001 /*
002 * Copyright 1997-2003 Sun Microsystems, Inc. All Rights Reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation. Sun designates this
008 * particular file as subject to the "Classpath" exception as provided
009 * by Sun in the LICENSE file that accompanied this code.
010 *
011 * This code is distributed in the hope that it will be useful, but WITHOUT
012 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
013 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
014 * version 2 for more details (a copy is included in the LICENSE file that
015 * accompanied this code).
016 *
017 * You should have received a copy of the GNU General Public License version
018 * 2 along with this work; if not, write to the Free Software Foundation,
019 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
020 *
021 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
022 * CA 95054 USA or visit www.sun.com if you need additional information or
023 * have any questions.
024 */
025
026 package java.awt.geom;
027
028 import java.util.*;
029
030 /**
031 * A utility class to iterate over the path segments of an ellipse
032 * through the PathIterator interface.
033 *
034 * @version 10 Feb 1997
035 * @author Jim Graham
036 */
037 class EllipseIterator implements PathIterator {
038 double x, y, w, h;
039 AffineTransform affine;
040 int index;
041
042 EllipseIterator(Ellipse2D e, AffineTransform at) {
043 this .x = e.getX();
044 this .y = e.getY();
045 this .w = e.getWidth();
046 this .h = e.getHeight();
047 this .affine = at;
048 if (w < 0 || h < 0) {
049 index = 6;
050 }
051 }
052
053 /**
054 * Return the winding rule for determining the insideness of the
055 * path.
056 * @see #WIND_EVEN_ODD
057 * @see #WIND_NON_ZERO
058 */
059 public int getWindingRule() {
060 return WIND_NON_ZERO;
061 }
062
063 /**
064 * Tests if there are more points to read.
065 * @return true if there are more points to read
066 */
067 public boolean isDone() {
068 return index > 5;
069 }
070
071 /**
072 * Moves the iterator to the next segment of the path forwards
073 * along the primary direction of traversal as long as there are
074 * more points in that direction.
075 */
076 public void next() {
077 index++;
078 }
079
080 // ArcIterator.btan(Math.PI/2)
081 public static final double CtrlVal = 0.5522847498307933;
082
083 /*
084 * ctrlpts contains the control points for a set of 4 cubic
085 * bezier curves that approximate a circle of radius 0.5
086 * centered at 0.5, 0.5
087 */
088 private static final double pcv = 0.5 + CtrlVal * 0.5;
089 private static final double ncv = 0.5 - CtrlVal * 0.5;
090 private static double ctrlpts[][] = {
091 { 1.0, pcv, pcv, 1.0, 0.5, 1.0 },
092 { ncv, 1.0, 0.0, pcv, 0.0, 0.5 },
093 { 0.0, ncv, ncv, 0.0, 0.5, 0.0 },
094 { pcv, 0.0, 1.0, ncv, 1.0, 0.5 } };
095
096 /**
097 * Returns the coordinates and type of the current path segment in
098 * the iteration.
099 * 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(
117 "ellipse iterator out of bounds");
118 }
119 if (index == 5) {
120 return SEG_CLOSE;
121 }
122 if (index == 0) {
123 double ctrls[] = ctrlpts[3];
124 coords[0] = (float) (x + ctrls[4] * w);
125 coords[1] = (float) (y + ctrls[5] * h);
126 if (affine != null) {
127 affine.transform(coords, 0, coords, 0, 1);
128 }
129 return SEG_MOVETO;
130 }
131 double ctrls[] = ctrlpts[index - 1];
132 coords[0] = (float) (x + ctrls[0] * w);
133 coords[1] = (float) (y + ctrls[1] * h);
134 coords[2] = (float) (x + ctrls[2] * w);
135 coords[3] = (float) (y + ctrls[3] * h);
136 coords[4] = (float) (x + ctrls[4] * w);
137 coords[5] = (float) (y + ctrls[5] * h);
138 if (affine != null) {
139 affine.transform(coords, 0, coords, 0, 3);
140 }
141 return SEG_CUBICTO;
142 }
143
144 /**
145 * Returns the coordinates and type of the current path segment in
146 * the iteration.
147 * The return value is the path segment type:
148 * SEG_MOVETO, SEG_LINETO, SEG_QUADTO, SEG_CUBICTO, or SEG_CLOSE.
149 * A double array of length 6 must be passed in and may be used to
150 * store the coordinates of the point(s).
151 * Each point is stored as a pair of double x,y coordinates.
152 * SEG_MOVETO and SEG_LINETO types will return one point,
153 * SEG_QUADTO will return two points,
154 * SEG_CUBICTO will return 3 points
155 * and SEG_CLOSE will not return any points.
156 * @see #SEG_MOVETO
157 * @see #SEG_LINETO
158 * @see #SEG_QUADTO
159 * @see #SEG_CUBICTO
160 * @see #SEG_CLOSE
161 */
162 public int currentSegment(double[] coords) {
163 if (isDone()) {
164 throw new NoSuchElementException(
165 "ellipse iterator out of bounds");
166 }
167 if (index == 5) {
168 return SEG_CLOSE;
169 }
170 if (index == 0) {
171 double ctrls[] = ctrlpts[3];
172 coords[0] = x + ctrls[4] * w;
173 coords[1] = y + ctrls[5] * h;
174 if (affine != null) {
175 affine.transform(coords, 0, coords, 0, 1);
176 }
177 return SEG_MOVETO;
178 }
179 double ctrls[] = ctrlpts[index - 1];
180 coords[0] = x + ctrls[0] * w;
181 coords[1] = y + ctrls[1] * h;
182 coords[2] = x + ctrls[2] * w;
183 coords[3] = y + ctrls[3] * h;
184 coords[4] = x + ctrls[4] * w;
185 coords[5] = y + ctrls[5] * h;
186 if (affine != null) {
187 affine.transform(coords, 0, coords, 0, 3);
188 }
189 return SEG_CUBICTO;
190 }
191 }
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