Generating a chart image from an rptdesign file

Hi All, 
 
We currently have a number of report design files that contain a single chart. I'd like to be able to create an image representing that chart from that definition, and then return the URL for that image to a web application for display. 
 
Currently, the only way I see to do this is to use the HTMLRenderOption, set the image directory to one available to the web application, and run the report. The chart will be automatically created as an image, and included into the generated HTML report, but also be available as an image from the specified image directory. 
 
I'd like to bypass having to create the HTML file, and just create the chart directly, using the data set defined in the design file, or even switching it out for another one at runtime based on the input parameters from the web application. 
 
So far, the only thing I've been able to accomplish is to write a simple test application that extracts the chart from the design file, and use a Generator object to render the chart. The only problem with this is that this method doesn't seem to automatically use the data set defined in the design file to populate the chart with data. Here's the simple class I wrote: 
 
<pre class='_prettyXprint _lang-auto _linenums:0'>
import org.eclipse.birt.chart.device.IDeviceRenderer;
import org.eclipse.birt.chart.exception.ChartException;
import org.eclipse.birt.chart.model.ChartWithAxes;
import org.eclipse.birt.chart.util.PluginSettings;
import org.eclipse.birt.core.framework.Platform;
import org.eclipse.birt.report.model.api.DesignConfig;
import org.eclipse.birt.report.model.api.DesignFileException;
import org.eclipse.birt.report.model.api.ExtendedItemHandle;
import org.eclipse.birt.report.model.api.IDesignEngine;
import org.eclipse.birt.report.model.api.IDesignEngineFactory;
import org.eclipse.birt.report.model.api.ReportDesignHandle;
import org.eclipse.birt.report.model.api.SessionHandle;
import org.eclipse.birt.report.model.api.extension.ExtendedElementException;
import org.eclipse.birt.chart.factory.GeneratedChartState;
import org.eclipse.birt.chart.factory.Generator;
import org.eclipse.birt.chart.factory.RunTimeContext;
import org.eclipse.birt.chart.model.attribute.Bounds;
import org.eclipse.birt.chart.model.attribute.impl.BoundsImpl;

import com.ibm.icu.util.ULocale;

public class ChartTest
{
private void createChart()
{
ReportDesignHandle designHandle = null;
DesignConfig config = new DesignConfig();

// config.setBIRTHome("C:/birt/birt-runtime-2_5_1/birt-runtime-2_5_1/ReportEngine ");
IDesignEngine engine = null;
try
{
Platform.startup(config);
IDesignEngineFactory factory = (IDesignEngineFactory) Platform.createFactoryObject(IDesignEngineFactory.EXTENSION_DESIGN_ENGINE_FACTORY);
engine = factory.createDesignEngine(config);
}
catch(Exception ex)
{
ex.printStackTrace();
}

SessionHandle sessionHandle = engine.newSessionHandle((ULocale) null);

try
{
designHandle = sessionHandle.openDesign("/nethome/eblack04/AnomalyGraphTemplate.rptdesign");
}
catch(DesignFileException e)
{
e.printStackTrace();
}

ExtendedItemHandle eih = (ExtendedItemHandle) designHandle.getBody().getContents().get(4);

ChartWithAxes chart = null;
try
{
chart = (ChartWithAxes)eih.getReportItem().getProperty("chart.instance");
System.out.println("Chart is " + (chart == null ? "" : "not ") + "null");

PluginSettings ps = PluginSettings.instance();
IDeviceRenderer renderer = ps.getDevice("dv.PNG");

renderer.setProperty(IDeviceRenderer.FILE_IDENTIFIER, "/nethome/eblack04/AnomalyGraphTemplate.png");

RunTimeContext rtc = new RunTimeContext( );
rtc.setULocale( ULocale.getDefault( ) );

final Generator gr = Generator.instance( );
GeneratedChartState gcs = null;
//Set the chart size
Bounds bounds = BoundsImpl.create( 0, 0, 450, 300 );
gcs = gr.build( renderer.getDisplayServer( ), chart, bounds, null, rtc, null );

//generate the chart
gr.render(renderer, gcs);
}
catch(ExtendedElementException e)
{
e.printStackTrace();
}
catch(ChartException e)
{
e.printStackTrace();
}
}

/**
* execute application
*
* @param args
*/
public static void main(String[] args)
{
new ChartTest().createChart();
}
}
</pre>
 
Do I have to pull out the data set defined in the report design file as well as the chart, and then set that data set into the chart before using the generator to create it? If so, how? Any help would be greatly appreciated on this. 
 
