--- /dev/null
+<?xml version="1.0" standalone="no"?>
+<!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>AbsolutePosition diagram</title>
+ <authors>
+ <person id="pbw" name="Peter B. West"
+ email="pbwest@powerup.com.au"/>
+ </authors>
+ </header>
+ <body>
+ <section>
+ <title>Properties$AbsolutePosition</title>
+ <figure src="AbsolutePosition.png" alt="AbsolutePosition diagram"/>
+ </section>
+
+ </body>
+</document>
+
--- /dev/null
+<?xml version="1.0" standalone="no"?>
+<!DOCTYPE document PUBLIC "-//APACHE//DTD Documentation V1.1//EN"
+ "http://cvs.apache.org/viewcvs.cgi/*checkout*/xml-forrest/src/resources/schema/dtd/document-v11.dtd">
+
+<document>
+ <header>
+ <title>BorderCommonStyle diagram</title>
+ <authors>
+ <person id="pbw" name="Peter B. West"
+ email="pbwest@powerup.com.au"/>
+ </authors>
+ </header>
+ <body>
+ <section>
+ <title>Properties$BorderCommonStyle</title>
+ <figure src="BorderCommonStyle.png" alt="BorderCommonStyle diagram"/>
+ </section>
+ </body>
+</document>
+
--- /dev/null
+<?xml version="1.0" standalone="no"?>
+<!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>..fo.PropNames diagram</title>
+ <person id="pbw" name="Peter B. West"
+ email="pbwest@powerup.com.au"/>
+ </authors>
+ </header>
+ <body>
+ <section>
+ <title>PropNames.class</title>
+ <figure src="PropNames.png" alt="PropNames.class diagram"/>
+ </section>
+ </body>
+</document>
+
--- /dev/null
+<?xml version="1.0" standalone="no"?>
+<!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>..fo.Properties diagram</title>
+ <authors>
+ <person id="pbw" name="Peter B. West"
+ email="pbwest@powerup.com.au"/>
+ </authors>
+ </header>
+ <body>
+ <section>
+ <title>Properties.class</title>
+ <figure src="Properties.png" alt="Properties.class diagram"/>
+ </section>
+ </body>
+</document>
+
--- /dev/null
+<?xml version="1.0" standalone="no"?>
+<!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>..fo.PropertyConsts diagram</title>
+ <authors>
+ <person id="pbw" name="Peter B. West"
+ email="pbwest@powerup.com.au"/>
+ </authors>
+ </header>
+ <body>
+ <section>
+ <title>PropertyConsts.class</title>
+ <figure src="PropertyConsts.png" alt="PropertyConsts.class diagram"/>
+ </section>
+ </body>
+</document>
+
--- /dev/null
+<?xml version="1.0" standalone="no"?>
+<!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>VerticalAlign diagram</title>
+ <authors>
+ <person id="pbw" name="Peter B. West"
+ email="pbwest@powerup.com.au"/>
+ </authors>
+ </header>
+ <body>
+ <section>
+ <title>Properties$VerticalAlign</title>
+ <figure src="VerticalAlign.png" alt="VerticalAlign diagram"/>
+ </section>
+ </body>
+</document>
+
--- /dev/null
+<?xml version="1.0" standalone="no"?>
+<!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>Implementing Properties</title>
+ <authors>
+ <person id="pbw" name="Peter B. West" email="pbwest@powerup.com.au"/>
+ </authors>
+ </header>
+ <body>
+ <section>
+ <title>An alternative properties implementation</title>
+ <note>
+ The following discussion focusses on the relationship between
+ Flow Objects in the Flow Object tree, and properties. There
+ is no (or only passing) discussion of the relationship between
+ properties and traits, and by extension, between properties
+ and the Area tree. The discussion is illustrated with some
+ pseudo-UML diagrams.
+ </note>
+ <p>
+ Property handling is complex and expensive. Varying numbers of
+ properties apply to individual Flow Objects
+ <strong>(FOs)</strong> in the <strong>FO
+ tree </strong> but any property may effectively be
+ assigned a value on any element of the tree. If that property
+ is inheritable, its defined value will then be available to
+ any children of the defining FO.
+ </p>
+ <note>
+ <em>(XSL 1.0 Rec)</em> <strong>5.1.4 Inheritance</strong>
+ ...The inheritable properties can be placed on any formatting
+ object.
+ </note>
+ <p>
+ Even if the value is not inheritable, it may be accessed by
+ its children through the <code>inherit</code> keyword or the
+ <code>from-parent()</code> core function, and potentially by
+ any of its descendents through the
+ <code>from-nearest-specified-value()</code> core function.
+ </p>
+ <p>
+ In addition to the assigned values of properties, almost every
+ property has an <strong>initial value</strong> which is used
+ when no value has been assigned.
+ </p>
+ <section>
+ <title>The history problem</title>
+ <p>
+ The difficulty and expense of handling properties comes from
+ this univeral inheritance possibility. The list of properties
+ which are assigned values on any particular <em>FO</em>
+ element will not generally be large, but a current value is
+ required for each property which applies to the <em>FO</em>
+ being processed.
+ </p>
+ <p>
+ The environment from which these values may be selected
+ includes, for each <em>FO</em>, for each applicable property,
+ the value assigned on this <em>FO</em>, the value which
+ applied to the parent of this <em>FO</em>, the nearest value
+ specified on an ancestor of this element, and the initial
+ value of the property.
+ </p>
+ </section>
+ <section>
+ <title>Data requirement and structure</title>
+ <p>
+ This determines the minimum set of properties and associated
+ property value assignments that is necessary for the
+ processing of any individual <em>FO</em>. Implicit in this
+ set is the set of properties and associated values,
+ effective on the current <em>FO</em>, that were assigned on
+ that <em>FO</em>.
+ </p>
+ <p>
+ This minimum requirement - the initial value, the
+ nearest ancestor specified value, the parent computed value
+ and the value assigned to the current element -
+ suggests a stack implementation.
+ </p>
+ </section>
+ <section>
+ <title>Stack considerations</title>
+ <p>
+ One possibility is to push to the stack only a minimal set
+ of required elements. When a value is assigned, the
+ relevant form or forms of that value (specified, computed,
+ actual) are pushed onto the stack. As long as each
+ <em>FO</em> maintains a list of the properties which were
+ assigned from it, the value can be popped when the focus of
+ FO processing retreats back up the <em>FO</em> tree.
+ </p>
+ <p>
+ The complication is that, for elements which are not
+ automatically inherited, when an <em>FO</em> is encountered
+ which does <strong>not</strong> assign a value to the
+ property, the initial value must either be already at the
+ top of the stack or be pushed onto the stack.
+ </p>
+ <p>
+ As a first approach, the simplest procedure may be to push a
+ current value onto the stack for every element - initial
+ values for non-inherited properties and the parental value
+ otherwise. Then perform any processing of assigned values.
+ This simplifies program logic at what is hopefully a small
+ cost in memory and processing time. It may be tuned in a
+ later iteration.
+ </p>
+ <section>
+ <title>Stack implementation</title>
+ <p>
+ Initial attempts at this implementation have used
+ <code>LinkedList</code>s as the stacks, on the assumption
+ that
+ </p>
+ <sl>
+ <!-- one of (dl sl ul ol li) -->
+ <li>random access would not be required</li>
+ <li>
+ pushing and popping of list elements requires nearly
+ constant (low) time
+ </li>
+ <li> no penalty for first addition to an empty list</li>
+ <li>efficient access to both bottom and top of stack</li>
+ </sl>
+ <p>
+ However, it may be required to perform stack access
+ operations from an arbitrary place on the stack, in which
+ case it would probably be more efficient to use
+ <code>ArrayList</code>s instead.
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>Class vs instance</title>
+ <p>
+ An individual stack would contain values for a particular
+ property, and the context of the stack is the property class
+ as a whole. The property instances would be represented by
+ the individual values on the stack. If properties are to be
+ represented as instantiations of the class, the stack
+ entries would presumably be references to, or at least
+ referenced from, individual property objects. However, the
+ most important information about individual property
+ instances is the value assigned, and the relationship of
+ this property object to its ancestors and its descendents.
+ Other information would include the ownership of a property
+ instance by a particular <em>FO</em>, and, in the other
+ direction, the membership of the property in the set of
+ properties for which an <em>FO</em> has defined values.
+ </p>
+ <p>
+ In the presence of a stack, however, none of this required
+ information mandates the instantiation of properties. All
+ of the information mentioned so far can be effectively
+ represented by a stack position and a link to an
+ <em>FO</em>. If the property stack is maintained in
+ parallel with a stack of <em>FOs</em>, even that link is
+ implicit in the stack position.
+ </p>
+ </section>
+ <p>
+ <strong>Next:</strong> <link href="classes-overview.html"
+ >property classes overview.</link>
+ </p>
+ </section>
+ </body>
+</document>
+
--- /dev/null
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE book PUBLIC "-//APACHE//DTD Cocoon Documentation Book V1.0//EN"
+ "http://cvs.apache.org/viewcvs.cgi/*checkout*/xml-cocoon2/src/documentation/xdocs/dtd/book-cocoon-v10.dtd">
+
+<book software="FOP"
+ title="ALT Design"
+ copyright="@year@ The Apache Software Foundation"
+ xmlns:xlink="http://www.w3.org/1999/xlink">
+
+ <menu label="Index">
+ <menu-item label="FOP Home" href="../../index.html"/>
+ <menu-item label="Design" href="../index.html"/>
+ </menu>
+ <menu label="About">
+ <menu-item label="Alt Design" href="index.html"/>
+ <menu-item label="co-routines" href="coroutines.html"/>
+ <menu-item label="galleys" href="galleys.html"/>
+ <menu-item label="footnotes" href="footnotes.html"/>
+ <menu-item label="keeps" href="keeps.html"/>
+ <menu-item label="space-specifiers" href="spaces.html"/>
+ <menu-item label="alt.properties" href="alt.properties.html"/>
+ <menu-item label="Classes overview" href="classes-overview.html"/>
+ <menu-item label="Properties classes" href="properties-classes.html"/>
+ <menu-item label="Properties" href="Properties.png.html"/>
+ <menu-item label="PropertyConsts" href="PropertyConsts.png.html"/>
+ <menu-item label="PropNames" href="PropNames.png.html"/>
+ <menu-item label="AbsolutePosition" href="AbsolutePosition.png.html"/>
+ <menu-item label="VerticalAlign" href="VerticalAlign.png.html"/>
+ <menu-item label="BorderCommonStyle" href="BorderCommonStyle.png.html"/>
+ <menu-item label="XML parsing" href="xml-parsing.html"/>
+ <menu-item label="Property parsing" href="propertyExpressions.html"/>
+ <menu-item label="Compound properties" href="compound-properties.html"/>
+ <menu-item label="Traits" href="traits.html"/>
+ <menu-item label="User agent refs" href="user-agent-refs.html"/>
+ </menu>
+</book>
+
--- /dev/null
+<?xml version="1.0" standalone="no"?>
+<!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>Property classes overview</title>
+ <authors>
+ <person id="pbw" name="Peter B. West"
+ email="pbwest@powerup.com.au"/>
+ </authors>
+ </header>
+ <body>
+ <section>
+ <title>Classes overview</title>
+ <section>
+ <title>The class of all properties</title>
+ <p>
+ If individual properties can have a "virtual reality" on the
+ stack, where is the stack itself to be instantiated? One
+ possibility is to have the stacks as <code>static</code>
+ data structures within the individual property classes.
+ However, the reduction of individual property instances to
+ stack entries allows the possibility of further
+ virtualization of property classes. If the individual
+ properties can be represented by an integer, i.e. a
+ <code>static final int</code>, the set of individual
+ property stacks can be collected together into one array.
+ Where to put such an overall collection? Creating an
+ über-class to accommodate everything that applies to
+ property classes as a whole allows this array to be defined
+ as a <em><code>static final</code> something[]</em>.
+ </p>
+ </section>
+ <section>
+ <title>The overall property classes</title>
+ <p>
+ This approach has been taken for the experimental code.
+ Rather than simply creating a overall class containing
+ common elements of properties and acting as a superclass,
+ advantage has been taken of the facility for nesting of
+ top-level classes. All of the individual property classes
+ are nested within the <code>Properties</code> class.
+ This has advantages and disadvantages.
+ </p>
+ <dl>
+ <dt>Disadvantages</dt>
+ <dd>
+ The file becomes extremely cumbersome. This can cause
+ problems with "intelligent" editors. E.g.
+ <em>XEmacs</em> syntax highlighting virtually grinds to a
+ halt with the current version of this file.<br/> <br/>
+
+ Possible problems with IDEs. There may be speed problems
+ or even overflow problems with various IDEs. The current
+ version of this and related files had only been tried with
+ the <em>[X]Emacs JDE</em> environment, without difficulties
+ apart from the editor speed problems mentioned
+ above.<br/> <br/>
+
+ Retro look and feel. Not the done Java thing.<br/> <br/>
+ </dd>
+ <dt>Advantages</dt>
+ <dd>
+ Everything to do with properties in the one place (more or
+ less.)<br/> <br/>
+
+ Eliminates the need for a large part of the (sometimes)
+ necessary evil of code generation. The One Big File of
+ <code>foproperties.xml</code>, with its ancillary xsl, is
+ absorbed into the One Bigger File of
+ <code>Properties.java</code>. The huge advantage of this
+ is that it <strong>is</strong> Java.
+ </dd>
+ </dl>
+ </section>
+ <section>
+ <title>The property information classes</title>
+ <p>
+ In fact, in order to keep the size of the file down to more
+ a more manageable level, the property information classes of
+ static data and methods have been split tentatively into
+ three:
+ </p>
+ <figure src="PropertyStaticsOverview.png" alt="Top level
+ property classes"/>
+ <dl>
+ <dt><link href="PropNames.html">PropNames</link></dt>
+ <dd>
+ Contains an array, <code>propertyNames</code>, of the names of
+ all properties, and a set of enumeration constants, one
+ for each property name in the <code>PropertyNames</code>
+ array. These constants index the name of the properties
+ in <code>propertyNames</code>, and must be manually kept in
+ sync with the entries in the array. (This was the last of
+ the classes split off from the original single class;
+ hence the naming tiredness.)
