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 <h1>BIRT Extension Mechanism : Part 1</h1>


 <div class="summary">
 <h2>Abstract</h2>


 <p>This article introduces the extension mechanism of BIRT report
 model, engine and designer, shows how to create custom extended report items
 step by
 step.</p>


 <div class="author">By&nbsp;Zhiqiang
 Qian,&nbsp;Actuate Corporation</div>


 <div class="copyright">Copyright &copy; [2008]
 [Actuate Corporation].</div>


 <div class="date">August 7, 2008</div>


 </div>


 <div class="content">
 <h2>Introduction</h2>


 <p>For many people,&nbsp;<a href="http://eclipse.org/birt">BIRT(Business
 Intelligence and Reporting Tools)</a> may
 only mean a regular reporting tool. But in fact, the real strength of
 BIRT is not only&nbsp;its built-in reporting functionality, but also
 its
 extension capabilities. By&nbsp;extensions, user can easily extend the
 functionality of BIRT, creating custom extended report items, adding custom
 emitters, and even having custom editor pages. The powerfulness of extensions
 enables user to create
 custom reporting features that can meet very specific requirements. In
 this
 article, we will explorer how to leverage the BIRT extension mechanism to
 extend the BIRT&nbsp;capabilities. The given samples will
 cover&nbsp;most of the essential extension points that provided by BIRT report
 model, engine and designer.<br>


 </p>


 <h2>The Basics</h2>


 <p>BIRT already contains the basic Label and Text report items,
 but&nbsp;these items can only show horizontal text. Sometimes, user
 would
 like to show angled text, in this case, alternative solution is needed.
 In following sections, we are introducing how to implement a
 RotatedText
 extended report&nbsp;item through BIRT extensions, and how to enhance
 the functionality step by step by implementing more extension points.</p>


 <p>Note: This example is a modified version based
 on&nbsp;RotatedText&nbsp;sample on BIRT CVS, the original code
 can&nbsp;be retrieved <a href="http://dev.eclipse.org/viewcvs/index.cgi/?root=BIRT_Project">here.</a></p>


 <p>To implement an extended report item, basically we need look at&nbsp;following extension points:</p>


 <ul>


   <li>org.eclipse.birt.report.model.reportItemModel</li>


   <li>org.eclipse.birt.report.designer.ui.reportitemUI</li>


   <li>org.eclipse.birt.report.engine.reportitemPresentation</li>


 </ul>


 <br>


 <img style="width: 514px; height: 156px;" alt="" src="images/extensions.png"><br>


 <p>These three extensions are the basics to implement an extended
 report item. In brief,&nbsp;
 "org.eclipse.birt.report.model.reportItemModel" provides the report
 model extensibility, "org.eclipse.birt.report.designer.ui.reportitemUI"
 provides the report designer extensibility and
 "org.eclipse.birt.report.engine.reportitemPresentation" provides the
 report engine extensibility. Now we will introduce them one by one.</p>


 <h3>1) org.eclipse.birt.report.model.reportItemModel</h3>


 <p>This extension point is provided by BIRT Report Model, normally user
 uses this extension point to define the extended report item model.</p>


 <img style="width: 1036px; height: 224px;" alt="" src="images/model-extension.png">
 <p>First we need define a new extended report item model
 extension&nbsp;as&nbsp;"RotatedText", this name is the&nbsp;identifier
 for the extended item, it's also the only symbol that connects between the report model
 and designer extensions.</p>


 <p>Then we define the model factory class as
 "org.eclipse.birt.sample.reportitem.rotatedtext.RotatedTextItemFactory".
 This factory class will be used to create and initialize the
 IReportItem instance,&nbsp;usually this class can also implement an
 additional&nbsp;IMessages interface to provide localization support:</p>


 <pre style="font-family: monospace;">public class RotatedTextItemFactory extends ReportItemFactory<br>{<br>	public IReportItem newReportItem( DesignElementHandle modelHanlde )<br>	{<br>		if ( modelHanlde instanceof ExtendedItemHandle &amp;&amp; RotatedTextItem.EXTENSION_NAME.equals( ( (ExtendedItemHandle) modelHanlde ).getExtensionName( ) ) )<br>		{<br>			return new RotatedTextItem( (ExtendedItemHandle) modelHanlde );<br>		}<br>	&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; return null;<br>	}<br><br>	public IMessages getMessages( )<br>	{<br>		// TODO implement this to support localization<br>		return null;<br>	}<br>}<br></pre>


 <p>There are some extra properties here that are not used by this example, we just introduce them briefly:</p>


 <ul>


   <li>defaultStyle</li>


   <ul>


     <li>specify the default style name, this will be used by BIRT
 to find and match the default style for this extended report item
 automatically.</li>


   </ul>


   <li>isNameRequired</li>


   <ul>


     <li>specify if the&nbsp;name is required for this extended report item.</li>


   </ul>


   <li>displayNameID</li>


   <ul>


     <li>specify the display name ID for this extended report item, the
 ID will be passed to&nbsp;IMessags interface to get the localized
 extended report item name.</li>


   </ul>


   <li>extendsFrom</li>


   <ul>


     <li>specify the name of the report item that this extended report
 item extends from, if this is not specified, the item will by default extend from
 "ExtendedItem".</li>


   </ul>


   <li>hasStyle</li>


   <ul>


     <li>specify if this extended report item supports styled properties, for some non-UI report items, it can be set to "false".</li>


   </ul>


 </ul>


 <p>Now we need define two new properties for the RotatedText extended report item:</p>


