如何在 JFreeChart 中将图标保留在图表的一侧 Java

Question

我有以下图表：

图表是动态的，具有放大和缩小功能。我想放置一个创建为的图标：

BufferedImage triangleIcon = null;
        try {
            triangleIcon = ImageIO.read(getClass().getClassLoader().getResource("Resources/Imagenes/triangulo.png"));
        } catch (IOException e) {
        }

并且可以放置在任意点为：

xyannotation = new XYImageAnnotation(XValue, YValue, triangleIcon);
this.xyplot.addAnnotation(xyannotation);

我想把这个图标放在任何 Y 值处，但总是在图表的左侧旁边，而不考虑缩放。类似于：

可能吗？

Answer 1

我看起来你想注释“……图表的一侧，忽略 X 轴的值”。按说，这样的annotations specify both coordinates in data space. One approach is a custom annotation that extends the abstract parent, AbstractXYAnnotation。覆盖 draw() 以将垂直 data 坐标转换为相应的 screen 坐标，同时固定水平 screen 坐标到绘图的 dataArea。平移和缩放以查看效果。

AffineTransform at = new AffineTransform();
…
@Override
public void draw(…) {
    RectangleEdge rangeEdge = plot.getRangeAxisEdge();
    double y = rangeAxis.valueToJava2D(yValue, dataArea, rangeEdge);
    at.setToIdentity();
    at.translate(dataArea.getX() + 1, y);
    …
}

示例代码：

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics2D;
import java.awt.Polygon;
import java.awt.Shape;
import java.awt.Stroke;
import java.awt.geom.AffineTransform;
import java.awt.geom.Rectangle2D;
import javax.swing.JFrame;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.annotations.AbstractXYAnnotation;
import org.jfree.chart.axis.ValueAxis;
import org.jfree.chart.plot.PlotRenderingInfo;
import org.jfree.chart.plot.XYPlot;
import org.jfree.chart.ui.RectangleEdge;
import org.jfree.data.xy.XYDataset;
import org.jfree.data.xy.XYSeries;
import org.jfree.data.xy.XYSeriesCollection;

/**
 * @see 
 * @see 
 */
public class XYShapeTest {

    private static final int N = 18_000;
    private static final int SIZE = 16;
    private final Shape pointer = createPolygon(SIZE);

    private static class AxisAnnotation extends AbstractXYAnnotation {

        private final AffineTransform at = new AffineTransform();
        private final Stroke stroke = new BasicStroke(4f);
        private final Shape shape;
        private final double yValue;

        public AxisAnnotation(Shape shape, double y) {
            this.shape = shape;
            this.yValue = y;
        }

        @Override
        public void draw(Graphics2D g2, XYPlot plot, Rectangle2D dataArea,
            ValueAxis domainAxis, ValueAxis rangeAxis,
            int rendererIndex, PlotRenderingInfo info) {
            RectangleEdge rangeEdge = plot.getRangeAxisEdge();
            double y = rangeAxis.valueToJava2D(yValue, dataArea, rangeEdge);
            at.setToIdentity();
            at.translate(dataArea.getX() + 1, y);
            g2.setStroke(stroke);
            g2.setPaint(Color.BLACK);
            g2.draw(at.createTransformedShape(shape));
        }
    }

    private Shape createPolygon(int size) {
        Polygon p = new Polygon();
        p.addPoint(0, 0);
        p.addPoint(0, 1);
        p.addPoint(2, 0);
        p.addPoint(0, -1);
        AffineTransform at = new AffineTransform();
        at.scale(size, size);
        return at.createTransformedShape(p);
    }

    private XYDataset createDataset() {
        XYSeries series = new XYSeries("Series");
        for (int i = 0; i <= N; i += 1_000) {
            series.add(i / 1_000, i);
        }
        return new XYSeriesCollection(series);
    }

    private JFreeChart createChart(final XYDataset dataset) {
        JFreeChart chart = ChartFactory.createXYLineChart("Test", "X", "Y", dataset);
        XYPlot plot = (XYPlot) chart.getPlot();
        plot.setDomainPannable(true);
        plot.setRangePannable(true);
        plot.addAnnotation(new AxisAnnotation(pointer, 9_000));
        return chart;
    }

    private void display() {
        JFrame f = new JFrame("XYShapeTest");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(new ChartPanel(createChart(createDataset())) {
            @Override
            public Dimension getPreferredSize() {
                return new Dimension(600, 300);
            }
        });
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new XYShapeTest()::display);
    }
}

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