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import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.geom.Arc2D;
import java.awt.image.BufferedImage;
import javax.swing.JComponent;
import javax.swing.JFrame;
class MyCanvas extends JComponent {
private BufferedImage offImg;
public void draw(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
// Draw the pie chart
Arc2D.Float arc = new Arc2D.Float(Arc2D.PIE);
arc.setFrame(140, 200, 67, 46);
arc.setAngleStart(45);
arc.setAngleExtent(270);
g2.setColor(Color.gray);
g2.draw(arc);
g2.setColor(Color.red);
g2.fill(arc);
g2.setColor(Color.black);
g2.drawString("Arc2D.PIE", 140, 190);
}
public Graphics2D createDemoGraphics2D(Graphics g) {
Graphics2D g2 = null;
if (offImg == null || offImg.getWidth() != getSize().width
|| offImg.getHeight() != getSize().height) {
offImg = (BufferedImage) createImage(getSize().width, getSize().height);
}
if (offImg != null) {
g2 = offImg.createGraphics();
g2.setBackground(getBackground());
}
// .. set attributes ..
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
// .. clear canvas ..
g2.clearRect(0, 0, getSize().width, getSize().height);
return g2;
}
public void paint(Graphics g) {
if (getSize().width <= 0 || getSize().height <= 0)
return;
Graphics2D g2 = createDemoGraphics2D(g);
draw(g2);
g2.dispose();
if (offImg != null && isShowing()) {
g.drawImage(offImg, 0, 0, this);
}
}
}
public class OffScreenPaint {
public static void main(String[] a) {
JFrame window = new JFrame();
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setBounds(30, 30, 300, 300);
window.getContentPane().add(new MyCanvas());
window.setVisible(true);
}
}
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