 <ul>


   <li>rotationAngle &nbsp; &nbsp;</li>


 </ul>


 &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;
 &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;
 the rotation angle, integer type, default&nbsp;as 0.<br>


 <img style="width: 1001px; height: 279px;" alt="" src="images/rotationangle-property.png">
 <ul>


   <li>text</li>


 </ul>


 &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;
 &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;
 the text content, string type, default as "Rotated Text".<br>


 <img style="width: 1000px; height: 274px;" alt="" src="images/text-property.png"><br>


 <br>


 <p>We can see a lot of things in the
 property setting page that we haven't used yet, normally they are for more complex property types, we
 just skip them here.<br>


 <br>
 Once we completed the model definition, we need give a basic IReportItem
 implementation. This class is used to encapsulate the extended report
 item model, providing some convenient property accessing APIs:</p>


 <pre>public class RotatedTextItem extends ReportItem<br>{<br>	public static final String EXTENSION_NAME = "RotatedText"; //$NON-NLS-1$<br>	public static final String TEXT_PROP = "text"; //$NON-NLS-1$<br>	public static final String ROTATION_ANGLE_PROP = "rotationAngle"; //$NON-NLS-1$<br><br>	private ExtendedItemHandle modelHandle;<br><br>	RotatedTextItem( ExtendedItemHandle modelHandle )<br>	{<br>		this.modelHandle = modelHandle;<br>	}<br><br>	public String getText( )<br>	{<br>		return modelHandle.getStringProperty( TEXT_PROP );<br>	}<br><br>	public int getRotationAngle( )<br>	{<br>		return modelHandle.getIntProperty( ROTATION_ANGLE_PROP );<br>	}<br><br>	public void setText( String value ) throws SemanticException<br>	{<br>		modelHandle.setProperty( TEXT_PROP, value );<br>	}<br><br>	public void setRotationAngle( int value ) throws SemanticException<br>	{<br>		modelHandle.setProperty( ROTATION_ANGLE_PROP, value );<br>	}<br>}<br></pre>


 <p>We can see&nbsp;most of the methods here are just getter/setters. For
 simple extended report item, this is normally already enough.</p>


 <h3>2) org.eclipse.birt.report.designer.ui.reportitemUI</h3>


 <p>This extension point is provided by BIRT Designer, user uses this
 extension point to define the UI behavior for&nbsp;extended report
 items.<br>


 <br>


 <img style="width: 1001px; height: 233px;" alt="" src="images/ui-extension.png"><br>


 <br>

 First we need bind the Designer extension with Model extension, to do
 this,&nbsp;we simply specify the extension name as "RotatedText".</p>


 <p>Next step, we specify some&nbsp;settings for this extended report item:</p>


 <ul>


   <li>Palette Settings</li>


   <ul>


     <li>specify the icon to be shown in Palette view, and the
 palette category as well. If the category is not specified, it will use
 the default "Report Items" category.</li>


   </ul>


 </ul>


 <img style="width: 495px; height: 111px;" alt="" src="images/palette-detail.png"><br>


 <br>


 <ul>


   <li>Editor Settings</li>


   <ul>


     <li>specify the report item visibility in different editor pages, and whether&nbsp;resizing control should be enabled.&nbsp;</li>


   </ul>


 </ul>


 <img style="width: 495px; height: 133px;" alt="" src="images/editor-detail.png"><br>


 <br>


 <ul>


   <li>Outline Settings</li>


   <ul>


     <li>specify the icon to be shown in Outline view, normally this is the same as in Palette view.</li>


   </ul>


 </ul>


 <img style="width: 497px; height: 90px;" alt="" src="images/icon-detail.png"><br>
 <p>


 The last step, specify the implementation class for UI provider:</p>


 <img style="width: 498px; height: 94px;" alt="" src="images/labelui-detail.png"><br>


 <p>The UI provider&nbsp;defines how to display and interact with the
 extended report item within the editor. BIRT designer support three types of
 basic UI providers:</p>


 <ul>


   <li>Label UI Provider</li>


   <ul>


     <li>user implements the&nbsp;IReportItemLabelProvider interface, it simply just requires&nbsp;an text content.</li>


   </ul>


   <li>Image UI Provider</li>


   <ul>


     <li>user implements the&nbsp;IReportItemImageProvider interface, it simply just requires&nbsp;an image content.</li>


   </ul>


   <li>Figure UI Provider</li>


   <ul>


     <li>user implements the IRportItemFigureProvider, This provider uses Figure interface from <a href="http://www.eclipse.org/gef/">GEF</a>, providing more flexibility and interactivity support.</li>


   </ul>


 </ul>


 <br>


 <p>In this example,&nbsp;we choose to implement the simplest Label UI
 Provider first, in consequent examples, we may introduce other type of UI providers.</p>


 <p>
 Our&nbsp;Label UI Provider implementation class is
 "org.eclipse.birt.sample.reportitem.rotatedText.RotatedTextLabelUI",
 the code looks very simple:</p>


 <pre>public class RotatedTextLabelUI implements IReportItemLabelProvider<br>{<br>	public String getLabel( ExtendedItemHandle handle )<br>	{<br>		try<br>		{<br>			IReportItem item = handle.getReportItem( );<br>			if ( item instanceof RotatedTextItem )<br>			{<br>				return ( (RotatedTextItem) item ).getText( );<br>			}<br>		}<br>		catch ( ExtendedElementException e )<br>		{<br>			e.printStackTrace( );<br>		}<br>		return null;<br>	}<br>}</pre>


