1 /*
2 * Copyright (c) 1997, 2003, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.awt.geom;
27
28 import java.util.*;
29
30 /**
31 * A utility class to iterate over the path segments of an ellipse
32 * through the PathIterator interface.
33 *
34 * @author Jim Graham
35 */
36 class EllipseIterator implements PathIterator {
37 double x, y, w, h;
38 AffineTransform affine;
39 int index;
40
41 EllipseIterator(Ellipse2D e, AffineTransform at) {
42 this.x = e.getX();
43 this.y = e.getY();
44 this.w = e.getWidth();
45 this.h = e.getHeight();
46 this.affine = at;
47 if (w < 0 || h < 0) {
48 index = 6;
49 }
50 }
51
52 /**
53 * Return the winding rule for determining the insideness of the
54 * path.
55 * @see #WIND_EVEN_ODD
56 * @see #WIND_NON_ZERO
57 */
58 public int getWindingRule() {
59 return WIND_NON_ZERO;
60 }
61
62 /**
63 * Tests if there are more points to read.
64 * @return true if there are more points to read
65 */
66 public boolean isDone() {
67 return index > 5;
68 }
69
70 /**
71 * Moves the iterator to the next segment of the path forwards
72 * along the primary direction of traversal as long as there are
73 * more points in that direction.
74 */
75 public void next() {
76 index++;
77 }
78
79 // ArcIterator.btan(Math.PI/2)
80 public static final double CtrlVal = 0.5522847498307933;
81
82 /*
83 * ctrlpts contains the control points for a set of 4 cubic
84 * bezier curves that approximate a circle of radius 0.5
85 * centered at 0.5, 0.5
86 */
87 private static final double pcv = 0.5 + CtrlVal * 0.5;
88 private static final double ncv = 0.5 - CtrlVal * 0.5;
89 private static double ctrlpts[][] = {
90 { 1.0, pcv, pcv, 1.0, 0.5, 1.0 },
91 { ncv, 1.0, 0.0, pcv, 0.0, 0.5 },
92 { 0.0, ncv, ncv, 0.0, 0.5, 0.0 },
93 { pcv, 0.0, 1.0, ncv, 1.0, 0.5 }
94 };
95
96 /**
97 * Returns the coordinates and type of the current path segment in
98 * the iteration.
99 * The return value is the path segment type:
100 * SEG_MOVETO, SEG_LINETO, SEG_QUADTO, SEG_CUBICTO, or SEG_CLOSE.
101 * A float array of length 6 must be passed in and may be used to
102 * store the coordinates of the point(s).
103 * Each point is stored as a pair of float x,y coordinates.
104 * SEG_MOVETO and SEG_LINETO types will return one point,
105 * SEG_QUADTO will return two points,
106 * SEG_CUBICTO will return 3 points
107 * and SEG_CLOSE will not return any points.
108 * @see #SEG_MOVETO
109 * @see #SEG_LINETO
110 * @see #SEG_QUADTO
111 * @see #SEG_CUBICTO
112 * @see #SEG_CLOSE
113 */
114 public int currentSegment(float[] coords) {
115 if (isDone()) {
116 throw new NoSuchElementException("ellipse iterator out of bounds");
117 }
118 if (index == 5) {
119 return SEG_CLOSE;
120 }
121 if (index == 0) {
122 double ctrls[] = ctrlpts[3];
123 coords[0] = (float) (x + ctrls[4] * w);
124 coords[1] = (float) (y + ctrls[5] * h);
125 if (affine != null) {
126 affine.transform(coords, 0, coords, 0, 1);
127 }
128 return SEG_MOVETO;
129 }
130 double ctrls[] = ctrlpts[index - 1];
131 coords[0] = (float) (x + ctrls[0] * w);
132 coords[1] = (float) (y + ctrls[1] * h);
133 coords[2] = (float) (x + ctrls[2] * w);
134 coords[3] = (float) (y + ctrls[3] * h);
135 coords[4] = (float) (x + ctrls[4] * w);
136 coords[5] = (float) (y + ctrls[5] * h);
137 if (affine != null) {
138 affine.transform(coords, 0, coords, 0, 3);
139 }
140 return SEG_CUBICTO;
141 }
142
143 /**
144 * Returns the coordinates and type of the current path segment in
145 * the iteration.
146 * The return value is the path segment type:
147 * SEG_MOVETO, SEG_LINETO, SEG_QUADTO, SEG_CUBICTO, or SEG_CLOSE.
148 * A double array of length 6 must be passed in and may be used to
149 * store the coordinates of the point(s).
150 * Each point is stored as a pair of double x,y coordinates.
151 * SEG_MOVETO and SEG_LINETO types will return one point,
152 * SEG_QUADTO will return two points,
153 * SEG_CUBICTO will return 3 points
154 * and SEG_CLOSE will not return any points.
155 * @see #SEG_MOVETO
156 * @see #SEG_LINETO
157 * @see #SEG_QUADTO
158 * @see #SEG_CUBICTO
159 * @see #SEG_CLOSE
160 */
161 public int currentSegment(double[] coords) {
162 if (isDone()) {
163 throw new NoSuchElementException("ellipse iterator out of bounds");
164 }
165 if (index == 5) {
166 return SEG_CLOSE;
167 }
168 if (index == 0) {
169 double ctrls[] = ctrlpts[3];
170 coords[0] = x + ctrls[4] * w;
171 coords[1] = y + ctrls[5] * h;
172 if (affine != null) {
173 affine.transform(coords, 0, coords, 0, 1);
174 }
175 return SEG_MOVETO;
176 }
177 double ctrls[] = ctrlpts[index - 1];
178 coords[0] = x + ctrls[0] * w;
179 coords[1] = y + ctrls[1] * h;
180 coords[2] = x + ctrls[2] * w;
181 coords[3] = y + ctrls[3] * h;
182 coords[4] = x + ctrls[4] * w;
183 coords[5] = y + ctrls[5] * h;
184 if (affine != null) {
185 affine.transform(coords, 0, coords, 0, 3);
186 }
187 return SEG_CUBICTO;
188 }
189 }