JAVA GUI ShowImage.java

import java.awt.*;
import java.awt.geom.*;
import javax.swing.*;

public class ShowImage extends JPanel
{
Image img = null; //代表影像的物件
public ShowImage(String filename)
{
img = getToolkit().getImage(filename); //載入指定的影像檔

}
public void paintComponent(Graphics g)
{
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
Dimension d = getSize(); //取得面板大小

//建立座標轉換物件
AffineTransform at = new AffineTransform();

//依 Panel 的區域大小來調整顯示比例
double sc = Math.min(d.width/(double)img.getWidth(null),d.height/(double)img.getHeight(null));
at.scale(sc,sc);
g2.drawImage(img,at,this); //顯示影像

}
public static void main(String[] args)
{
try
{
ShowImage dimg = new ShowImage(args[0]);
JFrame f = new JFrame(args[0]);
f.getContentPane().add(dimg);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setSize(640,480);
f.setVisible(true);
}
catch(Exception e)
{
System.out.println("用法: java ShowImage<影像檔名稱>");
System.exit(0);
}
}
}