getImageIcon() : how does it work?

[achana chan]

Hi all.
I'm trying to get an imageicon into BorderLayout and I'm getting this error message from the java console:
...
java.security.AccessControlException: access denied (java.io.FilePermission bottlenose.jpg read)
at java.security.AccessControlContext.checkPermission(Unknown Source)
...
This seems strange because following code works well:

  public class CustomTextField extends JTextArea
  {
    public CustomTextField(int rows, int columns)
    {
      super(null, null, rows, columns);
      Pictures = getImage(getDocumentBase(),"forestfire.jpg");
      //repaint();
    } 
    public void paintComponent(Graphics g)
    { 
      super.paintComponent(g);
      g.drawImage(Pictures, 0,0, this);
    }
  }

but there seems to be no javax.swing equivalent for getImageIcon.
Of course I'm assuming I need to use either getDocumentBase() or getCodeBase() to get pass the "access denied" problem. Following code should work, but it doesn't

    JPanel p2 = new JPanel();
    p2.setLayout(new BorderLayout());
    ImageIcon bottlenose = new ImageIcon(getDocumentBase(), "bottlenose.jpg");
    p2.add(new JLabel(bottlenose), BorderLayout.EAST);

TIA :-)
I think the question should be "how does one use getDocumentBase() win getImageIcon()" ?
Without getDocumentBase(), it seems I cannot get the image.

Okay, this code works and fetch the "icon" back.
But resize() didn't iconify my picture ie. it didn't shrink it so that it becomes an icon. I was hoping to put the iconified barn owl next to the label text...

import java.awt.*;
import javax.swing.*;
import java.net.*;
public class DisplayImage extends JApplet
{ 
  public void init()
  {
    ImageIcon iconOwl = null;
    try
    {
      icon = new ImageIcon(new URL(getCodeBase(),"images/owl.jpg"));
    } catch(MalformedURLException e)
    {
      System.out.println("Failed to create URL:\n" + e);
      return;
    }[B]
    // Set applet size to fit the image
    int imageWidth = iconOwl.getIconWidth();        // Get icon width
    int imageHeight = iconOwl.getIconHeight();      // and its height
    resize(imageWidth,imageHeight); [/B]                
    // Create panel a showing the image
    ImagePanel imagePanel = new ImagePanel(iconOwl.getImage());
    getContentPane().add(imagePanel);               
    // Add the panel to the content pane
  }
  // Class representing a panel displaying an image
  class ImagePanel extends JPanel
  {
    Image image;
    public ImagePanel(Image image)
    {
      this.image = image;
    }
    public void paint(Graphics g)
    {
      g.drawImage(image, 0, 0, this);                        
      // Display the image
    }
  }
}

By the way, it doesn't seem to matter whether I use SWING's super.paintComponent(g) or not ...
[ November 10, 2003: Message edited by: achana chan ]

[Daniel Searson]

The exception you are getting is because you are in a Java applet and Java applets aren't allowed to access other files. The method getImage() in the Applet/JApplet class is a way around this (I'm not entirely sure how it works, but it does).
Creating an ImageIcon using "new ImageIcon()" is not possible because it relies on normal I/O. So you get an access permission exception. Instead, use getImage() from the Applet class to create you're image. Then create a new ImageIcon using that Image object. This should get rid of that exception.
If you are doing anything in Swing you should use paintComponent() and NOT paint(). This stuffs up the way Swing does back buffering.
When you are setting the size of a JPanel, you should use setPreferredSize() instead of resize(). You will probably have more luck this way.
Hope that helps.

[achana chan]

Modifying the code has no visible effect. I can still get the image back. The problem seems not to be with getDocumentBase() or getCodeBase().
I just cannot iconify the image, when I use setPreferredSize(imageWidth,imageHeight), its more like a little viewport into a bigger picture.

public class DisplayImage2 extends JApplet
{ 
  public void init()
  {
    Image imageOwl = null;
    ImageIcon iconOwl = null;
    imageOwl = getImage(getDocumentBase(), "images/owl.jpg"); 
    iconOwl = new ImageIcon(imageOwl);[B]
    int imageWidth = iconOwl.getIconWidth();        // Get icon width
    int imageHeight = iconOwl.getIconHeight();      // and its height
    // Create panel a showing the image                 
    // Set applet size to fit the image
    ImagePanel imagePanel = new ImagePanel(iconOwl.getImage());
    imagePanel.setPreferredSize(new Dimension(imageWidth,imageHeight));[/B]
    getContentPane().add(imagePanel);                
    // Add the panel to the content pane
  }
  // Class representing a panel displaying an image
  class ImagePanel extends JPanel
  {
    Image image;
    public ImagePanel(Image image)
    {
      this.image = image;
    }
    public void paintComponent(Graphics g)
    {
      super.paintComponent(g);
      g.drawImage(image, 0, 0, this);                        
      // Display the image
    }
  }
}

[Santiago Escobar Robledo]

It's so late to answer, but to someone this could be useful ...

Daniel Searson wrote:The exception you are getting is because you are in a Java applet and Java applets aren't allowed to access other files. The method getImage() in the Applet/JApplet class is a way around this (I'm not entirely sure how it works, but it does). Creating an ImageIcon using "new ImageIcon()" is not possible because it relies on normal I/O. So you get an access permission exception.

That's true.

So, with ImageIcon you could do two things to avoid the AccessControlException because java.io.FilePermission:

1. To grant explicit permission to access local system resources ... resources that you will use in the applet.

grant
  {
    permission java.io.FilePermission 
    "${user.home}/PATH/image.jpg", "read";
  };

You could see the next link about "Security and Permissions": http://java.sun.com/developer/onlineTraining/Programming/JDCBook/appA.html


2. To use ClassLoader

For example:

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

public class ImageIcon extends Applet
{
	ImageIcon myIcon;
	ClassLoader cldr = this.getClass().getClassLoader();
	
	public void init()
	{
		// I get the URL of my file and save that in imageURL
		java.net.URL imageURL = cldr.getResource("image.jpg");
		 
		// Everything is perfect ... I've got my image  
		myIcon = new ImageIcon(imageURL);
	}
	
	public void paint(Graphics g)
	{
		// Finally, I paint my image  
		myIcon.paintIcon(this, g, 0, 0);
	}
}

Everything is in the same path:

src/
- ImageIcon.java
- image.jpg
- index.html -> To run the applet

You could see the next link: http://www.leepoint.net/notes-java/GUI-lowlevel/graphics/45imageicon.html


By the way, ImageIcon doesn't allow to resize the image. You could see this post: https://coderanch.com/t/331731/GUI/java/Resize-ImageIcon. It works perfect.