Java tutorial
import java.awt.AlphaComposite; import java.awt.Color; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.geom.Rectangle2D; import java.awt.image.BufferedImage; import javax.swing.JFrame; import javax.swing.JPanel; public class BasicShapes extends JPanel { public void paint(Graphics g) { BufferedImage bimage = new BufferedImage(200, 200, BufferedImage.TYPE_BYTE_INDEXED); Graphics2D g2d = bimage.createGraphics(); Color transparent = new Color(0, 0, 0, 0); g2d.setColor(transparent); g2d.setComposite(AlphaComposite.Src); g2d.fill(new Rectangle2D.Float(20, 20, 100, 20)); g2d.dispose(); } public static void main(String[] args) { JFrame frame = new JFrame("Basic Shapes"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.add(new BasicShapes()); frame.setSize(350, 250); frame.setLocationRelativeTo(null); frame.setVisible(true); } }