JFrame to image without showing the JFrame

Question

I am trying to render a JFrame to an image without ever displaying the JFrame itself (similar to what this question is asking). I have tried using this piece of code:

private 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;
}

However, this only works when the JFrame's setVisible(true) is set. This will cause the image to be displayed on the screen which is not something I want. I have also tried to create something like so:

public class MyFrame extends JFrame
{
    private BufferedImage bi;

    public MyFrame(String name, BufferedImage bi)
    { 
         this.bi = bi;
         super(name);
    }

    @Override
    public void paint(Graphics g)
    {
         g.drawImage(this.bufferedImage, 0, 0, null);
    }
}

This however displays black images (like the code above). I am pretty sure that what I am after is possible, the problem is that I can't really find how. My experience with custom Swing components is pretty limited, so any information will be appreciated.

Thanks.

[this could be works without caused issues with black ...](http://tips4java.wordpress.com/2008/10/13/screen-image/), no idea without an SSCCE — mKorbel, Sep 18 '12 at 13:07
@mKorbel: The code I have posted is exactly what I am trying to do. I have tried to use that class, but it also rendered black images. — npinti, Sep 18 '12 at 13:09
JComponents, then JFrames RootPane can returns its coordinates or Graphics in the cases, for already visible container, after call pack(), ContentPane isn't proper container for Graphics(2d), use JComponents / JPanel by override get/setPreferredSize or use scalled instance for Image (not sure about proper methods about additional methods, Image, Graphics are not my cup of Java) — mKorbel, Sep 18 '12 at 13:20

score 12 · Accepted Answer · answered Sep 18 '12 at 13:36

12

Here is a snippet that should do the trick:

Component c; // the component you would like to print to a BufferedImage
JFrame frame = new JFrame();
frame.setBackground(Color.WHITE);
frame.setUndecorated(true);
frame.getContentPane().add(c);
frame.pack();
BufferedImage bi = new BufferedImage(c.getWidth(), c.getHeight(), BufferedImage.TYPE_INT_ARGB);
Graphics2D graphics = bi.createGraphics();
c.print(graphics);
graphics.dispose();
frame.dispose();

answered Sep 18 '12 at 13:36

Guillaume Polet

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1

@DavidKroukamp Thanks. I just looked again, createGraphics returns a Graphics2D, so no need to cast ;-) Cheers. – Guillaume Polet Sep 18 '12 at 15:24
Thanks a lot this worked for me. I just needed to pass `jFrame.getContentPane()` together with what you suggested. One more thing, using `ARGB` produces a slightly pinkish image. I used the usual `RGB` to fix that. – npinti Sep 18 '12 at 15:38
@npinti it depends of what you are trying to achieve. If you want to also handle transparency, you will need ARGB, if not, RGB is your friend indeed ;) – Guillaume Polet Sep 18 '12 at 15:46
@GuillaumePolet: Yes indeed. Thankfully it is just a plain image, no need for transparency and extra stuff. – npinti Sep 19 '12 at 05:10
Doesn't work (works weird). Apart from drawing on `bi` which works, it also draws on top of the current GUI. – Mark Jeronimus Oct 08 '14 at 12:23
@MarkJeronimus It does work. You should probably post a question on SO with your complete example so that we can find out what's not working. – Guillaume Polet Oct 08 '14 at 20:55

David Kroukamp · Answer 2 · 2012-09-18T16:06:06.650

This method might do the trick:

public BufferedImage getImage(Component c) {
    BufferedImage bi = null;
    try {
        bi = new BufferedImage(c.getWidth(),c.getHeight(), BufferedImage.TYPE_INT_RGB);
        Graphics2D g2d =bi.createGraphics();
        c.print(g2d);
        g2d.dispose();
    } catch (Exception e) {
        e.printStackTrace();
        return null;
    }
    return bi;
}

you'd then do something like:

JFrame frame=...;
...
BufferedImage bImg=new ClassName().getImage(frame);
//bImg is now a screen shot of your frame

JFrame to image without showing the JFrame

2 Answers2

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