+ <br/> <br/>
+ </dd>
+ <dt><link href="PropertyConsts.html">PropertyConsts</link></dt>
+ <dd>
+ Contains two basic sets of data:<br/>
+ Property-indexed arrays and property set
+ definitions.<br/> <br/>
+
+ <strong>Property-indexed arrays</strong> are elaborations
+ of the property indexing idea discussed in relation to the
+ arrays of property stacks. One of the arrays is<br/> <br/>
+
+ <code>public static final LinkedList[]
+ propertyStacks</code><br/> <br/>
+
+ This is an array of stacks, implemented as
+ <code>LinkedList</code>s, one for each property.<br/> <br/>
+
+ The other arrays provide indexed access to fields which
+ are, in most cases, common to all of the properties. An
+ exception is<br/> <br/>
+
+ <code>public static final Method[]
+ complexMethods</code><br/> <br/>
+
+ which contains a reference to the method
+ <code>complex()</code> which is only defined for
+ properties which have complex value parsing requirements.
+ It is likely that a similar array will be defined for
+ properties which allow a value of <em>auto</em>.<br/> <br/>
+
+ The property-indexed arrays are initialized by
+ <code>static</code> initializers in this class. The
+ <code>PropNames</code> class and
+ <code>Properties</code>
+ nested classes are scanned in order to obtain or derive
+ the data necessary for initialization.<br/> <br/>
+
+ <strong>Property set definitions</strong> are
+ <code>HashSet</code>s of properties (represented by
+ integer constants) which belong to each of the categories
+ of properties defined. They are used to simplify the
+ assignment of property sets to individual FOs.
+ Representative <code>HashSet</code>s include
+ <em>backgroundProps</em> and
+ <em>tableProps</em>.<br/> <br/>
+ </dd>
+ <dt><link href="Properties.html">Properties</link></dt>
+ <dd>
+ <br/>
+ This class contains only sets of constants for use by the
+ individual property classes, but it also importantly
+ serves as a container for all of the property classes, and
+ some convenience pseudo-property classes.<br/> <br/>
+
+ <strong>Constants sets</strong> include:<br/> <br/>
+
+ <em>Datatype constants</em>. A bitmap set of
+ integer constants over a possible range of 2^0 to 2^31
+ (represented as -2147483648). E.g.<br/>
+ INTEGER = 1<br/>
+ ENUM = 524288<br/> <br/>
+ Some of the definitions are bit-ORed
+ combinations of the basic values. Used to set the
+ <em>dataTypes</em> field of the property
+ classes.<br/> <br/>
+
+ <em>Trait mapping constants</em>. A bitmap set of
+ integer constants over a possible range of 2^0 to 2^31
+ (represented as -2147483648), representing the manner in
+ which a property maps into a <em>trait</em>. Used to set
+ the <code>traitMapping</code> field of the property
+ classes.<br/> <br/>
+
+ <em>Initial value constants</em>. A sequence of
+ integer constants representing the datatype of the initial
+ value of a property. Used to set the
+ <code>initialValueType</code> field of the property
+ classes.<br/> <br/>
+
+ <em>Inheritance value constants</em>. A sequence
+ of integer constants representing the way in which the
+ property is normally inherited. Used to set the
+ <code>inherited</code> field of the property
+ classes.<br/> <br/>
+
+ <strong>Nested property classes</strong>. The
+ <em>Properties</em> class serves as the holding pen for
+ all of the individual property classes, and for property
+ pseudo-classes which contain data common to a number of
+ actual properties, e.g. <em>ColorCommon</em>.
+ </dd>
+ </dl>
+ </section>
+ <p>
+ <strong>Previous:</strong> <link href=
+ "alt.properties.html" >alt.properties</link>
+ </p>
+ <p>
+ <strong>Next:</strong> <link href=
+ "properties-classes.html" >Properties classes</link>
+ </p>
+ </section>
+ </body>
+</document>
+
--- /dev/null
+<?xml version="1.0" standalone="no"?>
+<!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>Compound properties</title>
+ <authors>
+ <person name="Peter B. West" email="pbwest@powerup.com.au"/>
+ </authors>
+ </header>
+ <body>
+ <section>
+ <title>Compound properties in XSLFO</title>
+ <table>
+ <tr>
+ <th>Property type</th>
+ <th>Section</th>
+ <th>Inherited</th>
+ <th>'inherit'</th>
+ </tr>
+ <tr>
+ <th><length-range></th>
+ </tr>
+ <tr>
+ <th>minimum</th>
+ </tr>
+ <tr>
+ <th>optimum</th>
+ </tr>
+ <tr>
+ <th>maximum</th>
+ </tr>
+ <tr>
+ <td>block-progression-dimension</td>
+ <td>7.14.1</td>
+ <td>no</td>
+ <td>yes</td>
+ </tr>
+ <tr>
+ <td>inline-progression-dimension</td>
+ <td>7.14.5</td>
+ <td>no</td>
+ <td>yes</td>
+ </tr>
+ <tr>
+ <td>leader-length</td>
+ <td>7.21.4</td>
+ <td>yes</td>
+ <td>yes</td>
+ </tr>
+ <tr>
+ <th><length-conditional></th>
+ </tr>
+ <tr>
+ <th>length</th>
+ </tr>
+ <tr>
+ <th>conditionality</th>
+ </tr>
+ <tr>
+ <td>border-after-width</td>
+ <td>7.7.12</td>
+ <td>no</td>
+ <td>yes</td>
+ </tr>
+ <tr>
+ <td>border-before-width</td>
+ <td>7.7.9</td>
+ <td>no</td>
+ <td>yes</td>
+ </tr>
+ <tr>
+ <td>border-end-width</td>
+ <td>7.7.18</td>
+ <td>no</td>
+ <td>yes</td>
+ </tr>
+ <tr>
+ <td>border-start-width</td>
+ <td>7.7.15</td>
+ <td>no</td>
+ <td>yes</td>
+ </tr>
+ <tr>
+ <td>padding-after</td>
+ <td>7.7.32</td>
+ <td>no</td>
+ <td>yes</td>
+ </tr>
+ <tr>
+ <td>padding-before</td>
+ <td>7.7.31</td>
+ <td>no</td>
+ <td>yes</td>
+ </tr>
+ <tr>
+ <td>padding-end</td>
+ <td>7.7.34</td>
+ <td>no</td>
+ <td>yes</td>
+ </tr>
+ <tr>
+ <td>padding-start</td>
+ <td>7.7.33</td>
+ <td>no</td>
+ <td>yes</td>
+ </tr>
+ <tr>
+ <th><length-bp-ip-direction></th>
+ </tr>
+ <tr>
+ <th>block-progression-direction</th>
+ </tr>
+ <tr>
+ <th>inline-progression-direction</th>
+ </tr>
+ <tr>
+ <td>border-separation</td>
+ <td>7.26.5</td>
+ <td>yes</td>
+ <td>yes</td>
+ </tr>
+ <tr>
+ <th><space></th>
+ </tr>
+ <tr>
+ <th>minimum</th>
+ </tr>
+ <tr>
+ <th>optimum</th>
+ </tr>
+ <tr>
+ <th>maximum</th>
+ </tr>
+ <tr>
+ <th>precedence</th>
+ </tr>
+ <tr>
+ <th>conditionality</th>
+ </tr>
+ <tr>
+ <td>letter-spacing</td>
+ <td>7.16.2</td>
+ <td>yes</td>
+ <td>yes</td>
+ </tr>
+ <tr>
+ <td>line-height</td>
+ <td>7.15.4</td>
+ <td>yes</td>
+ <td>yes</td>
+ </tr>
+ <tr>
+ <td>space-after</td>
+ <td>7.10.6</td>
+ <td>no</td>
+ <td>yes</td>
+ </tr>
+ <tr>
+ <td>space-before</td>
+ <td>7.10.5</td>
+ <td>no</td>
+ <td>yes</td>
+ </tr>
+ <tr>
+ <td>space-end</td>
+ <td>7.11.1</td>
+ <td>no</td>
+ <td>yes</td>
+ </tr>
+ <tr>
+ <td>space-start</td>
+ <td>7.11.2</td>
+ <td>no</td>
+ <td>yes</td>
+ </tr>
+ <tr>
+ <td>word-spacing</td>
+ <td>7.16.8</td>
+ <td>yes</td>
+ <td>yes</td>
+ </tr>
+ <tr>
+ <th><keep></th>
+ </tr>
+ <tr>
+ <th>within-line</th>
+ </tr>
+ <tr>
+ <th>within-column</th>
+ </tr>
+ <tr>
+ <th>within-page</th>
+ </tr>
+ <tr>
+ <td>keep-together</td>
+ <td>7.19.3</td>
+ <td>yes</td>
+ <td>yes</td>
+ </tr>
+ <tr>
+ <td>keep-with-next</td>
+ <td>7.19.4</td>
+ <td>no</td>
+ <td>yes</td>
+ </tr>
+ <tr>
+ <td>keep-with-previous</td>
+ <td>7.19.5</td>
+ <td>no</td>
+ <td>yes</td>
+ </tr>
+ </table>
+ </section>
+ </body>
+</document>
+
--- /dev/null
+<?xml version="1.0" standalone="no"?>
+<!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>Implementing co-routines</title>
+ <authors>
+ <person name="Peter B. West" email="pbwest@powerup.com.au"/>
+ </authors>
+ </header>
+ <body>
+ <section>
+ <title>Implementing Co-routines in FOP</title>
+ <p>
+ All general page layout systems have to solve the same
+ fundamental problem: expressing a flow of text with its own
+ natural structure as a series of pages corresponding to the
+ physical and logical structure of the output medium. This
+ simple description disguises many complexities. Version 1.0
+ of the Recommendation, in Section 3, <em>Introduction to
+ Formatting </em>, includes the following comments.
+ </p>
+ <note>
+ [Formatting] comprises several steps, some of which depend on
+ others in a non-sequential way.<br/> ...and...<br/>
+ [R]efinement is not necessarily a straightforward, sequential
+ procedure, but may involve look-ahead, back-tracking, or
+ control-splicing with other processes in the formatter.
+ </note>
+ <p>Section 3.1, <em>Conceptual Procedure</em>, includes:</p>
+ <note>
+ The procedure works by processing formatting objects. Each
+ object, while being processed, may initiate processing in
+ other objects. While the objects are hierarchically
+ structured, the processing is not; processing of a given
+ object is rather like a co-routine which may pass control to
+ other processes, but pick up again later where it left off.
+ </note>
+ <section>
+ <title>Application of co-routines</title>
+ <p>
+ If one looks only at the flow side of the equation, it's
+ difficult to see what the problem might be. The ordering of
+ the elements of the flow is preserved in the area tree, and
+ where elements are in an hierarchical relationship in the
+ flow, they will generally be in an hierarchical relationship
+ in the area tree. In such circumstances, the recursive
+ processing of the flow seems quite natural.
+ </p>
+ <p>
+ The problem becomes more obvious when one thinks about the
+ imposition of an unrelated page structure over the
+ hierarchical structure of the document content. Take, e.g.,
+ the processing of a nested flow structure which, at a certain
+ point, is scanning text and generating line-areas, nested
+ within other block areas and possibly other line areas. The
+ page fills in the middle of this process. Processing at the
+ lowest level in the tree must now suspend, immediately
+ following the production of the line-area which filled the
+ page. This same event, however, must also trigger the closing
+ and flushing to the area tree of every open area of which the last
+ line-area was a descendant.
+ </p>
+ <p>
+ Once all of these areas have been closed, some dormant process
+ or processes must wake up, flush the area sub-tree
+ representing the page, and open a new page sub-tree in the
+ area tree. Then the whole nested structure of flow objects
+ and area production must be re-activated, at the point in
+ processing at which the areas of the previous page were
+ finalised, but with the new page environment. The most
+ natural way of expressing the temporal relationship of these
+ processes is by means of co-routines.
+ </p>
+ <p>
+ Normal sub-routines (methods) display a hierarchical
+ relationship where process A suspends on invoking process B,
+ which on termination returns control to A which resumes from
+ the point of suspension. Co-routines instead have a parallel
+ relationship. Process A suspends on invoking process B, but
+ process B also suspends on returning control to process A. To
+ process B, this return of control appears to be an invocation
+ of process A. When process A subsequently invokes B and
+ suspends, B behaves as though its previous invocation of A has
+ returned, and it resumes from the point of that invocation.
+ So control bounces between the two, each one resuming where it
+ left off.<br/><br/>
+ <strong>Figure 1</strong>
+ </p>
+ <figure src="coroutines.png" alt="Co-routine diagram"/>
+ <p>
+ For example, think of a page-production method working on a
+ complex page-sequence-master.
+ </p>
+ <source>
+ void makePages(...) {
+ ...
+ while (pageSequence.hasNext()) {
+ ...
+ page = generateNextPage(...);
+ boolean over = flow.fillPage(page);
+ if (over) return;
+ }
+ }
+ </source>
+ <p>
+ The <code>fillPage()</code> method, when it fills a page, will
+ have unfinished business with the flow, which it will want to
+ resume at the next call; hence co-routines. One way to
+ implement them in Java is by threads synchronised on some
+ common argument-passing object.
+ </p>
+ </section>
+ </section>
+ </body>
+</document>
+
--- /dev/null
+<?xml version="1.0" standalone="no"?>
+<!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>Implementing footnotes</title>
+ <authors>
+ <person name="Peter B. West" email="pbwest@powerup.com.au"/>
+ </authors>
+ </header>
+ <body>
+ <section>
+ <title>Implementing footnotes in FOP</title>
+ <p>
+ Footnotes present difficulties for page layout primarily
+ because their point of invocation in the flow is different
+ from their point of appearance in the area tree. All of the
+ content lines of a footnote may appear on the same page as its
+ invocation point, all may appear on a following page, or the
+ lines may be split over a page or pages. (This characteristic
+ leads to another problem when a footnote overflows the last
+ page of flow content, but that difficulty will not be
+ discussed here.) This note considers some aspects of the
+ implementation of footnotes in a galley-based design.
+ </p>
+ <section>
+ <title>Footnotes and galleys</title>
+ <p>
+ In the structure described in the <link href=
+ "../galleys.html" >introduction to FOP galleys</link>,
+ footnotes would be pre-processed as galleys themselves, but
+ they would remain attached as subtrees to their points of
+ invocation in the main text. Allocation to a
+ footnote-reference-area would only occur in the resolution
+ to Area nodes.
