CODEWITHSUNDEEP
javaswinguser-interface
Johnny
Johnny

Reputation: 385

Paint to Off-Screen Image

I managed to draw GUI components on an image. However, it only can be done by having a JFrame set to be visible. The JPanel.setVisible() and validate() don't have any effect. It would draw an empty image if the JFrame is commented out.

It is not neat when I want some function to do off-screen GUI painting, then pop a JFrame out or the server running such code don't have a screen or graphic card.

Please help, thanks very much.

import java.awt.BorderLayout;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

import javax.imageio.ImageIO;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Snippet {

    public static void main(String[] args) {
        JButton test = new JButton("Test Button center");
        JButton test2 = new JButton("Test Button2 south");
        JButton test3 = new JButton("Test Button3 at east");
        BorderLayout bl = new BorderLayout();
        JPanel jp = new JPanel(bl, false);
        jp.add(test2,BorderLayout.SOUTH);
        jp.add(test, BorderLayout.CENTER);

        jp.add(test3, BorderLayout.EAST);

//      jp.validate();
//      jp.setVisible(true);
//      jp.show();
        JFrame jf = new JFrame();
        jf.getContentPane().add(jp, BorderLayout.CENTER);
        jf.pack();
        jf.setVisible(true);
        //jp.setBounds(10, 10, 400, 400);
        BufferedImage b = new BufferedImage(jf.getWidth(), jf.getHeight(), BufferedImage.TYPE_INT_ARGB);
        jp.paintAll(b.createGraphics());


        File output = new File("f:/screenie.png");

        try
        {
            ImageIO.write(b, "png", output);
        }
        catch (IOException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

Upvotes: 1

Views: 1211

Answers (1)

camickr
camickr

Reputation: 324118

i managed drawing GUI components on image, however, it only can be done by having a Jframe set to be visible,

Components need to have a size before they can be painted. By default the size of a component is (0, 0) so there is nothing to paint. When you invoke pack() or setVisible(...) - which invokes pack() for you - the size of each component is then determined.

Check out Screen Image which can be used to create an image of any component and will set the size for you before creating the image.

Upvotes: 1

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