Nick Dunn

package circle;

import java.awt.Dimension;
import java.awt.Graphics;
import javax.swing.JComponent;
import javax.swing.JFrame;

/**
 * Simple example that shows a standard way of drawing, manually calculating
 * x and y coordinates of the points of a circle.
 * @author Nick
 */
public class StandardCircle extends JComponent {

    private static final int NUM_DOTS = 20;
    private static final int SIZE = 200;

    public StandardCircle() {
        super();
        setPreferredSize(new Dimension(SIZE, SIZE));
    }

    /**
     * Draw a series of dots in a circular pattern
     * @param g
     */
    @Override
    public void paintComponent(Graphics g) {
        // Don't forget to call the super method
        super.paintComponent(g);

        int radius = getWidth() / 3;

        for (int i = 0; i < NUM_DOTS; i++) {
            double theta = 2 * Math.PI * ((double) i / NUM_DOTS);
            int x = (int) (radius * Math.cos(theta));
            int y = (int) (radius * Math.sin(theta));

            // these x and y are relative to center of circle; currently origin
            // is at upper left corner of window.  Add to x and y to
            // translate.
            x += getWidth() / 2;
            y += getHeight() / 2;

            g.drawOval(x, y, 1, 1);
        }

    }

    public static void main(String[] args) {
        JFrame frame = new JFrame("Standard circle");
        frame.add(new StandardCircle());
        frame.pack();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }

}