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1: /* CubicSegment.java -- Cubic segment used for BasicStroke 2: Copyright (C) 2006 Free Software Foundation, Inc. 3: 4: This file is part of GNU Classpath. 5: 6: GNU Classpath is free software; you can redistribute it and/or modify 7: it under the terms of the GNU General Public License as published by 8: the Free Software Foundation; either version 2, or (at your option) 9: any later version. 10: 11: GNU Classpath is distributed in the hope that it will be useful, but 12: WITHOUT ANY WARRANTY; without even the implied warranty of 13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14: General Public License for more details. 15: 16: You should have received a copy of the GNU General Public License 17: along with GNU Classpath; see the file COPYING. If not, write to the 18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19: 02110-1301 USA. 20: 21: Linking this library statically or dynamically with other modules is 22: making a combined work based on this library. Thus, the terms and 23: conditions of the GNU General Public License cover the whole 24: combination. 25: 26: As a special exception, the copyright holders of this library give you 27: permission to link this library with independent modules to produce an 28: executable, regardless of the license terms of these independent 29: modules, and to copy and distribute the resulting executable under 30: terms of your choice, provided that you also meet, for each linked 31: independent module, the terms and conditions of the license of that 32: module. An independent module is a module which is not derived from 33: or based on this library. If you modify this library, you may extend 34: this exception to your version of the library, but you are not 35: obligated to do so. If you do not wish to do so, delete this 36: exception statement from your version. */ 37: 38: 39: package gnu.java.awt.java2d; 40: 41: 42: import java.awt.geom.CubicCurve2D; 43: import java.awt.geom.Point2D; 44: 45: /** 46: * Cubic Bezier curve segment 47: */ 48: public class CubicSegment extends Segment 49: { 50: public Point2D cp1; // control points 51: public Point2D cp2; // control points 52: 53: /** 54: * Constructor - takes coordinates of the starting point, 55: * first control point, second control point and end point, 56: * respecively. 57: */ 58: public CubicSegment(double x1, double y1, double c1x, double c1y, 59: double c2x, double c2y, double x2, double y2) 60: { 61: super(); 62: P1 = new Point2D.Double(x1, y1); 63: P2 = new Point2D.Double(x2, y2); 64: cp1 = new Point2D.Double(c1x, c1y); 65: cp2 = new Point2D.Double(c2x, c2y); 66: } 67: 68: public CubicSegment(Point2D p1, Point2D cp1, Point2D cp2, Point2D p2) 69: { 70: super(); 71: P1 = p1; 72: P2 = p2; 73: this.cp1 = cp1; 74: this.cp2 = cp2; 75: } 76: 77: /** 78: * Clones this segment 79: */ 80: public Object clone() 81: { 82: CubicSegment segment = null; 83: 84: try 85: { 86: segment = (CubicSegment) super.clone(); 87: 88: segment.P1 = (Point2D) P1.clone(); 89: segment.P2 = (Point2D) P2.clone(); 90: segment.cp1 = (Point2D) cp1.clone(); 91: segment.cp2 = (Point2D) cp2.clone(); 92: } 93: catch (CloneNotSupportedException cnse) 94: { 95: InternalError ie = new InternalError(); 96: ie.initCause(cnse); 97: throw ie; 98: } 99: 100: return segment; 101: } 102: 103: /** 104: * Get the "top" and "bottom" segments of this segment. First array element is 105: * p0 + normal, second is p0 - normal. 106: */ 107: public Segment[] getDisplacedSegments(double radius) 108: { 109: // It is, apparently, impossible to derive a curve parallel to a bezier 110: // curve (unless it's a straight line), so we have no choice but to 111: // approximate the displaced segments. Similar to FlattenPathIterator. 112: 113: Segment segmentTop = null; 114: Segment segmentBottom = null; 115: this.radius = radius; 116: 117: CubicCurve2D[] curves = new CubicCurve2D[10]; 118: curves[0] = new CubicCurve2D.Double(P1.getX(), P1.getY(), cp1.getX(), 119: cp1.getY(), cp2.getX(), cp2.getY(), 120: P2.getX(), P2.getY()); 121: int numCurves = 1; 122: 123: // Hard-coded a recursion limit of 10 and flatness of 1... should we make 124: // this an option somewhere? 125: while (numCurves > 0) 126: { 127: // The curve is flat enough, or we've reached our recursion limit, 128: // so take the current start/end points and add it as a line segment 129: // to our final approximated curves 130: if (curves[numCurves - 1].getFlatnessSq() <= (radius / 3) || numCurves == 10) 131: { 132: Segment[] displaced = new LineSegment( 133: curves[numCurves - 1].getP1(), 134: curves[numCurves - 1].getP2()).getDisplacedSegments(radius); 135: if (segmentTop == null) 136: { 137: segmentTop = displaced[0]; 138: segmentBottom = displaced[1]; 139: } 140: else 141: { 142: segmentTop.add(displaced[0]); 143: segmentBottom.add(displaced[1]); 144: } 145: numCurves--; 146: } 147: 148: // Otherwise, subdivide again and continue 149: else 150: { 151: CubicCurve2D left = new CubicCurve2D.Double(); 152: CubicCurve2D right = new CubicCurve2D.Double(); 153: curves[numCurves - 1].subdivide(left, right); 154: curves[numCurves - 1] = right; 155: curves[numCurves] = left; 156: curves[numCurves - 1] = right; 157: curves[numCurves] = left; 158: numCurves++; 159: } 160: } 161: 162: return new Segment[] { segmentTop, segmentBottom }; 163: } 164: 165: public void reverse() 166: { 167: Point2D temp = P1; 168: P1 = P2; 169: P2 = temp; 170: temp = cp1; 171: cp1 = cp2; 172: cp2 = temp; 173: } 174: 175: public double[] cp1() 176: { 177: return new double[]{cp1.getX(), cp1.getY()}; 178: } 179: 180: public double[] cp2() 181: { 182: return new double[]{cp2.getX(), cp2.getY()}; 183: } 184: } // class CubicSegment