David Turner
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<html> |
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<title>FreeType 2 Introduction</title> |
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<basefont face="Georgia, Arial, Helvetica, Geneva"> |
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<body text="#000000" |
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bgcolor="#FFFFFF" |
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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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|
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<center><table width=750 cellspacing=10 cellpadding=30><tr><td> |
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<hr><p> |
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|
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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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|
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|
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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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|
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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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|
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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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|
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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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|
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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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|
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|
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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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|
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|
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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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|
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</ul> |
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|
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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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|
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</td></tr></table> |
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|
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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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|
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<h3>Supported font formats</h3> |
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|
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<p>FreeType 2 readily supports the following font formats:</p> |
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|
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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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|
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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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|
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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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|
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|
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<h3>Patent-free automatic hinter</h3> |
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|
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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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|
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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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|
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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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|
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|
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<h3>Modular design:</h3> |
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|
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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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|
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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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|
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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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|
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|
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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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|
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|
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|
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<h3>Advanced glyph management</h3> |
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|
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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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|
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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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|
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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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|
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|
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|
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<h3>Advanced font access</h3> |
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|
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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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|
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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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|
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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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|
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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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|
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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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|
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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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|
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|
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<h3>Simple & clean API</h3> |
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|
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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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|
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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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|
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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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|
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|
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<h3>Robust & Portable code</h3> |
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|
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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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|
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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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|
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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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|
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|
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<h3>Open Source & Vendor Independence</h3> |
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|
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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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|
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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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|
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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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|
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</td></tr></table> |
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|
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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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|
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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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|
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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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|
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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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|
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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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|
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</ul> |
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|
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</td></tr></table> |
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|
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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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|
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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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|
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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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|
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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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|
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</td></tr></table> |
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|
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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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|
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</td></tr></table> |
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</body> |
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</html> |
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@ -0,0 +1,502 @@ |
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<html> |
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<head> |
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<title>FreeType 2 FAQ</title> |
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<basefont face="Georgia, Arial, Helvetica, Geneva"> |
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<style content="text/css"> |
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P { text-align=justify } |
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H1 { text-align=center } |
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H2 { text-align=center } |
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LI { text-align=justify } |
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</style> |
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</head> |
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|
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<body text="#000000" |
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bgcolor="#FFFFFF" |
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link="#0000EF" |
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vlink="#51188E" |
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alink="#FF0000"> |
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|
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|
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<font size=1>http://www.freetype.org</font><p> |
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|
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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>The FreeType 2 FAQ</h1> |
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</center> |
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|
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<center><table width=750 cellspacing=10 cellpadding=30><tr><td> |
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<hr><p> |
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|
