BetterCircleTest.java

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BetterCircleTest.java
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import java.awt.*;
import java.applet.Applet;

/** Position circles down the diagonal so that their borders
 *  just touch. Illustrates that Java 1.1 lightweight 
 *  components can be partially transparent.
 *
  */

public class BetterCircleTest extends Applet {
  public void init() {
    setBackground(Color.lightGray);
    setLayout(null);
    BetterCircle circle;
    int radius = getSize().width/6;
    int deltaX = round(2.0 * (double)radius / Math.sqrt(2.0));
    for (int x=radius; x<6*radius; x=x+deltaX) {
      circle = new BetterCircle(Color.black, radius);
      add(circle);
      circle.setCenter(x, x);
    }
  }

  private int round(double num) {
    return((int)Math.round(num));
  }
}
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BetterCircle.java
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import java.awt.*;

/** An improved variation of the Circle class that uses Java 1.1
 *  lightweight components instead of Canvas.
 *
  */

public class BetterCircle extends Component {
  private Dimension preferredDimension;
  private int width, height;
  
  public BetterCircle(Color foreground, int radius) {
    setForeground(foreground);
    width = 2*radius;
    height = 2*radius;
    preferredDimension = new Dimension(width, height);
    setSize(preferredDimension);
  }

  public void paint(Graphics g) {
    g.setColor(getForeground());
    g.fillOval(0, 0, width, height);
  }

  public void setCenter(int x, int y) {
    setLocation(x - width/2, y - height/2);
  }

  /** Report the original size as the preferred size.
   *  That way, the BetterCircle doesn't get
   *  shrunk by layout managers.
   */
  
  public Dimension getPreferredSize() {
    return(preferredDimension);
  }

  /** Report same thing for minimum size as
   *  preferred size.
   */
  
  public Dimension getMinimumSize() {
    return(preferredDimension);
  }
}
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