 <p>You can see what it does is just reading the property from model and returning a text value.<br>


 <br>


 Once we completed the designer extension, we can run the desginer first and have a glance for&nbsp;what we already have now:<br>


 <br>


 OK, the Palette view already contains the new RotatedText extended report item.</p>


 <img style="width: 341px; height: 408px;" alt="" src="images/palette.png"> <br>


 <p>Right-click in the editor, we can see the RotatedText item is also available in the context menu.</p>


 <img style="width: 487px; height: 395px;" alt="" src="images/layout.png"><br>


 <p>Now&nbsp;try insert one RotatedText item to report, in Outline view, we can see the new RotatedText node.<br>


 </p>


 <img style="width: 347px; height: 438px;" alt="" src="images/outline.png"><br>


 <p>Select the RotatedText item, open the Properties view, it immediately
 lists all the properties that belong to this extended report item. Among
 them, we can see "Rotation Angle" and "Text
 Content" as well as other inherited properties. User can&nbsp;edit the
 property value in this view.
 </p>


 <img style="width: 728px; height: 346px;" alt="" src="images/properties.png"><br>


 <p>Now designer extension is done, let's step to the Report Engine extension.</p>


 <h3>3) org.eclipse.birt.report.engine.reportitemPresentation</h3>


 <p>This extension point is provided by BIRT Report Engine, user uses
 this extension point to define the presentation behavior of the
 extended report item.<br>


 </p>


 <div style="text-align: left;"><img style="width: 1003px; height: 166px;" alt="" src="images/engine-extension.png"><br>


 <p>First we also need specify the extension name as "RotatedText" to link it
 with&nbsp;Model extension, and specify the presentation implementation
 class
 as
 "org.eclipse.birt.sample.reportitem.rotatedtext.RotatedTextPresentationImpl".
 The presentation implementation class need implement the
 IReportItemPresentation interface.<br>


 <br>


 Our plan to implement the rotated text effect is to create an image
 dynamically, in this image, we use SWING graphics API to render the
 rotated text.&nbsp;</p>

 <p>Here is the code that all we need:</p>


 <pre>public class RotatedTextPresentationImpl extends ReportItemPresentationBase<br>{<br>	private RotatedTextItem textItem;<br><br>	public void setModelObject( ExtendedItemHandle modelHandle )<br>	{<br>		try<br>		{<br>			textItem = (RotatedTextItem) modelHandle.getReportItem( );<br>		}<br>		catch ( ExtendedElementException e )<br>		{<br>			e.printStackTrace( );<br>		}<br>	}<br><br>	public int getOutputType( )<br>	{<br>		return OUTPUT_AS_IMAGE;<br>	}<br><br>	public Object onRowSets( IRowSet[] rowSets ) throws BirtException<br>	{<br>		if ( textItem == null )<br>		{<br>			return null;<br>		}<br><br>		int angle = textItem.getRotationAngle( );<br>		String text = textItem.getText( );<br>		BufferedImage rotatedImage = SwingGraphicsUtil.createRotatedTextImage( text, angle, new Font( "Default", 0, 12 ) ); //$NON-NLS-1$<br>		ByteArrayInputStream bis = null;<br><br>		try<br>		{<br>			ImageIO.setUseCache( false );<br>			ByteArrayOutputStream baos = new ByteArrayOutputStream( );<br>			ImageOutputStream ios = ImageIO.createImageOutputStream( baos );<br>			ImageIO.write( rotatedImage, "png", ios ); //$NON-NLS-1$<br>			ios.flush( );<br>			ios.close( );<br>			bis = new ByteArrayInputStream( baos.toByteArray( ) );<br>		}<br>		catch ( IOException e )<br>		{<br>			e.printStackTrace( );<br>		}<br>		return bis;<br>	}<br>}<br></pre>


 <p>The logic is&nbsp;pretty straightforward, the main part is to
 generate an image dynamically in the&nbsp;onRowSets() method. To return
 the image, we simply create an in-memory stream to hold&nbsp;the image
 content.</p>


 <p>Here is the utility class that implements the key rotation rendering algorithm:</p>


