Sindbad~EG File Manager

/**
 * This class represents a Ray displayed by Diagrammer.
 * File: Ray.java
 *
 * This code is in the public domain.
 *
 * @author Brian Chan
 */
// 12.24.06  Beeson changed color to GREEN

package org.dynamicgeometry.diagrammer;

import java.awt.*;
import java.awt.font.FontRenderContext;
import java.awt.font.TextLayout;
import java.awt.geom.Point2D;

public class Ray extends Line {

	/**
	 * A constructor for Ray
	 *
	 */
	public Ray()
	{
		// calls a constructor of Line
		super();
	}

	/**
	 * A constructor for Ray
	 *
	 * @param A the end Point of the Ray
	 * @param B a point that lies on the Ray
	 */
	public Ray(Point A, Point B)
	{
        super(A,B);
	}

	/**
	 * Draws a Ray using the Graphics2D parameter.
	 *
	 * @param g the Object used to draw an Arc
	 */
	public void draw(Graphics2D g)
	{
		Point a,
		      b;

		// Checks if Arguments contains the proper values to draw a Line
		//  draw if visible
		if(this.visible &&
		   this.Arguments.size() == 2 &&
		   (a = (Point)Arguments.get(0)) instanceof Point &&
		   (b = (Point)Arguments.get(1)) instanceof Point)
		{
			Rectangle rect = g.getClipBounds();

			// if this Object is input
			if(this.isInput != 0)
			{
				// if this Object is selected and is input
				if(this.selected)
					g.setColor(Color.GREEN);

				// if this Object is not selected but is input
				else
					g.setColor(Color.BLUE);
			}

			// if this Object is not input
			else
			{
				// if this Object is selected and is input
				if(this.selected)
					g.setColor(Color.RED);

				// if this Object is not selected but is input
				else
					g.setColor(Color.GRAY);
			}

			// if the Ray is horizontal
			if(b.y == a.y)
			{
				g.drawLine((int)a.x,
						   (int)b.y,
						   (int)((a.x > b.x)?0:rect.width),
						   (int)b.y);
			}
			// if the Ray is vertical
			else if(b.x == a.x)
			{
				g.drawLine((int)a.x,
						   (int)a.y,
						   (int)b.x,
						   (int)((a.y > b.y)?0:rect.height));
			}
			else
			{
				double slope = (0.0 + b.y - a.y) / (0.0 + b.x - a.x);
				double base = (a.x < b.x)?a.y:b.y;
				double y = slope * (rect.width - Math.min(a.x, b.x)) + base;
				Point p1 = new Point();

				// calculates the Point p1 where the Ray intersects the bounding box
				if(b.x > a.x)
				{
					if(y < 0)
					{
						p1.x = Math.min(a.x, b.x) + (int)((-1 * base)/slope);
						p1.y = 0;
					}
					else if(y > rect.height)
					{
						p1.x = Math.max(a.x, b.x) + (int)((rect.height - Math.max(a.y, b.y))/slope);
						p1.y = rect.height;
					}
					else
					{
						p1.x = rect.width;
						p1.y = (int)y;
					}
				}
				else
				{
					y = slope * -1 * Math.min(a.x, b.x) + base;

					if(y < 0)
					{
						p1.x = Math.min(a.x, b.x) + (int)((-1 * base)/slope);
						p1.y = 0;
					}
					else if(y > rect.height)
					{
						p1.x = Math.min(a.x, b.x) +
						                (int)( (rect.height - Math.max(a.y, b.y) ) / slope);
						p1.y = rect.height;
					}
					else
					{
						p1.x = 0;
						p1.y = (int)y;
					}
				}

				g.drawLine((int)a.x, (int)a.y, (int)p1.x, (int)p1.y);
			}

			// Draws the Label for this Ray if it is initilized and visible
			if(this.label != null && this.label.getVisible())
			{
				FontRenderContext frc = g.getFontRenderContext();
				TextLayout layout = new TextLayout(this.label.toString(),
												   this.label.getFont(),
												   frc);
				this.label.setLocation(
						new Point2D.Double(
								(a.x + b.x) / 2 + EPSILON,
								(a.y + b.y) / 2 + EPSILON));
				layout.draw(g,
						    (float)this.label.getLocation().getX(),
						    (float)this.label.getLocation().getY() );
			}
		}
	}

	/**
	 * Determines if a mouse click is "close" enough to constitute a mouse
	 * click for this Object.
	 *
	 * Code used from:
	 * http://local.wasp.uwa.edu.au/~pbourke/geometry/sphereline/raysphere.c
	 *
	 * @param x the x coordinate of the mouse click
	 * @param y the y coordinate of this mouse click
	 * @return true if this Object was clicked, false if this Object was not clicked
	 */
	public boolean clickedOn(double x, double y)
	{
		Point p1,
              p2,
              sc,
              dp;

		// checks if there are valid Arguments for this Line and is visible
		if(this.visible &&
		   this.Arguments.size() == 2 &&
		   (p1 = (Point)Arguments.get(0)) instanceof Point &&
		   (p2 = (Point)Arguments.get(1)) instanceof Point)
		{
			sc = new Point(x, y);
			dp = new Point();

			double r = EPSILON,
		           a,
		           b,
		           c,
		           mu1,
		           mu2,
		           bb4ac;

		   dp.x = p2.x - p1.x;
		   dp.y = p2.y - p1.y;
		   a = dp.x * dp.x + dp.y * dp.y;
		   b = 2 * (dp.x * (p1.x - sc.x) + dp.y * (p1.y - sc.y));
		   c = sc.x * sc.x + sc.y * sc.y;
		   c += p1.x * p1.x + p1.y * p1.y;
		   c -= 2 * (sc.x * p1.x + sc.y * p1.y);
		   c -= r * r;
		   bb4ac = b * b - 4 * a * c;

		   if (bb4ac < 0)
		      return(false);

		   mu1 = (-b + Math.sqrt(bb4ac)) / (2 * a);
		   mu2 = (-b - Math.sqrt(bb4ac)) / (2 * a);

		   return (mu1 > 0 || mu2 > 0);
		}
		// otherwise, return false
		else return false;
	}
}