xdocs/rasterizerTutorial.xml - xmlgraphics-batik - Git at Google

 <?xml version="1.0"?>
 <!DOCTYPE document SYSTEM "./dtd/document-v10.dtd">

 <!-- ========================================================================= -->
 <!-- Copyright (C) The Apache Software Foundation. All rights reserved.        -->
 <!--                                                                           -->
 <!-- This software is published under the terms of the Apache Software License -->
 <!-- version 1.1, a copy of which has been included with this distribution in  -->
 <!-- the LICENSE file.                                                         -->
 <!-- ========================================================================= -->

 <!-- ========================================================================= -->
 <!-- author tkormann@apache.org                                                -->
 <!-- version $Id$ -->
 <!-- ========================================================================= -->

 <document>
     <header>
         <title>Image Transcoder Tutorial</title>
         <subtitle>A brief introduction to the image transcoder API</subtitle>
         <authors>
             <person name="Thierry Kormann" email="tkormann@apache.org"/>
         </authors>
     </header>

     <body>

 <!-- ##################################################################### -->
 <s1 title="Introduction">
   <p>
     The goal of the transcoder API (package
     <code>org.apache.batik.transcoder</code>) is to provide a generic
     API for transcoding an input to an output. First, this document
     explains the basic transcoder API that <code>Transcoder</code>,
     <code>TranscoderInput</code> and <code>TranscoderOutput</code>
     define -- and thus all transcoders have in common. Next, it
     describes how to use the image transcoder API (package
     <code>org.apache.batik.transcoder.image</code>) which lets you
     rasterize an SVG document fragment to a raster image such as JPEG
     or PNG.
   </p>
 </s1>

 <s1 title="The Transcoder API">
 <p>
 The <code>org.apache.batik.transcoder</code> package defines 5 major classes:
 </p>
 <dl>
 <dt><code>Transcoder</code></dt>
 <dd>
 Defines the interface that all transcoders implement. You can
 transcode a specific input using a specific output by invoking the
 <code>transcode</code> method. Although there is no assumption on the
 input and output format, a specific transcoder may or may not support
 a particular type of input or output. For example, the image
 transcoders accept an SVG <code>org.w3c.dom.Document</code>, a
 <code>Reader</code>, an <code>InputStream</code>, or a
 <code>URI</code> as an input but only supports a byte stream for the
 output.
 <br /><br />
 </dd>

 <dt><code>TranscoderInput</code></dt>
 <dd>
 Defines the input of a transcoder. There are various ways to create an
 input and the most commons are already part of the API. The default
 implementation lets you create an input using a
 <code>org.w3c.dom.Document</code>, a <code>Reader</code>, an
 <code>InputStream</code>, a <code>org.xml.sax.XMLReader</code>, or a
 <code>URI</code>.
 <br /><br />
 </dd>

 <dt><code>TranscoderOutput</code></dt>
 <dd>
 Defines the output of a transcoder. There are various ways to create an
 output and the most commons are already part of the API. The default
 implementation lets you create an output using a
 <code>org.w3c.dom.Document</code>, a <code>Writer</code>, an
 <code>OutputStream</code>, a <code>org.xml.sax.XMLFilter</code>, or a
 <code>URI</code>.
 <br /><br />
 </dd>

 <dt><code>TranscodingHints</code></dt>
 <dd>
 The <code>TranscodingHints</code> class contains different hints which can
 be used to control the various options or parameters of a
 transcoder. Each transcoder provides its own set of hints. A hint is
 specified by (key, value) pair. For example, the
 <code>JPEGTranscoder</code> provides a hint to control the encoding quality.
 <br /><br />
 </dd>

 <dt><code>ErrorHandler</code></dt>
 <dd>
 This class provides a way to get the errors and/or warnings that might
 occur while transcoding. A default implementation is provided but
 you can, for example, implement your own handler that display a dialog
 instead of stack trace.
 </dd>
 </dl>
 </s1>

 <!-- ##################################################################### -->
 <s1 title="How to Use the Image Transcoder API">
 <p>
 The <code>org.apache.batik.transcoder.image</code> package provides an
 easy way to transcode an SVG document to a raster image such as JPEG or
 PNG. Additional raster image formats can be added by subclassing the
 <code>ImageTranscoder</code> and implementing the
 <code>writeImage</code> method. Although, in next sections, the
 examples will use the JPEG transcoder, the PNG transcoder works the
 same way.
 </p>

