J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1997-2000 Sun Microsystems, Inc. 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. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | package java.awt.geom; |
| 27 | |
| 28 | /** |
| 29 | * The <code>PathIterator</code> interface provides the mechanism |
| 30 | * for objects that implement the {@link java.awt.Shape Shape} |
| 31 | * interface to return the geometry of their boundary by allowing |
| 32 | * a caller to retrieve the path of that boundary a segment at a |
| 33 | * time. This interface allows these objects to retrieve the path of |
| 34 | * their boundary a segment at a time by using 1st through 3rd order |
| 35 | * Bézier curves, which are lines and quadratic or cubic |
| 36 | * Bézier splines. |
| 37 | * <p> |
| 38 | * Multiple subpaths can be expressed by using a "MOVETO" segment to |
| 39 | * create a discontinuity in the geometry to move from the end of |
| 40 | * one subpath to the beginning of the next. |
| 41 | * <p> |
| 42 | * Each subpath can be closed manually by ending the last segment in |
| 43 | * the subpath on the same coordinate as the beginning "MOVETO" segment |
| 44 | * for that subpath or by using a "CLOSE" segment to append a line |
| 45 | * segment from the last point back to the first. |
| 46 | * Be aware that manually closing an outline as opposed to using a |
| 47 | * "CLOSE" segment to close the path might result in different line |
| 48 | * style decorations being used at the end points of the subpath. |
| 49 | * For example, the {@link java.awt.BasicStroke BasicStroke} object |
| 50 | * uses a line "JOIN" decoration to connect the first and last points |
| 51 | * if a "CLOSE" segment is encountered, whereas simply ending the path |
| 52 | * on the same coordinate as the beginning coordinate results in line |
| 53 | * "CAP" decorations being used at the ends. |
| 54 | * |
| 55 | * @see java.awt.Shape |
| 56 | * @see java.awt.BasicStroke |
| 57 | * |
| 58 | * @author Jim Graham |
| 59 | */ |
| 60 | public interface PathIterator { |
| 61 | /** |
| 62 | * The winding rule constant for specifying an even-odd rule |
| 63 | * for determining the interior of a path. |
| 64 | * The even-odd rule specifies that a point lies inside the |
| 65 | * path if a ray drawn in any direction from that point to |
| 66 | * infinity is crossed by path segments an odd number of times. |
| 67 | */ |
| 68 | public static final int WIND_EVEN_ODD = 0; |
| 69 | |
| 70 | /** |
| 71 | * The winding rule constant for specifying a non-zero rule |
| 72 | * for determining the interior of a path. |
| 73 | * The non-zero rule specifies that a point lies inside the |
| 74 | * path if a ray drawn in any direction from that point to |
| 75 | * infinity is crossed by path segments a different number |
| 76 | * of times in the counter-clockwise direction than the |
| 77 | * clockwise direction. |
| 78 | */ |
| 79 | public static final int WIND_NON_ZERO = 1; |
| 80 | |
| 81 | /** |
| 82 | * The segment type constant for a point that specifies the |
| 83 | * starting location for a new subpath. |
| 84 | */ |
| 85 | public static final int SEG_MOVETO = 0; |
| 86 | |
| 87 | /** |
| 88 | * The segment type constant for a point that specifies the |
| 89 | * end point of a line to be drawn from the most recently |
| 90 | * specified point. |
| 91 | */ |
| 92 | public static final int SEG_LINETO = 1; |
| 93 | |
| 94 | /** |
| 95 | * The segment type constant for the pair of points that specify |
| 96 | * a quadratic parametric curve to be drawn from the most recently |
| 97 | * specified point. |
| 98 | * The curve is interpolated by solving the parametric control |
| 99 | * equation in the range <code>(t=[0..1])</code> using |
| 100 | * the most recently specified (current) point (CP), |
| 101 | * the first control point (P1), |
| 102 | * and the final interpolated control point (P2). |
| 103 | * The parametric control equation for this curve is: |
| 104 | * <pre> |
| 105 | * P(t) = B(2,0)*CP + B(2,1)*P1 + B(2,2)*P2 |
| 106 | * 0 <= t <= 1 |
| 107 | * |
| 108 | * B(n,m) = mth coefficient of nth degree Bernstein polynomial |
| 109 | * = C(n,m) * t^(m) * (1 - t)^(n-m) |
| 110 | * C(n,m) = Combinations of n things, taken m at a time |
| 111 | * = n! / (m! * (n-m)!) |
