Sindbad~EG File Manager

/**
 * This class represents a Line displayed by Diagrammer.
 * This class is inherited by: Segment, Ray
 * File: Line.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 Line extends GeometricObject {

	/**
	 * A constructor of Line
	 *
	 */
	public Line()
	{
		// calls the constructor of Geometric Object
		super();
	}

	/**
	 * A constructor of Line
	 *
	 * @param A one Point that lies on the Line
	 * @param B another Point that lies on the Line
	 */
	public Line(Point A, Point B)
	{
		this();
        Arguments.add(A);
        Arguments.add(B);
	}

	/**
	 * Draws a Line 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)
		{
			// gets the bounding box g
			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 Line is horizontal
			if(b.y == a.y)
			{
				g.drawLine(0,
						   (int)b.y,
						   (int)rect.width,
						   (int)b.y);
			}
			// If the Line is vertical
			else if(b.x == a.x)
			{
				g.drawLine((int)b.x,
						   0,
						   (int)b.x,
						   (int)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(),
				      p2 = new Point();

				// Calculates p1, the location of where the Line intersects the left side of the bounding box
				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;
				}

				// y = mx + b
				y = slope * -1 * Math.min(a.x, b.x) + base;

				// Calculates p2, the location of where the Line intersects the right side of the bounding box
				if(y < 0)
				{
					p2.x = Math.min(a.x,
							        b.x) + (int)( (-1 * base) / slope);
					p2.y = 0;
				}
				else if(y > rect.height)
				{
					p2.x = Math.min(a.x,
							        b.x) + (int)( (rect.height - Math.max(a.y, b.y)) / slope);
					p2.y = rect.height;
				}
				else
				{
					p2.x = 0;
					p2.y = (int)y;
				}

				g.drawLine((int)p1.x,
						   (int)p1.y,
						   (int)p2.x,
						   (int)p2.y);
			}

			// Draws the Label for this Line 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,
		           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);
			else
				return(true);
		}
		// otherwise, return false
		else return false;
	}
}