 <s2 title="Creating an Image">
 <p>
 The following example, using the <code>JPEGTranscoder</code> shows how to
 trasnform a SVG document to a JPEG image.
 </p>
 <source>
 SaveAsJpeg.java
 ===============

 import java.io.*;
 import org.apache.batik.transcoder.image.JPEGTranscoder;
 import org.apache.batik.transcoder.TranscoderInput;
 import org.apache.batik.transcoder.TranscoderOutput;

 public class SaveAsJPEG {

     public static void main(String [] args) throws Exception {

         // create a JPEG transcoder
         <strong>JPEGTranscoder t = new JPEGTranscoder();</strong>
         // set the transcoding hints
         <strong>t.addTranscodingHint(JPEGTranscoder.KEY_XML_PARSER_CLASSNAME,
                              "org.apache.crimson.parser.XMLReaderImpl");</strong>
         <strong>t.addTranscodingHint(JPEGTranscoder.KEY_QUALITY,
                              new Float(.8));</strong>
         // create the transcoder input
         String svgURI = new File(args[0]).toURL().toString();
         <strong>TranscoderInput input = new TranscoderInput(svgURI);</strong>
         // create the transcoder output
         OutputStream ostream = new FileOutputStream("out.jpg");
         <strong>TranscoderOutput output = new TranscoderOutput(ostream);</strong>
         // save the image
         <strong>t.transcode(input, output);</strong>
         // flush and close the stream then exit
         ostream.flush();
         ostream.close();
         System.exit(0);
     }
 }
 </source>
 <p>
 The code creates a <code>JPEGTranscoder</code> and sets the
 transcoding hints. The first hint indicates the XML parser to use. The
 second hint sets the encoding quality. Then, an input and an output
 are created. The input is created using the first command line
 argument which should represent a URI. The output is a byte stream
 representing a file called "out.jpg". Finally, the
 <code>transcode</code> method is invoked and the byte stream is
 closed.
 </p>
 <p>
 Although not shown above, the program might have specified additional
 hints to indicate a user style sheet, the preferred language of the
 document or the background color.
 </p>
 <p>
 <strong>Try this:</strong>
 </p>
 <ol>
 <li>Compile and run the program: SaveAsJPEG.java. You will need a SVG document.<br />
 <code>% java SaveAsJPEG &lt;filename>.svg</code></li>
 <li>Take a look at: out.jpg</li>
 </ol>
 </s2>


 <s2 title="Defining the Size of the Image">
 <p>
 By adding the following line of code to the previous example, you will
 specify the raster image size (in pixels). The new transcoding hint
 <code>KEY_WIDTH</code> lets you specify the raster image width. As the
 raster image height is not provided (using the
 <code>KEY_HEIGHT</code>), the transcoder will compute the raster image
 dimension by keeping the aspect ratio of the SVG document.
 </p>
 <source>
 t.addTranscodingHint(JPEGTranscoder.KEY_WIDTH, new Integer(100));
 </source>
 <p>
 The transcoder will have the same behavior if you specify the
 <code>KEY_HEIGHT</code> without initializing the
 <code>KEY_WIDTH</code>. In all cases (though both keys are provided),
 the transcoder will preserve the apsect ratio of the SVG document.
 </p>
 </s2>

 <s2 title="Selecting an Area of Interest">
 <p>
 The image transcoder lets you specify an area of interest (ie. a part
 of the SVG document). The key <code>KEY_AOI</code> enables to select
 the region of the SVG document to render. The value of this key must
 be a <code>java.awt.Rectangle</code> specified in pixels and described
 in the SVG document's space. The following example shows how you can
 split a SVG document into 4 tiles.
 </p>
 <source>
 SaveAsJPEGTiles.java
 ====================

 import java.io.*;
 import java.awt.*;
 import org.apache.batik.transcoder.image.JPEGTranscoder;
 import org.apache.batik.transcoder.TranscoderInput;
 import org.apache.batik.transcoder.TranscoderOutput;

 public class SaveAsJPEGTiles {

     JPEGTranscoder trans = new JPEGTranscoder();

     public SaveAsJPEGTiles() {
         trans.addTranscodingHint(JPEGTranscoder.KEY_XML_PARSER_CLASSNAME,
                                  "org.apache.crimson.parser.XMLReaderImpl");
         trans.addTranscodingHint(JPEGTranscoder.KEY_QUALITY,
                                  new Float(.8));
     }