 <pre>public class SwingGraphicsUtil<br>{<br>	public static BufferedImage createRotatedTextImage( String text, int angle, Font ft )<br>	{<br>		Graphics2D g2d = null;<br>		try<br>		{<br>			if ( text == null || text.trim( ).length( ) == 0 )<br>			{<br>				return null;<br>			}<br>			BufferedImage stringImage = new BufferedImage( 1, 1, BufferedImage.TYPE_INT_ARGB );<br>			g2d = (Graphics2D) stringImage.getGraphics( );<br>			g2d.setFont( ft );<br>			FontMetrics fm = g2d.getFontMetrics( );<br>			Rectangle2D bounds = fm.getStringBounds( text, g2d );<br>			TextLayout tl = new TextLayout( text, ft, g2d.getFontRenderContext( ) );<br>			g2d.dispose( );<br>			g2d = null;<br>			return createRotatedImage( tl, (int) bounds.getWidth( ), (int) bounds.getHeight( ), angle );<br>		}<br>		catch ( Exception e )<br>		{<br>			e.printStackTrace( );<br>			if ( g2d != null )<br>			{<br>				g2d.dispose( );<br>			}<br>		}<br>		return null;<br>	}<br><br>	private static BufferedImage createRotatedImage( Object src, int width, int height, int angle )<br>	{<br>		angle = angle % 360;<br>		if ( angle &lt; 0 )<br>		{<br>			angle += 360;<br>		}<br>		if ( angle == 0 )<br>		{<br>			return renderRotatedObject( src, 0, width, height, 0, 0 );<br>		}<br>		else if ( angle == 90 )<br>		{<br>			return renderRotatedObject( src, -Math.PI / 2, height, width, -width, 0 );<br>		}<br>		else if ( angle == 180 )<br>		{<br>			return renderRotatedObject( src, Math.PI, width, height, -width, -height );<br>		}<br>		else if ( angle == 270 )<br>		{<br>			return renderRotatedObject( src, Math.PI / 2, height, width, 0, -height );<br>		}<br>		else if ( angle &gt; 0 &amp;&amp; angle &lt; 90 )<br>		{<br>			double angleInRadians = ( ( -angle * Math.PI ) / 180.0 );<br>			double cosTheta = Math.abs( Math.cos( angleInRadians ) );<br>			double sineTheta = Math.abs( Math.sin( angleInRadians ) );<br>			int dW = (int) ( width * cosTheta + height * sineTheta );<br>			int dH = (int) ( width * sineTheta + height * cosTheta );<br>			return renderRotatedObject( src, angleInRadians, dW, dH, -width * sineTheta * sineTheta, width * sineTheta * cosTheta );<br>		}<br>		else if ( angle &gt; 90 &amp;&amp; angle &lt; 180 )<br>		{<br>			double angleInRadians = ( ( -angle * Math.PI ) / 180.0 );<br>			double cosTheta = Math.abs( Math.cos( angleInRadians ) );<br>			double sineTheta = Math.abs( Math.sin( angleInRadians ) );<br>			int dW = (int) ( width * cosTheta + height * sineTheta );<br>			int dH = (int) ( width * sineTheta + height * cosTheta );<br>			return renderRotatedObject( src, angleInRadians, dW, dH, -( width + height * sineTheta * cosTheta ), -height / 2 );<br>		}<br>		else if ( angle &gt; 180 &amp;&amp; angle &lt; 270 )<br>		{<br>			double angleInRadians = ( ( -angle * Math.PI ) / 180.0 );<br>			double cosTheta = Math.abs( Math.cos( angleInRadians ) );<br>			double sineTheta = Math.abs( Math.sin( angleInRadians ) );<br>			int dW = (int) ( width * cosTheta + height * sineTheta );<br>			int dH = (int) ( width * sineTheta + height * cosTheta );<br>			return renderRotatedObject( src, angleInRadians, dW, dH, -( width * cosTheta * cosTheta ), -( height + width * cosTheta * sineTheta ) );<br>		}<br>		else if ( angle &gt; 270 &amp;&amp; angle &lt; 360 )<br>		{<br>			double angleInRadians = ( ( -angle * Math.PI ) / 180.0 );<br>			double cosTheta = Math.abs( Math.cos( angleInRadians ) );<br>			double sineTheta = Math.abs( Math.sin( angleInRadians ) );<br>			int dW = (int) ( width * cosTheta + height * sineTheta );<br>			int dH = (int) ( width * sineTheta + height * cosTheta );<br>			return renderRotatedObject( src, angleInRadians, dW, dH, ( height * cosTheta * sineTheta ), -( height * sineTheta * sineTheta ) );<br>		}<br>		return renderRotatedObject( src, 0, width, height, 0, 0 );<br>	}<br><br>	private static BufferedImage renderRotatedObject( Object src, double angle, int width, int height, double tx, double ty )<br>	{<br>		BufferedImage dest = new BufferedImage( width, height, BufferedImage.TYPE_INT_ARGB );<br>		Graphics2D g2d = (Graphics2D) dest.getGraphics( );<br>		g2d.setColor( Color.black );<br>		g2d.setRenderingHint( RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON );<br>		g2d.setRenderingHint( RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON );<br>		AffineTransform at = AffineTransform.getRotateInstance( angle );<br>		at.translate( tx, ty );<br>		g2d.setTransform( at );<br>		if ( src instanceof TextLayout )<br>		{<br>			TextLayout tl = (TextLayout) src;<br>			tl.draw( g2d, 0, tl.getAscent( ) );<br>		}<br>		else if ( src instanceof Image )<br>		{<br>			g2d.drawImage( (Image) src, 0, 0, null );<br>		}<br>		g2d.dispose( );<br>		return dest;<br>	}<br>}<br></pre>


 <h2>The Result</h2>


 <p>Now all&nbsp;required extension points are done, let's have a test.<br>


 <br>


 Create a report that contains some RotatedText items first:<br>


 </p>


 <img style="width: 865px; height: 273px;" alt="" src="images/design-layout.png"><br>


 <p>Here we inserted quite a few RotatedText items&nbsp;with different angle settings.<br>


 <br>


 Preview the report as HTML, it results like this:<br>


 </p>


 <img style="width: 703px; height: 218px;" alt="" src="images/html-output.png"><br>


 <p>Preview the report as PDF, it results like this:<br>


 </p>


 <img style="width: 757px; height: 482px;" alt="" src="images/pdf-output.png"><br>


 <br>


 <p>Done! So far we've successfully implemented a RotatedText extended
 report item for BIRT, and integrated it with Designer and Report Engine.<br>


 </p>


 </div>


 <h2>Summary</h2>


 <p>BIRT&nbsp;provides very good extension mechanism, which allows user
 to create custom reporting features. This article introduced how to write
 a custom RotatedText extended report item for BIRT.</p>


