ImagePanel.java

package pandaAgent;

import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class ImagePanel extends JPanel {
    /**
     *
     */
    private static final long serialVersionUID = 1725279731486866710L;
    // 描画する画像
    private BufferedImage image;

    public ImagePanel(String path) {
        try {
            this.image = ImageIO.read(getClass().getResource(path));
        } catch (IOException ex) {
            ex.printStackTrace();
            this.image = null;
        }
    }

    public void changeImage(String path)
    {
    	try
    	{
    		this.image = ImageIO.read(getClass().getResource(path));
    	}
    	catch(IOException ex)
    	{
    		ex.printStackTrace();
    		this.image = null;
    	}
    }

    @Override
    public void paintComponent(Graphics g) {
        Graphics2D g2D = (Graphics2D) g;

        // double imageWidth = image.getWidth();
        // double imageHeight = image.getHeight();
        // double panelWidth = this.getWidth();
        // double panelHeight = this.getHeight();

        // 画像がコンポーネントの何倍の大きさか計算
        // double sx = (panelWidth / imageWidth);
        // double sy = (panelHeight / imageHeight);

        // スケーリング
        // AffineTransform af = AffineTransform.getScaleInstance(sx, sy);
        AffineTransform af = null;
        g2D.drawImage(image, af, this);
    }

    // test
    public static void main(String[] args) {
        JFrame frame = new JFrame();
        frame.add(new ImagePanel("/gui/sample.png"));
        frame.setTitle("JPanelに画像を描画");
        frame.setSize(320, 240);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }
}