     public void tile(String inputFilename,
                      String outputFilename,
                      Rectangle aoi) throws Exception {
         <strong>trans.addTranscodingHint(JPEGTranscoder.KEY_WIDTH,
                                  new Integer(aoi.width));</strong>
         <strong>trans.addTranscodingHint(JPEGTranscoder.KEY_HEIGHT,
                                  new Integer(aoi.height));</strong>
         <strong>trans.addTranscodingHint(JPEGTranscoder.KEY_AOI, aoi);</strong>
         String svgURI = new File(inputFilename).toURL().toString();
         TranscoderInput input = new TranscoderInput(svgURI);
         OutputStream ostream = new FileOutputStream(outputFilename);
         TranscoderOutput output = new TranscoderOutput(ostream);
         trans.transcode(input, output);
         ostream.flush();
         ostream.close();
     }

     public static void main(String [] args) throws Exception {
         SaveAsJPEGTiles p = new SaveAsJPEGTiles();
         <strong>String in = "samples/anne.svg";
         int documentWidth = 450;
         int documentHeight = 500;</strong>
         int dw2 = documentWidth / 2;
         int dh2 = documentHeight / 2;
         p.tile(in, "tileTopLeft.jpg", new Rectangle(0, 0, dw2, dh2));
         p.tile(in, "tileTopRight.jpg", new Rectangle(dw2, 0, dw2, dh2));
         p.tile(in, "tileBottomLeft.jpg", new Rectangle(0, dh2, dw2, dh2));
         p.tile(in, "tileBottomRight.jpg", new Rectangle(dw2, dh2, dw2, dh2));
         System.exit(0);
     }
 }
 </source>
 <p>
 This code splits the same document "anne.svg" into four tiles of the
 same size. Considering the document and its original size, we can
 determine four regions. Then we rasterize each region using the
 <code>KEY_AOI</code> key. Note that we also specify the image width
 and height to be the same as the area of interest width and height (so
 we keep a 1:1 zoom factor). You can of course combine the
 <code>KEY_WIDTH</code>, <code>KEY_HEIGHT</code> keys with the
 <code>KEY_AOI</code>. In that case, first the area of interest will
 determine which part of the SVG document has to be rendered - then
 that part could be zoom in or out depending on the specified raster
 image size.
 </p>
 <p>
 <strong>Try this:</strong>
 </p>
 <ol>
 <li>Compile and run the program: SaveAsJPEGTiles.java. You will need the "anne.svg" document.<br />
 <code>% java SaveAsJPEGTiles</code></li>
 <li>Take a look at: tileTopRight.jpg, tileTopRight.jpg, tileBottomRight.jpg
  and tileBottomLeft.jpg</li>
 </ol>
 </s2>

 <s2 title="Generating an Image from a SVG DOM Tree">
 <p>
 The following code creates and saves a SVG DOM tree.
 </p>
 <source>
 DOMRasterizer.java
 ==================

 import java.io.*;
 import org.apache.batik.transcoder.image.JPEGTranscoder;
 import org.apache.batik.transcoder.TranscoderInput;
 import org.apache.batik.transcoder.TranscoderOutput;
 import org.apache.batik.dom.svg.SVGDOMImplementation;
 import org.w3c.dom.Document;
 import org.w3c.dom.Element;
 import org.w3c.dom.DOMImplementation;

 public class DOMRasterizer {

     public Document createDocument() {
         <strong>DOMImplementation impl = SVGDOMImplementation.getDOMImplementation();
         String svgNS = SVGDOMImplementation.SVG_NAMESPACE_URI;
         Document document =
             impl.createDocument(svgNS, "svg", null);
         Element root = document.getDocumentElement();</strong>
         root.setAttributeNS(null, "width", "450");
         root.setAttributeNS(null, "height", "500");

