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diff --git a/src/documentation/content/xdocs/DnI/fonts.xml b/src/documentation/content/xdocs/DnI/fonts.xml new file mode 100644 index 000000000..7c2b97263 --- /dev/null +++ b/src/documentation/content/xdocs/DnI/fonts.xml @@ -0,0 +1,297 @@ +<?xml version="1.0" encoding="utf-8"?> + +<!-- + * Copyright 2004 The Apache Software Foundation. + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + --> + +<!-- $Id$ --> + +<!-- +<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" + "docbookx.dtd"> + --> + + <chapter> + <title>Fonts</title> + + <section> + <title>Font setup</title> + + <para>Terminology: +<itemizedlist> + <listitem> + <simpara>Index, font index: The index of a character in a +font, i.e. the place of the glyph for a character in a font.</simpara> + </listitem> + <listitem> + <simpara>Code point: The same as font index.</simpara> + </listitem> + <listitem> + <simpara>Character value: The two-byte +(<literal>char</literal>) value by which a character is represented in +memory and in Unicode. Note that this only works straightforwardly for +the basal plane (BMP) of Unicode, i.e. for <literal>characters <= +0xFFFF</literal>.</simpara> + </listitem> + <listitem> + <simpara>Unicode code point: The same as the character +value.</simpara> + </listitem> + </itemizedlist></para> + + <para>During compilation for each of the 14 base fonts a class is +generated from the XML font metric files. Each font class contains +the metric information and an encoding table (a +<literal>CodePointMapping</literal> object). The metric information is +static, the encoding table is an object member.</para> + + <para>During compilation also a class +<literal>CodePointMapping</literal> is generated, which contains the +known encodings as static values. For each known encoding it contains +a table as a static final array of int. The array holds an alternation +of font index and character value; in fact it is a mapping from +<literal>table[2i]</literal> to <literal>table[2i+1]</literal>, where +<literal>table[2i]</literal> is the font index and +<literal>table[2i+1]</literal> is the character.</para> + + <para>When an encoding is needed in the process, a +<literal>CodePointMapping</literal> object is created from the +encoding table. It contains a table (<literal>char array</literal>) +called <literal>latin1Map</literal> of the font indices for the +characters of the Latin1 range (<literal>0-0xFF</literal>) in +character value order. It also contains two tables (<literal>char +array</literal>s), called characters and codepoints, for the higher +character values. The table characters contains the character values +in order, and the table codepoints contains the corresponding font +indexes for this encoding in the same order. The characters can be +retrieved from these tables as follows: + +<screen>char <= 0xFF: index = latin1Map[character] +char > 0xFF: + find i such that characters[i] == char; + then index = codepoints[i] +</screen></para> + + <para>In the code the characters are retrieved from the +<literal>CodePointMapping</literal> object with its method +<literal>mapChar(char c)</literal>.</para> + + <para>In FOP's preparation stage the fonts are set up in the +method <literal>Driver.getContentHandler</literal>. It calls the +<literal>renderer</literal>'s method +<literal>setupFontInfo(currentDocument)</literal>. The +<literal>Document</literal> object <literal>currentDocument</literal> +(which is the <literal>foTreeControl</literal> object) is able to +store the font setup info and has methods to access the fonts +registered with it.</para> + +<para>The <literal>PrintRenderer</literal> (PostScript and PDF) then +calls <literal>FontSetup.setup(fontInfo, fontList)</literal>, where +<literal>fontInfo</literal> is <literal>the</literal> Document object +and <literal>fontList</literal> is the list of user configured fonts +registered with the <literal>renderer</literal> in its member +<literal>fontList</literal>. + <screen> + [1] org.apache.fop.fonts.FontSetup.setup (FontSetup.java:98) + [2] org.apache.fop.render.PrintRenderer.setupFontInfo (PrintRenderer.java:77) + [3] org.apache.fop.apps.Driver.getContentHandler (Driver.java:551) + [4] org.apache.fop.apps.Driver.render (Driver.java:602) + [5] org.apache.fop.apps.Driver.render (Driver.java:589) + [6] org.apache.fop.apps.Fop.main (Fop.java:102) +</screen></para> + + <para><literal>FontSetup.setup</literal> takes three actions: +<orderedlist> + <listitem> + <simpara>An object is created for each of the base 14 fonts +and registered with the <literal>fontInfo</literal> object in its +member fonts.</simpara> + </listitem> + <listitem> + <simpara>A series of triplets (family, style, weight) is set +up. To each triplet a font is assigned; this font will be used when a +font with the characteristics of that triplet is requested. The +triplets registered with <literal>fontInfo</literal> in its member +<literal>triplets</literal>. The member <literal>triplets</literal> is +a map which uses a string of the form +<literal>family,style,weight</literal> as a key. There is also a class +<literal>FontTriplet</literal>, which is not used.</simpara> + </listitem> + + <listitem> + <simpara>The user configured fonts are added.