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DOCUMENT INDEX:<br> |
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<ul> |
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<li><p><a href="#general">General</a> |
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<ul> |
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<li><a href="#general-dead">I thought the FreeType project was dead. It this true?</a></li> |
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<li><a href="#general-long">Why did it take so long to release FreeType 2?</a></li> |
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<li><a href="#general-unix">Is FreeType 2 a Unix-only project?</a></li> |
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<li><a href="#general-x11">When will X11 support anti-aliased glyphs?</a></li> |
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<li><a href="#general-ft1">Is FreeType 2 backwards compatible with 1.x?</a></li> |
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<li><a href="#general-edit">Can I use FreeType 2 to edit fonts or create new ones?</a></li> |
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</ul></p> |
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</li> |
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<li><p><a href="#builds">Compilation & Configuration</a> |
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<ul> |
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<li><a href="#builds-compile">How do I compile the FreeType 2 library?</a></li> |
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<li><a href="#builds-config">How do I configure my library build?</a></li> |
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<li><a href="#builds-modules">How do I select the modules I need?</a></li> |
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<li><a href="#builds-flat">How do I compile all FreeType 2 files in a single directory?</a></li> |
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</ul> |
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</p></li> |
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<li><p><a href="#library">Using the FreeType 2 library</a></p></li> |
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<li><p><a href="#autohint">The FreeType 2 Autohinter</a> |
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<ul> |
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<li><a href="#autohint-license">Under which license is the auto-hinter released ?</a></li> |
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<li><a href="#autohint-work">How does auto-hinting work in FreeType 2 ?</a></li> |
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<li><a href="#autohint-cjk">Why doesn't the auto-hinter work well with CJK fonts ?</a></li> |
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</ul> |
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</p></li> |
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<li><p><a href="#other">Other questions</a> |
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<ul> |
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<li><a href="#other-antialias">What is the anti-aliasing algorithm used in the FreeType 2 renderer?</a></li> |
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<li><a href="#other-opentype">When will FreeType 2 support OpenType ?</a></li> |
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</ul></p> |
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</li> |
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</ul><p> |
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|
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|
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<hr><p> |
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|
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<table width="100%" cellspacing=5><tr bgcolor="#CCCCEE"><td> |
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<h2 align=center><a name="general">General questions & answers</h2> |
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</td></tr><tr><td> |
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|
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<a name="general-dead"> |
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<h3>I.1. I though the FreeType project was dead. Is this true?</h3> |
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<ul> |
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<p>Well, not exactly :-) It's true that the TrueType patents issues |
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have been less than a graceful event to handle but it didn't not |
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really killed the project per se, as Apple hasn't made an official |
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statement yet regarding the use of the patented "technology" in |
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open source projects (or other products).</p> |
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|
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<p>We have thus continued updating FreeType 1.x, and started developping |
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FreeType 2 with the idea of providing this time a completely patent |
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free font engine. However, we largely preferred not to broadly |
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communicate about it until we've got a satisfying implementation |
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to show.</p> |
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</ul> |
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|
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|
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<a name="general-long"> |
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<h3>I.2. Why did it take so long to release FreeType 2?</h3> |
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<ul> |
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<p>Several factors come to mind. The first one is that FreeType 2 is |
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a much more complex and dense project that was mostly developed |
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on non-working hours. And surely some important changes in the |
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life (like marriage, new jobs and kids) of some the FreeType |
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developers cannot be ignored :-)</p> |
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|
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<p>A second one is that a first version of the library was designed |
