circularcake.java

Java程序设计(美) David D. Riley著 机械工业出版社 书籍配套 代码

// Figure 9.10

import java.awt.*;
public class CircularCake  extends Cake  {
	
	/**	post:	getX() == x  and   getY() == y
	 *			and  getWidth() == getHeight() == d
	 *			and   getBackground() == Color.pink  
	 */
    public CircularCake( int x, int y, int d )  {
    	super(x, y, d, d);
		setBackground( Color.pink );
	}

	/**	post:	the cake is drawm as an oval filling the bounding rectangle
	 *	   		and the color of the cake is getBackground() 
	 */
	protected void paintCake( Graphics g )   {
		g.setColor( getBackground() );
		g.fillOval(0, 0, getWidth(), getHeight());
	}

	/**	post:   four black lines are drawn through the cake center to form
	 *          eight wedge-shaped pieces of equal size.  
	 */
	protected void paintEighthCuts( Graphics g )   {
		int ds, dl;
		g.setColor( Color.black );
		// draw horizontal and vertical lines, respectively
		g.drawLine(0, getHeight()/2, getWidth(), getHeight()/2);
		g.drawLine(getWidth()/2, 0, getWidth()/2, getHeight() );
        
		// draw diagonal lines
		ds = (int)( (getWidth() - getWidth()/Math.sqrt(2.0)) / 2.0 );
		dl = (int)( getWidth() / Math.sqrt(2.0) ) + ds;
		g.drawLine( ds, ds, dl, dl );
		g.drawLine( ds, dl, dl, ds );
	}
}