 <h2>Resources</h2>


 <p>[1] &nbsp;<a href="extension-tutorial-1.zip">The complete source code</a>: you can extract and import it into Eclipse workspace as a plugin project directly</p>


 <p>[2] &nbsp;BIRT Official Site: <a href="http://eclipse.org/birt">http://eclipse.org/birt</a></p>


 <p>[3] &nbsp;How to access Eclipse CVS: <a href="http://wiki.eclipse.org/CVS_Howto">http://wiki.eclipse.org/CVS_Howto</a></p>


 <p><br>


 <br>


 </p>


 <br>


 </div>


 </body>
 </html>
	<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
	<html>
	<head>








	<title>BIRT Extension Mechanism : Part 1</title>
	<meta http-equiv="Content-Type" content="text/html; charset=windows-1252">





	<link href="../article.css" type="text/css" rel="stylesheet">
	</head>


	<body>



	<h1>BIRT Extension Mechanism : Part 1</h1>



	<div class="summary">
	<h2>Abstract</h2>



	<p>This article introduces the extension mechanism of BIRT report
	model, engine and designer, shows how to create custom extended report items
	step by
	step.</p>



	<div class="author">By Zhiqiang
	Qian, Actuate Corporation</div>



	<div class="copyright">Copyright © [2008]
	[Actuate Corporation].</div>



	<div class="date">August 7, 2008</div>



	</div>



	<div class="content">
	<h2>Introduction</h2>



	<p>For many people, <a href="http://eclipse.org/birt">BIRT(Business
	Intelligence and Reporting Tools)</a> may
	only mean a regular reporting tool. But in fact, the real strength of
	BIRT is not only its built-in reporting functionality, but also
	its
	extension capabilities. By extensions, user can easily extend the
	functionality of BIRT, creating custom extended report items, adding custom
	emitters, and even having custom editor pages. The powerfulness of extensions
	enables user to create
	custom reporting features that can meet very specific requirements. In
	this
	article, we will explorer how to leverage the BIRT extension mechanism to
	extend the BIRT capabilities. The given samples will
	cover most of the essential extension points that provided by BIRT report
	model, engine and designer.<br>



	</p>



	<h2>The Basics</h2>



	<p>BIRT already contains the basic Label and Text report items,
	but these items can only show horizontal text. Sometimes, user
	would
	like to show angled text, in this case, alternative solution is needed.
	In following sections, we are introducing how to implement a
	RotatedText
	extended report item through BIRT extensions, and how to enhance
	the functionality step by step by implementing more extension points.</p>



	<p>Note: This example is a modified version based
	on RotatedText sample on BIRT CVS, the original code
	can be retrieved <a href="http://dev.eclipse.org/viewcvs/index.cgi/?root=BIRT_Project">here.</a></p>



	<p>To implement an extended report item, basically we need look at following extension points:</p>



	<ul>



	<li>org.eclipse.birt.report.model.reportItemModel</li>



	<li>org.eclipse.birt.report.designer.ui.reportitemUI</li>



	<li>org.eclipse.birt.report.engine.reportitemPresentation</li>



	</ul>



	<br>



	<img style="width: 514px; height: 156px;" alt="" src="images/extensions.png"><br>



	<p>These three extensions are the basics to implement an extended
	report item. In brief,
	"org.eclipse.birt.report.model.reportItemModel" provides the report
	model extensibility, "org.eclipse.birt.report.designer.ui.reportitemUI"
	provides the report designer extensibility and
	"org.eclipse.birt.report.engine.reportitemPresentation" provides the
	report engine extensibility. Now we will introduce them one by one.</p>



	<h3>1) org.eclipse.birt.report.model.reportItemModel</h3>



	<p>This extension point is provided by BIRT Report Model, normally user
	uses this extension point to define the extended report item model.</p>



	<img style="width: 1036px; height: 224px;" alt="" src="images/model-extension.png">
	<p>First we need define a new extended report item model
	extension as "RotatedText", this name is the identifier
	for the extended item, it's also the only symbol that connects between the report model
	and designer extensions.</p>


	<p>Then we define the model factory class as
	"org.eclipse.birt.sample.reportitem.rotatedtext.RotatedTextItemFactory".
	This factory class will be used to create and initialize the
	IReportItem instance, usually this class can also implement an
	additional IMessages interface to provide localization support:</p>



	<pre style="font-family: monospace;">public class RotatedTextItemFactory extends ReportItemFactory<br>{<br> public IReportItem newReportItem( DesignElementHandle modelHanlde )<br> {<br> if ( modelHanlde instanceof ExtendedItemHandle && RotatedTextItem.EXTENSION_NAME.equals( ( (ExtendedItemHandle) modelHanlde ).getExtensionName( ) ) )<br> {<br> return new RotatedTextItem( (ExtendedItemHandle) modelHanlde );<br> }<br>         return null;<br> }<br><br> public IMessages getMessages( )<br> {<br> // TODO implement this to support localization<br> return null;<br> }<br>}<br></pre>



	<p>There are some extra properties here that are not used by this example, we just introduce them briefly:</p>



	<ul>



	<li>defaultStyle</li>





	<ul>



	<li>specify the default style name, this will be used by BIRT
	to find and match the default style for this extended report item
	automatically.</li>





	</ul>



	<li>isNameRequired</li>





	<ul>



	<li>specify if the name is required for this extended report item.</li>





	</ul>



	<li>displayNameID</li>





	<ul>



	<li>specify the display name ID for this extended report item, the
	ID will be passed to IMessags interface to get the localized
	extended report item name.</li>