+ </p>
+ <p>
+ When footnotes are introduced, the communication between
+ galleys and layout manager, as mentioned <link href=
+ "../galleys.html#pre-processing" >above</link>, would be
+ affected. The returned information would two b-p-d values:
+ the primary line-area b-p-d impact and the footnote b-p-d
+ impact. The distinction is necessary for two reasons; to
+ alert the layout manager to the first footnote of the page,
+ and because the footnote b-p-d will always impact the
+ main-reference-area b-p-d, whereas the primary inline-area
+ may not, e.g. in the case of multiple span-areas.
+ </p>
+ </section>
+ <section>
+ <title>Multiple columns and footnotes</title>
+ <note>
+ A possible method for multi-column layout and balancing
+ with footnotes, using a galley-based approach.
+ </note>
+ <p>
+ This note assumes a galley, as discussed <link href=
+ "../galleys.html" >elsewhere</link>, flowing text with
+ footnotes and possibly other blocks into a possibly
+ multi-column area. The logic of flowing into multiple
+ columns is trivially applied to a single column. The galley
+ is manipulated within the context of the <em>layout
+ tree</em>.
+ </p>
+ <p>
+ Associated with the galley are two sets of data.
+ One contains the maps of all "natural" break-points and
+ the of all hyphenation break-points. This set is
+ constructed at the time of construction of the galley and
+ is a constant for a given galley. The second contains
+ dynamic data which represents one possible attempt to lay
+ out the galley. There may be multiple sets of such data
+ to reflect varying attempts. The data of this set are,
+ essentially, representations of line-areas, with the supporting
+ information necessary to determine these line-areas.
+ </p>
+ <p>
+ The line-area data includes the boundaries within the
+ galley of each line-area, the boundaries of each column
+ and the boundaries of the "page", or main area. When a
+ line-area boundary occurs at a hyphenation point, a
+ "virtual hyphen" is assumed and accounted for in the
+ i-p-d. As mentioned, individual footnote galleys will
+ hang from the parent galley. The associated data of the
+ footnote galleys is similar: a once-only break-points map,
+ and one or more line-area maps. No column boundaries are
+ required, but a page boundary is required at the end of
+ the last footnote or where a footnote breaks across a page
+ boundary.
+ </p>
+ <p>
+ A number of b-p-d values are also maintained. For each
+ line-area, the b-p-d, the main area b-p-d increment, the
+ footnote b-p-d increment and the footnote's page-related
+ b-p-d increment are required. The main-area b-p-d
+ increments for any particular line-area are dependent on
+ the column position of the line-area. Total b-p-d's are
+ also kept: total footnote b-p-d, total main area b-p-d,
+ and totals for each column.<br/><br/>
+ <strong>Figure 1</strong> Columns before first footnote.
+ </p>
+ <figure src="initial-column-values.png" alt="Columns before
+ first footnote"/>
+ </section>
+ <section>
+ <title>Balancing columns</title>
+ <p>
+ <strong>Figure 2</strong> Adding a line area with first
+ footnote.
+ </p>
+ <figure src="line-area-5.png"
+ alt="Columns after adding first footnote"/>
+ <p>
+ Columns are balanced dynamically in the galley preliminary
+ layout. While the galley retains its basic linear
+ structure, the accompanying data structures accomplish
+ column distribution and balancing. As each line-area is
+ added, the columns are re-balanced. <strong>N.B.</strong>
+ This re-balancing involves only some of the dynamic data
+ associated with the participating galley(s). The data
+ structures associating breakpoints with the beginning and
+ end of individual line areas does not change in
+ re-balancing; only the association of line-area with column,
+ and, possibly, the various impact values for each line-area.
+ <br/><br/>
+ <strong>Figure 3</strong> Adding a line area with next
+ footnote.
+ </p>
+ <figure src="line-area-6.png"
+ alt="Columns after adding next footnote"/>
+ </section>
+ <section>
+ <title>Layout managers in the flow of control</title>
+ <note>To be developed.</note>
+ </section>
+ </section>
+ </body>
+</document>
+
--- /dev/null
+<?xml version="1.0" standalone="no"?>
+<!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>Galleys</title>
+ <authors>
+ <person name="Peter B. West" email="pbwest@powerup.com.au"/>
+ </authors>
+ </header>
+ <body>
+ <section>
+ <title>Layout galleys in FOP</title>
+ <section>
+ <title>Galleys in Lout</title>
+ <p>
+ Jeffrey H. Kingston, in <link href =
+ "http://snark.niif.spb.su/~uwe/lout/design.pdf" ><em>The
+ Design and Implementation of the Lout Document Formatting
+ Language</em> Section 5</link>, describes the
+ <strong>galley</strong> abstraction which he implemented in
+ <em>Lout</em>. A document to be formatted is a stream of
+ text and symbols, some of which are <strong>receptive
+ symbols</strong>. The output file is the first receptive
+ symbol; the formatting document is the first galley. The
+ archetypical example of a receptive symbol is
+ <strong>@FootPlace</strong> and its corresponding galley
+ definition, <strong>@FootNote</strong>.
+ </p>
+ <p>
+ Each galley should be thought of as a concurrent process, and
+ each is associated with a semaphore (or synchronisation
+ object.) Galleys are free to "promote" components into
+ receptive targets as long as</p>
+ <ul>
+ <li>
+ an appropriate target has been encountered in the file,
+ </li>
+ <li>
+ the component being promoted contains no unresolved galley
+ targets itself, and
+ </li>
+ <li>
+ there is sufficient room for the galley component at the
+ target.
+ </li>
+ </ul>
+ <p>
+ If these conditions are not met, the galley blocks on its
+ semaphore. When conditions change so that further progress
+ may be possible, the semaphore is signalled. Note that the
+ galleys are a hierarchy, and that the processing and
+ promotion of galley contents happens <em>bottom-up</em>.
+ </p>
+ </section>
+ <section>
+ <title>Some features of galleys</title>
+ <p>
+ It is essential to note that galleys are self-managing; they
+ are effectively layout <em>bots</em> which require only a
+ receptive area. If a galley fills a receptive area (say, at
+ the completion of a page), the galley will wait on its
+ semaphore, and will remain stalled until a new receptive
+ area is uncovered in the continued processing (say, as the
+ filled page is flushed to output and a new empty page is
+ generated.)
+ </p>
+ <p>
+ Difficulties with this approach become evident when there
+ are mutual dependencies between receptive areas which
+ require negotiation between the respective galleys, and, in
+ some cases, arbitrary deadlock breaking when there is no
+ clear-cut resolution to conflicting demands. Footnote
+ processing and side floats are examples. A thornier example
+ is table column layout in <em>auto</em> mode, where the
+ column widths are determined by the contents. In
+ implementing galleys in FOP, these difficulties must be
+ taken into account, and some solutions proposed.
+ </p>
+ <p>
+ Galleys model the whole of the process of creating the final
+ formatted output; the document as a whole is regarded as a
+ galley which flushes in to the output file.
+ </p>
+ </section>
+ <section>
+ <title>The layout tree</title>
+ <anchor id="layout-tree"/>
+ <p>
+ This proposal for implementing galleys in FOP makes use of a
+ <strong>layout tree</strong>. As with the <link href=
+ "../layout.html" >layout managers</link><em></em> already
+ proposed, the layout tree acts as a bridge between the <link
+ href= "../fotree.html" >FO Tree</link> and the <link href=
+ "../areatree.html" >Area Tree</link>. If the elements of
+ the FO Tree are FO nodes, and the elements of the Area Tree
+ are Area nodes, representing areas to be drawn on the output
+ medium, the elements of the layout tree are <strong>galley
+ nodes</strong> and <strong>area tree fragments</strong>.
+ The area tree fragments are the final stages of the
+ resolution of the galleys; the output of the galleys will be
+ inserted directly into the Area Tree. The tree structure
+ makes it clear that the whole of the formatting process in
+ FOP, under this model, is a hierarchical series of galleys.
+ The dynamic data comes from fo:flow and fo:static-content,
+ and the higher-level receptive areas are derived from the
+ <em>layout-master-set</em>.
+ </p>
+ </section>
+ <section>
+ <title>Processing galleys</title>
+ <p>
+ Galleys are processed in two basic processing environments:
+ </p>
+ <section>
+ <title>Inline- and block-progression dimensions known</title>
+ <p>
+ The galley at set-up is provided with both an
+ <em>inline-progression-dimension</em> (<em>i-p-d</em>) and
+ a <em>block-progression-dimension</em> (<em>b-p-d</em>).
+ In this case, no further intervention is necessary to lay
+ out the galley. The galley has the possibility of laying
+ itself out, creating all necessary area nodes. This does
+ not preclude the possibility that some children of this
+ galley will not be able to be so directly laid out, and
+ will fall into the second category.
+ </p>
+ <p>
+ While the option of "automatic" layout exists, to use
+ such a method would relinquish the possibility of
+ monitoring the results of such layout and performing
+ fine-tuning.
+ </p>
+ </section>
+ <section>
+ <title>Inline- ior block-progression-dimensions unknown</title>
+ <p>
+ The galley cannot immediately be provided with an i-p-d
+ ior a b-p-d. This will occur in some of the difficult
+ cases mentioned earlier. In these cases, the parent
+ galley acts as a layout manager, similar to the sense used
+ in <link href= "../layout.html" >another
+ discussion</link>. The children, lacking full receptive
+ area dimensions, will proceed with galley pre-processing,
+ a procedure which will, of necessity, be followed
+ recursively by all of its children down to the atomic
+ elements of the galley. These atomic elements are the
+ individual <em>fo:character</em> nodes and images of fixed
+ dimensions.
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>Galley pre-processing</title>
+ <anchor id="pre-processing"/>
+ <p>
+ Galley pre-processing involves the spatial resolution of
+ objects from the flows to the greatest extent possible
+ without information on the dimensions of the target area.
+ Line-areas have a block progression dimension which is
+ determined by their contents. To achieve full generality in
+ layouts of indeterminate dimensions, the contents of
+ line-areas should be laid out as though their inline
+ progression dimension were limited only by their content.
+ In terms of inline-areas, galleys would process text and
+ resolve the dimensions of included images. Text would be
+ collected into runs with the same alignment
+ characteristics. In the process, all possible "natural" and
+ hyphenation break-points can be determined. Where a
+ line-area contains mixed fonts or embedded images, the b-p-d
+ of the individual line-areas which are eventually stacked
+ will, in general, depend on the line break points, but the
+ advantage of this approach is that such actual selections
+ can be backed out and new break points selected with a
+ minimum of re-calculation. This can potentially occur
+ whenever a first attempt at page layout is backed out.
+ <br/><br/>
+ <strong>Figure 1</strong>
+ </p>
+ <figure src="galley-preprocessing.png" alt="Galley
+ pre-processing diagram"/>
+ <p>
+ Once this pre-processing has been achieved, it is
+ envisaged that a layout manager might make requests to the
+ galley of its ability to fill an area of a given
+ inline-progression-dimension. A positive response would
+ be accompanied by the block-progression-dimension. The
+ other possibilities are a partial fill, which would also
+ require b-p-d data, and a failure due to insufficient
+ i-p-d, in which case the minimum i-p-d requirement would
+ be returned. Note that decisions about the
+ actual dimensions of line-areas to be filled can be
+ deferred until all options have been tested.
+ </p>
+ <p>
+ The other primary form of information provided by a
+ pre-processed galley is its minimum and maximum i-p-d, so
+ that decisions can be made by the parent on the spacing of
+ table columns. Apart from information requests,
+ higher-level processes can either make requests of the
+ galleys for chunks of nominated sizes, or simply provide the
+ galley with an i-p-d and b-p-d, which will trigger the
+ flushing of the galley components into Area nodes. Until
+ they have flushed, the galleys must be able to respond to a
+ sequence of information requests, more or less in the manner
+ of a request iterator, and separately manage the flushing of
+ objects into the area tree. The purpose of the "request
+ iterator" would be to support "incremental" information
+ requests like <em>getNextBreakPosition</em>.
+ </p>
+ </section>
+ </section>
+ </body>
+</document>
+
--- /dev/null
+<?xml version="1.0" standalone="no"?>
+<!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>FOP Alternative Design</title>
+ <subtitle>Alternative Design Approach to FOP</subtitle>
+ <version>$Revision$ $Name$</version>
+ <authors>
+ <person name="Peter B. West" email="pbwest@powerup.com.au"/>
+ </authors>
+ </header>
+ <body>
+ <section>
+ <title>Alternative Design</title>
+ <p>
+ This section of the FOP web site contains notes on approaches
+ to an alternative design for FOP. The individual documents
+ here are fragmentary, being notes of particular issues,
+ without an overall framework as yet.
+ </p>
+ <p>
+ The main aims of this redesign effort are:
+ </p>
+ <ul>
+ <li>full conformance with the Recommendation</li>
+ <li>increased performance</li>
+ <li>reduced memory footprint</li>
+ <li>no limitation on the size of files</li>
+ </ul>
+ <p>
+ In order to achieve these aims, the primary areas
+ of design interest are:
+ </p>
+ <ul>
+ <li>
+ Representing properties, for most purposes, as integers.
+ </li>
+ <li>
+ Distributing FOP processing over a number of threads with
+ single-point downstream communication and flow control by
+ means of traditional producer/consumer queues. The threads
+ so far under consideration are:
+ <ul>
+ <li>XML parser</li>
+ <li>FO tree builder</li>
+ <li>layout engine</li>
+ <li>Area tree builder</li>
+ </ul>
+ </li>
+ <li>
+ Representing trees with explicit Tree objects, rather than
+ as implicit relationships among other objects.
+ </li>
+ <li>
+ Caching integrated into the tree node access methods.
+ </li>
+ </ul>
+ <section>
+ <title>Status and availability</title>
+ <p>
+ The <em>ALT DESIGN</em> effort is not taking place on the
+ main line of development, represented by the <em>HEAD</em>
+ tag on the CVS trunk. The source is available via the
+ FOP_0-20-0_Alt-Design tag. This code has only a crude,
+ non-<em>Ant</em> build environment, and is expected only to
+ compile at this stage. Only the parser stage and the first
+ stage of FO tree building is present. However, the first
+ example of producer/consumer binding is working, the Tree
+ class with inner Tree.Node and inner
+ Tree.Node.<em>iterators</em> classes are available and
+ working. Property handling is quite advanced, and is likely
+ to be almost complete some time in July, 2002.
+ </p>
+ <p>
+ Only <link href="mailto:pbwest@powerup.com.au">Peter
+ West</link> is working on the ALT DESIGN sub-project.
+ </p>
+ </section>
+ </section>
+ </body>
+</document>
+
--- /dev/null
+<?xml version="1.0" standalone="no"?>
+<!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>Keeps and breaks</title>
+ <authors>
+ <person name="Peter B. West" email="pbwest@powerup.com.au"/>
+ </authors>
+ </header>
+ <body>
+ <section>
+ <title>Keeps and breaks in layout galleys</title>
+ <p>
+ The <link href= "galleys.html" >layout galleys</link> and the
+ <link href= "galleys.html#layout-tree" >layout tree</link>
+ which is their context have been discussed elsewhere. Here we
+ discuss a possible method of implementing keeps and breaks
+ within the context of layout galleys and the layout tree.
+ </p>
+ <section>
+ <title>Breaks</title>
+ <p>
+ Breaks may be handled by inserting a column- or page-break
+ pseudo-object into the galley stream. For break-before, the
+ object would be inserted before the area in which the flow
+ object, to which the property is attached, is leading. If
+ the flow object is leading in no ancestor context, the
+ pseudo-object is inserted before the object itself.
+ Corresponding considerations apply for break-after.
+ Selection of the position for these objects will be further
+ examined in the discussion on keeps.
+ </p>
+ </section>
+ <section>
+ <title>Keeps</title>
+ <p>
+ Conceptually, all keeps can be represented by a
+ keep-together pseudo-area. The keep-together property
+ itself is expressed during layout by wrapping all of the
+ generated areas in a keep-together area. Keep-with-previous
+ on formatting object A becomes a keep-together area spanning
+ the first non-blank normal area leaf node, L, generated by A
+ or its offspring, and the last non-blank normal area leaf
+ node preceding L in the area tree. Likewise, keep-with-next
+ on formatting object A becomes a keep-together area spanning
+ the last non-blank normal area leaf node, L, generated by A
+ or its offspring, and the first non-blank normal area leaf
+ node following L in the area tree.
+ <br/>TODO REWORK THIS for block vs inline
+ </p>
+ <p>
+ The obvious problem with this arrangement is that the
+ keep-together area violate the hierarachical arrangement of
+ the layout tree. They form a concurrent structure focussed
+ on the leaf nodes. This seems to be the essential problem
+ of handling keep-with-(previous/next); that it cuts across
+ the otherwise tree-structured flow of processing. Such
+ problems are endemic in page layout.
+ </p>
+ <p>
+ In any case, it seems that the relationships between areas
+ that are of interest in keep processing need some form of
+ direct expression, parallel to the layout tree itself.
+ Restricting ourselves too block-level elements, and looking
+ only at the simple block stacking cases, we get a diagram
+ like the attached PNG. In order to track the relationships
+ through the tree, we need four sets of links.
+ </p>
+ <p>
+ <strong>Figure 1</strong>
+ </p>
+ <anchor id="Figure1"/>
+ <figure src="block-stacking.png" alt="Simple block-stacking
+ diagram"/>
+ <p>
+ The three basic links are:
+ </p>
+ <ul>
+ <!-- one of (dl sl ul ol li) -->
+ <li>Leading edge to leading edge of first normal child.</li>
+ <li>Trailing edge to leading edge of next normal
+ sibling.</li>
+ <li>Trailing edge to trailing edge of parent.</li>
+ </ul>
+ <p>
+ Superimposed on the basic links are bridging links which
+ span adjacent sets of links. These spanning links are the
+ tree violators, and give direct access to the areas which
+ are of interest in keep processing. They could be
+ implemented as double-linked lists, either within the layout
+ tree nodes or as separate structures. Gaps in the spanning
+ links are joined by simply reproducing the single links, as
+ in the diagram. The whole layout tree for a page is
+ effectively threaded in order of interest, as far as keeps
+ are concerned.
+ </p>
+ <p>
+ The bonus of this structure is that it looks like a superset
+ of the stacking constraints. It gives direct access to all
+ sets of adjacent edges and sets of edges whose space
+ specifiers need to be resolved. Fences can be easily enough
+ detected during the process of space resolution.
+ </p>
+ </section>
+ </section>
+ </body>
+</document>
+
--- /dev/null
+<?xml version="1.0" standalone="no"?>
+<!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>Properties$classes</title>
+ <authors>
+ <person name="Peter B. West" email="pbwest@powerup.com.au"/>
+ </authors>
+ </header>
+ <body>
+ <section>
+ <title>fo.Properties and the nested properties classes</title>
+ <figure src="PropertyClasses.png" alt="Nested property and
+ top-level classes"/>
+ <section>
+ <title>Nested property classes</title>
+ <p>
+ Given the intention that individual properties have only a
+ <em>virtual</em> instantiation in the arrays of
+ <code>PropertyConsts</code>, these classes are intended to
+ remain as repositories of static data and methods. The name
+ of each property is entered in the
+ <code>PropNames.propertyNames</code> array of
+ <code>String</code>s, and each has a unique integer constant
+ defined, corresponding to the offset of the property name in
+ that array.
+ </p>
+ <section>
+ <title>Fields common to all classes</title>
+ <dl>
+ <dt><code>final int dataTypes</code></dt>
+ <dd>
+ This field defines the allowable data types which may be
+ assigned to the property. The value is chosen from the
+ data type constants defined in <code>Properties</code>, and
+ may consist of more than one of those constants,
+ bit-ORed together.
+ </dd>
+ <dt><code>final int traitMapping</code></dt>
+ <dd>
+ This field defines the mapping of properties to traits
+ in the <code>Area tree</code>. The value is chosen from the
+ trait mapping constants defined in <code>Properties</code>,
+ and may consist of more than one of those constants,
+ bit-ORed together.
+ </dd>
+ <dt><code>final int initialValueType</code></dt>
+ <dd>
+ This field defines the data type of the initial value
+ assigned to the property. The value is chosen from the
+ initial value type constants defined in
+ <code>Properties</code>.
+ </dd>
+ <dt><code>final int inherited</code></dt>
+ <dd>
+ This field defines the kind of inheritance applicable to
+ the property. The value is chosen from the inheritance
+ constants defined in <code>Properties</code>.
+ </dd>
+ </dl>
+ </section>
+ <section>
+ <title>Datatype dependent fields</title>
+ <dl>
+ <dt>Enumeration types</dt>
+ <dd>
+ <strong><code>final String[] enums</code></strong><br/>
+ This array contains the <code>NCName</code> text
+ values of the enumeration. In the current
+ implementation, it always contains a null value at
+ <code>enum[0]</code>.<br/> <br/>
+
+ <strong><code>final String[]
+ enumValues</code></strong><br/> When the number of
+ enumeration values is small,
+ <code>enumValues</code> is a reference to the
+ <code>enums</code> array.<br/> <br/>
+
+ <strong><code>final HashMap
+ enumValues</code></strong><br/> When the number of
+ enumeration values is larger,
+ <code>enumValues</code> is a
+ <code>HashMap</code> statically initialized to
+ contain the integer constant values corresponding to
+ each text value, indexed by the text
+ value.<br/> <br/>
+
+ <strong><code>final int</code></strong>
+ <em><code>enumeration-constants</code></em><br/> A
+ unique integer constant is defined for each of the
+ possible enumeration values.<br/> <br/>
+ </dd>
+ <dt>Many types:
+ <code>final</code> <em>datatype</em>
+ <code>initialValue</code></dt>
+ <dd>
+ When the initial datatype does not have an implicit
+ initial value (as, for example, does type
+ <code>AUTO</code>) the initial value for the property is
+ assigned to this field. The type of this field will
+ vary according to the <code>initialValueType</code>
+ field.
+ </dd>
+ <dt>AUTO: <code>PropertyValueList auto(property,
+ list)></code></dt>
+ <dd>
+ When <em>AUTO</em> is a legal value type, the
+ <code>auto()</code> method must be defined in the property
+ class.<br/>
+ <em>NOT YET IMPLEMENTED.</em>
+ </dd>
+ <dt>COMPLEX: <code>PropertyValueList complex(property,
+ list)></code></dt>
+ <dd>
+ <em>COMPLEX</em> is specified as a value type when complex
+ conditions apply to the selection of a value type, or
+ when lists of values are acceptable. To process and
+ validate such a property value assignment, the
+ <code>complex()</code> method must be defined in the
+ property class.
+ </dd>
+ </dl>
+ </section>
+ </section>
+ <section>
+ <title>Nested property pseudo-classes</title>
+ <p>
+ The property pseudo-classes are classes, like
+ <code>ColorCommon</code> which contain values, particularly
+ <em>enums</em>, which are common to a number of actual
+ properties.
+ </p>
+ </section>
+ <p>
+ <strong>Previous:</strong> <link href= "classes-overview.html"
+ >property classes overview.</link>
+ </p>
+ </section>
+ </body>
+</document>
+
--- /dev/null
+<?xml version="1.0" standalone="no"?>
+<!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>Property Expression Parsing</title>
+ <authors>
+ <person id="pbw" name="Peter B. West" email="pbwest@powerup.com.au"/>
+ </authors>
+ </header>
+ <body>
+ <section>
+ <title>Property expression parsing</title>
+ <note>
+ The following discussion of the experiments with alternate
+ property expression parsing is very much a work in progress,
+ and subject to sudden changes.
+ </note>
+ <p>
+ The parsing of property value expressions is handled by two
+ closely related classes: <code>PropertyTokenizer</code> and its
+ subclass, <code>PropertyParser</code>.
+ <code>PropertyTokenizer</code>, as the name suggests, handles
+ the tokenizing of the expression, handing <em>tokens</em>
+ back to its subclass,
+ <code>PropertyParser</code>. <code>PropertyParser</code>, in
+ turn, returns a <code>PropertyValueList</code>, a list of
+ <code>PropertyValue</code>s.
+ </p>
+ <p>
+ The tokenizer and parser rely in turn on the datatype
+ definition from the <code>org.apache.fop.datatypes</code>
+ package and the datatype <code>static final int</code>
+ constants from <code>PropertyConsts</code>.
+ </p>
+ <section>
+ <title>Data types</title>
+ <p>
+ The data types currently defined in
+ <code>org.apache.fop.datatypes</code> include:
+ </p>
+ <table>
+ <tr><th colspan="2">Numbers and lengths</th></tr>
+ <tr>
+ <th>Numeric</th>
+ <td colspan="3">
+ The fundamental numeric data type. <em>Numerics</em> of
+ various types are constructed by the classes listed
+ below.
+ </td>
+ </tr>
+ <tr>
+ <td/>
+ <th colspan="3">Constructor classes for <em>Numeric</em></th>
+ </tr>
+ <tr>
+ <td/><td>Angle</td>
+ <td colspan="2">In degrees(deg), gradients(grad) or
+ radians(rad)</td>
+ </tr>
+ <tr>
+ <td/><td>Ems</td>
+ <td colspan="2">Relative length in <em>ems</em></td>
+ </tr>
+ <tr>
+ <td/><td>Frequency</td>
+ <td colspan="2">In hertz(Hz) or kilohertz(kHz)</td>
+ </tr>
+ <tr>
+ <td/><td>IntegerType</td><td/>
+ </tr>
+ <tr>
+ <td/><td>Length</td>
+ <td colspan="2">In centimetres(cm), millimetres(mm),
+ inches(in), points(pt), picas(pc) or pixels(px)</td>
+ </tr>
+ <tr>
+ <td/><td>Percentage</td><td/>
+ </tr>
+ <tr>
+ <td/><td>Time</td>
+ <td>In seconds(s) or milliseconds(ms)</td>
+ </tr>
+ <tr><th colspan="2">Strings</th></tr>
+ <tr>
+ <th>StringType</th>
+ <td colspan="3">
+ Base class for data types which result in a <em>String</em>.
+ </td>
+ </tr>
+ <tr>
+ <td/><th>Literal</th>
+ <td colspan="2">
+ A subclass of <em>StringType</em> for literals which
+ exceed the constraints of an <em>NCName</em>.
+ </td>
+ </tr>
+ <tr>
+ <td/><th>MimeType</th>
+ <td colspan="2">
+ A subclass of <em>StringType</em> for literals which
+ represent a mime type.
+ </td>
+ </tr>
+ <tr>
+ <td/><th>UriType</th>
+ <td colspan="2">
+ A subclass of <em>StringType</em> for literals which
+ represent a URI, as specified by the argument to
+ <em>url()</em>.
+ </td>
+ </tr>
+ <tr>
+ <td/><th>NCName</th>
+ <td colspan="2">
+ A subclass of <em>StringType</em> for literals which
+ meet the constraints of an <em>NCName</em>.
+ </td>
+ </tr>
+ <tr>
+ <td/><td/><th>Country</th>
+ <td>An RFC 3066/ISO 3166 country code.</td>
+ </tr>
+ <tr>
+ <td/><td/><th>Language</th>
+ <td>An RFC 3066/ISO 639 language code.</td>
+ </tr>
+ <tr>
+ <td/><td/><th>Script</th>
+ <td>An ISO 15924 script code.</td>
+ </tr>
+ <tr><th colspan="2">Enumerated types</th></tr>
+ <tr>
+ <th>EnumType</th>
+ <td colspan="3">
+ An integer representing one of the tokens in a set of
+ enumeration values.
+ </td>
+ </tr>
+ <tr>
+ <td/><th>MappedEnumType</th>
+ <td colspan="2">
+ A subclass of <em>EnumType</em>. Maintains a
+ <em>String</em> with the value to which the associated
+ "raw" enumeration token maps. E.g., the
+ <em>font-size</em> enumeration value "medium" maps to
+ the <em>String</em> "12pt".
+ </td>
+ </tr>
+ <tr><th colspan="2">Colors</th></tr>
+ <tr>
+ <th>ColorType</th>
+ <td colspan="3">
+ Maintains a four-element array of float, derived from
+ the name of a standard colour, the name returned by a
+ call to <em>system-color()</em>, or an RGB
+ specification.
+ </td>
+ </tr>
+ <tr><th colspan="2">Fonts</th></tr>
+ <tr>
+ <th>FontFamilySet</th>
+ <td colspan="3">
+ Maintains an array of <em>String</em>s containing a
+ prioritized list of possibly generic font family names.
