SolarSystem.java

import javax.swing.*;
import java.awt.*;
import java.awt.image.*;
import java.awt.event.*;
import java.util.*;

/**
 * This class provides a graphical user interface to a model of the solar system
 * @author Joe Finney
 */
public class SolarSystem extends JFrame 
{
	private int width = 300;
	private int height = 300;
	private boolean exiting = false;

	private ArrayList<SolarObject> things = new ArrayList<SolarObject>();

	/**
	 * Create a view of the Solar System.
	 * Once an instance of the SolarSystem class is created,
	 * a window of the appropriate size is displayed, and
	 * objects can be displayed in the solar system
	 *
	 * @param width the width of the window in pixels.
	 * @param height the height of the window in pixels.
	 */
	public SolarSystem(int width, int height)
	{
		this.width = width;
		this.height = height;

		this.setTitle("The Solar System");
		this.setSize(width, height);
		this.setBackground(Color.BLACK);
		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		this.setVisible(true);		
	}

	/**
	 * A method called by the operating system to draw onto the screen - <p><B>YOU DO NOT (AND SHOULD NOT) NEED TO CALL THIS METHOD.</b></p>
	 */
	public void paint (Graphics gr)
	{
		BufferedImage i = new BufferedImage(this.getWidth(), this.getHeight(), BufferedImage.TYPE_INT_ARGB);
		Graphics2D g = i.createGraphics();
		
		//g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

		synchronized (this)
		{
			if (!this.exiting)
			{
				g.clearRect(0,0,width,height);
				for(SolarObject t : things)
				{
					g.setColor(t.col);
					g.fillOval(t.x, t.y, t.diameter, t.diameter);

					//try{ Thread.sleep(0); } catch (Exception e) {} 
				}
			}
			
			gr.drawImage(i, 0, 0, this);
		}
	}

	//
	// Shouldn't really handle colour this way, but the student's haven't been introduced
	// to constants properly yet, and Color.getColor() doesn't seem to work... hmmm....
	// 
	private Color getColourFromString(String col)
	{
		Color color;
		
		if (col.charAt(0) == '#')
		{
			color = new Color(
    	        Integer.valueOf( col.substring( 1, 3 ), 16 ),
        	    Integer.valueOf( col.substring( 3, 5 ), 16 ),
            	Integer.valueOf( col.substring( 5, 7 ), 16 ) );
		} 
		else 
		{
			try 
			{
				java.lang.reflect.Field field = Color.class.getField(col);
				color = (Color)field.get(null);
			} catch (Exception e) {
				color = Color.WHITE;
			}
		}
		return color;
	}
	
	/**
	 * Draws a round shape in the window at the given co-ordinates that represents an object in the solar system.
	 * The SolarSystem class uses <i>Polar Co-ordinates</i> to represent the location
	 * of objects in the solar system.
	 *
	 * @param distance the distance from the sun to the object.
	 * @param angle the angle (in degrees) that represents how far the planet is around its orbit of the sun.
	 * @param diameter the size of the object.
	 * @param col the colour of this object, as a string. Case insentive. <p>One of: BLACK, BLUE, CYAN, DARK_GRAY, GRAY, GREEN, LIGHT_GRAY, 
	 * MAGENTA, ORANGE, PINK, RED, WHITE, YELLOW. Alternatively, a 24 bit hexadecimal string representation of an RGB colour is also accepted, e.g. "#FF0000"</p>
	 */
	public void drawSolarObject(double distance, double angle, double diameter, String col)
	{
		Color colour = this.getColourFromString(col);
		double centreOfRotationX = ((double) width) / 2.0; 
		double centreOfRotationY = ((double) height) / 2.0; 

		double rads = Math.toRadians(angle);
		double x = (int) (centreOfRotationX + distance * Math.sin(rads)) - diameter / 2;
		double y = (int) (centreOfRotationY + distance * Math.cos(rads)) - diameter / 2;