	</ul>



	<li>extendsFrom</li>





	<ul>



	<li>specify the name of the report item that this extended report
	item extends from, if this is not specified, the item will by default extend from
	"ExtendedItem".</li>





	</ul>



	<li>hasStyle</li>





	<ul>



	<li>specify if this extended report item supports styled properties, for some non-UI report items, it can be set to "false".</li>





	</ul>



	</ul>



	<p>Now we need define two new properties for the RotatedText extended report item:</p>



	<ul>



	<li>rotationAngle    </li>



	</ul>





	the rotation angle, integer type, default as 0.<br>



	<img style="width: 1001px; height: 279px;" alt="" src="images/rotationangle-property.png">
	<ul>



	<li>text</li>



	</ul>





	the text content, string type, default as "Rotated Text".<br>



	<img style="width: 1000px; height: 274px;" alt="" src="images/text-property.png"><br>



	<br>



	<p>We can see a lot of things in the
	property setting page that we haven't used yet, normally they are for more complex property types, we
	just skip them here.<br>



	<br>
	Once we completed the model definition, we need give a basic IReportItem
	implementation. This class is used to encapsulate the extended report
	item model, providing some convenient property accessing APIs:</p>



	<pre>public class RotatedTextItem extends ReportItem<br>{<br> public static final String EXTENSION_NAME = "RotatedText"; //$NON-NLS-1$<br> public static final String TEXT_PROP = "text"; //$NON-NLS-1$<br> public static final String ROTATION_ANGLE_PROP = "rotationAngle"; //$NON-NLS-1$<br><br> private ExtendedItemHandle modelHandle;<br><br> RotatedTextItem( ExtendedItemHandle modelHandle )<br> {<br> this.modelHandle = modelHandle;<br> }<br><br> public String getText( )<br> {<br> return modelHandle.getStringProperty( TEXT_PROP );<br> }<br><br> public int getRotationAngle( )<br> {<br> return modelHandle.getIntProperty( ROTATION_ANGLE_PROP );<br> }<br><br> public void setText( String value ) throws SemanticException<br> {<br> modelHandle.setProperty( TEXT_PROP, value );<br> }<br><br> public void setRotationAngle( int value ) throws SemanticException<br> {<br> modelHandle.setProperty( ROTATION_ANGLE_PROP, value );<br> }<br>}<br></pre>



	<p>We can see most of the methods here are just getter/setters. For
	simple extended report item, this is normally already enough.</p>



	<h3>2) org.eclipse.birt.report.designer.ui.reportitemUI</h3>



	<p>This extension point is provided by BIRT Designer, user uses this
	extension point to define the UI behavior for extended report
	items.<br>



	<br>



	<img style="width: 1001px; height: 233px;" alt="" src="images/ui-extension.png"><br>



	<br>

	First we need bind the Designer extension with Model extension, to do
	this, we simply specify the extension name as "RotatedText".</p>



	<p>Next step, we specify some settings for this extended report item:</p>



	<ul>



	<li>Palette Settings</li>





	<ul>



	<li>specify the icon to be shown in Palette view, and the
	palette category as well. If the category is not specified, it will use
	the default "Report Items" category.</li>





	</ul>



	</ul>



	<img style="width: 495px; height: 111px;" alt="" src="images/palette-detail.png"><br>



	<br>



	<ul>



	<li>Editor Settings</li>





	<ul>



	<li>specify the report item visibility in different editor pages, and whether resizing control should be enabled. </li>





	</ul>



	</ul>



	<img style="width: 495px; height: 133px;" alt="" src="images/editor-detail.png"><br>



	<br>



	<ul>



	<li>Outline Settings</li>





	<ul>



	<li>specify the icon to be shown in Outline view, normally this is the same as in Palette view.</li>





	</ul>



	</ul>



	<img style="width: 497px; height: 90px;" alt="" src="images/icon-detail.png"><br>
	<p>


	The last step, specify the implementation class for UI provider:</p>



	<img style="width: 498px; height: 94px;" alt="" src="images/labelui-detail.png"><br>



	<p>The UI provider defines how to display and interact with the
	extended report item within the editor. BIRT designer support three types of
	basic UI providers:</p>



	<ul>



	<li>Label UI Provider</li>





	<ul>



	<li>user implements the IReportItemLabelProvider interface, it simply just requires an text content.</li>





	</ul>



	<li>Image UI Provider</li>





	<ul>



	<li>user implements the IReportItemImageProvider interface, it simply just requires an image content.</li>





	</ul>



	<li>Figure UI Provider</li>





	<ul>



	<li>user implements the IRportItemFigureProvider, This provider uses Figure interface from <a href="http://www.eclipse.org/gef/">GEF</a>, providing more flexibility and interactivity support.</li>





	</ul>



	</ul>


	<br>


	<p>In this example, we choose to implement the simplest Label UI
	Provider first, in consequent examples, we may introduce other type of UI providers.</p>


	<p>
	Our Label UI Provider implementation class is
	"org.eclipse.birt.sample.reportitem.rotatedText.RotatedTextLabelUI",
	the code looks very simple:</p>



	<pre>public class RotatedTextLabelUI implements IReportItemLabelProvider<br>{<br> public String getLabel( ExtendedItemHandle handle )<br> {<br> try<br> {<br> IReportItem item = handle.getReportItem( );<br> if ( item instanceof RotatedTextItem )<br> {<br> return ( (RotatedTextItem) item ).getText( );<br> }<br> }<br> catch ( ExtendedElementException e )<br> {<br> e.printStackTrace( );<br> }<br> return null;<br> }<br>}</pre>



