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+<?xml version="1.0" standalone="no"?>
+
+<!-- $Id$ -->
+<!DOCTYPE document PUBLIC "-//APACHE//DTD Documentation V1.1//EN"
+ "http://cvs.apache.org/viewcvs.cgi/*checkout*/xml-forrest/src/resources/schema/dtd/document-v11.dtd">
+
+<document>
+ <header>
+ <title>Fonts (Developer Information)</title>
+ </header>
+ <body>
+ <section>
+ <title>Goals</title>
+ <ul>
+ <li>refactor existing font logic for better clarity and to reduce duplication</li>
+ <li>parse registered font metric information on-the-fly (to make sure most up-to-date parsing is used??)</li>
+ <li>resolve whether the FontBBox, StemV, and ItalicAngle font metric information is important or not -- if so, parse the .pfb file to extract it when building the FOP xml metric file</li>
+ <li>handle fonts registered at the operating system (through AWT)</li>
+ <li>add support for parsing OpenType fonts</li>
+ </ul>
+ </section>
+ <section>
+ <title>Issues</title>
+ <ul>
+ <li>Why are we using our own font metric parsing and registration system, instead of the AWT system provided as part of Java?
+ <ul>
+ <li>Answer 1: Many of our customers use FOP in a so-called "headless" server environment -- that is, the operating system is operating in character mode, with no concept of a graphical environment. We need some mechanism of allowing these environments to get font information.</li>
+ <li>Answer 2: At some level, we don't yet fully trust AWT to handle fonts correctly. There are still unresolved discrepancies between the two systems.</li>
+ </ul>
+ </li>
+ </ul>
+ </section>
+ <section>
+ <title>Implementation</title>
+ <p>There are two main font functions needed within FOP:</p>
+ <ul>
+ <li>provision of a font object to be used in layout</li>
+ <li>embedding of a font file in output (such as PDF)</li>
+ </ul>
+ <p>For the first of these, we will implement something along the lines of a "Facade" Structural Pattern to hide the differences between the various font types and font sources from the rest of the system.
+Public classes will consist of TypeFaceFamily, TypeFace, and Font. (TypeFace roughly corresponds to the contents of a normal font file, while Font is a general typeface implemented at a specific point size, and perhaps with other specific parameters).
+When another part of FOP requests a font object, existing font objects will be checked first, and an appropriate one returned if possible.
+If not, the Font logic should resolve the TypeFace and TypeFaceFamily if possible, create a Font object, and return it.</p>
+ </section>
+ <section>
+ <title>Resources</title>
+ <section>
+ <title>Type 1 Fonts</title>
+ <ul>
+ <li><link href="http://partners.adobe.com/asn/developer/pdfs/tn/T1_SPEC.PDF">Adobe Type 1 Font Format</link></li>
+ <li>According to the Adobe web site, the documentation for the font metrics files (.pfm = printer font metrics) is written and controlled by Microsoft, since it is actually a workaround to allow Type 1 fonts to be used on a GUI screen in Windows. However, the document does not appear to be on the Microsoft web site. The best resource for this information is <link href="http://partners.adobe.com/asn/developer/pdfs/tn/5178.PFM.pdf">Adobe Technical Note #5178</link>: Building PFM Files for Postscript-Language CJK Fonts</li>
+ <li>FOP does not currently use the Adobe Font Metrics file, but the specification can be found in <link href="http://partners.adobe.com/asn/developer/pdfs/tn/5004.AFM_Spec.pdf">Adobe Technical Note #5004</link>: Adobe Font Metrics File Format Specification</li>
+ <li><link href="http://partners.adobe.com/asn/developer/pdfs/tn/5040.Download_Fonts.pdf">Adobe Technical Note #5040</link>: Supporting Downloadable Postscript Language Fonts may also include some useful information.</li>
+ </ul>
+ </section>
+ <section>
+ <title>TrueType Fonts</title>
+ <ul>
+ <li>The <link href="http://www.microsoft.com/typography/tt/ttf_spec/ttspec.zip">TrueType specification</link></li>
+ </ul>
+ </section>
+ <section>
+ <title>OpenType Fonts</title>
+ <ul>
+ <li>The <link href="http://download.microsoft.com/download/Typography/archive/v1.4/WIN98MeXP/EN-US/otsp14.exe">OpenType specification</link></li>
+ <li>The Adobe <link href="http://www.adobe.com/type/opentype/main.html">Introduction to OpenType fonts</link> page has some useful general information and links.</li>
+ </ul>
+ </section>
+ </section>
+ </body>
+</document>
+
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