src/documentation/content/xdocs/dev/design/optimise.xml - xmlgraphics-fop - Git at Google

 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
 <!--
   Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements.  See the NOTICE file distributed with
   this work for additional information regarding copyright ownership.
   The ASF licenses this file to You 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 document PUBLIC "-//APACHE//DTD Documentation V1.3//EN" "http://forrest.apache.org/dtd/document-v13.dtd">

 <document>
   <header>
     <title>Apache™ FOP Design: Optimisations</title>
     <version>$Revision$</version>
     <authors>
       <person name="Keiron Liddle" email="keiron@aftexsw.com"/>
     </authors>
   </header>

     <body>
 <section id="intro">
   <title>Introduction</title>
 <p>
 Apache™ FOP should be able to handle very large documents. A document can be
 supplied using SAX and the information should be passed entirely through
 the system, from fo elements to rendered output as soon as possible.
   </p>
   <p>
 A top level block area, immediately below the flow, can be added to the
 page layout as soon as the element is complete.
   </p>
   <p>
 The fo elements used to construct a page can be discarded as soon as the
 layout for the page is complete. Some information may be stored in the
 area tree of the page in order to handle unresolved page references
 and links.
   </p>
   <p>
 Once the layout of a page has been completed, all elements are fully
 resolved, then the page can be rendered. Some renderers may support
 out of order rendering of pages.
   </p>
   <p>
 The main problem that will remain is that any page with forward
 references will need to be stored until the refence is resolved.
 This means that the information contained in the page should be
 as minimal as possible.
   </p>
   <p>
 Line areas can be optimised once the layout for the line has
 been finalised. Consecutive characters with the same properties
 can be combined into a "word" to hold the information with
 limited overhead.
   </p>
   <p>
 If there are a large number of pages where forward references
 cannot be resolved the a method of writing a page onto disk
 could be used to save memory. The easiest way to achieve this
 is to make the page and all children serializable.
    </p>
   </section>

     </body>
 </document>
	<?xml version="1.0" encoding="UTF-8" standalone="no"?>
	<!--
	Licensed to the Apache Software Foundation (ASF) under one or more
	contributor license agreements. See the NOTICE file distributed with
	this work for additional information regarding copyright ownership.
	The ASF licenses this file to You 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 document PUBLIC "-//APACHE//DTD Documentation V1.3//EN" "http://forrest.apache.org/dtd/document-v13.dtd">

	<document>
	<header>
	<title>Apache™ FOP Design: Optimisations</title>
	<version>$Revision$</version>
	<authors>
	<person name="Keiron Liddle" email="keiron@aftexsw.com"/>
	</authors>
	</header>

	<body>
	<section id="intro">
	<title>Introduction</title>
	<p>
	Apache™ FOP should be able to handle very large documents. A document can be
	supplied using SAX and the information should be passed entirely through
	the system, from fo elements to rendered output as soon as possible.
	</p>
	<p>
	A top level block area, immediately below the flow, can be added to the
	page layout as soon as the element is complete.
	</p>
	<p>
	The fo elements used to construct a page can be discarded as soon as the
	layout for the page is complete. Some information may be stored in the
	area tree of the page in order to handle unresolved page references
	and links.
	</p>
	<p>
	Once the layout of a page has been completed, all elements are fully
	resolved, then the page can be rendered. Some renderers may support
	out of order rendering of pages.
	</p>
	<p>
	The main problem that will remain is that any page with forward
	references will need to be stored until the refence is resolved.
	This means that the information contained in the page should be
	as minimal as possible.
	</p>
	<p>
	Line areas can be optimised once the layout for the line has
	been finalised. Consecutive characters with the same properties
	can be combined into a "word" to hold the information with
	limited overhead.
	</p>
	<p>
	If there are a large number of pages where forward references
	cannot be resolved the a method of writing a page onto disk
	could be used to save memory. The easiest way to achieve this
	is to make the page and all children serializable.
	</p>
	</section>

	</body>
	</document>