import java.awt.Color;

import java.awt.Dimension;

import java.awt.Graphics;

import java.awt.Graphics2D;

import java.awt.RenderingHints;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import java.awt.geom.AffineTransform;



import javax.swing.JFrame;

import javax.swing.JPanel;

import javax.swing.SwingUtilities;

import javax.swing.Timer;



/**

 * Progress Dial 

 * @author Greg Cope

 *

 */

public class Progress extends JPanel {

	

	private static final long serialVersionUID = 4321421L;

	int barCount = 12;

	int current = 0;//current activated bar

	private javax.swing.Timer timer = null;//animating timer

	

	/**

	 * Constructor that automatically creates a timer to animate the progress bar

	 */

	public Progress(){

		setBackground(Color.WHITE);

		setOpaque(true);

		timer = new Timer(60, new ActionListener(){



			@Override

			public void actionPerformed(ActionEvent e) {

				current++;

				if ( current > barCount - 1){

					current = 0;

				}

				repaint();

			}

			

		});

		timer.start();

	}

	

	@Override

	public void paintComponent(Graphics gr){

		Graphics2D g = (Graphics2D)gr;

		super.paintComponent(g);

		g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

		int width = getWidth() > getHeight() ? getWidth() : getHeight();//get the shortest dimensions

		int padding = (int)(width * 0.20d);

		AffineTransform at = new AffineTransform(g.getTransform());

		int center = width/2;

		int innerRadius = 10;

		int barHeight = 10;

		//get indexes for coloring the bars neighboring current

		int prev = current - 1 < 0 ? barCount - 1 : current - 1;

		int prevPrev = current - 2 >= 0 ? current - 2 : (current - 2 == -1 ? barCount - 1 : barCount - 2) ;

		for ( int i = 0; i < barCount; i++ ){

			double degrees = (i * 360d / barCount);

			g.setTransform(at);

			g.translate(center - innerRadius, center);

			g.rotate(Math.toRadians(degrees));

			//cryptic syntax below for brevity

			int opacity = i == current ? 255 : (i == prev ? 175 : (i == prevPrev ? 125 : 50));

			g.setColor(new Color(0,0,0,opacity));

			g.fillRoundRect(2*innerRadius,-barHeight/2, width / 2 - padding, barHeight, 10, 10);

		}

	}

	

	public static void main(String[] args) throws Exception{

		SwingUtilities.invokeAndWait(new Runnable(){

			@Override

			public void run() {

				Progress p = new Progress();

				JFrame frame = new JFrame();

				p.setPreferredSize(new Dimension(200,200));

				frame.add(p);

				frame.pack();

				frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

				frame.setVisible(true);

			}

			

		});

	}

}