[JAVA2D] how can newbe create a .png or .jpg file from a JFrame oder other complex graphical "container"?

[Sven Mielordt]

Dear J2D enthusiastics... 
I'm a newbe here and yesterday downloaded the latest version of Java 1.4.1_01 to use 
the static class methods ImageIO.read() and ImageIO.write() to first read an image and 
give it out as a differently formatted file again:

File f = new  File("pic1.jpg"); 
BufferedImage  bi =  ImageIO.read(f); 
File  outfile = new File("pic2.png"); 
ImageIO.write(bi, "png", outfile);

That works out properly as expected.

Now the problem arises: 
I tried to get some simplified approach to mathematical funtion plots by using the 
Plotlib Toolkit from Bernhard Bablok (www.bablokb.de). It really works fine to plot 
something like the normal distribution or other funtions into a window on the screen. 
I then modified the FktTest.java-file a little bit to enable it to give a .jpg or 
.png-file from the displayed image.
BUT:
the following code fragment only gives a pic of the right size -but it only contains 
uniform grey pixels and nothing from that I can see on the screen.....

frame1.getContentPane().add(t); // original code by Bernhard Bablok, adds contents
frame1.pack();  // original code by Bernhard Bablok
      BufferedImage im2 = (BufferedImage)frame1.createImage(500,500); // my code
      File outfile2  = new File("C:\\Java2D\\plotfile_CC25.png"); // my code
      ImageIO.write(im2, "png",  outfile2); // my code: only gray pixel file generated!
frame1.show(); // original code by Bernhard Bablok: works properly

My questions: how can I create a .png or .jpg file from a JFrame oder other complex 
graphical "containers"? Is there a simple method to serialize the topically displayed 
window(s) and then convert the stream into a BuffereredImage and then to feed it into 
ImageIO.write()?
I also append the GraphTest.java file; it is the test file I really used.

nice Xmas and thank you in advance .... Sven Mielordt

**************** 
sender:  
Sven Mielordt  
Gro�beerenstra�e 81  
D 10963 Berlin
Germany
Tel +49 30 2511999 
[EMAIL PROTECTED] 
*****************

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GraphTest.java
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