Heptagon Maker

Heptagon.java

import java.awt.*;

public class Heptagon {
	
    private int x, y, radius;
    private double area;
    private Color theColor;
    private boolean isVisible;
    private Polygon polygon;
    
    /**
     * Construct a new Heptagon centered at initX, initY with a
     * color indicated by initColor. The new Heptagon is visible by
     * default.
     * 
     * @param initX the x coordinate of the center of the 7-sided thingy.
     * @param initY the y coordinate of the center of the heptagon.
     * @param initRadius an arbitrary value of the distance from (initX, initY) to a point at which
     * two sides meet at roughly 5(pi)/7 radians
     * @param initColor the color of the heptagon.
     */
public Heptagon(int initX, int initY, int initRadius, Color initColor) {
    x = initX;
    y = initY;
    radius = initRadius;
    theColor = initColor;
    isVisible = true;
    polygon = new Polygon();
}

/**
 * Increases the size of the heptagon by the specified factor.
 * @param factor the amount by which you wish to increase the area of the heptagon.
 */
	@Override
	public void scale(double factor) {
        if (factor > 0) {
            radius = (int) (Math.round(radius * factor));
        }
		
	}
	
	/**
	 * Move the center of the heptagon.
	 * @param newX
	 * @param newY
	 */
	public void move(int newX, int newY) {
		x = newX;
		y = newY;
		polygon.reset();
	}

	/**
	 * Draws the heptagon using a Graphics object.
	 * Points are calculated and placed based on the radius relative 
	 * to the starting x and y co-ordinates using basic trigonometric functions
	 * and therefore may not create a perfect regular heptagon where all sides 
	 * meet at 5(pi)/7 radians. 
	 * @param g a pointer to a pre-initialized Graphics drawing object.
	 */
	public void draw(Graphics g) {
		g.setColor(theColor);
		for (int i = 0; i < 7; i++){
			polygon.addPoint((int) (x + radius * Math.cos(i * 2 * Math.PI / 7)),
			(int) (y + radius * Math.sin(i * 2 * Math.PI / 7)));}
			g.drawPolygon(polygon);
			g.fillPolygon(polygon);
	}
	
	/**
	 * Calculates and returns the area of the heptagon accurate to 2 decimal places
	 * using the formula A = 7/4 * a^2 * cot(pi/7) where a is the length of a side
	 * calculated based on the radius relative to the starting x and y co-ordinates. 
	 * @return area the approximate area of the heptagon, accurate to ~2 decimal places.
	 */
	public Double getArea() {
		// imagine we make points 1 and 2 from the draw() method above
		double x1 =  x + radius * Math.cos(1 * 2 * Math.PI / 7);
		double x2 =  x + radius * Math.cos(2 * 2 * Math.PI / 7);
		double y1 =  y + radius * Math.sin(1 * 2 * Math.PI / 7);
		double y2 =  y + radius * Math.sin(2 * 2 * Math.PI / 7);
		// calculate the distance between these points
		double xd = Math.abs(x1-x2);
		double yd = Math.abs(y1-y2);
		// and finally, determine the length of one side of the heptagon
		double side = Math.sqrt((Math.pow(xd, 2))+(Math.pow(yd, 2)));
		// now implement the area formula mentioned above
		area = ((7/4) * Math.pow(side, 2)) * (1/(Math.tan((Math.PI / 7))));
		return area;
	}

	/**
	 * Tells you the current color being used for drawing.
	 * @return theColor the current color being used for drawing.
	 */
	@Override
	public Color getColor() {
		return theColor;
	}

	/**
	 * Sets a new color for drawing.
	 * @param newColor the new color you wish to use.
	 */
	@Override
	public void setColor(Color newColor) {
		theColor = newColor;
		
	}

	/**
	 * Sets the heptagon to visible or not.
	 * @param visible true for visible, false for hidden.
	 */
	@Override
	public void setVisible(boolean visible) {
		isVisible = visible;
		
	}
/**
 * Tells you whether the heptagon is visible.
 * @return isVisible true if visible, false if hidden.
 */
	@Override
	public boolean isVisible() {
		return isVisible;
	}

}