         Element e;
         e = document.createElementNS(svgNS, "rect");
         e.setAttributeNS(null, "x", "10");
         e.setAttributeNS(null, "y", "10");
         e.setAttributeNS(null, "width", "200");
         e.setAttributeNS(null, "height", "300");
         e.setAttributeNS(null, "style", "fill:red;stroke:black;stroke-width:4");
         root.appendChild(e);

         e = document.createElementNS(svgNS, "circle");
         e.setAttributeNS(null, "cx", "225");
         e.setAttributeNS(null, "cy", "250");
         e.setAttributeNS(null, "r", "100");
         e.setAttributeNS(null, "style", "fill:green;fill-opacity:.5");
         root.appendChild(e);

         return document;
     }

     public void save(Document document) throws Exception {
         JPEGTranscoder t = new JPEGTranscoder();
         t.addTranscodingHint(JPEGTranscoder.KEY_QUALITY,
                              new Float(.8));
         <strong>TranscoderInput input = new TranscoderInput(document);</strong>
         OutputStream ostream = new FileOutputStream("out.jpg");
         TranscoderOutput output = new TranscoderOutput(ostream);
         t.transcode(input, output);
         ostream.flush();
         ostream.close();
     }

     public static void main(String [] args) throws Exception {
         DOMRasterizer rasterizer = new DOMRasterizer();
         Document document = rasterizer.createDocument();
         rasterizer.save(document);
         System.exit(0);
     }
 }
 </source>
 <p>
 This code is divided into two distinct parts.
 </p>
 <dl>
 <dt>Creating a SVG DOM tree</dt>
 <dd>
 <br />See the <code>createDocument</code> method<br /> Three steps are
 required at this time. The first one consists on getting the Batik SVG
 DOM implementation (via the SVGDOMImplementation class). Then, you can
 create a <code>org.w3c.dom.Document</code> (which is a SVG Document by
 the way) by invoking the <code>createDocument</code> method with the
 svg namespace URI and the "svg" document element. At last, you can get
 the document element and start to build your DOM tree.  <br /><br />
 </dd>
 <dt>Rasterizing your DOM</dt>
 <dd>
 <br />See the <code>save</code> method<br /> Similar to the previous
 examples, you can transcode a SVG document to a raster image by
 creating a <code>TransocderInput</code> with this time, the SVG Document.
 <br /><br />
 </dd>
 </dl>
 <p>
 <strong>Try this:</strong>
 </p>
 <ol>
 <li>Compile and run the program: DOMRasterizer.java.<br />
 <code>% java DOMRasterizer</code></li>
 <li>Take a look at: out.jpg</li>
 </ol>
 </s2>

 </s1>


     </body>
 </document>
	<?xml version="1.0"?>
	<!DOCTYPE document SYSTEM "./dtd/document-v10.dtd">

	<!-- ========================================================================= -->
	<!-- Copyright (C) The Apache Software Foundation. All rights reserved. -->
	<!-- -->
	<!-- This software is published under the terms of the Apache Software License -->
	<!-- version 1.1, a copy of which has been included with this distribution in -->
	<!-- the LICENSE file. -->
	<!-- ========================================================================= -->

	<!-- ========================================================================= -->
	<!-- author tkormann@apache.org -->
	<!-- version $Id$ -->
	<!-- ========================================================================= -->

	<document>
	<header>
	<title>Image Transcoder Tutorial</title>
	<subtitle>A brief introduction to the image transcoder API</subtitle>
	<authors>
	<person name="Thierry Kormann" email="tkormann@apache.org"/>
	</authors>
	</header>

	<body>

	<!-- ##################################################################### -->
	<s1 title="Introduction">
	<p>
	The goal of the transcoder API (package
	<code>org.apache.batik.transcoder</code>) is to provide a generic
	API for transcoding an input to an output. First, this document
	explains the basic transcoder API that <code>Transcoder</code>,
	<code>TranscoderInput</code> and <code>TranscoderOutput</code>
	define -- and thus all transcoders have in common. Next, it
	describes how to use the image transcoder API (package
	<code>org.apache.batik.transcoder.image</code>) which lets you
	rasterize an SVG document fragment to a raster image such as JPEG
	or PNG.
	</p>
	</s1>

	<s1 title="The Transcoder API">
	<p>
	The <code>org.apache.batik.transcoder</code> package defines 5 major classes:
	</p>
	<dl>
	<dt><code>Transcoder</code></dt>
	<dd>
	Defines the interface that all transcoders implement. You can
	transcode a specific input using a specific output by invoking the
	<code>transcode</code> method. Although there is no assumption on the
	input and output format, a specific transcoder may or may not support
	a particular type of input or output. For example, the image
	transcoders accept an SVG <code>org.w3c.dom.Document</code>, a
	<code>Reader</code>, an <code>InputStream</code>, or a
	<code>URI</code> as an input but only supports a byte stream for the
	output.
	<br /><br />
	</dd>

