Thread: BackgroundPanel.java cannot be placed in BorderLayout.NORTH

i am trying to put a picture on the top of my swing GUI that stretches horizontally to fit the width of the window as it resizes

http://www.camick.com/java/source/BackgroundPanel.java
this is the code for a commonly used function that scales images to their components size. it works by overloading the paintcontainer class, which is called every time the window resizes, which then calls the paint class. they simply grab the size of the container and draw the image to those dimensions

the image that needs to be resized must be placed in BorderLayout.NORTH, because the rest of my GUI is in BorderLayout.CENTER, but BackgroundPanel cant be placed in NORTH, the image disappears, even with a minimum size set. it cant be placed inside a panel inside a panel inside NORTH either. ive been reading over the code for BackgroundPanel and its driving me crazy i cant figure out why

here is some short example code, not my program but it simplifies the problem:

import java.awt.*;
import javax.swing.*;
import java.awt.event.WindowEvent;
 
public class JPanel1 extends JFrame 
{
	public static void main(String[] args) 
	{
		new JPanel1();
	}
 
	public JPanel1() 
	{
		enableEvents(AWTEvent.WINDOW_EVENT_MASK);
		add(mainJPanel());
		pack();
		setVisible(true);
	}
 
 
	//debug space center to streatch
	private JPanel mainJPanel()
	{
		JPanel JPanel = new JPanel();
		BorderLayout layout = new BorderLayout();
		this.setMinimumSize( new Dimension( 224, 224 ) );
		JPanel.setLayout(layout);
		JPanel.add(mainJPanel2(),BorderLayout.NORTH);
		return(JPanel);
	}
 
 
	//debug space center to streatch
	private JPanel mainJPanel2()
	{
		JPanel JPanel = new JPanel();
		BorderLayout layout = new BorderLayout();
		JPanel.setLayout(layout);
		JPanel.add(JPanel2(),BorderLayout.CENTER);
		return(JPanel);
	}
 
 
	private JPanel JPanel2() 
	{
		BorderLayout layout = new BorderLayout();
		this.setLayout(layout);
		Toolkit toolkit = Toolkit.getDefaultToolkit(); 
		Image duke = toolkit.getImage("sun.jpg");
		BackgroundPanel panel = new BackgroundPanel(duke, BackgroundPanel.SCALED);
		//panel.setMinimumSize( new Dimension( 224, 224 ) );
		this.setMinimumSize( new Dimension( 224, 224 ) );
		GradientPaint paint = new GradientPaint(0, 0, Color.BLUE, 600, 0, Color.RED);
		panel.setPaint(paint);
		return panel;
	}
 
	//exit when closed
    public void processWindowEvent(WindowEvent event)
	{
		if(event.getID() == WindowEvent.WINDOW_CLOSING)
		System.exit(0);
    }
 
}

I don't know why right know, but your paintComponent method in BackgroundPanel class is not working. Try to add System.out.println there, you will see.

Cross posted
BackgroundPanel.java cannot be placed in BorderLayout.NORTH (Swing / AWT / SWT / JFace forum at JavaRanch)

db

Also at
BackgroundPanel.java cannot be placed in BorderLayout.NORTH - Java Forums
BackgroundPanel.java cannot be placed in BorderLayout.NORTH - Dev Shed
BackgroundPanel.java cannot be placed in BorderLayout.NORTH
BackgroundPanel.java cannot be placed in BorderLayout.NORTH | Java.net

db

try changing NORTH to CENTER, it works perfectly if u do that. but i need it in NORTH

the problem has been solved, i needed prefered size not minimym size,
thank you very much for your efforts

Ah, I feel pity that I didn't suggest you that before. I remember I was thinking that you may need both, preferred and the minimum sizes set. Next time I will try to be more confident with the knowledge I have