| 112 | * </pre> |
| 113 | */ |
| 114 | public static final int SEG_QUADTO = 2; |
| 115 | |
| 116 | /** |
| 117 | * The segment type constant for the set of 3 points that specify |
| 118 | * a cubic parametric curve to be drawn from the most recently |
| 119 | * specified point. |
| 120 | * The curve is interpolated by solving the parametric control |
| 121 | * equation in the range <code>(t=[0..1])</code> using |
| 122 | * the most recently specified (current) point (CP), |
| 123 | * the first control point (P1), |
| 124 | * the second control point (P2), |
| 125 | * and the final interpolated control point (P3). |
| 126 | * The parametric control equation for this curve is: |
| 127 | * <pre> |
| 128 | * P(t) = B(3,0)*CP + B(3,1)*P1 + B(3,2)*P2 + B(3,3)*P3 |
| 129 | * 0 <= t <= 1 |
| 130 | * |
| 131 | * B(n,m) = mth coefficient of nth degree Bernstein polynomial |
| 132 | * = C(n,m) * t^(m) * (1 - t)^(n-m) |
| 133 | * C(n,m) = Combinations of n things, taken m at a time |
| 134 | * = n! / (m! * (n-m)!) |
| 135 | * </pre> |
| 136 | * This form of curve is commonly known as a Bézier curve. |
| 137 | */ |
| 138 | public static final int SEG_CUBICTO = 3; |
| 139 | |
| 140 | /** |
| 141 | * The segment type constant that specifies that |
| 142 | * the preceding subpath should be closed by appending a line segment |
| 143 | * back to the point corresponding to the most recent SEG_MOVETO. |
| 144 | */ |
| 145 | public static final int SEG_CLOSE = 4; |
| 146 | |
| 147 | /** |
| 148 | * Returns the winding rule for determining the interior of the |
| 149 | * path. |
| 150 | * @return the winding rule. |
| 151 | * @see #WIND_EVEN_ODD |
| 152 | * @see #WIND_NON_ZERO |
| 153 | */ |
| 154 | public int getWindingRule(); |
| 155 | |
| 156 | /** |
| 157 | * Tests if the iteration is complete. |
| 158 | * @return <code>true</code> if all the segments have |
| 159 | * been read; <code>false</code> otherwise. |
| 160 | */ |
| 161 | public boolean isDone(); |
| 162 | |
| 163 | /** |
| 164 | * Moves the iterator to the next segment of the path forwards |
| 165 | * along the primary direction of traversal as long as there are |
| 166 | * more points in that direction. |
| 167 | */ |
| 168 | public void next(); |
| 169 | |
| 170 | /** |
| 171 | * Returns the coordinates and type of the current path segment in |
| 172 | * the iteration. |
| 173 | * The return value is the path-segment type: |
| 174 | * SEG_MOVETO, SEG_LINETO, SEG_QUADTO, SEG_CUBICTO, or SEG_CLOSE. |
| 175 | * A float array of length 6 must be passed in and can be used to |
| 176 | * store the coordinates of the point(s). |
| 177 | * Each point is stored as a pair of float x,y coordinates. |
| 178 | * SEG_MOVETO and SEG_LINETO types returns one point, |
| 179 | * SEG_QUADTO returns two points, |
| 180 | * SEG_CUBICTO returns 3 points |
| 181 | * and SEG_CLOSE does not return any points. |
| 182 | * @param coords an array that holds the data returned from |
| 183 | * this method |
| 184 | * @return the path-segment type of the current path segment. |
| 185 | * @see #SEG_MOVETO |
| 186 | * @see #SEG_LINETO |
| 187 | * @see #SEG_QUADTO |
| 188 | * @see #SEG_CUBICTO |
| 189 | * @see #SEG_CLOSE |
| 190 | */ |
| 191 | public int currentSegment(float[] coords); |
| 192 | |
| 193 | /** |
| 194 | * Returns the coordinates and type of the current path segment in |
| 195 | * the iteration. |
| 196 | * The return value is the path-segment type: |
| 197 | * SEG_MOVETO, SEG_LINETO, SEG_QUADTO, SEG_CUBICTO, or SEG_CLOSE. |
| 198 | * A double array of length 6 must be passed in and can be used to |
| 199 | * store the coordinates of the point(s). |
| 200 | * Each point is stored as a pair of double x,y coordinates. |
| 201 | * SEG_MOVETO and SEG_LINETO types returns one point, |
| 202 | * SEG_QUADTO returns two points, |
| 203 | * SEG_CUBICTO returns 3 points |
| 204 | * and SEG_CLOSE does not return any points. |
| 205 | * @param coords an array that holds the data returned from |
| 206 | * this method |
| 207 | * @return the path-segment type of the current path segment. |
| 208 | * @see #SEG_MOVETO |
| 209 | * @see #SEG_LINETO |
| 210 | * @see #SEG_QUADTO |
| 211 | * @see #SEG_CUBICTO |
| 212 | * @see #SEG_CLOSE |
| 213 | */ |
| 214 | public int currentSegment(double[] coords); |
| 215 | } |