Creating a Gantt Chart from a plot object

[Sergio]

Hi. how I can create a Gantt Chart without using the ChartFactory.createGanttChart() method?, I mean using a plot so I can use a renderer and a tooltip generator and customize the chart, let me know and thanks for your help

[David Gilbert]

Hi Sergio,

Of course. If you look in the source code for the createGanttChart(...) method, and all the other methods in the ChartFactory class, you will see that they just create a regular JFreeChart object by putting together assorted classes (plots, axes, renderers, etc).

These 'ready-made' charts are just commonly used combinations to help people who don't want to get too close to the inner details of JFreeChart...there's nothing to stop you mixing and matching to create different charts, in fact I encourage it. An advantage of creating each of the objects yourself is that you can customise each one at the time of creating the chart, rather than having to fetch references and cast them to the correct subclass.

Regards,

Dave Gilbert

[Sergio]

Hi David,
I'm trying to use this code for gettting the chart displayed, but it doesn't display anything similar to a gantt chart

CategoryAxis categoryAxis = new HorizontalCategoryAxis("");
ValueAxis valueAxis = new VerticalNumberAxis("");
VerticalIntervalBarRenderer renderer = new VerticalIntervalBarRenderer();
renderer.setToolTipGenerator(new IntervalCategoryToolTipGenerator());
CategoryPlot plot = new VerticalCategoryPlot(dataset, categoryAxis, valueAxis, renderer);
JFreeChart chart = new JFreeChart("", JFreeChart.DEFAULT_TITLE_FONT, plot, true);
chart.setBackgroundPaint(java.awt.Color.white);

ChartUtilities.writeChartAsJPEG(out, chart, 900, 700);

What I'm doing wrong?, it's just that I don't know what plots I should use and how.. thanks for your support, I really appreciate it.

Regards, Sergio.

[Sergio]

There's a line that I shouldnt have included

ChartUtilities.writeChartAsJPEG(out, chart, 900, 700);

ignore it please, thanks

[Sergio]

This is the whole code,


CategoryAxis categoryAxis = new VerticalCategoryAxis("Activity");
DateAxis dateAxis = new HorizontalDateAxis("Date");
CategoryToolTipGenerator toolTipGenerator = new IntervalCategoryToolTipGenerator(sdf);
CategoryItemRenderer renderer = new HorizontalIntervalBarRenderer(toolTipGenerator);
Plot plot = new HorizontalCategoryPlot(dataset, categoryAxis, dateAxis,renderer);
JFreeChart chart = new JFreeChart("Activities for " + fdm,JFreeChart.DEFAULT_TITLE_FONT, plot, true);

ChartRenderingInfo info = new ChartRenderingInfo(new StandardEntityCollection());
String filename = ServletUtilities.saveChartAsPNG(chart, 850, 700, info, request.getSession());
ChartUtilities.writeImageMap(out, filename, info);
out.flush();
String graphURL = request.getContextPath() + "/servlet/DisplayChart?filename=" + filename;
out.println("<div align=center> <img src=" + graphURL + " height=850 width= 700 border=0 usemap=\"#" + filename + "\"> </div>");