1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
|
<?xml version="1.0" encoding="utf-8"?>
<!--
* Copyright 2004 The Apache Software Foundation.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
-->
<!-- $Id$ -->
<!--
<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"docbookx.dtd">
-->
<chapter>
<title>Phase 1: Building the FO tree</title>
<section>
<title>Creating the FO nodes</title>
<para>FOP's first task is building a suitable data structure from
the XML input, which is an XML file with formatting objects or a
result tree with formatting objects from an XSLT transformation. One
could call this FOP's data binding. The data structure is an FO tree,
i.e., a tree of FONode objects. The structure of the FO tree exactly
parallels the structure of the XML file or the corresponding DOM tree,
but instead of XML nodes its nodes are objects of type
<literal>org.apache.fop.fo.FONode</literal>. The FO tree is built on
the basis of SAX parser events. The parser is responsible for parsing
the XML document; it calls FOP's callbacks when SAX events
occur.</para>
<para>FOP's callbacks are implemented by the
<literal>FOTreeBuilder</literal> <literal>treebuilder</literal>
object, which is a SAX content handler. It was constructed in the
preparation phase, and registered with the parser as the content
handler. It has meaningful implementations of the methods
<literal>startDocument</literal>, <literal>endDocument</literal>,
<literal>startElement</literal>, <literal>endElement</literal>, and
<literal>characters</literal>.</para>
<para><literal>treebuilder</literal> delegates its
<literal>startDocument</literal> and <literal>endDocument</literal>
methods to its <literal>FOTreeHandler</literal> object
<literal>foInputHandler</literal>. <literal>FOTreeHandler</literal> is
a subclas of <literal>FOInputHandler</literal>.
<screen>
treebuilder.foInputHandler = {
runtime: instance of java.lang.Runtime(id=635)
pageCount: 0
initialMemory: 0
startTime: 0
foTreeListeners: instance of java.util.HashSet(id=636)
org.apache.fop.fo.FOInputHandler.foTreeControl: instance of org.apache.fop.apps.Document(id=634)
org.apache.avalon.framework.logger.AbstractLogEnabled.m_logger: instance of org.apache.avalon.framework.logger.ConsoleLogger(id=342)
}
</screen></para>
<para>The first important task of <literal>treebuilder</literal> is
creating a suitable FO node for each element in the XML document. This
is done in its <literal>startElement</literal> method. Its most
important tool in this process is its <literal>fobjTable</literal>
object. <literal>fobjTable</literal> is a map of maps. For each
namespace supported by FOP it contains a map of local XML element name
to a Node maker object <literal>fobjMaker</literal>, of type
<literal>ElementMapping.Maker</literal>. In addition to the FO
namespace it contains makers for FOP's extensions namespace, the SVG
namespace and Batik's extensions namespace.
<screen>
treebuilder.fobjTable = "{
http://www.w3.org/1999/XSL/Format={
static-content=org.apache.fop.fo.FOElementMapping$SC@39e5b5,
table=org.apache.fop.fo.FOElementMapping$Ta@117f31e,
external-graphic=org.apache.fop.fo.FOElementMapping$EG@15a6029,
table-column=org.apache.fop.fo.FOElementMapping$TC@5f6303,
table-and-caption=org.apache.fop.fo.FOElementMapping$TAC@5d9084,
table-footer=org.apache.fop.fo.FOElementMapping$TB@bad8a8,
declarations=org.apache.fop.fo.FOElementMapping$Dec@e61fd1,
wrapper=org.apache.fop.fo.FOElementMapping$W@331059,
page-sequence=org.apache.fop.fo.FOElementMapping$PS@766a24,
single-page-master-reference=org.apache.fop.fo.FOElementMapping$SPMR@32784a,
footnote=org.apache.fop.fo.FOElementMapping$Foot@1774b9b,
multi-switch=org.apache.fop.fo.FOElementMapping$MS@104c575,
bidi-override=org.apache.fop.fo.FOElementMapping$BO@3fa5ac,
layout-master-set=org.apache.fop.fo.FOElementMapping$LMS@95cfbe,
float=org.apache.fop.fo.FOElementMapping$F@179dce4,
list-item=org.apache.fop.fo.FOElementMapping$LI@1950198,
basic-link=org.apache.fop.fo.FOElementMapping$BL@19bb25a,
multi-property-set=org.apache.fop.fo.FOElementMapping$MPS@da6bf4,
table-row=org.apache.fop.fo.FOElementMapping$TR@1e58cb8,
region-end=org.apache.fop.fo.FOElementMapping$RE@179935d,
block=org.apache.fop.fo.FOElementMapping$B@b9e45a,
leader=org.apache.fop.fo.FOElementMapping$L@3ef810,
table-header=org.apache.fop.fo.FOElementMapping$TB@100363,
list-item-body=org.apache.fop.fo.FOElementMapping$LIB@14e8cee,