	<dt><code>TranscoderInput</code></dt>
	<dd>
	Defines the input of a transcoder. There are various ways to create an
	input and the most commons are already part of the API. The default
	implementation lets you create an input using a
	<code>org.w3c.dom.Document</code>, a <code>Reader</code>, an
	<code>InputStream</code>, a <code>org.xml.sax.XMLReader</code>, or a
	<code>URI</code>.
	<br /><br />
	</dd>

	<dt><code>TranscoderOutput</code></dt>
	<dd>
	Defines the output of a transcoder. There are various ways to create an
	output and the most commons are already part of the API. The default
	implementation lets you create an output using a
	<code>org.w3c.dom.Document</code>, a <code>Writer</code>, an
	<code>OutputStream</code>, a <code>org.xml.sax.XMLFilter</code>, or a
	<code>URI</code>.
	<br /><br />
	</dd>

	<dt><code>TranscodingHints</code></dt>
	<dd>
	The <code>TranscodingHints</code> class contains different hints which can
	be used to control the various options or parameters of a
	transcoder. Each transcoder provides its own set of hints. A hint is
	specified by (key, value) pair. For example, the
	<code>JPEGTranscoder</code> provides a hint to control the encoding quality.
	<br /><br />
	</dd>

	<dt><code>ErrorHandler</code></dt>
	<dd>
	This class provides a way to get the errors and/or warnings that might
	occur while transcoding. A default implementation is provided but
	you can, for example, implement your own handler that display a dialog
	instead of stack trace.
	</dd>
	</dl>
	</s1>

	<!-- ##################################################################### -->
	<s1 title="How to Use the Image Transcoder API">
	<p>
	The <code>org.apache.batik.transcoder.image</code> package provides an
	easy way to transcode an SVG document to a raster image such as JPEG or
	PNG. Additional raster image formats can be added by subclassing the
	<code>ImageTranscoder</code> and implementing the
	<code>writeImage</code> method. Although, in next sections, the
	examples will use the JPEG transcoder, the PNG transcoder works the
	same way.
	</p>

	<s2 title="Creating an Image">
	<p>
	The following example, using the <code>JPEGTranscoder</code> shows how to
	trasnform a SVG document to a JPEG image.
	</p>
	<source>
	SaveAsJpeg.java
	===============

	import java.io.*;
	import org.apache.batik.transcoder.image.JPEGTranscoder;
	import org.apache.batik.transcoder.TranscoderInput;
	import org.apache.batik.transcoder.TranscoderOutput;

	public class SaveAsJPEG {

	public static void main(String [] args) throws Exception {

	// create a JPEG transcoder
	<strong>JPEGTranscoder t = new JPEGTranscoder();</strong>
	// set the transcoding hints
	<strong>t.addTranscodingHint(JPEGTranscoder.KEY_XML_PARSER_CLASSNAME,
	"org.apache.crimson.parser.XMLReaderImpl");</strong>
	<strong>t.addTranscodingHint(JPEGTranscoder.KEY_QUALITY,
	new Float(.8));</strong>
	// create the transcoder input
	String svgURI = new File(args[0]).toURL().toString();
	<strong>TranscoderInput input = new TranscoderInput(svgURI);</strong>
	// create the transcoder output
	OutputStream ostream = new FileOutputStream("out.jpg");
	<strong>TranscoderOutput output = new TranscoderOutput(ostream);</strong>
	// save the image
	<strong>t.transcode(input, output);</strong>
	// flush and close the stream then exit
	ostream.flush();
	ostream.close();
	System.exit(0);
	}
	}
	</source>
	<p>
	The code creates a <code>JPEGTranscoder</code> and sets the
	transcoding hints. The first hint indicates the XML parser to use. The
	second hint sets the encoding quality. Then, an input and an output
	are created. The input is created using the first command line
	argument which should represent a URI. The output is a byte stream
	representing a file called "out.jpg". Finally, the
	<code>transcode</code> method is invoked and the byte stream is
	closed.
	</p>
	<p>
	Although not shown above, the program might have specified additional
	hints to indicate a user style sheet, the preferred language of the
	document or the background color.
	</p>
	<p>
	<strong>Try this:</strong>
	</p>
	<ol>
	<li>Compile and run the program: SaveAsJPEG.java. You will need a SVG document.<br />
	<code>% java SaveAsJPEG <filename>.svg</code></li>
	<li>Take a look at: out.jpg</li>
	</ol>
	</s2>