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one year ago (and already worked with a multitude of font drivers), |
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though with a design that was judged by its authors as well as |
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beta testers as not enough flexible or consistent. In short, it worked |
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well but we were not exactly proud of it (call us perfectionists). |
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It has then be significantly reworked to become what we're now |
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distributing as FreeType 2</p> |
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|
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<p>Finally, it would have been hard to distribute such a library without |
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an alternative technology to replace the patented bytecode interpreter. |
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This involved significant research work that could only be performed |
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correctly full-time, and we had to found a company to fund such a |
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development and still make it available under a BSD-like license. |
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Huge thanks to <a href="http://www.catharon.com">Catharon Productions, Inc.</a> |
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for their commitment to this project.</p> |
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|
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<p>And of course, we added support for more font files, and we'll |
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continue to as long as the specs are available and that we find an |
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interest in it. For example, FreeType 2 is to date the only |
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software library available on the market that supports the new |
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Adobe "CEF" font format.</p> |
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</ul> |
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|
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<a name="general-unix"> |
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<h3>I.3. Is FreeType 2 a Unix-only project?</h3> |
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<ul> |
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<p>Absolutely not, even though many people still seem to think so :-) |
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FreeType 2, just like version 1.x, can be compiled on any platform with |
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an ANSI compiler. Some beta versions of the library are even heavily |
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used in brand new OSes (see the <a href="http://www.atheos.cx">AtheOS |
||||
</a> screenshots for examples).</p> |
||||
|
||||
<p>The library is itself mainly developped on several platforms |
||||
(Windows & Linux, though a great deal has also been achieved on OS/2) |
||||
and the code is highly generic and modular to adapt even the most |
||||
strict environments like low-memory embedded systems.</p> |
||||
|
||||
</ul> |
||||
|
||||
<a name="general-x11"> |
||||
<h3>I.4. When will X11/XFree support anti-aliased text?</h3> |
||||
<ul> |
||||
<p>This question isn't exactly related to FreeType as we have no direct |
||||
connection to the XFree people, but we've been asked so frequently |
||||
about it that it deserves a prominent place in this FAQ :-)</p> |
||||
|
||||
<p>FreeType has been capable of anti-aliasing since version 1.0. The |
||||
reason why XFree doesn't support it is directly related to the |
||||
limitations of the design and specification of X11. More specifically:</p> |
||||
|
||||
<ul> |
||||
<li><p> |
||||
X11 assumes that all glyph images are monochrome bitmaps, |
||||
hence the X font library and server are unable to send anything |
||||
else to the X server. |
||||
</p></li> |
||||
|
||||
<li><p> |
||||
Even if the X font library/server was able to generate anti-aliased |
||||
bitmaps (and this has been already done through extensions), the X |
||||
rendering model doesn't allow translucent composition of "gray" pixmaps |
||||
onto an arbitrary drawable. |
||||
</p></li> |
||||
</ul> |
||||
|
||||
<p>As both the font and rendering models of X11 are limited, it's basically |
||||
impossible to draw anti-aliased glyphs without performing <em>huge</em> |
||||
hacks within the server.</p> |
||||
|
||||
<p>Note that Keith Packard, from XFree fame, has recently started working |
||||
on a new rendering model for X11 in order to support new features |
||||
(mainly transparency and anti-aliased fonts). This will be provided |
||||
through protocol extensions. The question of knowing wether legacy X |
||||
applications will be able to display anti-aliased text is still very |
||||
uncertain. |
||||
</p> |
||||
</ul> |
||||
|
||||
<a name="general-ft1"> |
||||
<h3>I.5. Is FreeType 2 backwards compatible with FreeType 1.x?</h3> |
||||
<ul> |
||||
<p>Not directly, though we had the project to provide an optional binary |
||||
compatibility layer on top of it in order to easily re-link applications |
||||
with the new version. However, this idea has been dropped as it is |
||||
possible to install and use the two versions independtly on any |
||||
system (read: no namespace conflicts).</p> |
||||
|
||||
<p>The FreeType 2 API is a lot simpler than the one in 1.x while being |
||||
much more powerful. We thus encourage you to adapt your source code |
||||
to it as this should not involve much work.</p> |
||||
|
||||
</ul> |
||||
|
||||
<a name="general-edit"> |
||||
<h3>I.6. Can I use FreeType 2 to edit fonts or create new ones?</h3> |
||||
<ul> |
||||
<p>The answer is a definitive NO, because the library was specifically |
||||
designed to <em>read</em> font files with small code size and very |
||||
low memory usage.</p> |
||||
|
||||
<p>We thus do not plan to support editing or creation in the font |
||||
engine in any way, as this would imply a complete rewrite. This |
||||
doesn't mean that we won't introduce a font editing/creation library |
||||
in the future, as this really depends on how many people are asking |
||||
for it (or how much they would be willing to pay for it), as well as |
||||
the time of the FreeType developers.</p> |
||||
|
||||
<p>Do not expect anything in this direction until we officially announce |
||||
something though. There are other axis of development for this project |
||||
(like text-layout capabilities, glyph caching, etc..) that may be more |