	<p>You can see what it does is just reading the property from model and returning a text value.<br>



	<br>


	Once we completed the designer extension, we can run the desginer first and have a glance for what we already have now:<br>



	<br>



	OK, the Palette view already contains the new RotatedText extended report item.</p>



	<img style="width: 341px; height: 408px;" alt="" src="images/palette.png"> <br>



	<p>Right-click in the editor, we can see the RotatedText item is also available in the context menu.</p>



	<img style="width: 487px; height: 395px;" alt="" src="images/layout.png"><br>



	<p>Now try insert one RotatedText item to report, in Outline view, we can see the new RotatedText node.<br>



	</p>



	<img style="width: 347px; height: 438px;" alt="" src="images/outline.png"><br>



	<p>Select the RotatedText item, open the Properties view, it immediately
	lists all the properties that belong to this extended report item. Among
	them, we can see "Rotation Angle" and "Text
	Content" as well as other inherited properties. User can edit the
	property value in this view.
	</p>



	<img style="width: 728px; height: 346px;" alt="" src="images/properties.png"><br>


	<p>Now designer extension is done, let's step to the Report Engine extension.</p>



	<h3>3) org.eclipse.birt.report.engine.reportitemPresentation</h3>



	<p>This extension point is provided by BIRT Report Engine, user uses
	this extension point to define the presentation behavior of the
	extended report item.<br>



	</p>



	<div style="text-align: left;"><img style="width: 1003px; height: 166px;" alt="" src="images/engine-extension.png"><br>



	<p>First we also need specify the extension name as "RotatedText" to link it
	with Model extension, and specify the presentation implementation
	class
	as
	"org.eclipse.birt.sample.reportitem.rotatedtext.RotatedTextPresentationImpl".
	The presentation implementation class need implement the
	IReportItemPresentation interface.<br>



	<br>


	Our plan to implement the rotated text effect is to create an image
	dynamically, in this image, we use SWING graphics API to render the
	rotated text. </p>

	<p>Here is the code that all we need:</p>



	<pre>public class RotatedTextPresentationImpl extends ReportItemPresentationBase<br>{<br> private RotatedTextItem textItem;<br><br> public void setModelObject( ExtendedItemHandle modelHandle )<br> {<br> try<br> {<br> textItem = (RotatedTextItem) modelHandle.getReportItem( );<br> }<br> catch ( ExtendedElementException e )<br> {<br> e.printStackTrace( );<br> }<br> }<br><br> public int getOutputType( )<br> {<br> return OUTPUT_AS_IMAGE;<br> }<br><br> public Object onRowSets( IRowSet[] rowSets ) throws BirtException<br> {<br> if ( textItem == null )<br> {<br> return null;<br> }<br><br> int angle = textItem.getRotationAngle( );<br> String text = textItem.getText( );<br> BufferedImage rotatedImage = SwingGraphicsUtil.createRotatedTextImage( text, angle, new Font( "Default", 0, 12 ) ); //$NON-NLS-1$<br> ByteArrayInputStream bis = null;<br><br> try<br> {<br> ImageIO.setUseCache( false );<br> ByteArrayOutputStream baos = new ByteArrayOutputStream( );<br> ImageOutputStream ios = ImageIO.createImageOutputStream( baos );<br> ImageIO.write( rotatedImage, "png", ios ); //$NON-NLS-1$<br> ios.flush( );<br> ios.close( );<br> bis = new ByteArrayInputStream( baos.toByteArray( ) );<br> }<br> catch ( IOException e )<br> {<br> e.printStackTrace( );<br> }<br> return bis;<br> }<br>}<br></pre>



	<p>The logic is pretty straightforward, the main part is to
	generate an image dynamically in the onRowSets() method. To return
	the image, we simply create an in-memory stream to hold the image
	content.</p>



	<p>Here is the utility class that implements the key rotation rendering algorithm:</p>



