| /* QuadSegment.java -- QuadCurve segment used for BasicStroke |
| Copyright (C) 2006 Free Software Foundation, Inc. |
| |
| This file is part of GNU Classpath. |
| |
| GNU Classpath is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2, or (at your option) |
| any later version. |
| |
| GNU Classpath is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GNU Classpath; see the file COPYING. If not, write to the |
| Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| 02110-1301 USA. |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| |
| package gnu.java.awt.java2d; |
| |
| |
| import java.awt.geom.Point2D; |
| import java.awt.geom.QuadCurve2D; |
| |
| /** |
| * Quadratic Bezier curve segment |
| * |
| * Note: Most peers don't support quadratics directly, so it might make |
| * sense to represent them as cubics internally and just be done with it. |
| * I think we should be peer-agnostic, however, and stay faithful to the |
| * input geometry types as far as possible. |
| */ |
| public class QuadSegment extends Segment |
| { |
| public Point2D cp; // control point |
| |
| /** |
| * Constructor, takes the coordinates of the start, control, |
| * and end point, respectively. |
| */ |
| public QuadSegment(double x1, double y1, double cx, double cy, double x2, |
| double y2) |
| { |
| super(); |
| P1 = new Point2D.Double(x1, y1); |
| P2 = new Point2D.Double(x2, y2); |
| cp = new Point2D.Double(cx, cy); |
| } |
| |
| public QuadSegment(Point2D p1, Point2D cp, Point2D p2) |
| { |
| super(); |
| P1 = p1; |
| P2 = p2; |
| this.cp = cp; |
| } |
| |
| public QuadSegment(QuadCurve2D curve) |
| { |
| super(); |
| P1 = curve.getP1(); |
| P2 = curve.getP2(); |
| this.cp = curve.getCtrlPt(); |
| } |
| |
| /** |
| * Clones this segment |
| */ |
| public Object clone() |
| { |
| QuadSegment segment = null; |
| |
| try |
| { |
| segment = (QuadSegment) super.clone(); |
| |
| segment.P1 = (Point2D) P1.clone(); |
| segment.P2 = (Point2D) P2.clone(); |
| segment.cp = (Point2D) cp.clone(); |
| } |
| catch (CloneNotSupportedException cnse) |
| { |
| InternalError ie = new InternalError(); |
| ie.initCause(cnse); |
| throw ie; |
| } |
| |
| return segment; |
| } |
| |
| /** |
| * Get the "top" and "bottom" segments of a given segment. |
| * First array element is p0 + normal, second is p0 - normal. |
| */ |
| public Segment[] getDisplacedSegments(double radius) |
| { |
| this.radius = radius; |
| double x0 = P1.getX(); |
| double y0 = P1.getY(); |
| double x1 = cp.getX(); |
| double y1 = cp.getY(); |
| double x2 = P2.getX(); |
| double y2 = P2.getY(); |
| |
| QuadCurve2D left = new QuadCurve2D.Double(); |
| QuadCurve2D right = new QuadCurve2D.Double(); |
| QuadCurve2D orig = new QuadCurve2D.Double(x0, y0, x1, y1, x2, y2); |
| orig.subdivide(left, right); |
| |
| QuadSegment s1 = offsetSubdivided(left, true); |
| QuadSegment s2 = offsetSubdivided(left, false); |
| |
| s1.add( offsetSubdivided(right, true) ); |
| s2.add( offsetSubdivided(right, false) ); |
| |
| return new Segment[]{s1, s2}; |
| } |
| |
| private QuadSegment offsetSubdivided(QuadCurve2D curve, boolean plus) |
| { |
| double[] n1 = normal(curve.getX1(), curve.getY1(), |
| curve.getCtrlX(), curve.getCtrlY()); |
| double[] n2 = normal(curve.getCtrlX(), curve.getCtrlY(), |
| curve.getX2(), curve.getY2()); |
| |
| Point2D cp; |
| QuadSegment s; |
| if( plus ) |
| { |
| cp = lineIntersection(curve.getX1() + n1[0], |
| curve.getY1() + n1[1], |
| curve.getCtrlX() + n1[0], |
| curve.getCtrlY() + n1[1], |
| curve.getCtrlX() + n2[0], |
| curve.getCtrlY() + n2[1], |
| curve.getX2() + n2[0], |
| curve.getY2() + n2[1], true); |
| s = new QuadSegment(curve.getX1() + n1[0], curve.getY1() + n1[1], |
| cp.getX(), cp.getY(), |
| curve.getX2() + n2[0], curve.getY2() + n2[1]); |
| } |
| else |
| { |
| cp = lineIntersection(curve.getX1() - n1[0], |
| curve.getY1() - n1[1], |
| curve.getCtrlX() - n1[0], |
| curve.getCtrlY() - n1[1], |
| curve.getCtrlX() - n2[0], |
| curve.getCtrlY() - n2[1], |
| curve.getX2() - n2[0], |
| curve.getY2() - n2[1], true); |
| |
| s = new QuadSegment(curve.getX1() - n1[0], curve.getY1() - n1[1], |
| cp.getX(), cp.getY(), |
| curve.getX2() - n2[0], curve.getY2() - n2[1]); |
| } |
| |
| return s; |
| } |
| |
| private Point2D lineIntersection(double X1, double Y1, |
| double X2, double Y2, |
| double X3, double Y3, |
| double X4, double Y4, |
| boolean infinite) |
| { |
| double x1 = X1; |
| double y1 = Y1; |
| double rx = X2 - x1; |
| double ry = Y2 - y1; |
| |
| double x2 = X3; |
| double y2 = Y3; |
| double sx = X4 - x2; |
| double sy = Y4 - y2; |
| |
| double determinant = sx * ry - sy * rx; |
| double nom = (sx * (y2 - y1) + sy * (x1 - x2)); |
| |
| // lines can be considered parallel. |
| if (Math.abs(determinant) < 1E-6) |
| return null; |
| |
| nom = nom / determinant; |
| |
| // check if lines are within the bounds |
| if(!infinite && (nom > 1.0 || nom < 0.0)) |
| return null; |
| |
| return new Point2D.Double(x1 + nom * rx, y1 + nom * ry); |
| } |
| |
| public void reverse() |
| { |
| Point2D p = P1; |
| P1 = P2; |
| P2 = p; |
| } |
| |
| public double[] cp1() |
| { |
| return new double[]{cp.getX(), cp.getY()}; |
| } |
| |
| public double[] cp2() |
| { |
| return new double[]{cp.getX(), cp.getY()}; |
| } |
| } |