import com.sun.java.swing.*;
import java.awt.*;
import java.awt.geom.*;

public class Transparencies extends JPanel {
  private static double gap=10, width=60, offset=20,
                        deltaX=gap+width+offset;
  private Rectangle2D.Double
    blueSquare =
      new Rectangle2D.Double(gap+offset, gap+offset,
                             width, width),
    redSquare =
      new Rectangle2D.Double(gap, gap, width, width);

  private AlphaComposite makeComposite(float alpha) {
    int type = AlphaComposite.SRC_OVER;
    return(AlphaComposite.getInstance(type, alpha));
  }

  private void drawSquares(Graphics2D g2d,
                           float alpha) {
    Composite originalComposite = g2d.getComposite();
    g2d.setPaint(Color.blue);
    g2d.fill(blueSquare);
    g2d.setComposite(makeComposite(alpha));
    g2d.setPaint(Color.red);
    g2d.fill(redSquare);
    g2d.setComposite(originalComposite);
  }

  public void paintComponent(Graphics g) {
    Graphics2D g2d = (Graphics2D)g;
    g2d.clearRect(0, 0,
                  getSize().width, getSize().height);
    for(int i=0; i<11; i++) {
      drawSquares(g2d, i*0.1f);
      g2d.translate(deltaX, 0);
    }
  }

  public static void main(String[] args) {
    String title = "Transparency test: alpha of " +
                   "the red square ranges from " +
                   "0.0 at the left to 1.0 at " +
                   "the right.";
    WindowUtil.openInJFrame(new Transparencies(),
                            (int)(11*deltaX + 2*gap),
                            (int)(deltaX + 3*gap),
                            title,
                            Color.lightGray);
  }
}