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/Users/lyon/j4p/src/ip/transforms/GeometryUtils.java
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1 /*
2 * Created by IntelliJ IDEA.
3 * User: lyon
4 * Date: Feb 15, 2003
5 * Time: 1:25:41 PM
6 * To change template for new class use
7 * Code Style | Class Templates options (Tools | IDE Options).
8 */
9 package ip.transforms;
10
11 import java.awt.*;
12
13 public class GeometryUtils {
14 private static void nextPointTest() {
15 System.out.println(
16 "input line:(0,10)->(100,100)" +
17 " next point is:" + getNextPointOnLine(
18 new Point(0, 10), new Point(100, 100))
19 );
20 }
21
22 public static void getNextDirectionTest() {
23 System.out.println(
24 "The points 1,1 and 23,23 have the next direction of:"
25 + getNextDirection(new Point(1, 1), new Point(23, 23))
26 );
27 }
28
29 /**
30 * getNextDirection returns an integer ranging from -1 to 8.
31 * -1 means it does not know the direction
32 * Here are the 8 directions
33 * 6 7 8
34 * 5 1
35 * 4 3 2
36 */
37 public static int getNextDirection(Point startPoint, Point endPoint) {
38 Point p2 = getNextPointOnLine(startPoint, endPoint);
39 int x1 = startPoint.x;
40 int y1 = startPoint.y;
41 int x2 = p2.x;
42 int y2 = p2.y;
43 int dx = x2 - x1;
44 int dy = y2 - y1;
45 if (dx > 0 && dy < 0) return 2;
46 if (dx == 0 && dy < 0) return 3;
47 if (dx < 0 && dy < 0) return 4;
48 if (dx < 0 && dy == 0) return 5;
49 if (dx < 0 && dy > 0) return 6;
50 if (dx == 0 && dy > 0) return 7;
51 if (dx > 0 && dy > 0) return 8;
52 if (dx > 0 && dy == 0) return 1;
53 return -1;
54 }
55
56 /**
57 * grabs a few points in the general direction
58 */
59 public static Points getNextPoints(Point p1, Point p2) {
60 Point p0 = getNextPointOnLine(p1, p2);
61 Points p = new Points();
62
63 int dx = p0.x - p1.x;
64 int dy = p0.y - p1.y;
65 /**
66 * 00,01,10,11
67 */
68
69 p.addPoint(p0);
70 p.addPoint(new Point(p0.x + dx, p0.y));
71 p.addPoint(new Point(p0.x, p0.y + dy));
72 p.addPoint(new Point(p0.x + dx, p0.y + dy));
73 return p;
74
75 }
76
77 /**
78 * Use Bresenham's algorithm to get the next point on a line.
79 */
80
81 public static Point getNextPointOnLine(Point p1, Point p2) {
82 int x1 = p1.x;
83 int y1 = p1.y;
84 int x2 = p2.x;
85 int y2 = p2.y;
86 int x = x1;
87 int y = y1;
88 int d = 0;
89 int dx = x2 - x1;
90 int dy = y2 - y1;
91 int c, m;
92 int xInc = 1;
93 int yInc = 1;
94
95 if (dx < 0) {
96 xInc = -1;
97 dx = -dx;
98 }
99
100 if (dy < 0) {
101 yInc = -1;
102 dy = -dy;
103 }
104
105 if (dy <= dx) {
106 c = 2 * dx;
107 m = 2 * dy;
108
109 x += xInc;
110
111 d += m;
112
113 if (d > dx) {
114 y += yInc;
115 d -= c;
116 }
117 return new Point(x, y);
118 }
119
120 c = 2 * dy;
121 m = 2 * dx;
122 y += yInc;
123
124 d += m;
125
126 if (d > dy) {
127 x += xInc;
128 d -= c;
129 }
130 return new Point(x, y);
131
132 }
133
134 static void drawLine(Graphics g, int x1, int y1, int x2, int y2) {
135 int x = x1;
136 int y = y1;
137 int d = 0;
138 int hx = x2 - x1;
139 int hy = y2 - y1;
140 int c, M;
141 int xInc = 1;
142 int yInc = 1;
143
144 if (hx < 0) {
145 xInc = -1;
146 hx = -hx;
147 }
148
149 if (hy < 0) {
150 yInc = -1;
151 hy = -hy;
152 }
153
154 if (hy <= hx) {
155 c = 2 * hx;
156 M = 2 * hy;
157
158 for (; ;) {
159 ConvolutionUtils.drawPel(g, x, y);
160
161 if (x == x2) break;
162
163 x += xInc;
164
165 d += M;
166
167 if (d > hx) {
168 y += yInc;
169 d -= c;
170 }
171
172 }
173
174 } else {
175 c = 2 * hy;
176 M = 2 * hx;
177
178 for (; ;) {
179 ConvolutionUtils.drawPel(g, x, y);
180
181 if (y == y2) break;
182
183 y += yInc;
184
185 d += M;
186
187 if (d > hy) {
188 x += xInc;
189 d -= c;
190 }
191 }
192 }
193 }
194 }
195