Re: why doesn't the ImageIcon appear in the JscrollPanel?

Anatorian wrote:
> I wrote a simple Swing program. When the click a button and select a jpg 
> file, I want to show this picture in the JScollPanel, but it doesn't 
> appear. The source is here:
> private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) 
> {                                            if(evt.getSource() == 
> this.jButton3) {
>        JFileChooser chooser = new JFileChooser();
>        chooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
>        FileNameExtensionFilter filter = new FileNameExtensionFilter("JPG 
> & GIF Images", "jpg", "gif");
>        chooser.setFileFilter(filter);
>        int returnVal = chooser.showOpenDialog(this);
>        if(returnVal == JFileChooser.APPROVE_OPTION) {
>            
> this.jTextField4.setText(chooser.getSelectedFile().getAbsolutePath());
>            try{
>                this.jScrollPane2.add(new ImagePanel(1, 
> chooser.getSelectedFile()));
>            } catch(Exception e) {
>                e.printStackTrace();
>            }
>                   }
>    }
> } 
> package auction.client;
> 
> import java.awt.Graphics;
> import java.awt.Image;
> import java.awt.geom.Point2D;
> import java.io.File;
> import java.io.IOException;
> import java.util.HashSet;
> import java.util.Set;
> import java.util.logging.Level;
> import java.util.logging.Logger;
> import javax.imageio.ImageIO;
> import javax.swing.ImageIcon;
> import javax.swing.JPanel;
> 
> public class ImagePanel extends JPanel {
>    //identifier
>    private int ID;
>       //on-screen position
>    private Point2D.Double position;
>       //imageIcon to paint on screen
>    private ImageIcon imageIcon;
>       //stores all ImagePanel children
>    private Set panelChildren;
>       //constructor initilizes position and image
>    public ImagePanel(int identifier, String imageFileName) throws 
> IOException {
>        super(null);//specify null layou
>        this.imageIcon = this.createImageIcon(imageFileName);
>               this.init(identifier);
>    }
>       public ImagePanel(int identifier, byte[] imageData) {
>        super(null);
>        this.imageIcon = this.createImageIcon(imageData);
>               this.init(identifier);
>    }
>       public ImagePanel(int identifier, ImageIcon icon) {
>        super(null);
>        this.imageIcon = icon;
>               this.init(identifier);
>    }
>       public ImagePanel(int identifier, File iconFile) throws IOException {
>        super(null);
>        this.imageIcon = this.createImageIcon(iconFile);
>               this.init(identifier);
>    }
>       private void init(int identifier) {
>        setOpaque(false);//make transparent
>               // set unique identifier
>        ID = identifier;
>               // set location
>        position = new Point2D.Double(0, 0);
>        setLocation(0,0);
>               Image image = imageIcon.getImage();
>        setSize(image.getWidth(this), image.getHeight(this));
>               //create Set to store Panel childre
>        panelChildren = new HashSet();
>    }
>       private ImageIcon createImageIcon(String fileName) {
>        try {
>            return new ImageIcon(ImageIO.read(new File(fileName)));
>        } catch (IOException ex) {
>            
> Logger.getLogger(ImagePanel.class.getName()).log(Level.SEVERE, null, ex);
>        }
>        return null;
>    }
>       private ImageIcon createImageIcon(byte[] imageData) {
>        return new ImageIcon(imageData);
>    }
>       private ImageIcon createImageIcon(File file) throws IOException {
>        return new ImageIcon(ImageIO.read(file));
>    }
>       //paint Panel to scree
>    public void paintComponent(Graphics g) {
>        super.paintComponent(g);
>               //if image is ready, paint it to screen
>        imageIcon.paintIcon(this, g, 0, 0);
>    }
>       public void add(ImagePanel panel, int index) {
>        panelChildren.add(panel);
>        super.add(panel, index);
>    }
>       public void remove(ImagePanel panel) {
>        panelChildren.remove(panel);
>        super.remove(panel);
>    }
>       public void setIcon(ImageIcon icon) {
>        this.imageIcon = icon;
>    }
> 
>    public ImageIcon getImageIcon() {
>        return imageIcon;
>    }
> 
>    public Point2D.Double getPosition() {
>        return position;
>    }
> 
>    public void setPosition(double x, double y) {
>        this.position.setLocation(x, y);
>        this.setLocation((int) x, (int) y);
>    }
> 
>    public int getID() {
>        return ID;
>    }
>       public Set getChildren() {
>        return panelChildren;
>    }
>    }
> 
> Who can help me?

Who knows, your code is a mess.  It is best to post a compilable example 
that we can then test to see where your problem lies.  When you have 
problems this is the good way for you to isolate it and then work on 
fixing it in your more complicated code.  Of course the simpler your 
code the less problems you are going to have.  Any way here is a simple 
example of how to display an image in a frame in a scroll pane.

import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.net.*;
import javax.swing.*;

public class test extends JFrame {
     final JScrollPane sp = new JScrollPane();
     final JFileChooser fc = new JFileChooser();

     public test() {
         setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

         sp.setPreferredSize(new Dimension(400,300));
         add(sp,BorderLayout.CENTER);

         JButton b = new JButton("Select Image");
         b.addActionListener(new ActionListener() {
             public void actionPerformed(ActionEvent ae) {
                 int result = fc.showOpenDialog(test.this);
                 if (result == JFileChooser.APPROVE_OPTION) {
                     try {
                         File f = fc.getSelectedFile();
                         URL url = f.toURI().toURL();
                         ImageIcon i = new ImageIcon(url);
                         sp.setViewportView(new JLabel(i));
                     } catch (MalformedURLException murle) {
                         murle.printStackTrace();
                     }
                 }
             }
         });
         add(b,BorderLayout.SOUTH);
         pack();
         setVisible(true);
     }

     public static void main(String[] args) {
         EventQueue.invokeLater(new Runnable() {
             public void run() {
                 new test();
             }
         });
     }
}

Be careful of setting your layouts to null, most of the time using a 
layout is better than not.  In my example above, I can resize the frame 
and my scroll pane resizes too.  If my image is smaller than the scroll 
pane it centers.  This is all a benefit of the layout manager.

-- 

Knute Johnson
email s/nospam/linux/

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