||||
important to us at the moment..</p> |
||||
</ul> |
||||
|
||||
</td></tr></table> |
||||
|
||||
<table width="100%" cellspacing=5><tr bgcolor="#CCCCEE"><td> |
||||
<h2 align=center><a name="builds">Compilation & Configuration</h2> |
||||
</td></tr><tr><td> |
||||
|
||||
<a name="builds-compile"> |
||||
<h3>II.1. How do I compile the FreeType 2 library?</h3> |
||||
<ul> |
||||
<p>The library can be compiled in various ways, and a detailed documentation |
||||
is available in the file "<tt>freetype2/docs/BUILD</tt>". However, we'll |
||||
summarize the process to a few cases:</p> |
||||
|
||||
<h3>a. by using the command-line 2 build system</h3> |
||||
|
||||
<p>The engine comes with a sophisticated build system that is used |
||||
to configure and compile a build of the library. You'll need |
||||
<em>GNU Make</em> installed on your platform (NOTE: It will <b>not</b> |
||||
work with other Make tools).</p> |
||||
|
||||
<p>Basically, you'll need to invoke <tt>make</tt> a first time in the |
||||
top-level FreeType 2 directory in order to setup the build. This will |
||||
detect your current platform and choose a configuration sub-makefile to |
||||
drive the build. A specific compiler can be selected on some platforms |
||||
by providing an additional target. For example, on Win32:</p> |
||||
|
||||
<ul> |
||||
<li><b><tt>make visualc</tt></b> will select the Visual C++ compiler</li> |
||||
<li><b><tt>make lcc</tt></b> will select the Win32-lcc compiler</li> |
||||
</ul> |
||||
|
||||
<p>Note that on Unix, the first time make is called, a configure script |
||||
located in "<tt>freetype2/builds/unix</tt>" will be run in order to |
||||
automatically detect the platform & compiler.</p> |
||||
|
||||
<p>A summary will be displayed showing the detected platform and compiler |
||||
selected. You'll then be able to start the build by invoking <tt>make</tt> |
||||
a second time. In case of problem, consult the <tt>BUILD</tt> document.</p> |
||||
|
||||
|
||||
<h3>b. by direct compilation</h3> |
||||
|
||||
<p>You can also directly compile the library from the command line by |
||||
using these simple rules:</p> |
||||
|
||||
<ul> |
||||
<li><p> |
||||
You should place the directories "<tt>freetype2/include</tt>" and |
||||
"<tt>freetype2/src</tt>" in your include path in order to compile |
||||
any component of the library. You can also add the system-specific |
||||
build directory (i.e. "<tt>builds/<em>system</em>/</tt>") in the |
||||
case where an alternate implementation of some of the components |
||||
is available there (e.g. the memory-mapped i/o implementation |
||||
on some Unix systems). |
||||
</p></li> |
||||
|
||||
<li><p> |
||||
The components of the library are located in sub-directories of |
||||
"<tt>src</tt>", for example: "<tt>src/base</tt>", |
||||
"<tt>src/truetype</tt>", etc.. |
||||
</p></li> |
||||
|
||||
<li><p> |
||||
Each component is normally compiled through a single C file that |
||||
"wraps" other sources in the component's directory. For example, |
||||
your should compile the TrueType font driver by compiling the |
||||
file "<tt>src/truetype/truetype.c</tt>". The list of C files to |
||||
compile for a feature-complete build of the library is given in |
||||
the <tt>BUILD</tt> document. |
||||
</p></li> |
||||
</ul> |
||||
|
||||
<h3>c. in a graphical IDE</h3> |
||||
<ul> |
||||
<p>Well, the process is vastly similar to the one described in b., |
||||
except that you need to set the include paths, source code paths, |
||||
etc.. in dialog boxes before running the compilation. |
||||
</p> |
||||
</ul> |
||||
|
||||
</ul> |
||||
|
||||
<a name="builds-config"> |
||||
<h3>II.2. How do I configure my build of the library?</h3> |
||||
<ul> |
||||
<p>Each build of the library is configured through two header files |
||||
located in "<tt>include/freetype/config</tt>":</p> |
||||
|
||||
<ul> |
||||
<li><p><b><tt>ftoption.h</tt></b><br> |
||||
This file contains various configuration macros whose definition |
||||
can be toggled on a per-build basis. Each macro is heavily |
||||
commented in this file's comment, and we invite you to refer |
||||
to it directly.</p></li> |
||||
|
||||
<li><p><b><tt>ftmodule.h</tt></b><br> |
||||
This file contains the list of all the modules that are initially |
||||
registered (added) when the function <b><tt>FT_Init_FreeType</tt></b> |
||||
is called. See the next answer to know how to change it and |
||||
why it may be important.</p></li> |
||||
</ul> |
||||
|
||||
<p>Alternatively, some specific implementations of some FT2 components |
||||
can be provided in a "<tt>builds/<em>system</em>/</tt>" directory |
||||
(e.g. the Unix-specific <tt>ftsystem.c</tt> that uses memory-mapped |
||||
file for i/o).</p> |
||||
</ul> |
||||
|
||||
<a name="builds-modules"> |
||||
<h3>II.3. How do I select the modules I need in my build?</h3> |
||||
<ul> |
||||
<p>The function <tt><b>FT_Init_FreeType</b></tt> creates a new instance |
||||
of the FT2 library and registers a set of "default" modules before |
||||
returning to the calling application. Its default implementation |
||||
is in the file "<tt>src/base/ftinit.c</tt>".</p> |
||||
|
||||
<p>The list of default modules used by <tt>ftinit.c</tt> is located in |
||||
the configuration file "<tt>include/freetype/config/ftmodule.h</tt>". |
||||
It is normally automatically generated by the build system by |
||||
invoking the "<tt><b>make modules</b></tt>" command in the top |
||||
level FT2 directory (note: only works with GNU Make, you can |
||||
edit the file by hand otherwise). It does so by parsing all |
||||
sub-directories of "<tt>src</tt>" that contain a file named |
||||
<tt>module.mk</tt>.</p> |
||||
|
||||
<p>Note that a specific port or project is free to provide its own |
||||
implementation of <tt>ftinit.c</tt> in order to ensure a different |
||||
initialisation sequence. For example, one could do something like:</p> |
||||
|
||||
<ul> |
||||
<li><p>compile each module as a shared library (DLL or .so) with |
||||
a common "entry point" to retrieve a pointer to its |
||||
module class (there is already some code that allows this |
||||
when compiling each module).</p></li> |
||||
|
||||
<li><p>place these modules in a directory like |
||||
"<tt>/usr/lib/freetype2/modules/</tt>"</p></li> |
||||
|
||||
<li><p>provide an implementation of <tt>ftinit.c</tt> that would |
||||
scan the directory for valid modules.</p></li> |
||||
</ul> |
||||
|
||||
<p>This example only emphasize the flexibility that is left to |
||||
developers when building the library.</p> |
||||
|
||||
</ul> |
||||
|
||||
<a name="builds-flat"> |
||||
<h3>II.4. How do I compile all FreeType 2 files in a single directory?</h3> |
||||
<ul> |
||||
<p>Some projects may need, for the sake of simplicity or ease of |
