Home > ColdFusion, Java > Creating a Dial Chart with ColdFusion and JFreeChart

Creating a Dial Chart with ColdFusion and JFreeChart

A recent question on stackoverflow.com prompted me to take a look at how to create dial charts with JFreeChart (rather than ACF’s webcharts3D engine).  Since you never know when starter code snippets will come in handy, here is the rudimentary example I put together for creating Dial Charts.  You can obviously do much more with it. Just review the api and/or the developer guide.

Sample Dial Chart


Download latest jfreeChart. Copy the following jars into {cf_root}\WEB-INF\lib and restart CF. Note, jar version numbers may vary.

  • jfreechart-1.0.13.jar
  • jcommon-1.0.16.jar

Dial Chart Example (Compatibility MX7+)

// my chart settings
chartTitle = "My Dial Chart";
arrowValue  = 55;
dialMinimum = 0;
dialMaximum = 100;
chartWidth  = 500;
chartHeight = 500;

// initialize basic components of the chart
// see jFreeChart API on how to customize the components settings further
DefaultValueDataset = createObject("java", "org.jfree.data.general.DefaultValueDataset");
pointerValue    = DefaultValueDataset.init(arrowValue);
dialPointer     = createObject("java", "org.jfree.chart.plot.dial.DialPointer$Pointer").init();
dialFrame       = createObject("java", "org.jfree.chart.plot.dial.StandardDialFrame").init();
dialBackground  = createObject("java", "org.jfree.chart.plot.dial.DialBackground").init();

// tweak the default range to make it more appealing.
// see angle/extent: http://java.sun.com/developer/technicalArticles/GUI/java2d/java2dpart1.html
dialScale = createObject("java", "org.jfree.chart.plot.dial.StandardDialScale").init();

//initialize plot and apply settings
plot = createObject("java", "org.jfree.chart.plot.dial.DialPlot").init();
plot.addScale(0, dialScale);

// create chart and convert it to an image
chart = createObject("java", "org.jfree.chart.JFreeChart").init(chartTitle, plot);
chartImage = chart.createBufferedImage(chartWidth, chartHeight);
ImageFormat = createObject("java", "org.jfree.chart.encoders.ImageFormat");
EncoderUtil = createObject("java", "org.jfree.chart.encoders.EncoderUtil");
bytes = EncoderUtil.encode( chartImage, ImageFormat.PNG);

<!--- display in browser --->
<cfcontent type="image/png" variable="#bytes#">
Categories: ColdFusion, Java Tags: ,
  1. No comments yet.
  1. No trackbacks yet.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: