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  1. PO
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    <p>After several unsuccessful tries, I decided to limit the number of <code>LegendItem</code> shown on the chart.</p> <p>To change the legend items to display in the <code>LegendTitle</code> I used a slider. The most difficult part was to recreate the a new LegendTitle when using the slider; I am not sure that my solution is optimal or elegant but at least it is working.</p> <p><img src="https://i.stack.imgur.com/F6i5q.png" alt="Result"></p> <p>To make this possible I needed to listen to series creation (<code>ChartChangeEventType.DATASET_UPDATED</code>) to refresh the LegendTitle and set slider values.</p> <p>So here is the code:</p> <pre><code>public class MyExampleChartComposite extends ChartComposite { // snip /** * A slider to choose the legend items to display */ private Slider legendSlider; /** * Number of legend items to display on the chart */ private final static int NUMBER_OF_LEGENDITEMS_TO_DISPLAY = 10; private void createPartControl(Composite parent, int style) { JFreeChart chart = createChart(); setChart(chart); legendSlider = new Slider(parent, SWT.NONE|SWT.H_SCROLL); legendSlider.addSelectionListener(new SelectionListener() { @Override public void widgetSelected(SelectionEvent arg0) { refreshLegend(); } }); private JFreeChart createChart() { chart.addChangeListener(new ChartChangeListener() { @Override public void chartChanged(ChartChangeEvent e) { if (e.getType().equals(ChartChangeEventType.DATASET_UPDATED)) { refreshLegend(); } } }); } /** * Refresh the the LegendItems and the slider, * according to slider selection. */ public void refreshLegend() { // Display LegendItems according to the selection // display the 10 nearest legend item (current selected element included) int begin = legendSlider.getSelection() - (NUMBER_OF_LEGENDITEMS_TO_DISPLAY/2); int end = legendSlider.getSelection() + (NUMBER_OF_LEGENDITEMS_TO_DISPLAY/2 -1); int seriesEndIndex = Math.max(getSeriesCount()-1, 0); // if begin is less than 0 // set it to 0, and increase end to display 10 items if (begin &lt; 0) { begin = 0; end = NUMBER_OF_LEGENDITEMS_TO_DISPLAY - 1; } // if end is greater than the number of series plotted // set it to the max possible value and increase begin to // display 10 items if (end &gt; seriesEndIndex) { end = seriesEndIndex; begin = seriesEndIndex - (NUMBER_OF_LEGENDITEMS_TO_DISPLAY - 1); } end = Math.min(seriesEndIndex, end); begin = Math.max(begin, 0); // Refresh only if begin != end if (end != begin) { refreshLegendItems(begin, end); refreshLegendSlider(); } else { // in this case no more series are plotted on the chart // clear legend getChart().clearSubtitles(); } } /** * Refresh the LegendTitle. * Display only LegendItems between beginIndex and toIndex, * to preserve space for the chart. * @param beginIndex index of the {@link LegendItemCollection} used as the beginning of the new {@link LegendTitle} * @param endIndex index of the {@link LegendItemCollection} used as the end of the new {@link LegendTitle} */ private void refreshLegendItems(int beginIndex, int endIndex) { // Last 10 items final LegendItemCollection result = new LegendItemCollection(); // get the renderer to retrieve legend items XYPlot plot = getChart().getXYPlot(); XYItemRenderer renderer = plot.getRenderer(); // Number of series displayed on the chart // Construct the legend for (int i = beginIndex; i &lt;= endIndex; i++) { LegendItem item = renderer.getLegendItem(0, i); result.add(item); } // Because the only way to create a new LegendTitle is to // create a LegendItemSource first LegendItemSource source = new LegendItemSource() { LegendItemCollection lic = new LegendItemCollection(); {lic.addAll(result);} public LegendItemCollection getLegendItems() { return lic; } }; // clear previous legend title getChart().clearSubtitles(); // Create the new LegendTitle and set its position LegendTitle legend = new LegendTitle(source); legend.setHorizontalAlignment(HorizontalAlignment.CENTER); legend.setVerticalAlignment(VerticalAlignment.CENTER); legend.setPosition(RectangleEdge.BOTTOM); legend.setBorder(1.0, 1.0, 1.0, 1.0); legend.setVisible(true); // Add the LegendTitle to the graph getChart().addLegend(legend); } /** * Set values of the slider according to the number of series * plotted on the graph */ private void refreshLegendSlider() { int max = getSeriesCount() -1; int selection = Math.min(legendSlider.getSelection(), max); legendSlider.setValues(selection, 0, max, 1, 1, 1); } } </code></pre>
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    1. POJfreeChart limit the number of legend items displayed
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    1. USzeropouet
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    1. COMy issue was quite different from yours but I was able to use the insight you shared regarding these JFree classes (especially `LegendTitle` and `LegendItemSource`). Thanks much!
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      1. USJesse Hautala
 

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