multi-properties=org.apache.fop.fo.FOElementMapping$MP@67064,
region-after=org.apache.fop.fo.FOElementMapping$RA@bcda2d,
multi-case=org.apache.fop.fo.FOElementMapping$MC@97d01f,
block-container=org.apache.fop.fo.FOElementMapping$BC@e0a386,
title=org.apache.fop.fo.FOElementMapping$T@feb48,
retrieve-marker=org.apache.fop.fo.FOElementMapping$RM@11ff436,
color-profile=org.apache.fop.fo.FOElementMapping$CP@da3a1e,
character=org.apache.fop.fo.FOElementMapping$Ch@11dba45,
simple-page-master=org.apache.fop.fo.FOElementMapping$SPM@b03be0,
page-sequence-master=org.apache.fop.fo.FOElementMapping$PSM@2af081,
footnote-body=org.apache.fop.fo.FOElementMapping$FB@113a53d,
marker=org.apache.fop.fo.FOElementMapping$M@c5495e,
table-body=org.apache.fop.fo.FOElementMapping$TB@53fb57,
inline=org.apache.fop.fo.FOElementMapping$In@19a32e0,
table-cell=org.apache.fop.fo.FOElementMapping$TCell@8238f4,
list-block=org.apache.fop.fo.FOElementMapping$LB@16925b0,
region-start=org.apache.fop.fo.FOElementMapping$RS@297ffb,
table-caption=org.apache.fop.fo.FOElementMapping$TCaption@914f6a,
conditional-page-master-reference=org.apache.fop.fo.FOElementMapping$CPMR@1f4cbee,
list-item-label=org.apache.fop.fo.FOElementMapping$LIL@787d6a,
multi-toggle=org.apache.fop.fo.FOElementMapping$MT@71dc3d,
initial-property-set=org.apache.fop.fo.FOElementMapping$IPS@1326484,
repeatable-page-master-alternatives=org.apache.fop.fo.FOElementMapping$RPMA@16546ef,
repeatable-page-master-reference=org.apache.fop.fo.FOElementMapping$RPMR@1428ea,
flow=org.apache.fop.fo.FOElementMapping$Fl@18a49e0,
page-number=org.apache.fop.fo.FOElementMapping$PN@1f82982,
instream-foreign-object=org.apache.fop.fo.FOElementMapping$IFO@16d2633,
inline-container=org.apache.fop.fo.FOElementMapping$IC@e70e30,
root=org.apache.fop.fo.FOElementMapping$R@154864a,
region-before=org.apache.fop.fo.FOElementMapping$RBefore@3c9217,
region-body=org.apache.fop.fo.FOElementMapping$RB@9b42e6,
page-number-citation=org.apache.fop.fo.FOElementMapping$PNC@14520eb
},
http://xml.apache.org/fop/extensions={
bookmarks=org.apache.fop.fo.extensions.ExtensionElementMapping$B@1d7fbfb,
label=org.apache.fop.fo.extensions.ExtensionElementMapping$L@e020c9,
outline=org.apache.fop.fo.extensions.ExtensionElementMapping$O@888e6c
},
http://www.w3.org/2000/svg={
<default>=org.apache.fop.fo.extensions.svg.SVGElementMapping$SVGMaker@1742700,
svg=org.apache.fop.fo.extensions.svg.SVGElementMapping$SE@acb158
},
http://xml.apache.org/batik/ext={
<default>=org.apache.fop.fo.extensions.svg.BatikExtensionElementMapping$SVGMaker@1af33d6,
batik=org.apache.fop.fo.extensions.svg.BatikExtensionElementMapping$SE@17431b9
}
}"
</screen></para>
<para>The values in this map are objects of subclasses of
<literal>ElementMapping.Maker</literal>.
<literal>ElementMapping.Maker</literal> is a static nested class of
<literal>ElementMapping</literal>. It has no members and a single
object method <literal>FONode make(FONode parent)</literal>. The
subclasses are static nested classes of
<literal>FOElementMapping</literal>. Each subclass has its own
implementation of the <literal>make</literal> method, and returns its
own subclass of FONode. For example,
<literal>FOElementMapping$R</literal> returns a
<literal>org.apache.fop.fo.pagination.Root</literal> object.</para>
<para><literal>treebuilder</literal> delegates its
<literal>endElement</literal> method to the node's
<literal>end</literal> method, which allows FOP to take appropriate
action at the end of each FO element. The only node type whose
<literal>end</literal> method takes special action, is
<literal>org.apache.fop.fo.pagination.PageSequence</literal>. It hands
control to FOP's next phase, building of the area tree.</para>
</section>
<section>
<title>Creating the property values</title>
<para>Formatting objects have many attributes by which the user
may finetune their behaviour. When the FO tree is built, the
attributes must be converted to properties. This conversion process
must implement XSLT's sometimes complicated rules of default values,
inheritance, shorthand notations etc. This is one of the tasks of the
property subsystem, which is described in its own <link
linkend="ch.properties">chapter</link>.</para>
</section>
</chapter>
<!-- Local Variables: -->
<!-- current-language-environment: UTF-8 -->
<!-- coding: utf-8 -->
<!-- default-input-method: TeX -->
<!-- End: -->
|
