如何最大化圖像大小作爲JPanel的大小

Question

如何通過JPanel的大小最大化圖片的大小？

Answer 1

試試這個SSCCE。

import java.awt.*; 
import javax.swing.*; 
import javax.swing.border.*; 
import java.net.URL; 
import javax.imageio.ImageIO; 

public class ImagePanel extends JPanel { 

    private Image image = null; 

    ImagePanel(LayoutManager layout) { 
     super(layout); 
    } 

    public void setImage(ImageIcon icon) { 
     image = icon.getImage().getScaledInstance(this.getWidth(), this.getHeight(), Image.SCALE_DEFAULT); 
     repaint(); 
    } 

    @Override 
    public void paintComponent(Graphics g) { 
     super.paintComponent(g); 
     if (image != null) { 
      System.out.println("imagepanel painting"); 
      g.drawImage(image,0,0,getWidth(),getHeight(),null); // see javadoc for more info on the parameters 
     } 
    } 

    public static void main(String[] args) throws Exception { 
     JFrame f = new JFrame("Image Panel"); 
     f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     URL url = new URL("http://pscode.org/media/citymorn2.jpg"); 
     Image image = ImageIO.read(url); 

     ImagePanel ip = new ImagePanel(new GridLayout(4,4,20,20)); 
     ip.setBorder(new EmptyBorder(50,50,50,50)); 
     for (int ii=0; ii<16; ii++) { 
      ip.add(new JButton("" + ii)); 
     } 

     ip.setPreferredSize(new Dimension(640,480)); 
     f.setContentPane(ip); 
     f.pack(); 
     f.setVisible(true); 

     ip.setImage(new ImageIcon(image)); 
    } 
}