So I've been trying to export an image that I've drawn on a JPanel into an image. I've been using this method:
BufferedImage image = new BufferedImage(getWidth(), getHeight(), BufferedImage.TYPE_INT_RGB);
Graphics2D g = image.createGraphics();
paint(g);
try { ImageIO.write(image, "png", new File([location goes here]); } catch (IOException e) {}
I get an image in my intended location but I get a compressed version of what my JPanel shows. The same happens if I try to export a BMP as well. Is there a way to get a pixel-perfect image exported from the JPanel? Thanks in advance.
Create BufferedImage to store your painting. When you paint, paint on BufferedImage. When you need to display paint on JPanel, draw BufferedImage on JPanel. This way, you can load / save painting to file.
To add an image to JPanel, the Java Swing framework provides built-in classes such as ImageIO and ImageIcon that you can use to fetch an image.
You can simply create your jPanel using drag and drop, as you always do and then for changing the panel's color and making it transparent or semi-transparent you can use this code: panel. setBackground(new Color(0.0f, 0.0f, 0.0f, 0.5f));
JPanel, a part of the Java Swing package, is a container that can store a group of components.
The panel needs to be laid out based on it's requirements. If the panel hasn't being realized on the screen yet, it may not render the way you expect it do
The following example assumes that the panel has not being displayed on the screen...
setSize(getPreferredSize());
BufferedImage image = new BufferedImage(getWidth(), getHeight(), BufferedImage.TYPE_INT_RGB);
Graphics2D g = image.createGraphics();
printAll(g);
g.dispose();
try {
ImageIO.write(image, "png", new File([location goes here]);
} catch (IOException e) {
e.printStackTrace();
}
You should avoid calling paint
yourself, it can throw an exception if the component has not being realized on the screen, instead, use printAll
Also, if your create a resource, you should dispose of it ;)
Updated
I did this quick example. Screen shoot on top, jpeg on left, png on right.
jpeg is 30kb and png is 320kb
I used this to create it...
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.Graphics2D;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class PaintComponent {
public static void main(String[] args) {
new PaintComponent();
}
public PaintComponent() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private JPanel paintPane;
public TestPane() {
paintPane = new JPanel(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridwidth = GridBagConstraints.REMAINDER;
paintPane.add(new JLabel("I'm a label"), gbc);
paintPane.add(new JTextField("I'm a text field", 20), gbc);
paintPane.add(new JLabel(new ImageIcon("some\pretty\picture")), gbc);
setLayout(new BorderLayout());
add(paintPane);
JButton paint = new JButton("Capture");
paint.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
BufferedImage image = new BufferedImage(paintPane.getWidth(), paintPane.getHeight(), BufferedImage.TYPE_INT_RGB);
Graphics2D g = image.createGraphics();
paintPane.printAll(g);
g.dispose();
try {
ImageIO.write(image, "jpg", new File("Paint.jpg"));
ImageIO.write(image, "png", new File("Paint.png"));
} catch (IOException exp) {
exp.printStackTrace();
}
}
});
add(paint, BorderLayout.SOUTH);
}
}
}
I would make sure that you are actually looking at the correct files ;)
If you are trying to make an image of a panel that is not visible on a window then check out Screen Image. It will invoke doLayout()
on the panel to make sure the components are displayed properly.
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With