</simpara> + </listitem> + </orderedlist></para> + + <para>In the following listing <literal>treeBuilder</literal> is +the tree builder object set up in the preparation stage, and +<literal>foTreeControl</literal> is the document object. The list of +user configured fonts of the <literal>renderer</literal> is empty, and +the list of used fonts is still empty. + +<screen> + treeBuilder.foTreeControl.fonts = "{ + F1=org.apache.fop.fonts.base14.Helvetica@e3c624, + F2=org.apache.fop.fonts.base14.HelveticaOblique@e020c9, + F3=org.apache.fop.fonts.base14.HelveticaBold@13e58d4, + F4=org.apache.fop.fonts.base14.HelveticaBoldOblique@15a6029, + F5=org.apache.fop.fonts.base14.TimesRoman@17494c8, + F6=org.apache.fop.fonts.base14.TimesItalic@1e57e8f, + F7=org.apache.fop.fonts.base14.TimesBold@888e6c, + F8=org.apache.fop.fonts.base14.TimesBoldItalic@d3db51, + F9=org.apache.fop.fonts.base14.Courier@5f6303, + F10=org.apache.fop.fonts.base14.CourierOblique@117f31e, + F11=org.apache.fop.fonts.base14.CourierBold@1d7fbfb, + F12=org.apache.fop.fonts.base14.CourierBoldOblique@5d9084 + F13=org.apache.fop.fonts.base14.Symbol@39e5b5, + F14=org.apache.fop.fonts.base14.ZapfDingbats@1b5998f, +}" +</screen> + +<screen> + treeBuilder.foTreeControl.triplets = "{ + Computer-Modern-Typewriter,normal,400=F9, + Courier,italic,400=F10, + Courier,italic,700=F12, + Courier,normal,400=F9, + Courier,normal,700=F11, + Courier,oblique,400=F10, + Courier,oblique,700=F12, + Helvetica,italic,400=F2, + Helvetica,italic,700=F4, + Helvetica,normal,400=F1, + Helvetica,normal,700=F3, + Helvetica,oblique,400=F2, + Helvetica,oblique,700=F4, + Symbol,normal,400=F13, + Times Roman,italic,400=F6, + Times Roman,italic,700=F8, + Times Roman,normal,400=F5, + Times Roman,normal,700=F7, + Times Roman,oblique,400=F6, + Times Roman,oblique,700=F8, + Times,italic,400=F6, + Times,italic,700=F8, + Times,normal,400=F5, + Times,normal,700=F7, + Times,oblique,400=F6, + Times,oblique,700=F8, + Times-Roman,italic,400=F6, + Times-Roman,italic,700=F8, + Times-Roman,normal,400=F5, + Times-Roman,normal,700=F7, + Times-Roman,oblique,400=F6, + Times-Roman,oblique,700=F8, + ZapfDingbats,normal,400=F14, + any,italic,400=F6, + any,italic,700=F8, + any,normal,400=F5, + any,normal,700=F7, + any,oblique,400=F6, + any,oblique,700=F8, + monospace,italic,400=F10, + monospace,italic,700=F12, + monospace,normal,400=F9, + monospace,normal,700=F11, + monospace,oblique,400=F10, + monospace,oblique,700=F12, + sans-serif,italic,400=F2, + sans-serif,italic,700=F4, + sans-serif,normal,400=F1, + sans-serif,normal,700=F3, + sans-serif,oblique,400=F2, + sans-serif,oblique,700=F4, + serif,italic,400=F6, + serif,italic,700=F8, + serif,normal,400=F5, + serif,normal,700=F7, + serif,oblique,400=F6 + serif,oblique,700=F8, +}" +</screen> + +<screen> + treeBuilder.foTreeControl.atModel.renderer.fontList = null + treeBuilder.foTreeControl.usedFonts = "{}" +</screen></para> + + <para>User configured fonts should be listed in the member +<literal>fontList</literal> of the <literal>renderer</literal>. The +objects in the list are <literal>EmbedFontInfo</literal> objects. They +are created from the path to the metrics file, boolean kerning, the +list of triplets for which this font may be used, the path to the font +file. The triplets are <literal>FontTriplet</literal> objects. The +list may be created from an Avalon configuration object with +<literal>FontSetup.buildFontListFromConfiguration(Configuration +cfg)</literal>.</para> + + <para><literal>>FontSetup.addConfiguredFonts</literal> creates a +<literal>LazyFont</literal> font object from each +<literal>EmbedFontInfo</literal> object. <literal>LazyFont</literal> +fonts are not loaded until they are actually used. This makes it +possible to register a large number of fonts at low cost.</para> + + <para>Font weights are integers between 100 and 900. +<literal>Font.NORMAL</literal> and <literal>Font.BOLD</literal> are +set to 400 and 700, respectively. See +<literal>FontUtil.parseCSS2FontWeight</literal>.</para> + + </section> + + <section> + <title>Classes and interfaces used in the font package</title> + + <screen>IF FontMetrics +SubIF FontDescriptor + +IF MutableFont + +Abstract Class TypeFace: FontMetrics +Classes Courier etc. + +Abstract Class TypeFace: FontMetrics +Abstract Class CustomFont: FontDescriptor, MutableFont +Abstract Class CIDFont, Class SingleByteFont +Class MultiByteFont (sub CIDFont) + +Abstract Class TypeFace: FontMetrics +Abstract Class CustomFont: FontDescriptor, MutableFont +Class SingleByteFont + +Abstract Class TypeFace: FontMetrics +Class LazyFont: FontDescriptor + +Abstract Class TypeFace: FontMetrics +Class FontMetricsMapper, for AWT fonts +</screen> + + <para><literal>SingleByteFont</literal>, +<literal>MultiByteFont</literal>: A font is not really single or +multibyte. Rather the name <literal>SingleByteFont</literal> indicates +that the font does not contain more than 256 glyphs; the +implementation is optimized for this. In +<literal>MultiByteFont</literal> (actually CIDFont Type2) the +implementation is optimized for fonts with an unknown number of +glyphs.</para> + + </section> + + </chapter> + +<!-- Local Variables: --> +<!-- current-language-environment: UTF-8 --> +<!-- coding: utf-8 --> +<!-- default-input-method: TeX --> +<!-- End: --> |