View Javadoc

1   /*
2   * The contents of this file are subject to the BT "ZEUS" Open Source 
3   * Licence (L77741), Version 1.0 (the "Licence"); you may not use this file 
4   * except in compliance with the Licence. You may obtain a copy of the Licence
5   * from $ZEUS_INSTALL/licence.html or alternatively from
6   * http://www.labs.bt.com/projects/agents/zeus/licence.htm
7   * 
8   * Except as stated in Clause 7 of the Licence, software distributed under the
9   * Licence is distributed WITHOUT WARRANTY OF ANY KIND, either express or 
10  * implied. See the Licence for the specific language governing rights and 
11  * limitations under the Licence.
12  * 
13  * The Original Code is within the package zeus.*.
14  * The Initial Developer of the Original Code is British Telecommunications
15  * public limited company, whose registered office is at 81 Newgate Street, 
16  * London, EC1A 7AJ, England. Portions created by British Telecommunications 
17  * public limited company are Copyright 1996-9. All Rights Reserved.
18  * 
19  * THIS NOTICE MUST BE INCLUDED ON ANY COPY OF THIS FILE
20  */
21  
22  
23  
24  package zeus.util;
25  
26  import java.util.*;
27  import java.awt.*;
28  
29  public class ArrowData {
30  
31  public static final double ARROW_ANGLE    = Math.PI/12.0;
32  public static final double ARROW_RATIO    = 0.1;
33  public static final double ARROW_LMIN     = 7;
34  public static final double ARROW_LMAX     = 14;
35  public static final double ARROW_LENGTH   = 10;
36  public static final double MTOL      	  = 1.0E-12;
37  
38  public static Point[] getPoints( double x1, double y1, double x2, double y2 ) {
39  
40       double L, A, B;
41       Point[] xpoints = new Point[4];
42       for( int i = 0; i < 4; i++ )
43          xpoints[i] = new Point(0,0);
44  
45       // L = Math.sqrt( Math.pow(y2-y1,2.0)+Math.pow(x2-x1,2.0) );
46       // L *= ARROW_RATIO;
47  
48       // if ( L < ARROW_LMAX || L > ARROW_LMIN ) L = ARROW_LENGTH;
49       L = ARROW_LENGTH;
50  
51       B = GetAngle(x1,y1,x2,y2);
52       A = B-ARROW_ANGLE;
53  
54       xpoints[0].x = (int) (x2-L*Math.cos(A));
55       xpoints[0].y = (int) (y2-L*Math.sin(A));
56  
57       xpoints[1].x = (int) x2;
58       xpoints[1].y = (int) y2;
59  
60       A = B+ARROW_ANGLE;
61  
62       xpoints[2].x = (int) (x2-L*Math.cos(A));
63       xpoints[2].y = (int) (y2-L*Math.sin(A));
64  
65       xpoints[3].x = xpoints[0].x;
66       xpoints[3].y = xpoints[0].y;
67  
68       return xpoints;
69  }
70  
71  public static double GetAngle( double x1, double y1, double x2, double y2 ) {
72         double B, x, y;
73  
74         x = x2 - x1;
75         y = y2 - y1;
76  
77         if ( Math.abs(x) < MTOL && Math.abs(y) < MTOL ) return( 0.0 );
78  
79         B = Math.atan(y/x);
80  
81              if ( x >= 0.0  && y >= 0.0 ) B += 0.0;
82         else if ( x <  0.0  && y >= 0.0 ) B += Math.PI;
83         else if ( x <  0.0  && y <  0.0 ) B += Math.PI;
84         else if ( x >= 0.0  && y <  0.0 ) B += 2.0*Math.PI;
85  
86         return( B );
87  }
88  
89  }
90