+ </td>
+ </tr>
+ <tr><th colspan="2">Pseudo-types</th></tr>
+ <tr>
+ <td colspan="4">
+ A variety of pseudo-types have been defined as
+ convenience types for frequently appearing enumeration
+ token values, or for other special purposes.
+ </td>
+ </tr>
+ <tr>
+ <th>Inherit</th>
+ <td colspan="3">
+ For values of <em>inherit</em>.
+ </td>
+ </tr>
+ <tr>
+ <th>Auto</th>
+ <td colspan="3">
+ For values of <em>auto</em>.
+ </td>
+ </tr>
+ <tr>
+ <th>None</th>
+ <td colspan="3">
+ For values of <em>none</em>.
+ </td>
+ </tr>
+ <tr>
+ <th>Bool</th>
+ <td colspan="3">
+ For values of <em>true/false</em>.
+ </td>
+ </tr>
+ <tr>
+ <th>FromNearestSpecified</th>
+ <td colspan="3">
+ Created to ensure that, when associated with
+ a shorthand, the <em>from-nearest-specified-value()</em>
+ core function is the sole component of the expression.
+ </td>
+ </tr>
+ <tr>
+ <th>FromParent</th>
+ <td colspan="3">
+ Created to ensure that, when associated with
+ a shorthand, the <em>from-parent()</em>
+ core function is the sole component of the expression.
+ </td>
+ </tr>
+ </table>
+ </section>
+ <section>
+ <title>Tokenizer</title>
+ <p>
+ The tokenizer returns one of the following token
+ values:
+ </p>
+ <source>
+ static final int
+ EOF = 0
+ ,NCNAME = 1
+ ,MULTIPLY = 2
+ ,LPAR = 3
+ ,RPAR = 4
+ ,LITERAL = 5
+ ,FUNCTION_LPAR = 6
+ ,PLUS = 7
+ ,MINUS = 8
+ ,MOD = 9
+ ,DIV = 10
+ ,COMMA = 11
+ ,PERCENT = 12
+ ,COLORSPEC = 13
+ ,FLOAT = 14
+ ,INTEGER = 15
+ ,ABSOLUTE_LENGTH = 16
+ ,RELATIVE_LENGTH = 17
+ ,TIME = 18
+ ,FREQ = 19
+ ,ANGLE = 20
+ ,INHERIT = 21
+ ,AUTO = 22
+ ,NONE = 23
+ ,BOOL = 24
+ ,URI = 25
+ ,MIMETYPE = 26
+ // NO_UNIT is a transient token for internal use only. It is
+ // never set as the end result of parsing a token.
+ ,NO_UNIT = 27
+ ;
+ </source>
+ <p>
+ Most of these tokens are self-explanatory, but a few need
+ further comment.
+ </p>
+ <dl>
+ <dt>AUTO</dt>
+ <dd>
+ Because of its frequency of occurrence, and the fact that
+ it is always the <em>initial value</em> for any property
+ which supports it, AUTO has been promoted into a
+ pseudo-type with its on datatype class. Therefore, it is
+ also reported as a token.
+ </dd>
+ <dt>NONE</dt>
+ <dd>
+ Similarly to AUTO, NONE has been promoted to a pseudo-type
+ because of its frequency.
+ </dd>
+ <dt>BOOL</dt>
+ <dd>
+ There is a <em>de facto</em> boolean type buried in the
+ enumeration types for many of the properties. It had been
+ specified as a type in its own right in this code.
+ </dd>
+ <dt>MIMETYPE</dt>
+ <dd>
+ The property <code>content-type</code> introduces this
+ complication. It can have two values of the form
+ <strong>content-type:</strong><em>mime-type</em>
+ (e.g. <code>content-type="content-type:xml/svg"</code>) or
+ <strong>namespace-prefix:</strong><em>prefix</em>
+ (e.g. <code>content-type="namespace-prefix:svg"</code>). The
+ experimental code reduces these options to the payload
+ in each case: an <code>NCName</code> in the case of a
+ namespace prefix, and a MIMETYPE in the case of a
+ content-type specification. <code>NCName</code>s cannot
+ contain a "/".
+ </dd>
+ </dl>
+ </section>
+ <section>
+ <title>Parser</title>
+ <p>
+ The parser retuns a <code>PropertyValueList</code>,
+ necessary because of the possibility that a list of
+ <code>PropertyValue</code> elements may be returned from the
+ expressions of soem properties.
+ </p>
+ <p>
+ <code>PropertyValueList</code>s may contain
+ <code>PropertyValue</code>s or other
+ <code>PropertyValueList</code>s. This latter provision is
+ necessitated for the peculiar case of of
+ <em>text-shadow</em>, which may contain whitespace separated
+ sublists of either two or three elements, separated from one
+ another by commas. To accommodate this peculiarity, comma
+ separated elements are added to the top-level list, while
+ whitespace separated values are always collected into
+ sublists to be added to the top-level list.
+ </p>
+ <p>
+ Other special cases include the processing of the core
+ functions <code>from-parent()</code> and
+ <code>from-nearest-specified-value()</code> when these
+ function calls are assigned to a shorthand property, or used
+ with a shorthand property name as an argument. In these
+ cases, the function call must be the sole component of the
+ expression. The pseudo-element classes
+ <code>FromParent</code> and
+ <code>FromNearestSpecified</code> are generated in these
+ circumstances so that an exception will be thrown if they
+ are involved in expression evaluation with other
+ components. (See Rec. Section 5.10.4 Property Value
+ Functions.)
+ </p>
+ <p>
+ The experimental code is a simple extension of the existing
+ parser code, which itself borrowed heavily from James
+ Clark's XT processor.
+ </p>
+ </section>
+ </section>
+ </body>
+</document>
+
--- /dev/null
+<?xml version="1.0" standalone="no"?>
+<!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>Keeps and space-specifiers</title>
+ <authors>
+ <person name="Peter B. West" email="pbwest@powerup.com.au"/>
+ </authors>
+ </header>
+ <body>
+ <section>
+ <title>Keeps and space-specifiers in layout galleys</title>
+ <p>
+ The <link href= "galleys.html" >layout galleys</link> and the
+ <link href= "galleys.html#layout-tree" >layout tree</link>
+ which is the context of this discussion have been discussed
+ elsewhere. A <link href="keeps.html">previous document</link>
+ discussed data structures which might facilitate the lining of
+ blocks necessary to implement keeps. Here we discuss the
+ similarities between the keep data structures and those
+ required to implement space-specifier resolution.
+ </p>
+ <section>
+ <title>Space-specifiers</title>
+ <note>
+ <strong>4.3 Spaces and Conditionality</strong>
+ ... Space-specifiers occurring in sequence may interact with
+ each other. The constraint imposed by a sequence of
+ space-specifiers is computed by calculating for each
+ space-specifier its associated resolved space-specifier in
+ accordance with their conditionality and precedence.
+ </note>
+ <note>
+ 4.2.5 Stacking Constraints ... The intention of the
+ definitions is to identify areas at any level of the tree
+ which have only space between them.
+ </note>
+ <p>
+ The quotations above are pivotal to understanding the
+ complex discussion of spaces with which they are associated,
+ all of which exists to enable the resolution of adjacent
+ <space>s. It may be helpful to think of <em>stacking
+ constraints</em> as <em><space>s interaction</em> or
+ <em><space>s stacking interaction</em>.
+ </p>
+ </section>
+ <section>
+ <title>Block stacking constraints</title>
+ <p>
+ In the discussion of block stacking constraints in Section
+ 4.2.5, the notion of <em>fence</em> is introduced. For
+ block stacking constraints, a fence is defined as either a
+ reference-area boundary or a non-zero padding or border
+ specification. Fences, however, do not come into play
+ when determining the constraint between siblings. (See
+ <link href="#Figure1">Figure 1</link>.)
+ </p>
+ <p><strong>Figure 1</strong></p><anchor id="Figure1"/>
+ <figure src="block-stacking-constraints.png"
+ alt="block-stacking-constraints.png"/>
+ <note>
+ Figure 1 assumes a block-progression-direction of top to
+ bottom.
+ </note>
+ <p>
+ In <link href="#Figure1">Diagram a)</link>, block A has
+ non-zero padding and borders, in addition to non-zero
+ spaces. Note, however, that the space-after of A is
+ adjacent to the space-before of block P, so borders and
+ padding on these siblings have no impact on the interaction
+ of their <space>s. The stacking constraint A,P is
+ indicated by the red rectangle enclosing the space-after of
+ A and the space-before of P.
+ </p>
+ <p>
+ In <link href="#Figure1">Diagram b)</link>, block B is the
+ first block child of P. The stacking constraint A,P is as
+ before; the stacking constraint P,B is the space-before of
+ B, as indicated by the enclosing magenta rectangle. In this
+ case, however, the non-zero border of P prevents the
+ interaction of the A,P and P,B stacking constraints. There
+ is a <em>fence-before</em> P. The fence is notional; it has
+ no precise location, as the diagram may lead one to believe.
+ </p>
+ <p>
+ In <link href="#Figure1">Diagram c)</link>, because of the
+ zero-width borders and padding on block P, the fence-before
+ P is not present, and the adjacent <space>s of blocks
+ A, P and B are free to interact. In this case, the stacking
+ constraints A,P and P,B are as before, but now there is an
+ additional stacking constraint A,B, represented by the light
+ brown rectangle enclosing the other two stacking
+ constraints.
+ </p>
+ <p>
+ The other form of fence occurs when the parent block is a
+ reference area. Diagram b) of <link href="#Figure2">Figure
+ 2</link> illustrates this situation. Block C is a
+ reference-area, involving a 180 degree change of
+ block-progression-direction (BPD). In the diagram, the
+ inner edge of block C represents the content rectangle, with
+ its changed BPD. The thicker outer edge represents the
+ outer boundary of the padding, border and spaces of C.
+ </p>
+ <p>
+ While not every reference-area will change the
+ inline-progression-direction (IPD) and BPD of an area, no
+ attempt is made to discriminate these cases. A
+ reference-area always a fence. The fence comes into play in
+ analogous circumstances to non-zero borders or padding.
+ Space resolution between a reference area and its siblings
+ is not affected.
+ </p>
+ <p>
+ In the case of <link href="#Figure2">Diagram b)</link>,
+ these are block stacking constraints B,C and C,A. Within
+ the reference-area, bock stacing constraints C,D and E,C are
+ unaffected. However, the fence prevents block stacking
+ constraints such as B,E or D,A. When there is a change of
+ BPD, as <link href="#Figure2">Diagram b)</link> makes
+ visually obvious, it is difficult to imagine which blocks
+ would have such a constraint, and what the ordering of the
+ constraint would be.
+ </p>
+ <p><strong>Figure 2</strong></p>
+ <anchor id="Figure2"/>
+ <figure src="block-stacking-keeps.png"
+ alt="block-stacking-keeps.png"/>
+ </section>
+ <section>
+ <title>Keep relationships between blocks</title>
+ <p>
+ As complicated as space-specifiers become when
+ reference-areas are involved, the keep relationships as
+ described in the <link
+ href="keeps.html#Figure1">keeps</link> document, are
+ unchanged. This is also illustrated in <link
+ href="#Figure2">Figure 2</link>. Diagram b) shows the
+ relative placement of blocks in the rendered output when a
+ 180 degree change of BPD occurs, with blocks D and E
+ stacking in the reverse direction to blocks B and C.
+ Diagram c) shows what happens when the page is too short to
+ accommodate the last block. D is still laid out, but E is
+ deferred to the next page.
+ </p>
+ <p>
+ Note that this rendering reality is expressed directly in
+ the area (and layout) tree view. Consequently, any keep
+ relationships expressed as links threading through the
+ layout tree will not need to be modified to account for
+ reference-area boundaries, as is the case with similar
+ space-specifier edge links. E.g., a keep-with-next
+ condition on block B can be resolved along the path of these
+ links (B->C->D) into a direct relationship of B->D,
+ irrespective of the reference-area boundary.
+ </p>
+ <p>
+ While the same relationships obviously hold when a reference
+ area induces no change of BPD, the situation for BPD changes
+ perpendicular to the parent's BPD may not be so clear. In
+ general, it probably does not make much sense to impose keep
+ conditions across such a boundary, but there seems to be
+ nothing preventing such conditions. They can be dealt with
+ in the same way, i.e., the next leaf block linked in area
+ tree order must be the next laid out. If a keep condition
+ is in place, an attempt must be made to meet it. A number
+ of unusual considerations would apply, e.g. the minimum
+ inline-progression-dimension of the first leaf block within
+ the reference-area as compared to the minimum IPD of
+ subsequent blocks, but <em>prima facie</em>, the essential
+ logic of the keeps links remains.