	<s2 title="Defining the Size of the Image">
	<p>
	By adding the following line of code to the previous example, you will
	specify the raster image size (in pixels). The new transcoding hint
	<code>KEY_WIDTH</code> lets you specify the raster image width. As the
	raster image height is not provided (using the
	<code>KEY_HEIGHT</code>), the transcoder will compute the raster image
	dimension by keeping the aspect ratio of the SVG document.
	</p>
	<source>
	t.addTranscodingHint(JPEGTranscoder.KEY_WIDTH, new Integer(100));
	</source>
	<p>
	The transcoder will have the same behavior if you specify the
	<code>KEY_HEIGHT</code> without initializing the
	<code>KEY_WIDTH</code>. In all cases (though both keys are provided),
	the transcoder will preserve the apsect ratio of the SVG document.
	</p>
	</s2>

	<s2 title="Selecting an Area of Interest">
	<p>
	The image transcoder lets you specify an area of interest (ie. a part
	of the SVG document). The key <code>KEY_AOI</code> enables to select
	the region of the SVG document to render. The value of this key must
	be a <code>java.awt.Rectangle</code> specified in pixels and described
	in the SVG document's space. The following example shows how you can
	split a SVG document into 4 tiles.
	</p>
	<source>
	SaveAsJPEGTiles.java
	====================

	import java.io.*;
	import java.awt.*;
	import org.apache.batik.transcoder.image.JPEGTranscoder;
	import org.apache.batik.transcoder.TranscoderInput;
	import org.apache.batik.transcoder.TranscoderOutput;

	public class SaveAsJPEGTiles {

	JPEGTranscoder trans = new JPEGTranscoder();

	public SaveAsJPEGTiles() {
	trans.addTranscodingHint(JPEGTranscoder.KEY_XML_PARSER_CLASSNAME,
	"org.apache.crimson.parser.XMLReaderImpl");
	trans.addTranscodingHint(JPEGTranscoder.KEY_QUALITY,
	new Float(.8));
	}

	public void tile(String inputFilename,
	String outputFilename,
	Rectangle aoi) throws Exception {
	<strong>trans.addTranscodingHint(JPEGTranscoder.KEY_WIDTH,
	new Integer(aoi.width));</strong>
	<strong>trans.addTranscodingHint(JPEGTranscoder.KEY_HEIGHT,
	new Integer(aoi.height));</strong>
	<strong>trans.addTranscodingHint(JPEGTranscoder.KEY_AOI, aoi);</strong>
	String svgURI = new File(inputFilename).toURL().toString();
	TranscoderInput input = new TranscoderInput(svgURI);
	OutputStream ostream = new FileOutputStream(outputFilename);
	TranscoderOutput output = new TranscoderOutput(ostream);
	trans.transcode(input, output);
	ostream.flush();
	ostream.close();
	}

	public static void main(String [] args) throws Exception {
	SaveAsJPEGTiles p = new SaveAsJPEGTiles();
	<strong>String in = "samples/anne.svg";
	int documentWidth = 450;
	int documentHeight = 500;</strong>
	int dw2 = documentWidth / 2;
	int dh2 = documentHeight / 2;
	p.tile(in, "tileTopLeft.jpg", new Rectangle(0, 0, dw2, dh2));
	p.tile(in, "tileTopRight.jpg", new Rectangle(dw2, 0, dw2, dh2));
	p.tile(in, "tileBottomLeft.jpg", new Rectangle(0, dh2, dw2, dh2));
	p.tile(in, "tileBottomRight.jpg", new Rectangle(dw2, dh2, dw2, dh2));
	System.exit(0);
	}
	}
	</source>
	<p>
	This code splits the same document "anne.svg" into four tiles of the
	same size. Considering the document and its original size, we can
	determine four regions. Then we rasterize each region using the
	<code>KEY_AOI</code> key. Note that we also specify the image width
	and height to be the same as the area of interest width and height (so
	we keep a 1:1 zoom factor). You can of course combine the
	<code>KEY_WIDTH</code>, <code>KEY_HEIGHT</code> keys with the
	<code>KEY_AOI</code>. In that case, first the area of interest will
	determine which part of the SVG document has to be rendered - then
	that part could be zoom in or out depending on the specified raster
	image size.
	</p>
	<p>
	<strong>Try this:</strong>
	</p>
	<ol>
	<li>Compile and run the program: SaveAsJPEGTiles.java. You will need the "anne.svg" document.<br />
	<code>% java SaveAsJPEGTiles</code></li>
	<li>Take a look at: tileTopRight.jpg, tileTopRight.jpg, tileBottomRight.jpg
	and tileBottomLeft.jpg</li>
	</ol>
	</s2>

