background image in contentpane

public void paint(Graphics g) {
        Graphics2D g2d = (Graphics2D)g;
   
        // Draw background...
   
        // Set alpha.  0.0f is 100% transparent and 1.0f is 100% opaque.
        float alpha = .3f;
        g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, alpha));
   
        // Draw foreground...
    }

Though a custom panel is not really necessary. You can display an image using a JLabel.

http://java.sun.com/j2se/1.4.2/docs/api/javax/swing/JLabel.html#JLabel(javax.swing.Icon)

Let me know if you need firther assistance.

I have tried to use JLabel ,

private JLabel bg_image = new JLabel(new ImageIcon("main_bg.jpg"));
  :
  :
bg_image.setBounds(new Rectangle(0, 0, 400, 300));
this.getContentPane().add(bg_image, null);

there is no compilation error but I can see nothing on changing to this. Does anybody know why ?

Cristy

where is the image located?

hte image is located in the same folder as the .java file

Cristy

Try

    private JLabel bg_image = new JLabel(new ImageIcon( YourClass.class.getResource("main_bg.jpg") ));

replace "YourClass" with the name of your own class this is in

oh, zzynx, using your method, I could see the image, but it is not really a background image ??
It covers up all my other JLabel and JButtons, what should I do ?

Thanks,
Cristy

>> using your method, I could see the image
Good!

>> It covers up all my other JLabel and JButtons, what should I do ?
Did you try any of the previous comments above?
What's your code?

 private JLabel bg_image = new JLabel(new ImageIcon( testMEID.class.getResource("main_bg.jpg") ));
  private JLabel lb_pname = new JLabel();
  private JLabel lb_dob = new JLabel();
  private JLabel lb_place = new JLabel();

    :
    :
    lb_pname.setText("Name :");
    lb_pname.setBounds(new Rectangle(30, 185, 60, 20));
    lb_pname.setForeground(Color.blue);      
    txt_pname.setBounds(new Rectangle(100, 185, 200, 25));
   

    lb_dob.setText("Date of Birth:");
    lb_dob.setBounds(new Rectangle(30, 220, 60, 20));
    lb_dob.setForeground(Color.blue);      
    txt_dob.setBounds(new Rectangle(100, 220, 120, 25));


    lb_place.setText("Place of Birth :");
    lb_place.setBounds(new Rectangle(30, 255, 60, 20));
    lb_place.setForeground(Color.blue);      
    txt_place.setBounds(new Rectangle(100, 255, 120, 25));

  :
  :

    this.getContentPane().add(bg_image, null);
    this.getContentPane().add(lb_pname, null);  
    this.getContentPane().add(lb_dob, null);
    this.getContentPane().add(lb_place, null);    

    this.getContentPane().add(txt_pname, null);
    this.getContentPane().add(txt_dob, null);
    this.getContentPane().add(txt_place, null);
  :
  :


I can only see the textbox but cannot see other JLabels and JButton... pls help.

missing 1 statment :

bg_image.setBounds(new Rectangle(0, 0, 640, 480));

the jpg is 640 x 480 which is supposed to be the size of my background image.


Thanks,
Cristy

>> this.getContentPane().add(bg_image, null);
That's not how you add a **background** image.
Now, you simply add your JLabel like all other components.

Please apply what you read in the link of my first comment or ashok's comment.

>>Which is just a duplication of what ashok3sep already posted.

No it isn't. In Swing paintComponent should be overridden not paint

You don't use JLabel to display background images. The code i posted is correct and works fine

>> In Swing paintComponent should be overridden not paint
I thought for top level containers (eg. JFrame) you should only override paint(),
while for others you should override paintComponent().
Isn't JApplet also a top level container?

>>as a background image for the content pane in a JApplet ?

The content pane of a JApplet is a JPanel - i'm not sure where the JFrame needed to come in - it's not relevant

> You don't use JLabel to display background images. The code i posted is correct and works fine

The code you posted reinvents the wheel, the JLabel class alrfeady supports displaying images (with more control than the code you posted).

>  i'm not sure where the JFrame needed to come in - it's not relevant

No it the top level container that is irrelevant.

