ContentsBasic ChartingPlace a chart legend

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Placing a legend involves some experimentation and taste. It is done simply by an invocation of the PdfPage.drawLegend() method. The parameters are fairly self-explanatory, but the location, size, and color are bound to need a little tweaking. code / output

Legends are interesting and important when more information is represented on the chart. As we wrap up this section of the tutorial, let's place a few more value sets. code / output

We've made a number of changes that need explanation:

• Value set definitions have been moved out of the doGet() method
• Line 23 and 24 - the noisyWave value set has a higher resolution than the sineWave
• Line 67 - to make the information easier to read, a LineValueSet is used instead of an area

For a final round of changes before we move on to more advanced topics, we add a bar value set and replace the noisyWave line representation with a BurstGlyphValueSet. code / output

A few things to take note of in this sample:

• The legend keeps up with the value sets which are appended, and the order they are displayed in the legend is controlled by the order that they are appended to the chart
• Unless you need to modify a specialized value set, it is more flexible to generalize them with references to their superclass
• The value arrays can be reused. Because the ValueSets only make a reference to the array at the time they are constructed, the values in the array can be changed at any time prior to PdfChart.drawMain()

That pretty well completes the basics of regular chart creation with the Servlet Utilities. Next, I'll explain how to extend ValueSet for those cases where the provided ValueSets won't work.

ContentsBasic ChartingPlace a chart legend

Previous: Axis labels | Next: Charting