+ </p>
+ </section>
+ </section>
+ </body>
+</document>
+
--- /dev/null
+<?xml version="1.0" standalone="no"?>
+<!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>Traits</title>
+ <authors>
+ <person name="Peter B. West" email="pbwest@powerup.com.au"/>
+ </authors>
+ </header>
+ <body>
+ <section>
+ <title>Traits</title>
+ <table>
+ <tr>
+ <th>Trait</th>
+ <th>Applies to</th>
+ <th>Refs</th>
+ <th>Derived from</th>
+ </tr>
+ <tr>
+ <th>Common Traits</th>
+ </tr>
+ <tr>
+ <td>block-progression-direction</td>
+ <td>All areas</td>
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice4.html#area-common"
+ >4.2.2 Common Traits</link><br/>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice7.html#writing-mode"
+ >7.27.7 writing-mode</link>
+ </td>
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice7.html#reference-orientation"
+ >7.27.7 reference-orientation</link>
+ </td>
+ </tr>
+ <tr>
+ <td>inline-progression-direction</td>
+ <td>All areas</td>
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice4.html#area-common"
+ >4.2.2 Common Traits</link><br/>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice7.html#writing-mode"
+ >7.27.7 writing-mode</link>
+ </td>
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice7.html#reference-orientation"
+ >7.27.7 reference-orientation</link>
+ </td>
+ </tr>
+ <tr>
+ <td>shift-direction</td>
+ <td>Inline areas</td>
+ </tr>
+ <tr>
+ <td>glyph-orientation</td>
+ <td>Glyph-areas</td>
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice4.html#area-common"
+ >4.2.2 Common Traits</link><br/>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice4.html#area-glyph"
+ >4.6.2 Glyph-areas</link><br/>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice4.html#area-linebuild"
+ >4.7.2 Line-building</link><br/>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice4.html#rend-intrinsic"
+ >4.9.5 Intrinsic Marks</link><br/>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice7.html#font-model"
+ >7.8.1 Fonts and Font Data</link><br/>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice7.html#writing-mode-related"
+ >7.27 Writing-mode-related Properties</link>
+ </td>
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice7.html#glyph-orientation-horizontal"
+ >7.27.2 glyph-orientation-horizontal</link><br/>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice7.html#glyph-orientation-vertical"
+ >7.27.3 glyph-orientation-vertical</link><br/>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice7.html#direction"
+ >7.27.1 direction</link><br/>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice7.html#writing-mode"
+ >7.27.7 writing-mode</link>
+ </td>
+ </tr>
+ <tr>
+ <td>is-reference-area</td>
+ <td>All areas</td>
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice5.html#section-N6691-Non-property-Based-Trait-Generation"
+ >5.6 Non-property Based Trait Generation</link>
+ </td>
+ <td>
+ Set "true" on:<br/>
+ simple-page-master<br/>
+ title<br/>
+ region-body<br/>
+ region-before<br/>
+ region-after<br/>
+ region-start<br/>
+ region-end<br/>
+ block-container<br/>
+ inline-container<br/>
+ table<br/>
+ table-caption<br/>
+ table-cell
+ </td>
+ </tr>
+ <tr>
+ <td>is-viewport-area</td>
+ <td></td>
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice4.html#area-common"
+ >4.2.2 Common Traits</link>
+ </td>
+ </tr>
+ <tr>
+ <td>top-position</td>
+ </tr>
+ <tr>
+ <td>bottom-position</td>
+ </tr>
+ <tr>
+ <td>left-position</td>
+ </tr>
+ <tr>
+ <td>right-position</td>
+ </tr>
+ <tr>
+ <td>left-offset</td>
+ </tr>
+ <tr>
+ <td>top-offset</td>
+ </tr>
+ <tr>
+ <td>is-first</td>
+ </tr>
+ <tr>
+ <td>is-last</td>
+ </tr>
+ <tr>
+ <td>generated-by</td>
+ </tr>
+ <tr>
+ <td>returned-by</td>
+ </tr>
+ <tr>
+ <td>nominal-font</td>
+ </tr>
+ <tr>
+ <td>blink</td>
+ <td></td>
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice5.html#refine-text-decoration"
+ >5.5.6 Text-decoration Property
+ </link>
+ </td>
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice7.html#text-decoration"
+ >7.16.4 "text-decoration"
+ </link>
+ </td>
+ </tr>
+ <tr>
+ <td>underline-score</td>
+ <td></td>
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice5.html#refine-text-decoration"
+ >5.5.6 Text-decoration Property
+ </link>
+ </td>
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice7.html#text-decoration"
+ >7.16.4 "text-decoration"
+ </link>
+ </td>
+ </tr>
+ <tr>
+ <td>underline-score-color</td>
+ <td></td>
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice5.html#refine-text-decoration"
+ >5.5.6 Text-decoration Property
+ </link>
+ </td>
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice7.html#text-decoration"
+ >7.16.4 "text-decoration"
+ </link>
+ </td>
+ </tr>
+ <tr>
+ <td>overline-score</td>
+ <td></td>
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice5.html#refine-text-decoration"
+ >5.5.6 Text-decoration Property
+ </link>
+ </td>
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice7.html#text-decoration"
+ >7.16.4 "text-decoration"
+ </link>
+ </td>
+ </tr>
+ <tr>
+ <td>overline-score-color</td>
+ <td></td>
+
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice5.html#refine-text-decoration"
+ >5.5.6 Text-decoration Property
+ </link>
+ </td>
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice7.html#text-decoration"
+ >7.16.4 "text-decoration"
+ </link>
+ </td>
+ </tr>
+ <tr>
+ <td>through-score</td>
+ <td></td>
+
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice5.html#refine-text-decoration"
+ >5.5.6 Text-decoration Property
+ </link>
+ </td>
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice7.html#text-decoration"
+ >7.16.4 "text-decoration"
+ </link>
+ </td>
+ </tr>
+ <tr>
+ <td>through-score-color</td>
+ <td></td>
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice5.html#refine-text-decoration"
+ >5.5.6 Text-decoration Property
+ </link>
+ </td>
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice7.html#text-decoration"
+ >7.16.4 "text-decoration"
+ </link>
+ </td>
+ </tr>
+ <tr>
+ <th>Other Indirectly Derived Traits</th>
+ </tr>
+ <tr>
+ <td>alignment-point</td>
+ <td/>
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice4.html#area-intro"
+ >4.1 Introduction</link>
+ </td>
+ </tr>
+ <tr>
+ <td>alignment-baseline</td>
+ <td/>
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice4.html#area-intro"
+ >4.1 Introduction</link>
+ </td>
+ </tr>
+ <tr>
+ <td>baseline-shift</td>
+ <td/>
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice4.html#area-intro"
+ >4.1 Introduction</link>
+ </td>
+ </tr>
+ <tr>
+ <td>dominant-baseline-identifier</td>
+ <td/>
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice4.html#area-intro"
+ >4.1 Introduction</link>
+ </td>
+ </tr>
+ <tr>
+ <td>actual-baseline-table</td>
+ <td/>
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice4.html#area-intro"
+ >4.1 Introduction</link>
+ </td>
+ </tr>
+ <tr>
+ <td>start-intrusion-adjustment</td>
+ <td/>
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice4.html#area-intro"
+ >4.1 Introduction</link>
+ </td>
+ </tr>
+ <tr>
+ <td>end-intrusion-adjustment</td>
+ <td/>
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice4.html#area-intro"
+ >4.1 Introduction</link>
+ </td>
+ </tr>
+ <tr>
+ <td>page-number</td>
+ <td/>
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice4.html#area-intro"
+ >4.1 Introduction</link>
+ </td>
+ </tr>
+ <tr>
+ <td>script</td>
+ <td/>
+ <td>
+ <link href=
+ "http://www.w3.org/TR/xsl/slice4.html#area-intro"
+ >4.1 Introduction</link>
+ </td>
+ </tr>
+ </table>
+ </section>
+ </body>
+</document>
+
--- /dev/null
+<?xml version="1.0" standalone="no"?>
+<!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>User agent refs</title>
+ <authors>
+ <person name="Peter B. West" email="pbwest@powerup.com.au"/>
+ </authors>
+ </header>
+ <body>
+ <section>
+ <title>User Agent references in XSLFO</title>
+ <section>
+ <title>4.9.2 Viewport Geometry</title>
+ <p>
+ If the block-progression-dimension of the reference-area is
+ larger than that of the viewport-area and the overflow trait
+ for the reference-area is scroll, then the
+ inline-scroll-amount and block-scroll-amount are determined
+ by a scrolling mechanism, if any, provided by the
+ <strong>user agent</strong>. Otherwise, both are zero.
+ </p>
+ </section>
+ <section>
+ <title>5.1.3 Actual Values</title>
+ <p>
+ A computed value is in principle ready to be used, but a
+ user agent may not be able to make use of the value in a
+ given environment. For example, a <strong>user
+ agent</strong> may only be able to render borders with
+ integer pixel widths and may, therefore, have to adjust the
+ computed width to an integral number of media pixels.
+ </p>
+ </section>
+ <section>
+ <title>5.5.7 Font Properties</title>
+ <p>
+ There is no XSL mechanism to specify a particular font;
+ instead, a selected font is chosen from the fonts available
+ to the <strong>User Agent</strong> based on a set of
+ selection criteria. The selection criteria are the following
+ font properties: "font-family", "font-style",
+ "font-variant", "font-weight", "font-stretch", and
+ "font-size", plus, for some formatting objects, one or more
+ characters.
+ </p>
+ </section>
+ <section>
+ <title>5.9.13.1 Pixels</title>
+ <p>
+ If the <strong>User Agent</strong> chooses a measurement for
+ a 'px' that does not match an integer number of device dots
+ in each axis it may produce undesirable effects...
+ </p>
+ </section>
+ <section>
+ <title>5.10.4 Property Value Functions</title>
+ <section>
+ <title>Function: object merge-property-values( NCName)</title>
+ <p>
+ The merge-property-values function returns a value of the
+ property whose name matches the argument, or if omitted
+ for the property for which the expression is being
+ evaluated. The value returned is the specified value on
+ the last fo:multi-property-set, of the parent
+ fo:multi-properties, that applies to the <strong>User
+ Agent</strong> state. If there is no such value, the
+ computed value of the parent fo:multi-properties is
+ returned...
+ </p>
+ <p>
+ The test for applicability of a <strong>User
+ Agent</strong> state is specified using the "active-state"
+ property.
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>6.3 Formatting Objects Summary</title>
+ <section>
+ <title>multi-property-set</title>
+ <p>
+ The fo:multi-property-set is used to specify an
+ alternative set of formatting properties that, dependent
+ on a <strong>User Agent</strong> state, are applied to the
+ content.
+ </p>
+ </section>
+ <section>
+ <title>title</title>
+ <p>
+ The fo:title formatting object is used to associate a
+ title with a given page-sequence. This title may be used
+ by an interactive <strong>User Agent</strong> to identify
+ the pages. For example, the content of the fo:title can be
+ formatted and displayed in a "title" window or in a "tool
+ tip".
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>6.4.1.2 Page-masters</title>
+ <p>
+ ... When pages are used with a <strong>User Agent</strong>
+ such as a Web browser, it is common that the each document
+ has only one page. The viewport used to view the page
+ determines the size of the page. When pages are placed on
+ non-interactive media, such as sheets of paper, pages
+ correspond to one or more of the surfaces of the paper.
+ </p>
+ </section>
+ <section>
+ <title>6.4.20 fo:title</title>
+ <section>
+ <title>Common Usage:</title>
+ <p>
+ ... This title may be used by an interactive <strong>User
+ Agent</strong> to identify the pages.
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>6.6.3 fo:character</title>
+ <section>
+ <title>Constraints:</title>
+ <p>
+ The dimensions of the areas are determined by the font
+ metrics for the glyph.
+ </p>
+ <p>
+ When formatting an fo:character with a
+ "treat-as-word-space" value of "true", the <strong>User
+ Agent</strong> may use a different method for determining
+ the inline-progression-dimension of the area.
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>6.9 Dynamic Effects: Link and Multi Formatting
+ Objects</title>
+ <section>
+ <title>6.9.1 Introduction</title>
+ <p>
+ Dynamic effects, whereby user actions (including
+ <strong>User Agent</strong> state) can influence the
+ behavior and/or representation of portions of a document,
+ can be achieved through the use of the formatting objects
+ included in this section:
+ </p>
+ <ul>
+ <li>One-directional single-target links.</li>
+ <li>
+ The ability to switch between the display of two or more
+ formatting object subtrees. This can be used for, e.g.,
+ expandable/collapsible table of contents, display of an
+ icon or a full table or graphic.
+ </li>
+ <li>
+ The ability to switch between different property values,
+ such as color or font-weight, depending on a
+ <strong>User Agent</strong> state, such as "hover".
+ </li>
+ </ul>
+ </section>
+ </section>
+ <section>
+ <title>6.10 Out-of-Line Formatting Objects</title>
+ <section>
+ <title>6.10.1.3 Conditional Sub-Regions</title>
+ <p>
+ ... There may be limits on how much space conditionally
+ generated areas can borrow from the
+ region-reference-area. It is left to the <strong>user
+ agent</strong> to decide these limits.
+ </p>
+ <p>
+ ... An interactive <strong>user agent</strong> may choose
+ to create "hot links" to the footnotes from the
+ footnote-citation, or create "hot links" to the
+ before-floats from an implicit citation, instead of
+ realizing conditional sub-regions.
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>6.10.2 fo:float</title>
+ <section>
+ <title>Constraints:</title>
+ <p>
+ ... The <strong>user agent</strong> may make its own
+ determination, after taking into account the intrusion
+ adjustments caused by one or more overlapping side-floats,
+ that the remaining space in the
+ inline-progression-direction is insufficient for the next
+ side-float or normal block-area. The <strong>user
+ agent</strong> may address this by causing the next
+ side-float or normal block-area to "clear" one of the
+ relevant side-floats, as described in the "clear" property
+ description, so the intrusion adjustment is sufficiently
+ reduced. Of the side-floats that could be cleared to meet
+ this constraint, the side-float that is actually cleared
+ must be the one whose after-edge is closest to the
+ before-edge of the parent reference-area.
+ </p>
+ <p>
+ The <strong>user agent</strong> may determine sufficiency
+ of space by using a fixed length, or by some heuristic
+ such as whether an entire word fits into the available
+ space, or by some combination, in order to handle text and
+ images.
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>6.10.3 fo:footnote</title>
+ <section>
+ <title>Constraints:</title>
+ <p>
+ ... The second block-area and any additional block-areas
+ returned by an fo:footnote must be placed on the
+ immediately subsequent pages to the page containing the
+ first block-area returned by the fo:footnote, before any
+ other content is placed. If a subsequent page does not
+ contain a region-body, the <strong>user agent</strong>
+ must use the region-master of the last page that did
+ contain a region-body to hold the additional block-areas.
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>7.3 Reference Rectangle for Percentage Computations</title>
+ <p>...</p>
+ <section>
+ <title>Exceptions ...</title>
+ <p>
+ 5. When the absolute-position is "fixed", the containing
+ block is defined by the nearest ancestor viewport area. If
+ there is no ancestor viewport area, the containing block
+ is defined by the <strong>user agent</strong>.
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>7.6.5 "pause-after" 7.6.6 "pause-before" 7.6.17 "voice-family"</title>
+ <p>Initial: depends on <strong>user agent</strong></p>
+ </section>
+ <section>
+ <title>7.7.1 "background-attachment"</title>
+ <section>
+ <title>fixed</title>
+ <p>
+ ... <strong>User agents</strong> may treat fixed as
+ scroll. However, it is recommended they interpret fixed
+ correctly, at least for the HTML and BODY elements, since
+ there is no way for an author to provide an image only for
+ those browsers that support fixed.
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>7.7.9 "border-before-width"</title>
+ <section>
+ <title><length-conditional></title>
+ <p>
+ ... If border-before-width is specified using one of the
+ width keywords the .conditional component is set to
+ "discard" and the .length component to a <strong>User
+ Agent</strong> dependent length.
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>7.7.19 "border-top-color"</title>
+ <section>
+ <title><color></title>
+ <p>
+ ... If an element's border color is not specified with a
+ "border" property, <strong>user agents</strong> must use
+ the value of the element's "color" property as the
+ computed value for the border color.
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>7.7.20 "border-top-style"</title>
+ <p>
+ Conforming HTML <strong>user agents</strong> may interpret
+ 'dotted', 'dashed', 'double', 'groove', 'ridge', 'inset',
+ and 'outset' to be 'solid'.
+ </p>
+ </section>
+ <section>
+ <title>7.7.21 "border-top-width"</title>
+ <section>
+ <title>thin ... medium ... thick ...</title>
+ <p>
+ ... The interpretation of the first three values depends
+ on the <strong>user agent</strong>.
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>7.8.2 "font-family"</title>
+ <p>Initial: depends on <strong>user agent</strong></p>
+ </section>
+ <section>
+ <title>7.8.3 "font-selection-strategy"</title>
+ <p>
+ There is no XSL mechanism to specify a particular font;
+ instead, a selected font is chosen from the fonts available
+ to the <strong>User Agent</strong> based on a set of
+ selection criteria. The selection criteria are the following
+ font properties: "font-family", "font-style",
+ "font-variant", "font-weight", "font-stretch", and
+ "font-size", plus, for some formatting objects, one or more
+ characters.
+ </p>
+ <p>
+ ... This fallback may be to seek a match using a
+ <strong>User Agent</strong> default "font-family", or it may
+ be a more elaborate fallback strategy where, for example,
+ "Helvetica" would be used as a fallback for "Univers".
+ </p>
+ <p>
+ If no match has been found for a particular character, there
+ is no selected font and the <strong>User Agent</strong>
+ should provide a visual indication that a character is not
+ being displayed (for example, using the 'missing character'
+ glyph).
+ </p>
+ </section>
+ <section>
+ <title>7.8.4 "font-size"</title>
+ <section>
+ <title><absolute-size></title>
+ <p>
+ An <absolute-size> keyword refers to an entry in a
+ table of font sizes computed and kept by the <strong>user
+ agent</strong>. Possible values are:<br/>[ xx-small |
+ x-small | small | medium | large | x-large | xx-large ]
+ </p>
+ </section>
+ <section>
+ <title><relative-size></title>
+ <p>
+ A <relative-size> keyword is interpreted relative to
+ the table of font sizes and the font size of the parent
+ element. Possible values are:<br/>[ larger | smaller
+ ]<br/>For example, if the parent element has a font size
+ of "medium", a value of "larger" will make the font size
+ of the current element be "large". If the parent element's
+ size is not close to a table entry, the <strong>user
+ agent</strong> is free to interpolate between table
+ entries or round off to the closest one. The <strong>user
+ agent</strong> may have to extrapolate table values if the
+ numerical value goes beyond the keywords.
+ </p>
+ </section>
+ <section>
+ <title><length></title>
+ <p>
+ A length value specifies an absolute font size (that is
+ independent of the <strong>user agent</strong>'s font
+ table).
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>7.8.8 "font-variant"</title>
+ <section>
+ <title>small-caps</title>
+ <p>
+ ... If a genuine small-caps font is not available,
+ <strong>user agents</strong> should simulate a small-caps
+ font...
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>7.8.9 "font-weight"</title>
+ <section>
+ <title>XSL modifications to the CSS definition:</title>
+ <p>
+ ... The association of other weights within a family to
+ the numerical weight values is intended only to preserve
+ the ordering of weights within that family. <strong>User
+ agents</strong> must map names to values in a way that
+ preserves visual order; a face mapped to a value must not
+ be lighter than faces mapped to lower values. There is no
+ guarantee on how a <strong>user agent</strong> will map
+ fonts within a family to weight values. However, the
+ following heuristics...
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>7.13.1 "alignment-adjust"</title>
+ <section>
+ <title>auto</title>
+ <p>
+ ... If the baseline-identifier does not exist in the
+ baseline-table for the glyph or other inline-area, then
+ the <strong>User Agent</strong> may either use heuristics
+ to determine where that missing baseline would be or may
+ use the dominant-baseline as a fallback.
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>7.13.3 "baseline-shift"</title>
+ <section>
+ <title>sub/super</title>
+ <p>
+ ... Because in most fonts the subscript position is
+ normally given relative to the "alphabetic" baseline, the
+ <strong>User Agent</strong> may compute the effective
+ position for sub/superscripts <em>[sub: spec typo!]</em>
+ when some other baseline is dominant. ... If there is no
+ applicable font data the <strong>User Agent</strong> may
+ use heuristics to determine the offset.
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>7.13.5 "dominant-baseline"</title>
+ <p>
+ ... If there is no baseline-table in the nominal font or if
+ the baseline-table lacks an entry for the desired baseline,
+ then the <strong>User Agent</strong> may use heuristics to
+ determine the position of the desired baseline.
+ </p>
+ </section>
+ <section>
+ <title>7.14.11 "scaling-method"</title>
+ <section>
+ <title>auto</title>
+ <p>
+ The <strong>User Agent</strong> is free to choose either
+ resampling, integer scaling, or any other scaling method.
+ </p>
+ </section>
+ <section>
+ <title>integer-pixels</title>
+ <p>
+ The <strong>User Agent</strong> should scale the image
+ such that each pixel in the original image is scaled to
+ the nearest integer number of device-pixels that yields an
+ image less-then-or-equal-to the image size derived from
+ the content-height, content-width, and scaling properties.
+ </p>
+ </section>
+ <section>
+ <title>resample-any-method</title>
+ <p>
+ The <strong>User Agent</strong> should resample the
+ supplied image to provide an image that fills the size
+ derived from the content-height, content-width, and
+ scaling properties. The <strong>user agent</strong> may
+ use any sampling method.
+ </p>
+ </section>
+ <p>
+ ... This is defined as a preference to allow the
+ <strong>user agent</strong> the flexibility to adapt to
+ device limitations and to accommodate over-constrained
+ situations involving min/max dimensions and scale factors.
+ </p>
+ </section>
+ <section>
+ <title>7.14.12 "width"</title>
+ <p>
+ ... The width of a replaced element's box is intrinsic and
+ may be scaled by the <strong>user agent </strong> if the
+ value of this property is different than 'auto'.
+ </p>
+ </section>
+ <section>
+ <title>7.15.4 "line-height"</title>
+ <section>
+ <title>normal</title>
+ <p>
+ Tells <strong>user agents</strong> to set the computed
+ value to a "reasonable" value based on the font size of
+ the element.
+ </p>
+ </s3>
+ <p>
+ ... When an element contains text that is rendered in more
+ than one font, <strong>user agents</strong> should determine
+ the "line-height" value according to the largest font size.
+ </p>
+ </section>
+ <section>
+ <title>7.15.9 "text-align"</title>
+ <p>
+ ... The actual justification algorithm used is <strong>user
+ agent</strong> and written language dependent.<br/>
+ Conforming <strong>user agents</strong> may interpret the
+ value 'justify' as 'left' or 'right', depending on whether
+ the element's default writing direction is left-to-right or
+ right-to-left, respectively.
+ </p>
+ </section>
+ <section>
+ <title>7.15.11 "text-indent"</title>
+ <p>
+ ... <strong>User agents</strong> should render this
+ indentation as blank space.
+ </p>
+ </section>
+ <section>
+ <title>7.16.2 "letter-spacing"</title>
+ <section>
+ <title>normal</title>
+ <p>
+ The spacing is the normal spacing for the current
+ font. This value allows the <strong>user agent</strong> to
+ alter the space between characters in order to justify
+ text.
+ </p>
+ </section>
+ <section>
+ <title><length></title>
+ <p>
+ This value indicates inter-character space in addition to
+ the default space between characters. Values may be
+ negative, but there may be implementation-specific
+ limits. <strong>User agents</strong> may not further
+ increase or decrease the inter-character space in order to
+ justify text.
+ </p>
+ </section>
+ <p>
+ Character-spacing algorithms are <strong>user agent</strong>
+ dependent. Character spacing may also be influenced by
+ justification (see the "text-align" property).<br/> When the
+ resultant space between two characters is not the same as
+ the default space, <strong>user agents</strong> should not
+ use ligatures.<br/> Conforming <strong>user agents</strong>
+ may consider the value of the 'letter-spacing' property to
+ be 'normal'.
+ </p>
+ <section>
+ <title>XSL modifications to the CSS definition:</title>
+ <p>
+ ... For "normal": .optimum = "the normal spacing for the
+ current font" / 2, .maximum = auto, .minimum = auto,
+ .precedence = force, and .conditionality = discard. A
+ value of auto for a component implies that the limits are
+ <strong>User Agent</strong> specific.
+ </p>
+ <p>
+ ... The CSS statement that "Conforming <strong>user
+ agents</strong> may consider the value of the
+ 'letter-spacing' property to be 'normal'." does not apply
+ in XSL, if the <strong>User Agent</strong> implements the
+ "Extended" property set.
+ </p>
+ <p>
+ ... The algorithm for resolving the adjusted values
+ between word spacing and letter spacing is <strong>User
+ Agent</strong> dependent.
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>7.16.4 "text-decoration"</title>
+ <p>
+ ... If the element has no content or no text content (e.g.,
+ the IMG element in HTML), <strong>user agents</strong> must
+ ignore this property.
+ </p>
+ <section>
+ <title>blink</title>
+ <p>
+ ... Conforming <strong>user agents</strong> are not
+ required to support this value.
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>7.16.6 "text-transform"</title>
+ <p>
+ ... Conforming <strong>user agents</strong> may consider the
+ value of "text-transform" to be "none" for characters that
+ are not from the ISO Latin-1 repertoire and for elements in
+ languages for which the transformation is different from
+ that specified by the case-conversion tables of Unicode or
+ ISO 10646.
+ </p>
+ </section>
+ <section>
+ <title>7.16.8 "word-spacing"</title>
+ <p>
+ ... Word spacing algorithms are <strong>user
+ agent</strong>-dependent.
+ </p>
+ <section>
+ <title>XSL modifications to the CSS definition:</title>
+ <p>
+ ... The algorithm for resolving the adjusted values
+ between word spacing and letter spacing is <strong>User
+ Agent</strong> dependent.
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>7.17.1 "color"</title>
+ <p>Initial: depends on <strong>user agent</strong></p>
+ </section>
+ <section>
+ <title>7.17.3 "rendering-intent"</title>
+ <section>
+ <title>auto</title>
+ <p>
+ This is the default behavior. The <strong>User
+ Agent</strong> determines the best intent based on the
+ content type. For image content containing an embedded
+ profile, it shall be assumed that the intent specified
+ within the profile is the desired intent. Otherwise, the
+ <strong>user agent</strong> shall use the current profile
+ and force the intent, overriding any intent that might be
+ stored in the profile itself.
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>7.20.2 "overflow"</title>
+ <section>
+ <title>scroll</title>
+ <p>
+ This value indicates that the content is clipped and that
+ if the <strong>user agent</strong> uses a scrolling
+ mechanism that is visible on the screen (such as a scroll
+ bar or a panner), that mechanism should be displayed for a
+ box whether or not any of its content is clipped.
+ </p>
+ </section>
+ <section>
+ <title>auto</title>
+ <p>
+ The behavior of the "auto" value is <strong>user
+ agent</strong> dependent, but should cause a scrolling
+ mechanism to be provided for overflowing boxes.
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>7.21.2 "leader-pattern"</title>
+ <section>
+ <title>dots</title>
+ <p>
+ ... The choice of dot character is dependent on the
+ <strong>user agent</strong>.
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>7.21.4 "leader-length"</title>
+ <p>
+ ... <strong>User agents</strong> may choose to use the value
+ of "leader-length.optimum" to determine where to break the
+ line, then use the minimum and maximum values during line
+ justification.
+ </p>
+ </section>
+ <section>
+ <title>7.25.11 "media-usage"</title>
+ <section>
+ <title>auto</title>
+ <p>
+ The <strong>User Agent</strong> determines which value of
+ "media-usage" (other than the "auto" value) is used. The
+ <strong>User Agent</strong> may consider the type of media
+ on which the presentation is to be placed in making this
+ determination.<br/> NOTE:<br/> For example, the
+ <strong>User Agent </strong> could use the following
+ decision process. If the media is not continuous and is of
+ fixed bounded size, then the "paginate" (described below)
+ is used. Otherwise, the "bounded-in-one-dimension" is
+ used.
+ </p>
+ </section>
+ <section>
+ <title>bounded-in-one-dimension</title>
+ <p>
+ ... It is an error if more or less than one of
+ "page-height" or "page-width" is specified on the first
+ page master that is used. The <strong>User Agent</strong>
+ may recover as follows:...
+ </p>
+ </section>
+ <section>
+ <title>unbounded</title>
+ <p>
+ Only one page is generated per fo:page-sequence descendant
+ from the fo:root. Neither "page-height" nor "page-width"
+ may be specified on any page master that is used. If a
+ value is specified for either property, it is an error and
+ a <strong>User Agent</strong> may recover by ignoring the
+ specified value. ...
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>7.25.13 "page-height"</title>
+ <section>
+ <title>auto</title>
+ <p>
+ The "page-height" shall be determined, in the case of
+ continuous media, from the size of the <strong>User
+ Agent</strong> window...
+ </p>
+ </section>
+ <section>
+ <title>NOTE:</title>
+ <p>
+ A <strong>User Agent</strong> may provide a way to declare
+ the media for which formatting is to be done. This may be
+ different from the media on which the formatted result is
+ viewed. For example, a browser <strong>User Agent</strong>
+ may be used to preview pages that are formatted for sheet
+ media. In that case, the size calculation is based on the
+ media for which formatting is done rather than the media
+ being currently used.
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>7.25.15 "page-width"</title>
+ <section>
+ <title>auto</title>
+ <p>
+ The "page-width" shall be determined, in the case of
+ continuous media, from the size of the <strong>User
+ Agent</strong> window...
