Mercurial > dive4elements > gnv-client

comparison gnv-artifacts/src/main/java/de/intevation/gnv/utils/IndexBuffer.java @ 1119:7c4f81f74c47

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
merged gnv-artifacts
author Thomas Arendsen Hein <thomas@intevation.de>
date Fri, 28 Sep 2012 12:14:00 +0200
parents f953c9a559d8
children
comparison
equal deleted inserted replaced
1027:fca4b5eb8d2f 1119:7c4f81f74c47
1 /*
2 * Copyright (c) 2010 by Intevation GmbH
3 *
4 * This program is free software under the LGPL (>=v2.1)
5 * Read the file LGPL.txt coming with the software for details
6 * or visit http://www.gnu.org/licenses/ if it does not exist.
7 */
8
9 package de.intevation.gnv.utils;
10
11 import java.awt.Point;
12
13 import java.awt.geom.Point2D;
14
15 import java.util.List;
16
17 /**
18 * Create buffers around integer pairs (i_1..n), j_1..n).
19 *
20 * @author <a href="mailto:sascha.teichmann@intevation.de">Sascha L. Teichmann</a>
21 */
22 public class IndexBuffer
23 {
24 public static final double EPSILON = 1e-6d;
25 public static final double OFFSET = 1.0d;
26
27 public static final String I_COLUMN = "IPOSITION";
28 public static final String J_COLUMN = "JPOSITION";
29
30 public static final class Segment {
31
32 private Segment next;
33
34 private Point2D.Double n;
35 private double d1;
36 private double d2;
37
38 private int iMin;
39 private int iMax;
40
41 private int jMin;
42 private int jMax;
43
44 public Segment(Point a, Point b, Segment next) {
45
46 this.next = next;
47
48 iMin = Math.min(a.x, b.x)-1;
49 iMax = Math.max(a.x, b.x)+1;
50
51 jMin = Math.min(a.y, b.y)-1;
52 jMax = Math.max(a.y, b.y)+1;
53
54 if (a.x > b.x) {
55 Point p = a; a = b; b = p;
56 }
57
58 Point2D.Double p1, p2, p3;
59
60 if (a.y < b.y) {
61 p1 = new Point2D.Double(a.x - OFFSET, a.y + 1 + OFFSET);
62 p2 = new Point2D.Double(b.x - OFFSET, b.y + 1 + OFFSET);
63 p3 = new Point2D.Double(a.x + 1 + OFFSET, a.y - OFFSET);
64 }
65 else {
66 p1 = new Point2D.Double(a.x + 1 + OFFSET, a.y + 1 + OFFSET);
67 p2 = new Point2D.Double(b.x + 1 + OFFSET, b.y + 1 + OFFSET);
68 p3 = new Point2D.Double(b.x - OFFSET, b.y - OFFSET);
69 }
70
71 n = normalize(orthogonal(sub(p1, p2)));
72
73 d1 = dot(n, p1);
74 d2 = dot(n, p3);
75
76 if (d1 > d2) {
77 double d = d1;
78 d1 = d2;
79 d2 = d;
80 }
81 }
82
83 public boolean check(int i, int j) {
84 if (i < iMin || i > iMax || j < jMin || j > jMax) {
85 return false;
86 }
87 double v = dot(n, i, j);
88 return v >= d1 && v <= d2;
89 }
90
91 public void toWhereClause(StringBuilder sb, String iColumn, String jColumn) {
92 sb.append('(')
93 .append(iColumn).append(" >= ").append(iMin).append(" AND ")
94 .append(iColumn).append(" <= ").append(iMax).append(" AND ")
95 .append(jColumn).append(" >= ").append(jMin).append(" AND ")
96 .append(jColumn).append(" <= ").append(jMax).append(" AND (")
97 .append(n.x).append('*').append(iColumn).append(" + ")
98 .append(n.y).append('*').append(jColumn)
99 .append(") BETWEEN ").append(d1).append(" AND ").append(d2).append(')');
100 }
101 } // class Segment
102
103 protected Segment head;
104
105 protected String iColumn;
106 protected String jColumn;
107
108 public IndexBuffer(List<? extends Point> points) {
109 this(points, I_COLUMN, J_COLUMN);
110 }
111
112 public IndexBuffer(List<? extends Point> points, String iColumn, String jColumn) {
113 this.iColumn = iColumn;
114 this.jColumn = jColumn;
115
116 for (int i = 1, N = points.size(); i < N; ++i) {
117 Point p1 = (Point)points.get(i-1);
118 Point p2 = (Point)points.get(i);
119 head = new Segment(p1, p2, head);
120 }
121 }
122
123 public boolean check(int i, int j) {
124
125 Segment current = head;
126 while (current != null) {
127 if (current.check(i, j)) {
128 return true;
129 }
130 current = current.next;
131 }
132 return false;
133 }
134
135 public String toWhereClause() {
136
137 StringBuilder sb = new StringBuilder();
138
139 Segment current = head;
140
141 while (current != null) {
142 if (current != head) {
143 sb.append(" OR ");
144 }
145 current.toWhereClause(sb, iColumn, jColumn);
146 current = current.next;
147 }
148
149 return sb.toString();
150 }
151
152 public static Point2D.Double sub(Point2D.Double p1, Point2D.Double p2) {
153 return new Point2D.Double(p1.x - p2.x, p1.y - p2.y);
154 }
155
156 public static final double dot(Point2D.Double p1, Point2D.Double p2) {
157 return p1.x*p2.x + p1.y*p2.y;
158 }
159
160 public static final double dot(Point2D.Double p1, double x, double y) {
161 return p1.x*x + p1.y*y;
162 }
163
164 public static final Point2D.Double scale(Point2D.Double p, double s) {
165 return new Point2D.Double(s*p.x, s*p.y);
166 }
167
168 public static final Point2D.Double normalize(Point2D.Double p) {
169 double len2 = Math.sqrt(dot(p, p));
170 return len2 > EPSILON ? scale(p, 1d/len2) : p;
171 }
172
173 public static final Point2D.Double orthogonal(Point2D.Double p) {
174 return new Point2D.Double(p.y, -p.x);
175 }
176 }
177 // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :
http://dive4elements.wald.intevation.org