	<pre>public class SwingGraphicsUtil<br>{<br> public static BufferedImage createRotatedTextImage( String text, int angle, Font ft )<br> {<br> Graphics2D g2d = null;<br> try<br> {<br> if ( text == null \|\| text.trim( ).length( ) == 0 )<br> {<br> return null;<br> }<br> BufferedImage stringImage = new BufferedImage( 1, 1, BufferedImage.TYPE_INT_ARGB );<br> g2d = (Graphics2D) stringImage.getGraphics( );<br> g2d.setFont( ft );<br> FontMetrics fm = g2d.getFontMetrics( );<br> Rectangle2D bounds = fm.getStringBounds( text, g2d );<br> TextLayout tl = new TextLayout( text, ft, g2d.getFontRenderContext( ) );<br> g2d.dispose( );<br> g2d = null;<br> return createRotatedImage( tl, (int) bounds.getWidth( ), (int) bounds.getHeight( ), angle );<br> }<br> catch ( Exception e )<br> {<br> e.printStackTrace( );<br> if ( g2d != null )<br> {<br> g2d.dispose( );<br> }<br> }<br> return null;<br> }<br><br> private static BufferedImage createRotatedImage( Object src, int width, int height, int angle )<br> {<br> angle = angle % 360;<br> if ( angle < 0 )<br> {<br> angle += 360;<br> }<br> if ( angle == 0 )<br> {<br> return renderRotatedObject( src, 0, width, height, 0, 0 );<br> }<br> else if ( angle == 90 )<br> {<br> return renderRotatedObject( src, -Math.PI / 2, height, width, -width, 0 );<br> }<br> else if ( angle == 180 )<br> {<br> return renderRotatedObject( src, Math.PI, width, height, -width, -height );<br> }<br> else if ( angle == 270 )<br> {<br> return renderRotatedObject( src, Math.PI / 2, height, width, 0, -height );<br> }<br> else if ( angle > 0 && angle < 90 )<br> {<br> double angleInRadians = ( ( -angle * Math.PI ) / 180.0 );<br> double cosTheta = Math.abs( Math.cos( angleInRadians ) );<br> double sineTheta = Math.abs( Math.sin( angleInRadians ) );<br> int dW = (int) ( width * cosTheta + height * sineTheta );<br> int dH = (int) ( width * sineTheta + height * cosTheta );<br> return renderRotatedObject( src, angleInRadians, dW, dH, -width * sineTheta * sineTheta, width * sineTheta * cosTheta );<br> }<br> else if ( angle > 90 && angle < 180 )<br> {<br> double angleInRadians = ( ( -angle * Math.PI ) / 180.0 );<br> double cosTheta = Math.abs( Math.cos( angleInRadians ) );<br> double sineTheta = Math.abs( Math.sin( angleInRadians ) );<br> int dW = (int) ( width * cosTheta + height * sineTheta );<br> int dH = (int) ( width * sineTheta + height * cosTheta );<br> return renderRotatedObject( src, angleInRadians, dW, dH, -( width + height * sineTheta * cosTheta ), -height / 2 );<br> }<br> else if ( angle > 180 && angle < 270 )<br> {<br> double angleInRadians = ( ( -angle * Math.PI ) / 180.0 );<br> double cosTheta = Math.abs( Math.cos( angleInRadians ) );<br> double sineTheta = Math.abs( Math.sin( angleInRadians ) );<br> int dW = (int) ( width * cosTheta + height * sineTheta );<br> int dH = (int) ( width * sineTheta + height * cosTheta );<br> return renderRotatedObject( src, angleInRadians, dW, dH, -( width * cosTheta * cosTheta ), -( height + width * cosTheta * sineTheta ) );<br> }<br> else if ( angle > 270 && angle < 360 )<br> {<br> double angleInRadians = ( ( -angle * Math.PI ) / 180.0 );<br> double cosTheta = Math.abs( Math.cos( angleInRadians ) );<br> double sineTheta = Math.abs( Math.sin( angleInRadians ) );<br> int dW = (int) ( width * cosTheta + height * sineTheta );<br> int dH = (int) ( width * sineTheta + height * cosTheta );<br> return renderRotatedObject( src, angleInRadians, dW, dH, ( height * cosTheta * sineTheta ), -( height * sineTheta * sineTheta ) );<br> }<br> return renderRotatedObject( src, 0, width, height, 0, 0 );<br> }<br><br> private static BufferedImage renderRotatedObject( Object src, double angle, int width, int height, double tx, double ty )<br> {<br> BufferedImage dest = new BufferedImage( width, height, BufferedImage.TYPE_INT_ARGB );<br> Graphics2D g2d = (Graphics2D) dest.getGraphics( );<br> g2d.setColor( Color.black );<br> g2d.setRenderingHint( RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON );<br> g2d.setRenderingHint( RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON );<br> AffineTransform at = AffineTransform.getRotateInstance( angle );<br> at.translate( tx, ty );<br> g2d.setTransform( at );<br> if ( src instanceof TextLayout )<br> {<br> TextLayout tl = (TextLayout) src;<br> tl.draw( g2d, 0, tl.getAscent( ) );<br> }<br> else if ( src instanceof Image )<br> {<br> g2d.drawImage( (Image) src, 0, 0, null );<br> }<br> g2d.dispose( );<br> return dest;<br> }<br>}<br></pre>



	<h2>The Result</h2>



	<p>Now all required extension points are done, let's have a test.<br>



	<br>


	Create a report that contains some RotatedText items first:<br>



	</p>



	<img style="width: 865px; height: 273px;" alt="" src="images/design-layout.png"><br>



	<p>Here we inserted quite a few RotatedText items with different angle settings.<br>



	<br>


	Preview the report as HTML, it results like this:<br>



	</p>



	<img style="width: 703px; height: 218px;" alt="" src="images/html-output.png"><br>



	<p>Preview the report as PDF, it results like this:<br>



	</p>



	<img style="width: 757px; height: 482px;" alt="" src="images/pdf-output.png"><br>



	<br>



	<p>Done! So far we've successfully implemented a RotatedText extended
	report item for BIRT, and integrated it with Designer and Report Engine.<br>



	</p>



	</div>



	<h2>Summary</h2>



	<p>BIRT provides very good extension mechanism, which allows user
	to create custom reporting features. This article introduced how to write
	a custom RotatedText extended report item for BIRT.</p>



	<h2>Resources</h2>



	<p>[1]  <a href="extension-tutorial-1.zip">The complete source code</a>: you can extract and import it into Eclipse workspace as a plugin project directly</p>



	<p>[2]  BIRT Official Site: <a href="http://eclipse.org/birt">http://eclipse.org/birt</a></p>



	<p>[3]  How to access Eclipse CVS: <a href="http://wiki.eclipse.org/CVS_Howto">http://wiki.eclipse.org/CVS_Howto</a></p>



	<p><br>



	<br>



	</p>



	<br>



	</div>



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