Dear all,

I have tried to write a test.java using the following code :

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


public class test {
  public static void main(String args[]) {
    JFrame frame = new JFrame("Background Example");
    final ImageIcon imageIcon = new ImageIcon("main_bg.jpg");
    JTextArea textArea = new JTextArea() {
      Image image = imageIcon.getImage();
      Image grayImage = GrayFilter.createDisabledImage(image);
      {setOpaque(false);}  // instance initializer
      public void paintComponent (Graphics g) {
        g.drawImage(grayImage, 0, 0, this);
        super.paintComponent(g);
      }
    };
    JScrollPane scrollPane = new JScrollPane(textArea);
    Container content = frame.getContentPane();
    content.add(scrollPane, BorderLayout.CENTER);
    frame.setDefaultCloseOperation(3);
    frame.setSize(640, 480);
    frame.setVisible(true);
  }
}


I was able to compile it successfully, but when I use appletview test.java, I cannot see anything, how should I test my code to see if it is working properly ??

Sorry for so many question caused,
but that's why I am here...
Cristy

typo, should be  appletviewer test.java, but no response.

Cristy

thats an appliation, not an applet. run it with

java -classpath . test

ok. I test that successfully.

But what I am writing is something like this :

public class test extends JApplet
{
     :
     :
     'some code like I posted in my above reply
    :
    :

   and I already have

  public void init()
  {
    try
    {
      jbInit();
    }
    catch(Exception e)
    {
      e.printStackTrace();
    }


  }

}
 
but I have no public static void main(String args[]) { } in my codings,  how can I integrate the above exmaple into my code ? Would u mind to explain a bit more?

Regard,
Cristy

Maybe base on the example from http://www.jguru.com/faq/view.jsp?EID=9691
can someone show me how I can add my JLabels, JButtons, and JTextArea on it ?

Thanks a lot,
Cristy

You would add your fields something like this:


/*
 *  <applet codebase="." code="BackImgApplet.class" width="300" height="300">
 *  <param name="imageUrl" value="main_bg.jpg" />
 *  </applet>
 */
import javax.swing.*;
import java.awt.*;

public class BackImgApplet extends JApplet {
  private JLabel lb_pname;
  private JTextField tf_pname;
  private JLabel lb_place;


  public void init() {
    lb_pname = new JLabel("Name :");
    tf_pname = new JTextField(20);

    Image image = new ImageIcon(getParameter("imageUrl")).getImage();
    setContentPane(new BackgroundImageDisplayer(image));
    Container contentPane = getContentPane();
    contentPane.add(lb_pname);
    contentPane.add(tf_pname);
  }


  private class BackgroundImageDisplayer extends JPanel {
    private Image image;


    public BackgroundImageDisplayer(Image image) {
      super();
      this.image = image;
    }


    public void paintComponent(Graphics g) {
      super.paintComponent(g);
      g.drawImage(image, 0, 0, this);

    }
  }

}

Hi CEHJ,

I copy paste your code and compile succesffuly, but when I load it in the html as following, it said applet noinited :

<HTML>
<BODY bgcolor=black>
<APPLET CODE="BackImgApplet"
      HEIGHT="480"
      WIDTH="640"
        ALIGN="bottom">
This browser does not appear to support Applets.
</APPLET>
</BODY>
</HTML>

I have also tried to replace the html with this:

<applet codebase="." code="BackImgApplet.class" width="300" height="300">
 <param name="imageUrl" value="main_bg.jpg" />
 </applet>

but the same error message. any idea ?

Cristy

First run the code (as posted) as i mentioned earlier:

appletviewer BackImgApplet.java

Your background image file should be in the applet's codebase.

Here are my remarks:

I consider my first comment as useful.
Apparently my hint about class.getResource("main_bg.jpg") was also useful:
>> using your method, I could see the image
- So I expect to be in the points split.
- Furthermore, CEHJ's comment also deserves to be in the split.

- although ashok was correct in overwriting paint() for a JFrame, using a JFrame was not relevant for the Q about JApplet.
- objects talked about using a JLabel, but although
     * he said     >> Let me know if you need firther assistance
     * it was clear that the user needed that / had problems with it  >> I have tried to use JLabel...
  none of his further comments explained how to use JLabel for a background image
  (too busy explaining why others' comments were not OK ;°)