Capture image of component

[Andrew Thompson]

To: comp.lang.java.gui,comp.l
Capture image of component
http://sdnshare.sun.com/view.jsp?id=2434

I put this little code example up at SDNShare to answer
a question on the Sun forums. Since it is so cute, I
thought I'd reproduce it here*.

* c.l.j.g. & h, w/ f-u set to c.l.j.h. only. Set the follow-ups
as you see fit.

<sscce>
import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.Image;
import java.awt.Graphics;

import java.awt.image.BufferedImage;

import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.awt.event.InputEvent;

import javax.swing.*;

import javax.swing.border.TitledBorder;

import javax.imageio.ImageIO;

import java.io.File;

/**
Create a screenshot of a component.
@author Andrew Thompson
*/
class ComponentImageCapture {

static final String HELP =
"Type Ctrl-0 to get a screenshot of the current GUI.\n" +
"The screenshot will be saved to the current " +
"directory as 'screenshot.png'.";

public static BufferedImage getScreenShot(
Component component) {

BufferedImage image = new BufferedImage(
component.getWidth(),
component.getHeight(),
BufferedImage.TYPE_INT_RGB
);
// call the Component's paint method, using
// the Graphics object of the image.
component.paint( image.getGraphics() );
return image;
}

public static void main(String[] args) {
Runnable r = new Runnable() {
public void run() {
final JFrame f = new JFrame("Test Screenshot");

JMenuItem screenshot =
new JMenuItem("Screenshot");
screenshot.setAccelerator(
KeyStroke.getKeyStroke(
KeyEvent.VK_0,
InputEvent.CTRL_DOWN_MASK
));
screenshot.addActionListener(
new ActionListener(){
public void actionPerformed(ActionEvent ae) {
BufferedImage img = getScreenShot(
f.getContentPane() );
JOptionPane.showMessageDialog(
null,
new JLabel(
new ImageIcon(
img.getScaledInstance(
img.getWidth(null)/2,
img.getHeight(null)/2,
Image.SCALE_SMOOTH )
)));
try {
// write the image as a PNG
ImageIO.write(
img,
"png",
new File("screenshot.png"));
} catch(Exception e) {
e.printStackTrace();
}
}
} );
JMenu menu = new JMenu("Other");
menu.add(screenshot);
JMenuBar mb = new JMenuBar();
mb.add(menu);
f.setJMenuBar(mb);

JPanel p = new JPanel( new BorderLayout(5,5) );
p.setBorder( new TitledBorder("Main GUI") );
p.add( new JScrollPane(new JTree()),
BorderLayout.WEST );
p.add( new JScrollPane( new JTextArea(HELP,10,30) ),
BorderLayout.CENTER );
p.validate();

f.setContentPane( p );
f.pack();
f.setLocationRelativeTo(null);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
}
};
SwingUtilities.invokeLater(r);
}
}
</sscce>

--
Andrew Thompson
http://pscode.org/

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