face for example.</li>
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<li>provides ASCII glyph names whenever available in the font
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(TrueType, OpenType, Type1, etc..)</li>
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<li>provides access to important tables for SFNT-based font formats
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(i.e. TrueType, OpenType, CEF, etc..), like the name table,
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font header, maximum profile, etc...</li>
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<li>automatic synthesis of Unicode-based character maps for
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those fonts or formats that do not provide one. This is
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extremely useful with Type 1 fonts which are normally
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limited to a stupid 256-characters encoding.</li>
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</ul>
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<h3>Simple & clean API</h3>
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<p>The FreeType 2 high-level API is simple and straightforward, as it
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has been specifically designed to make the most commmon font operations
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easy</p>
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<p>As a comparison, the number of function calls needed to perform a
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the tasks of font face creation/opening and glyph loading/rendering
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has been reduced by a factor of 4 !!</p>
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<p>The API is also independent of any font-format specific issue, though
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it provides standard extensions to access format-specific tables and
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information. More extensions can also be easily added through new
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modules</p>
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<h3>Robust & Portable code</h3>
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<p>Because it is written in industry-standard ANSI C, FreeType 2 compiles
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on all platforms with a compliant compiler. Because the default build
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only relies on the C library, it is free of any system-specific
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dependencies, even if it is possible to "enhance" certain components
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by providing a specific implementation.</p>
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<p>The code doesn't use global or static variables. Client applications
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can provide their own memory manager. Font files can be read from
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a disk file, memory, or through a client-provided input stream. This
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allows to support compressed font files, remote fonts, fonts embedded
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in other streams (e.g. Type42 fonts), etc..</p>
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<p>An advanced i/o sub-system is used to optimise file access, as well
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as reduce memory usage of the library when the file is memory-based
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( ROM, RAM, memory-mapped ).</p>
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<h3>Open Source & Vendor Independence</h3>
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<p>Finally, FreeType 2 is released under its own BSD-like open source
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license, one of the less restricting licenses available, and this
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means that:</p>
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<ul>
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<li><p>
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It can be included in all kinds of products, be they proprietary
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or not.
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</p></li>
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<li><p>
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As any module can be added or replaced anytime, any third party
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vendor has the ability to provide its own set of modules (under
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its own license) in order to support proprietary font formats or
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more advanced features (e.g. a new auto-hinter, or a new
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anti-aliasing renderer for LCDs or TV screens).
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</p></li>
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</ul>
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<p>One could even imagine an application using the FreeType 2 API with
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a "wrapper" module used to access system-specific fonts (like through
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the Windows GDI). This would mean native font support with more portable
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application code (as simply changing the wrapper module would be required
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to port the application to another system).</p>
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</td></tr></table>
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<table width="100%" cellspacing=5><tr bgcolor="#CCCCEE"><td>
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<h2 align=center><a name="requirements">Requirements</h2>
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</td></tr><tr><td>
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<p>FreeType 2 is written in ANSI C and should compile with no problems
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on a great variety of platforms. We have taken care of removing all
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compilation warnings from major compliant compilers. Detailed compilation
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instructions are provided in the software archive.</p>
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<p>This version of the library has been succesfully compiled and run
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under the following systems: Dos, OS/2, Windows, Macintosh, Unix
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(including the 64-bits DEC Unix, a.k.a. "True64"). You should not
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encounter major problems compiling it on any other kind of platform.
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In all cases, contact us if you do.</p>
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<p>Note that a small set of demonstration programs is also separately
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available. They include a tiny graphics sub-system that is used to
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display and show-off the library's capabilities on the following
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platforms: X11, MacOS, OS/2 & Windows.</p>
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<p>Please visit our <a href="http://www.freetype.org/download.html">
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Download section</a> to access the software archives.</p>
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</ul>
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</td></tr></table>
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<table width="100%" cellspacing=5><tr bgcolor="#CCCCEE"><td>
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<h2 align=center><a name="patents">Patents issues</h2>
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</td></tr><tr><td>
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<p>The FreeType 2 source code includes a TrueType bytecode interpreter that
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is covered by the Apple patents. However, this piece of code is never
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compiled by default in this release (unlike in previous betas) making
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a default build of the library <em>entirely patent-free !!</em></p>
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<p>Note that in order to compile the interpreter, one needs to define
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the configuration macro <tt><b>TT_CONFIG_OPTION_BYTECODE_INTERPRETER</b></tt> configuration
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macro in the file "<tt>ftoption.h</tt>". More details are available in
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the software archive. Note that the use of the interpreter is normally
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protected by US, UK and French patents. In the event you'd absolutely
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need it, you may have to <a href="mailto:patents@apple.org">contact
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Apple legal department</a> for licensing conditions, depending on your
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location and the places you distribute/sell your products.</p>
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<p>Please do not ask us any detailed information regarding licensing, as
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we're still discussing with Apple this issue, we're unable to inform
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the public of what's currently going on..</p>
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</td></tr></table>
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<hr>
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<p>
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<a href="index.html">Back to FreeType homepage</a><p>
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</td></tr></table>
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</body>
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</html>
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