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copied!<p>In addition to @tulskiy's helpful observations, I would add two points:</p> <ol> <li><p>Always construct your GUI on the <a href="http://download-llnw.oracle.com/javase/tutorial/uiswing/concurrency/initial.html" rel="nofollow noreferrer">event dispatch thread</a>, as shown below.</p></li> <li><p>An <a href="http://sscce.org/" rel="nofollow noreferrer">sscce</a> should be a <em>Short, Self Contained, Correct (Compilable), Example</em>. As a convenience, don't require others to recreate multiple public classes; use top-level (package-private) or nested classes. As this is a graphics problem, use a public or synthetic image that reflects your problem.</p></li> </ol> <p>In the example below, <code>paintComponent()</code> alters the graphics context's transform to effect the rotation. Note that the operations are performed in the (apparent) reverse of the declaration order: First, the image's center is translated to the origin; second, the image is rotated; third, the image's center is translated to the center of the panel. You can see the effect by resizing the panel.</p> <p>Addendum: See also this alternative <a href="https://stackoverflow.com/questions/5722219">approach</a> using <code>AffineTransform</code>.</p> <p><img src="https://i.stack.imgur.com/T2gKx.png" alt="image"></p> <pre><code>package overflow; import java.awt.*; import java.awt.event.*; import java.awt.image.BufferedImage; import java.util.Random; import javax.swing.*; /** * @see https://stackoverflow.com/questions/3371227 * @see https://stackoverflow.com/questions/3405799 */ public class RotateApp { private static final int N = 3; public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { @Override public void run() { JFrame frame = new JFrame(); frame.setLayout(new GridLayout(N, N, N, N)); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); for (int i = 0; i < N * N; i++) { frame.add(new RotatePanel()); } frame.pack(); frame.setVisible(true); } }); } } class RotatePanel extends JPanel implements ActionListener { private static final int SIZE = 256; private static double DELTA_THETA = Math.PI / 90; private final Timer timer = new Timer(25, this); private Image image = RotatableImage.getImage(SIZE); private double dt = DELTA_THETA; private double theta; public RotatePanel() { this.setBackground(Color.lightGray); this.setPreferredSize(new Dimension( image.getWidth(null), image.getHeight(null))); this.addMouseListener(new MouseAdapter() { @Override public void mousePressed(MouseEvent e) { image = RotatableImage.getImage(SIZE); dt = -dt; } }); timer.start(); } @Override public void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2d = (Graphics2D) g; g2d.translate(this.getWidth() / 2, this.getHeight() / 2); g2d.rotate(theta); g2d.translate(-image.getWidth(this) / 2, -image.getHeight(this) / 2); g2d.drawImage(image, 0, 0, null); } @Override public void actionPerformed(ActionEvent e) { theta += dt; repaint(); } @Override public Dimension getPreferredSize() { return new Dimension(SIZE, SIZE); } } class RotatableImage { private static final Random r = new Random(); static public Image getImage(int size) { BufferedImage bi = new BufferedImage( size, size, BufferedImage.TYPE_INT_ARGB); Graphics2D g2d = bi.createGraphics(); g2d.setRenderingHint( RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); g2d.setPaint(Color.getHSBColor(r.nextFloat(), 1, 1)); g2d.setStroke(new BasicStroke(size / 8)); g2d.drawLine(0, size / 2, size, size / 2); g2d.drawLine(size / 2, 0, size / 2, size); g2d.dispose(); return bi; } } </code></pre>

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