Sindbad~EG File Manager

/**
 * This class represents a Ray displayed by Diagrammer.
 * File: Segment.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.*;
import java.awt.geom.Point2D;

public class Segment extends Line {

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

	/**
	 * A constructor for Segment.
	 *
	 * @param A one end Point of the Segment
	 * @param B another end Point of Segment
	 */
	public Segment(Point A, Point B)
	{
		// calls a constructor of Line
		super(A,B);
	}

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

		// Checks if the Arguments are valid to draw a Segment
		//  draws if this Segment is visible
		if(this.visible &&
		   this.Arguments.size() == 2 &&
		   (a = (Point)Arguments.get(0)) instanceof Point &&
		   (b = (Point)Arguments.get(1)) instanceof Point)
		{
			// 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.BLACK);
			}

			g.drawLine((int)a.x,
					   (int)a.y,
					   (int)b.x,
					   (int)b.y);

			// draws the Label for this Segment if it is set 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 && mu1 < 1) || (mu2 > 0 && mu2 < 1);
		}
		// otherwise, return false
		else return false;
	}
}