Copying JComponent into an Image

[Tom McC]

Hello!

I have a couple of charting classes that I want to be able to include in PDF reports created by my program. The classes all extend JComponent. My problem is that when I convert the Components to images, I always get a black image.

I'm using this code that I pieced together from various places:

import javax.imageio.*;
import java.awt.image.BufferedImage;
import java.awt.Graphics2D;
 
Dimension size = myComponent.getSize();
BufferedImage image = new BufferedImage(size.width,size.height, BufferedImage.TYPE_INT_RGB);
 
Graphics2D g2 = image.createGraphics();
g2.setBackground(Color.WHITE);
g2.setColor(Color.BLACK);
 
myComponent.printAll(g2);
 
try {
   File f = new File("c:\\component.png");
   ImageIO.write((RenderedImage)image, "png", f);
} catch (Exception e) {
   e.printStackTrace();
       }

Now, I've tried adding the charting component to a JPanel and then trying to print that component onto the image, and I am able to see the JPanel's default background color, but no sign of the charting component.

I've also tried using a few different variations of Buffered Image types (other than TYPE_INT_RGB), but felt I was getting nowhere. Is there something here I'm missing?

(And PS: What's the difference between print() and paint() for a Component?)

Thanks!
Tom

[Michael Dunn]

you'll find a couple of links here (code that does what you describe)
the link of camickr's is the better, but the other one is worth a look as well

http://forum.java.sun.com/thread.jspa?threadID=604040

[Tom McC]

Michael, the code on that page (ScreenImage.java) is very handy; I'm saving that one.

Unforunately, it still didn't work for these charting components. I ended up browsing through the code (which has been put through an obfuscator) and finding a render(Graphics) method which did the trick. How odd that even though the charts extend JComponent and show up in a program fine, they refuse to draw onto an image, something other JComponents did fine.

Thanks so much for the prompt reply and useful link, however!