如何在 XYImageAnnotation 中调整图像位置

Question

我在 JFreeChart 中有一个图标：

BufferedImage torreIcon = null;

try {
    torreIcon = ImageIO.read(getClass().getClassLoader().getResource(
        "Resources/Imagenes/torre_control_2.png"));
    } catch (IOException e) {
        e.printStackTrace();
    }
}

并且我已将此图标添加到 XYPlot:

XYAnnotation xyannotation = new XYImageAnnotation(0, 1900, torreIcon);
this.xyplot.addAnnotation(xyannotation);

图表中的结果是：

问题是当我放大时：

我希望图标始终位于 x 轴旁边，而不是 space，并且当然具有相同的大小。可能吗？

Answer 1

If I put (0, 0) coordinates, the icon center is put in 0, 0 and the image is not above x axis.

正确；除非另有说明，否则 XYImageAnnotation 使用 RectangleAnchor.CENTER.

在指定数据 space 坐标处居中

I put manually the coordinates that makes the icon put above the x axis initially, and as we can see the y coordinate that make this is 1900.

而是在构造 XYImageAnnotation 时指定所需的 RectangleAnchor:

new XYImageAnnotation(0, 0, image, RectangleAnchor.BOTTOM)

下面的示例将蓝色框添加到方便的图像中，以查看图像相对于锚点的绘制方式。原点的 RectangleAnchor.BOTTOM 如下图所示。当您平移和缩放时，图像保持锚定到原点。尝试其他 RectangleAnchor 个实例以查看效果。

import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.image.BufferedImage;
import javax.swing.Icon;
import javax.swing.JFrame;
import javax.swing.UIManager;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.annotations.XYImageAnnotation;
import org.jfree.chart.plot.XYPlot;
import org.jfree.chart.ui.RectangleAnchor;
import org.jfree.data.xy.XYDataset;
import org.jfree.data.xy.XYSeries;
import org.jfree.data.xy.XYSeriesCollection;

/**
 * @see 
 */
public class XYImageTest {

    private static final int N = 1;

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

    private JFreeChart createChart(final XYDataset dataset, Image image) {
        JFreeChart chart = ChartFactory.createXYLineChart("Test", "X", "Y", dataset);
        XYPlot plot = (XYPlot) chart.getPlot();
        plot.setDomainPannable(true);
        plot.setRangePannable(true);
        plot.addAnnotation(new XYImageAnnotation(0, 0, image, RectangleAnchor.BOTTOM));
        return chart;
    }

    private void display() {
        Icon icon = UIManager.getIcon("OptionPane.informationIcon");
        BufferedImage image = new BufferedImage(icon.getIconWidth(),
            icon.getIconHeight(), BufferedImage.TYPE_INT_ARGB);
        Graphics g = image.getGraphics();
        g.setColor(Color.blue);
        g.drawRect(0, 0, image.getWidth() - 1, image.getHeight() - 1);
        icon.paintIcon(null, g, 0, 0);
        g.dispose();
        JFrame f = new JFrame("XYImageTest");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(new ChartPanel(createChart(createDataset(), image)) {
            @Override
            public Dimension getPreferredSize() {
                return new Dimension(400, 300);
            }
        });
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

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

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