||||
building, to compile the FT2 library with all source files |
||||
copied to a single directory. This is possible.</p> |
||||
|
||||
<p>To do so, you'll need to copy all source files located under |
||||
"<tt>src</tt>" to your own directory (you must retain the |
||||
include files in a distinct hierarchy though), then compile |
||||
each of the FreeType 2 component with the macro |
||||
<tt><b>FT_FLAT_COMPILE</b></tt>. This will change the way |
||||
<tt><b>#include</b></tt> works during the build.</p> |
||||
</ul> |
||||
|
||||
</td></tr></table> |
||||
|
||||
<table width="100%" cellspacing=5><tr bgcolor="#CCCCEE"><td> |
||||
<h2 align=center><a name="library">Using the FreeType 2 library</h2> |
||||
</td></tr><tr><td> |
||||
|
||||
</td></tr></table> |
||||
|
||||
<table width="100%" cellspacing=5><tr bgcolor="#CCCCEE"><td> |
||||
<h2 align=center><a name="autohint">The FreeType 2 auto-hinter</h2> |
||||
</td></tr><tr><td> |
||||
|
||||
<a name="autohint-license"> |
||||
<h3>IV.1. Under which license is the FreeType 2 auto-hinter released</h3> |
||||
<ul> |
||||
<p>The auto-hinter was initially designed and implemented under contract |
||||
for <a href="http://www.catharon.com">Catharon Productions, Inc</a> |
||||
which gladly accepted to released it under an open-source license |
||||
compatible with the FreeType one.</p> |
||||
|
||||
<p>This license can be found in "<tt>src/autohint/CatharonLicense.txt</tt>" |
||||
and requires that you cite Catharon Productions in your documentation |
||||
(just like you do with FreeType) when using the auto-hinting module.</p> |
||||
|
||||
<p>Other than that, you still have the same freedom than with the good old |
||||
FreeType license. Enjoy !</p> |
||||
</ul> |
||||
|
||||
<a name="autohint-work"> |
||||
<h3>IV.2. How does the auto-hinter works ?</h3> |
||||
<ul> |
||||
<p>Well, a complete description would be difficult. Have a look at the |
||||
dedicated <a href="autohinting/index.html">auto-hinter pages</a> on the FreeType |
||||
site, as they describe most of its details with graphics and explanations. |
||||
You could also look at the source code if you want to :-)</p> |
||||
|
||||
<p>To give a few details, the auto-hinter is used to perform grid-fitting |
||||
on scalable font formats that use bezier outlines as their primary glyph |
||||
image format (this means nearly all scalable font formats today). When |
||||
a given font driver doesn't provide its own hinter, the auto-hinter is |
||||
used by default. When a format-specific hinter is provided, it is still |
||||
possible to use the auto-hinter using the |
||||
<tt><b>FT_LOAD_FORCE_AUTOHINT</b></tt> bit flag when calling |
||||
<tt>FT_Load_Glyph</tt>.</p> |
||||
|
||||
<p>The auto-hinter currently doesn't use external hints to do its job, |
||||
as it automatically computes global metrics (when it "opens" a font |
||||
for the first time) and glyph "hints" from their outline. Note that |
||||
we plan the ability to specify external hints, given that it is based |
||||
on a constraint system. That could be used to support native hints |
||||
in Type 1/Type 2 fonts, for example.</p> |
||||
</ul> |
||||
|
||||
<a name="autohint-cjk"> |
||||
<h3>IV.3. Why does the auto-hinter doesn't work correctly with CJK fonts ?</h3> |
||||
<ul> |
||||
<p>The auto-hinter was first designed to manage and hint latin-based fonts, |
||||
as they consist of most of the fonts available today. It doesn't hint |
||||
asian fonts, as well as a few other complex scripts, because we didn't |
||||
put enough research on the topic yet. Hinting CJK isn't really more |
||||
difficult than latin, just different with a set of different constraints |
||||
(basically, more distortion of glyphs is acceptable as long as certain |
||||
features like triple-stem positions are respected more strictly..).</p> |
||||
|
||||
<p>We thus plan to handle such a case rather rapidly.. Please be patient.</p> |
||||
</ul> |
||||
|
||||
|
||||
</td></tr></table> |
||||
|
||||
<table width="100%" cellspacing=5><tr bgcolor="#CCCCEE"><td> |
||||
<h2 align=center><a name="other">Other questions</h2> |
||||
</td></tr><tr><td> |
||||
|
||||
<a name="other-antialias"> |
||||
<h3>V.1. What is the anti-aliasing algorithm used by FreeType 2 ?</h3> |
||||
<ul> |
||||
<p>The algorithm has been specifically designed for FreeType. It is |
||||
based on ideas that were originally found in the implementation |
||||
of the <a href="http://www.levien.com/libart">libArt</a> graphics |
||||
library to compute the <em>exact pixel coverage</em> of a vector |
||||
image with absolutely now sub-sampling/filtering. |
||||
</p> |
||||
|
||||
<p>However, these two implementations are radically distinct and use |
||||
vastly different models. The FreeType 2 renderer is optimized |
||||
specifically for rendering small complex shapes, like glyphs, at |
||||
very high speed while using very few memory; while libArt shines |
||||
at general shape/polygon processing, especially large ones.</p> |
||||
|
||||
<p>The FT2 anti-aliasing renderer is indeed <em>faster</em> than the |
||||
monochrome renderer for small character sizes (typically < 20 pixels). |
||||
This is explained because the monochrome renderer must perform two |
||||
passes on the outline in order to perform drop-out control according |
||||
to the TrueType spec (we could drop this requirement later though).</p> |
||||
|
||||
<p>We'll try to document its design in a later document, though this is |
||||
not a priority for now.</p> |
||||
</ul> |
||||
|
||||
<a name="other-opentype"> |
||||
<h3>V.2. When will FreeType 2 support OpenType ?</h3> |
||||
<ul> |
||||
<p>Well, the engine already reads OpenType/CFF files perfectly. What it |
||||
doesn't do is handle "OpenType Layout" tables yet.</p> |
||||
|
||||
<p>FreeType 1 comes with a set of extensions that are used to load |
||||
and manage OpenType Layout tables. It even has a demonstration program |
||||
named "<tt>ftstrtto</tt>" used to demonstrate its capabilities that |
||||
runs pretty smooth.</p> |
||||
|
||||
<p>For FreeType 2, we have decided that the layout operations provided |
||||
through these tables is better placed in a specific text-layout library, |
||||
(many people having asked for such a thing). This new engine would not |
||||
depend on FT2 explicitely and will be developed as a separate project. |
||||
We plan to announce it in a few weeks with all gory details, |
||||
once the definitive 2.0 release of FreeType has been made.</p> |
||||
</ul> |
||||
|
||||
</td></tr></table> |
||||
|
||||
<hr> |
||||
<p> |
||||
<a href="index.html">Back to FreeType homepage</a><p> |
||||
|
||||
</td></tr></table> |
||||
</body> |
||||
</html> |
||||
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Reference in new issue