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>7.26.5 "border-separation"</title>
+ <s3 title="<length-bp-ip-direction>">
+ <p>
+ ... Rows, columns, row groups, and column groups cannot
+ have borders (i.e., <strong>user agents</strong> must
+ ignore the border properties for those elements).
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>7.26.7 "caption-side"</title>
+ <p>
+ ... For a caption that is on the left or right side of a
+ table box, on the other hand, a value other than "auto" for
+ "width" sets the width explicitly, but "auto" tells the
+ <strong>user agent</strong> to chose a "reasonable width".
+ </p>
+ </section>
+ <section>
+ <title>7.27.2 "glyph-orientation-horizontal"</title>
+ <section>
+ <title><angle></title>
+ <p>
+ ... The <strong>User Agent</strong> shall round the value
+ of the angle to the closest of the permitted values.
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>7.27.3 "glyph-orientation-vertical"</title>
+ <section>
+ <title>auto</title>
+ <p>
+ ... The determination of which characters should be
+ auto-rotated may vary across <strong>User Agents</strong>.
+ </p>
+ </section>
+ <section>
+ <title><angle></title>
+ <p>
+ ... The <strong>User Agent</strong> shall round the value
+ of the angle to the closest of the permitted values.
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>7.27.6 "unicode-bidi"</title>
+ <section>
+ <title>XSL modifications to the CSS definition:</title>
+ <p>
+ ... Fallback:<br/> If it is not possible to present the
+ characters in the correct order, then the
+ <strong>UserAgent </strong> should display either a
+ 'missing character' glyph or display some indication that
+ the content cannot be correctly rendered.
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>7.28.1 "content-type"</title>
+ <p>
+ ... This property specifies the content-type and may be used
+ by a <strong>User Agent</strong> to select a rendering
+ processor for the object.
+ </p>
+ <section>
+ <title>auto</title>
+ <p>
+ No identification of the content-type. The <strong>User
+ Agent</strong> may determine it by "sniffing" or by other
+ means.
+ </p>
+ </section>
+ </section>
+ <section>
+ <title>7.29.5 "border-color"</title>
+ <p>
+ ... If an element's border color is not specified with a
+ "border" property, <strong>user agents</strong> must use the
+ value of the element's "color" property as the computed
+ value for the border color.
+ </p>
+ </section>
+ <section>
+ <title>7.29.9 "border-spacing"</title>
+ <p>
+ ... Rows, columns, row groups, and column groups cannot have
+ borders (i.e., <strong>user agents</strong> must ignore the
+ border properties for those elements).
+ </p>
+ </section>
+ <section>
+ <title>7.29.13 "font"</title>
+ <p>
+ ... If no font with the indicated characteristics exists on
+ a given platform, the <strong>user agent</strong> should
+ either intelligently substitute (e.g., a smaller version of
+ the "caption" font might be used for the "small-caption"
+ font), or substitute a <strong>user agent</strong> default
+ font.
+ </p>
+ </section>
+ <section>
+ <title>7.29.19 "pause"</title>
+ <p>Initial: depends on <strong>user agent</strong></p>
+ </section>
+ <section>
+ <title>7.29.21 "size"</title>
+ <p>
+ ... Relative page boxes allow <strong>user agents</strong>
+ to scale a document and make optimal use of the target size.
+ </p>
+ <p>
+ ... <strong>User agents</strong> may allow users to control
+ the transfer of the page box to the sheet (e.g., rotating an
+ absolute page box that's being printed).
+ </p>
+ <ul>
+ <li>
+ Rendering page boxes that do not fit a target sheet<br/>
+ If a page box does not fit the target sheet dimensions,
+ the <strong>user agent</strong> may choose to:
+ <ul>
+ <li>
+ Rotate the page box 90 degrees if this will make the
+ page box fit.
+ </li>
+ <li>Scale the page to fit the target.</li>
+ </ul>
+ The <strong>user agent</strong> should consult the user
+ before performing these operations.
+ </li>
+ <li>
+ Positioning the page box on the sheet<br/> When the page
+ box is smaller than the target size, the <strong>user
+ agent</strong> is free to place the page box anywhere on
+ the sheet.
+ </li>
+ </ul>
+ </section>
+ <section>
+ <title>7.29.23 "white-space"</title>
+ <section>
+ <title>normal</title>
+ <p>
+ This value directs <strong>user agents</strong> to
+ collapse sequences of whitespace, and break lines as
+ necessary to fill line boxes. ...
+ </p>
+ </section>
+ <section>
+ <title>pre</title>
+ <p>
+ This value prevents <strong>user agents</strong> from
+ collapsing sequences of whitespace. ...
+ </p>
+ </section>
+ <p>
+ ... Conforming <strong>user agents</strong> may ignore the
+ 'white-space' property in author and user style sheets but
+ must specify a value for it in the default style sheet.
+ </p>
+ </section>
+ </section>
+ </body>
+</document>
+
--- /dev/null
+<?xml version="1.0" standalone="no"?>
+<!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>Integrating XML Parsing</title>
+ <authors>
+ <person name="Peter B. West" email="pbwest@powerup.com.au"/>
+ </authors>
+ </header>
+ <body>
+ <section>
+ <title>An alternative parser integration</title>
+ <p>
+ This note proposes an alternative method of integrating the
+ output of the SAX parsing of the Flow Object (FO) tree into
+ FOP processing. The pupose of the proposed changes is to
+ provide for better decomposition of the process of analysing
+ and rendering an fo tree such as is represented in the output
+ from initial (XSLT) processing of an XML source document.
+ </p>
+ <section>
+ <title>Structure of SAX parsing</title>
+ <p>
+ Figure 1 is a schematic representation of the process of SAX
+ parsing of an input source. SAX parsing involves the
+ registration, with an object implementing the
+ <code>XMLReader</code> interface, of a
+ <code>ContentHandler</code> which contains a callback
+ routine for each of the event types encountered by the
+ parser, e.g., <code>startDocument()</code>,
+ <code>startElement()</code>, <code>characters()</code>,
+ <code>endElement()</code> and <code>endDocument()</code>.
+ Parsing is initiated by a call to the <code>parser()</code>
+ method of the <code>XMLReader</code>. Note that the call to
+ <code>parser()</code> and the calls to individual callback
+ methods are synchronous: <code>parser()</code> will only
+ return when the last callback method returns, and each
+ callback must complete before the next is called.<br/><br/>
+ <strong>Figure 1</strong>
+ </p>
+ <figure src="SAXParsing.png" alt="SAX parsing schematic"/>
+ <p>
+ In the process of parsing, the hierarchical structure of the
+ original FO tree is flattened into a number of streams of
+ events of the same type which are reported in the sequence
+ in which they are encountered. Apart from that, the API
+ imposes no structure or constraint which expresses the
+ relationship between, e.g., a startElement event and the
+ endElement event for the same element. To the extent that
+ such relationship information is required, it must be
+ managed by the callback routines.
+ </p>
+ <p>
+ The most direct approach here is to build the tree
+ "invisibly"; to bury within the callback routines the
+ necessary code to construct the tree. In the simplest case,
+ the whole of the FO tree is built within the call to
+ <code>parser()</code>, and that in-memory tree is subsequently
+ processed to (a) validate the FO structure, and (b)
+ construct the Area tree. The problem with this approach is
+ the potential size of the FO tree in memory. FOP has
+ suffered from this problem in the past.
+ </p>
+ </section>
+ <section>
+ <title>Cluttered callbacks</title>
+ <p>
+ On the other hand, the callback code may become increasingly
+ complex as tree validation and the triggering of the Area
+ tree processing and subsequent rendering is moved into the
+ callbacks, typically the <code>endElement()</code> method.
+ In order to overcome acute memory problems, the FOP code was
+ recently modified in this way, to trigger Area tree building
+ and rendering in the <code>endElement()</code> method, when
+ the end of a page-sequence was detected.
+ </p>
+ <p>
+ The drawback with such a method is that it becomes difficult
+ to detemine the order of events and the circumstances in
+ which any particular processing events are triggered. When
+ the processing events are inherently self-contained, this is
+ irrelevant. But the more complex and context-dependent the
+ relationships are among the processing elements, the more
+ obscurity is engendered in the code by such "side-effect"
+ processing.
+ </p>
+ </section>
+ <section>
+ <title>From passive to active parsing</title>
+ <p>
+ In order to solve the simultaneous problems of exposing the
+ structure of the processing and minimising in-memory
+ requirements, the experimental code separates the parsing of
+ the input source from the building of the FO tree and all
+ downstream processing. The callback routines become
+ minimal, consisting of the creation and buffering of
+ <code>XMLEvent</code> objects as a <em>producer</em>. All
+ of these objects are effectively merged into a single event
+ stream, in strict event order, for subsequent access by the
+ FO tree building process, acting as a
+ <em>consumer</em>. In itself, this does not reduce the
+ footprint. This occurs when the approach is generalised to
+ modularise FOP processing.<br/><br/> <strong>Figure 2</strong>
+ </p>
+ <figure src="XML-event-buffer.png" alt="XML event buffer"/>
+ <p>
+ The most useful change that this brings about is the switch
+ from <em>passive</em> to <em>active</em> XML element
+ processing. The process of parsing now becomes visible to
+ the controlling process. All local validation requirements,
+ all object and data structure building, is initiated by the
+ process(es) <em>get</em>ting from the queue - in the case
+ above, the FO tree builder.
+ </p>
+ </section>
+ <section>
+ <title>XMLEvent methods</title>
+ <anchor id="XMLEvent-methods"/>
+ <p>
+ The experimental code uses a class <strong>XMLEvent</strong>
+ to provide the objects which are placed in the queue.
+ <em>XMLEvent</em> includes a variety of methods to access
+ elements in the queue. Namespace URIs encountered in
+ parsing are maintined in a <code>static</code>
+ <code>HashMap</code> where they are associated with a unique
+ integer index. This integer value is used in the signature
+ of some of the access methods.
+ </p>
+ <dl>
+ <dt>XMLEvent getEvent(SyncedCircularBuffer events)</dt>
+ <dd>
+ This is the basis of all of the queue access methods. It
+ returns the next element from the queue, which may be a
+ pushback element.
+ </dd>
+ <dt>XMLEvent getEndDocument(events)</dt>
+ <dd>
+ <em>get</em> and discard elements from the queue
+ until an ENDDOCUMENT element is found and returned.
+ </dd>
+ <dt> XMLEvent expectEndDocument(events)</dt>
+ <dd>
+ If the next element on the queue is an ENDDOCUMENT event,
+ return it. Otherwise, push the element back and throw an
+ exception. Each of the <em>get</em> methods (except
+ <em>getEvent()</em> itself) has a corresponding
+ <em>expect</em> method.
+ </dd>
+ <dt>XMLEvent get/expectStartElement(events)</dt>
+ <dd> Return the next STARTELEMENT event from the queue.</dd>
+ <dt>XMLEvent get/expectStartElement(events, String
+ qName)</dt>
+ <dd>
+ Return the next STARTELEMENT with a QName matching
+ <em>qName</em>.
+ </dd>
+ <dt>
+ XMLEvent get/expectStartElement(events, int uriIndex,
+ String localName)
+ </dt>
+ <dd>
+ Return the next STARTELEMENT with a URI indicated by the
+ <em>uriIndex</em> and a local name matching <em>localName</em>.
+ </dd>
+ <dt>
+ XMLEvent get/expectStartElement(events, LinkedList list)
+ </dt>
+ <dd>
+ <em>list</em> contains instances of the nested class
+ <code>UriLocalName</code>, which hold a
+ <em>uriIndex</em> and a <em>localName</em>. Return
+ the next STARTELEMENT with a URI indicated by the
+ <em>uriIndex</em> and a local name matching
+ <em>localName</em> from any element of
+ <em>list</em>.
+ </dd>
+ <dt>XMLEvent get/expectEndElement(events)</dt>
+ <dd>Return the next ENDELEMENT.</dd>
+ <dt>XMLEvent get/expectEndElement(events, qName)</dt>
+ <dd>Return the next ENDELEMENT with QName
+ <em>qname</em>.</dd>
+ <dt>XMLEvent get/expectEndElement(events, uriIndex, localName)</dt>
+ <dd>
+ Return the next ENDELEMENT with a URI indicated by the
+ <em>uriIndex</em> and a local name matching
+ <em>localName</em>.
+ </dd>
+ <dt>
+ XMLEvent get/expectEndElement(events, XMLEvent event)
+ </dt>
+ <dd>
+ Return the next ENDELEMENT with a URI matching the
+ <em>uriIndex</em> and <em>localName</em>
+ matching those in the <em>event</em> argument. This
+ is intended as a quick way to find the ENDELEMENT matching
+ a previously returned STARTELEMENT.
+ </dd>
+ <dt>XMLEvent get/expectCharacters(events)</dt>
+ <dd>Return the next CHARACTERS event.</dd>
+ </dl>
+ </section>
+ <section>
+ <title>FOP modularisation</title>
+ <p>
+ This same principle can be extended to the other major
+ sub-systems of FOP processing. In each case, while it is
+ possible to hold a complete intermediate result in memory,
+ the memory costs of that approach are too high. The
+ sub-systems - xml parsing, FO tree construction, Area tree
+ construction and rendering - must run in parallel if the
+ footprint is to be kept manageable. By creating a series of
+ producer-consumer pairs linked by synchronized buffers,
+ logical isolation can be achieved while rates of processing
+ remain coupled. By introducing feedback loops conveying
+ information about the completion of processing of the
+ elements, sub-systems can dispose of or precis those
+ elements without having to be tightly coupled to downstream
+ processes.<br/><br/>
+ <strong>Figure 3</strong>
+ </p>
+ <figure src="processPlumbing.png" alt="FOP modularisation"/>
+ </section>
+ </section>
+ </body>
+</document>
+
</menu>
<menu label="About">
<menu-item label="Index" href="index.html"/>
+ <menu-item label="Understanding" href="understanding/index.html"/>
</menu>
<menu label="Overview">
<menu-item label="Architecture" href="architecture.html"/>
<menu label="Status">
<menu-item label="Status" href="status.html"/>
</menu>
+ <menu label="Alternate">
+ <menu-item label="ALT DESIGN" href="alt.design/index.html"/>
+ </menu>
</book>
projects / xmlgraphics-fop.git / commitdiff