	<s2 title="Generating an Image from a SVG DOM Tree">
	<p>
	The following code creates and saves a SVG DOM tree.
	</p>
	<source>
	DOMRasterizer.java
	==================

	import java.io.*;
	import org.apache.batik.transcoder.image.JPEGTranscoder;
	import org.apache.batik.transcoder.TranscoderInput;
	import org.apache.batik.transcoder.TranscoderOutput;
	import org.apache.batik.dom.svg.SVGDOMImplementation;
	import org.w3c.dom.Document;
	import org.w3c.dom.Element;
	import org.w3c.dom.DOMImplementation;

	public class DOMRasterizer {

	public Document createDocument() {
	<strong>DOMImplementation impl = SVGDOMImplementation.getDOMImplementation();
	String svgNS = SVGDOMImplementation.SVG_NAMESPACE_URI;
	Document document =
	impl.createDocument(svgNS, "svg", null);
	Element root = document.getDocumentElement();</strong>
	root.setAttributeNS(null, "width", "450");
	root.setAttributeNS(null, "height", "500");

	Element e;
	e = document.createElementNS(svgNS, "rect");
	e.setAttributeNS(null, "x", "10");
	e.setAttributeNS(null, "y", "10");
	e.setAttributeNS(null, "width", "200");
	e.setAttributeNS(null, "height", "300");
	e.setAttributeNS(null, "style", "fill:red;stroke:black;stroke-width:4");
	root.appendChild(e);

	e = document.createElementNS(svgNS, "circle");
	e.setAttributeNS(null, "cx", "225");
	e.setAttributeNS(null, "cy", "250");
	e.setAttributeNS(null, "r", "100");
	e.setAttributeNS(null, "style", "fill:green;fill-opacity:.5");
	root.appendChild(e);

	return document;
	}

	public void save(Document document) throws Exception {
	JPEGTranscoder t = new JPEGTranscoder();
	t.addTranscodingHint(JPEGTranscoder.KEY_QUALITY,
	new Float(.8));
	<strong>TranscoderInput input = new TranscoderInput(document);</strong>
	OutputStream ostream = new FileOutputStream("out.jpg");
	TranscoderOutput output = new TranscoderOutput(ostream);
	t.transcode(input, output);
	ostream.flush();
	ostream.close();
	}

	public static void main(String [] args) throws Exception {
	DOMRasterizer rasterizer = new DOMRasterizer();
	Document document = rasterizer.createDocument();
	rasterizer.save(document);
	System.exit(0);
	}
	}
	</source>
	<p>
	This code is divided into two distinct parts.
	</p>
	<dl>
	<dt>Creating a SVG DOM tree</dt>
	<dd>
	<br />See the <code>createDocument</code> method<br /> Three steps are
	required at this time. The first one consists on getting the Batik SVG
	DOM implementation (via the SVGDOMImplementation class). Then, you can
	create a <code>org.w3c.dom.Document</code> (which is a SVG Document by
	the way) by invoking the <code>createDocument</code> method with the
	svg namespace URI and the "svg" document element. At last, you can get
	the document element and start to build your DOM tree. <br /><br />
	</dd>
	<dt>Rasterizing your DOM</dt>
	<dd>
	<br />See the <code>save</code> method<br /> Similar to the previous
	examples, you can transcode a SVG document to a raster image by
	creating a <code>TransocderInput</code> with this time, the SVG Document.
	<br /><br />
	</dd>
	</dl>
	<p>
	<strong>Try this:</strong>
	</p>
	<ol>
	<li>Compile and run the program: DOMRasterizer.java.<br />
	<code>% java DOMRasterizer</code></li>
	<li>Take a look at: out.jpg</li>
	</ol>
	</s2>

	</s1>


	</body>
	</document>