Painting components over images

[D N Taylor]

I've exteneded a JFrame and overridden it's paint() method because I want to draw an image in the background and then display a component on top of it (label, button, etc). But my component is not displaying in the right place. It only displays in the top left corner, even though I've set the location to something else. I don't think I'm painting it right somehow.

Here's a snippet:


JLabel label1 = new JLabel("hello");
label1.setSize(150, 50);
label1.setLocation(200, 200);
...

public void paint(Graphics g)
{
Graphics offScreenGraphics = offScreenImage.getGraphics();

offScreenGraphics.drawImage(myImage, 0, 0, 800, 600, 0, 0, 800, 600, this);

paint(offScreenGraphics);

label1.paint(offScreenGraphics);

g.drawImage(offScreenImage, 0, 0, this);

offScreenGraphics.dispose();
}


Any help or suggestions much appreciated!!

Thanks,

D Taylor

[jefff willis]

This is just a thought, but it may be related to the layout manager that you are using to display these things.

Also, your paint() method is calling two other paint() methods. I'm a little confused there. Make sure that part of you code is correct.

[Craig Wood]

Swing will paint all of a containers components for you. All you have to do is render your background image to a component and then add the child components as usual. Here's the recommended way:

import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.*;
import java.net.*;
import javax.imageio.ImageIO;
import javax.swing.*;
 
public class BackgroundImage
{
    public BackgroundImage()
    {
        BufferedImage[] images = loadImages();
        JPanel cougar = new BackgroundImageComponent(images[0]);
        cougar.add(new JButton("button 1"));
        cougar.add(new JButton("button 2"));
        JPanel contentPane = new BackgroundImageComponent(images[1]);
        contentPane.setLayout(new GridBagLayout());
        GridBagConstraints gbc = new GridBagConstraints();
        gbc.weighty = 1.0;               // allow vertical dispersion
        gbc.weightx = 1.0;               // horizontal dispersion
        gbc.gridwidth = gbc.RELATIVE;    // next to last component in row
        contentPane.add(new JButton("another button"), gbc);
        gbc.gridy = 1;                   // next row down
        contentPane.add(new JTextField(8), gbc);
        gbc.gridy++;                     // next row
        contentPane.add(new JTextField(12), gbc);
        gbc.gridy = gbc.RELATIVE;        // reset to default value
        gbc.gridheight = 3;              // 3 columns high
        gbc.gridheight = gbc.REMAINDER;  // last component in row
        contentPane.add(cougar, gbc);
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setContentPane(contentPane);
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }
 
    private BufferedImage[] loadImages()
    {
        String prefix = "images/";
        String[] fileNames = { "cougar.jpg", "owls.jpg" };
        BufferedImage[] images = new BufferedImage[fileNames.length];
        for(int j = 0; j < images.length; j++)
            try
            {
                URL url = getClass().getResource(prefix + fileNames[j]);
                images[j] = ImageIO.read(url);
            }
            catch(MalformedURLException mue)
            {
                System.err.println("url: " + mue.getMessage());
            }
            catch(IOException ioe)
            {
                System.err.println("read: " + ioe.getMessage());
            }
        return images;
    }
 
    public static void main(String[] args)
    {
        new BackgroundImage();
    }
}
 
class BackgroundImageComponent extends JPanel
{
    BufferedImage image;
 
    public BackgroundImageComponent(BufferedImage image)
    {
        this.image = image;
    }
 
    protected void paintComponent(Graphics g)
    {
        super.paintComponent(g);
        int w = getWidth();
        int h = getHeight();
        int imageWidth = image.getWidth();
        int imageHeight = image.getHeight();
        int x = (w - imageWidth)/2;          // center the image
        int y = (h - imageHeight)/2;         // in its container
        g.drawImage(image, x, y, this);
    }
 
    public Dimension getPreferredSize()
    {
        return new Dimension(image.getWidth(), image.getHeight());
    }
}