How to get (a part of) Graphics2D as an Image?

Question

I have drawn something on a Graphics2D object. On another Graphics2D object, I want to draw just a part of the first Graphics2D object (subImage). To be able to call getSubimage() I need a BufferedImage. So how can I "convert" a Graphics2D to a BufferedImage?

Answer 1

import java.awt.*;
import java.awt.geom.*;
import java.awt.image.BufferedImage;
import javax.swing.*;
public class SubTest {
    JTabbedPane tabbedPane;
    DemoGraphicPanel dgPanel;
    private void demonstrate(final Rectangle r) {
        tabbedPane.addTab("full image", new JPanel() {
            BufferedImage image = makeImage();
            protected void paintComponent(Graphics g) {
                super.paintComponent(g);
                g.drawImage(image, 0, 0, this);
        tabbedPane.addTab("clipped image", new JPanel() {
            BufferedImage image = makeClippedImage(r);
            protected void paintComponent(Graphics g) {
                super.paintComponent(g);
                g.drawImage(image, r.x, r.y, this);
        tabbedPane.addTab("clipped draw", new JPanel() {
            BufferedImage image = makeImage();
            protected void paintComponent(Graphics g) {
                super.paintComponent(g);
                g.setClip(r);
                g.drawImage(image, 0, 0, this);
                //g.setColor(Color.blue);
                //((Graphics2D)g).draw(r);
        tabbedPane.addTab("subImage", new JPanel() {
            BufferedImage image = makeImage().getSubimage(r.x, r.y,
                                                  r.width, r.height);
            protected void paintComponent(Graphics g) {
                super.paintComponent(g);
                g.drawImage(image, r.x, r.y, this);
        // Resize to accomodate multiple rows of tabs.
        //((Window)tabbedPane.getTopLevelAncestor()).pack();
        SwingUtilities.windowForComponent(tabbedPane).pack();
    private BufferedImage makeImage() {
        int w = dgPanel.getWidth();
        int h = dgPanel.getHeight();
        int type = BufferedImage.TYPE_INT_RGB;
        BufferedImage image = new BufferedImage(w, h, type);
        Graphics2D g2 = image.createGraphics();
        dgPanel.paint(g2);
        g2.dispose();
        return image;
    private BufferedImage makeClippedImage(Rectangle r) {
        int w = r.width;
        int h = r.height;
        int type = BufferedImage.TYPE_INT_RGB;
        BufferedImage image = new BufferedImage(w, h, type);
        Graphics2D g2 = image.createGraphics();
        g2.translate(-r.x, -r.y);
        dgPanel.paint(g2);
        g2.dispose();
        return image;
    private JTabbedPane getContent(Rectangle r) {
        dgPanel = new DemoGraphicPanel(r);
        tabbedPane = new JTabbedPane();
        tabbedPane.addTab("original", dgPanel);
        return tabbedPane;
    public static void main(String[] args) {
        final Rectangle clip = new Rectangle(100, 100, 150, 150);
        final SubTest test = new SubTest();
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.getContentPane().add(test.getContent(clip));
        f.pack();
        f.setLocation(200,200);
        f.setVisible(true);
        // All events in single-file queue.
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                test.demonstrate(clip);
class DemoGraphicPanel extends JPanel {
    Rectangle r;
    Dimension size = new Dimension(400,400);
    DemoGraphicPanel(Rectangle r) {
        this.r = r;
        setBackground(new Color(240, 220, 220));
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        int w = size.width;
        int h = size.height;
        g.setColor(Color.red);
        g.drawLine(0,0,w,h);
        g.setColor(Color.blue);
        g.drawLine(0,h,w,0);
        g.setColor(Color.red);
        g.drawRect(r.x, r.y, r.width-1, r.height-1);
    public Dimension getPreferredSize() {
        return size;
}