Thanks, 
 
Todd

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Comments

johnw

Normally, yes, you would need to populate the charts dataset with the data results of the operation.

A much easier option than messing with all of that is to download the source for the HTML emitter, and modify the End method to write out to an image file using the Swing JEditorPane. It will take an HTML page and render it to an image that can be saved. If you set the render option to return snippets instead of the whole page, it wont render the Master Page header and footer, and will do what you want. I've had to do this previously to generate preview images of reports.

ToddB

Thanks for the suggestion John. I'll start looking into that now. Would you happen to have any code snippets that outline your directions? It'll probably make things go a little faster.

If it wasn't for this suggestion, I would have probably had to go with my backup plan, which was to use the HTMLRenderOption to create my report and chart image, but set the image directory to be uniquely named to the report I'm creating. In this way, I could discard the generated HTML page, and just use the image and not have to worry about other report's images within the same directory, and whose is whose.

It's kind of a hacky way of doing it, but it will work. I prefer your solution. Thanks again.

johnw

I have not tested this for thread safety, but I don't recall ever having an issue with it. Some cleanup might be in order. The end method and render method would look like this.

public void end( IReportContent report )
{
logger.log( Level.FINE, "[HTMLReportEmitter] End body." ); //$NON-NLS-1$
if ( report != null )
{
List errors = report.getErrors( );
if ( errors != null && !errors.isEmpty( ) )
{
outputErrors( errors );
}
}
if ( !isEmbeddable )
{
writer.closeTag( HTMLTags.TAG_BODY );
writer.closeTag( HTMLTags.TAG_HTML );
}
else
{
writer.closeTag( HTMLTags.TAG_DIV );
}

writer.endWriter( );
writer.close( );
if ( out != null )
{
try
{
out.close( );
}
catch ( IOException e )
{
logger.log( Level.WARNING, e.getMessage( ), e );
}
}

//We have closed our out, now it is time to render our image, and output to our original image
BufferedImage renderedImage = this.renderPreviewImage(this.tempFile.getAbsolutePath());
try {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
ImageIO.write(renderedImage, "JPG", baos);
byte[] bytesOut = baos.toByteArray();

//this.originalOut.write(contentType.getBytes());
this.originalOut.write(baos.toByteArray());
this.originalOut.close();
} catch (IOException e) {
e.printStackTrace();
}
}

/**
* Given an HTML location, render a preview of it
* @param reportLocation
* @return
*/
public BufferedImage renderPreviewImage(String reportLocation)
{
JEditorPane jPane = null;

loaded = false;
try {
File f = new File(reportLocation);
jPane = new JEditorPane();

jPane.setEditable(false);
jPane.setMargin(new Insets(0,0,0,0));
jPane.addPropertyChangeListener(new PropertyChangeListener() {
public void propertyChange(PropertyChangeEvent evt) {
if (evt.getPropertyName().equals("page")) {
loaded = true;
}
}
});

jPane.setPage(f.toURL());
while (!loaded) {
Thread.yield();
}
} catch (MalformedURLException e1) {
e1.printStackTrace();
} catch (IOException e1) {
e1.printStackTrace();
}

Dimension prefSize = jPane.getPreferredSize();
BufferedImage image = new BufferedImage(prefSize.width, jPane.getPreferredSize().height,
BufferedImage.TYPE_INT_ARGB);

Graphics g = image.getGraphics();
jPane.setSize(prefSize);
jPane.paint(g);

g.dispose();

return image;
}

internet

Hello,
I have the same problem.
Can anybody post a code example for this, please ?