关键Arc2D
是边界矩形。要使半弧H
单位高,边界必须是2 * H
单位高。
AFAIK,PolarPlot
不支持注释。
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import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.geom.Arc2D;
import java.util.Random;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartFrame;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.annotations.XYLineAnnotation;
import org.jfree.chart.annotations.XYShapeAnnotation;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.chart.plot.XYPlot;
import org.jfree.data.xy.XYDataset;
import org.jfree.data.xy.XYSeries;
import org.jfree.data.xy.XYSeriesCollection;
/** @see http://stackoverflow.com/questions/6604211 */
public class ArcTest {
private static final Random r = new Random();
private static final double PI = 180d;
private static final int X = 3;
private static final int Y = 0;
private static final int W = 44;
private static final int H = 17;
public static void main(String[] args) {
JFreeChart chart = ChartFactory.createXYLineChart(
"ArcTest", "X", "Y", createDataset(),
PlotOrientation.VERTICAL, true, true, false);
XYPlot plot = chart.getXYPlot();
XYLineAnnotation line = new XYLineAnnotation(
X, Y, X, H, new BasicStroke(2f), Color.blue);
plot.addAnnotation(line);
Arc2D.Double arc = new Arc2D.Double(
X, Y, W, 2 * H, PI, PI, Arc2D.OPEN);
plot.addAnnotation(new XYShapeAnnotation(arc,
new BasicStroke(2.0f), Color.blue));
ChartFrame frame = new ChartFrame("First", chart);
frame.pack();
frame.setVisible(true);
}
private static XYDataset createDataset() {
XYSeriesCollection result = new XYSeriesCollection();
XYSeries series = new XYSeries("ArcTest");
series.add(0, 0);
series.add(W, W);
result.addSeries(series);
return result;
}
}