		synchronized (this)
		{
			if (things.size() > 1000)
			{
				System.out.println("\n\n");
				System.out.println(" ********************************************************* ");
				System.out.println(" ***** Only 1000 Entities Supported per Solar System ***** ");
				System.out.println(" ********************************************************* ");
				System.out.println("\n\n");
				System.out.println("If you are't trying to add this many things");
				System.out.println("to your SolarSystem, then you have probably");
				System.out.println("forgotten to call the finishedDrawing() method");
				System.out.println("See the JavaDOC documentation for more information");
				System.out.println("\n-- Joe");
				System.out.println("\n\n");

				this.dispatchEvent(new WindowEvent(this, WindowEvent.WINDOW_CLOSING));
			}
			else
			{
				SolarObject t = new SolarObject((int)x, (int)y, (int)diameter, colour);
				things.add(t);
			}
		}
	}

	/**
	 * Draws a round shape in the window at the given co-ordinates. 
	 * The SolarSystem class uses <i>Polar Co-ordinates</i> to represent the location
	 * of objects in the solar system. This method operates in the same fashion as drawSolarObject, but
	 * provides additional co-ordinates to allow the programmer to use an arbitrary point about which
	 * the object orbits (e.g. a planet rather than the sun).
	 *
	 * @param distance the distance from this object to the point about which it is orbiting.
	 * @param angle the angle (in degrees) that represents how far the object is around its orbit.
	 * @param diameter the size of the object.
	 * @param col the colour of this object, as a string. Case insentive. <p>One of: BLACK, BLUE, CYAN, DARK_GRAY, GRAY, GREEN, LIGHT_GRAY, 
	 * MAGENTA, ORANGE, PINK, RED, WHITE, YELLOW</p>
	 * @param centreOfRotationDistance the distance part of the polar co-ordinate about which this object orbits.
	 * @param centreOfRotationAngle the angular part of the polar co-ordinate about which this object orbits.
	 */
	public void drawSolarObjectAbout(double distance, double angle, double diameter, String col, double centreOfRotationDistance, double centreOfRotationAngle)
	{
		Color colour = this.getColourFromString(col);
		double centrerads = Math.toRadians(centreOfRotationAngle);
		double centreOfRotationX = (((double) width) / 2.0) + centreOfRotationDistance * Math.sin(centrerads); 
		double centreOfRotationY = (((double) height) / 2.0) + centreOfRotationDistance * Math.cos(centrerads); 

		double rads = Math.toRadians(angle);
		double x = (int) (centreOfRotationX + distance * Math.sin(rads)) - diameter / 2;
		double y = (int) (centreOfRotationY + distance * Math.cos(rads)) - diameter / 2;

		synchronized (this)
		{
			if (things.size() > 1000)
			{
				System.out.println("\n\n");
				System.out.println(" ********************************************************* ");
				System.out.println(" ***** Only 1000 Entities Supported per Solar System ***** ");
				System.out.println(" ********************************************************* ");
				System.out.println("\n\n");
				System.out.println("If you are't trying to add this many things");
				System.out.println("to your SolarSystem, then you have probably");
				System.out.println("forgotten to call the finishedDrawing() method");
				System.out.println("See the JavaDOC documentation for more information");
				System.out.println("\n-- Joe");
				System.out.println("\n\n");

				this.dispatchEvent(new WindowEvent(this, WindowEvent.WINDOW_CLOSING));
			}
			else
			{
				SolarObject t = new SolarObject((int)x, (int)y, (int)diameter, colour);
				things.add(t);
			}
		}
	}

	/**
	 * Makes all objects drawn recently drawn to be made visible on the screen.
	 *  
	 * Once called, all suns, planets and moons are displayed in the window.
	 */
	public void finishedDrawing()
	{
		try
		{
			this.repaint();
			Thread.sleep(10);
			synchronized (this)
			{
				things.clear();
			}
		}
		catch (Exception e) { }
	}
	
	private class SolarObject 
	{
		public int x;
		public int y;
		public int diameter;
		public Color col;

		public SolarObject(int x, int y, int diameter, Color col)
		{
			this.x = x;
			this.y = y;
			this.diameter = diameter;
			this.col = col;
		}
	}
}