/* * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code 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 * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.awt.geom; import java.util.*; /** * A utility class to iterate over the path segments of an ellipse * through the PathIterator interface. * * @author Jim Graham */ class EllipseIterator implements PathIterator { double x, y, w, h; AffineTransform affine; int index; EllipseIterator(Ellipse2D e, AffineTransform at) { this.x = e.getX(); this.y = e.getY(); this.w = e.getWidth(); this.h = e.getHeight(); this.affine = at; if (w < 0 || h < 0) { index = 6; } } /** * Return the winding rule for determining the insideness of the * path. * @see #WIND_EVEN_ODD * @see #WIND_NON_ZERO */ public int getWindingRule() { return WIND_NON_ZERO; } /** * Tests if there are more points to read. * @return true if there are more points to read */ public boolean isDone() { return index > 5; } /** * Moves the iterator to the next segment of the path forwards * along the primary direction of traversal as long as there are * more points in that direction. */ public void next() { index++; } // ArcIterator.btan(Math.PI/2) public static final double CtrlVal = 0.5522847498307933; /* * ctrlpts contains the control points for a set of 4 cubic * bezier curves that approximate a circle of radius 0.5 * centered at 0.5, 0.5 */ private static final double pcv = 0.5 + CtrlVal * 0.5; private static final double ncv = 0.5 - CtrlVal * 0.5; private static double[][] ctrlpts = { { 1.0, pcv, pcv, 1.0, 0.5, 1.0 }, { ncv, 1.0, 0.0, pcv, 0.0, 0.5 }, { 0.0, ncv, ncv, 0.0, 0.5, 0.0 }, { pcv, 0.0, 1.0, ncv, 1.0, 0.5 } }; /** * Returns the coordinates and type of the current path segment in * the iteration. * The return value is the path segment type: * SEG_MOVETO, SEG_LINETO, SEG_QUADTO, SEG_CUBICTO, or SEG_CLOSE. * A float array of length 6 must be passed in and may be used to * store the coordinates of the point(s). * Each point is stored as a pair of float x,y coordinates. * SEG_MOVETO and SEG_LINETO types will return one point, * SEG_QUADTO will return two points, * SEG_CUBICTO will return 3 points * and SEG_CLOSE will not return any points. * @see #SEG_MOVETO * @see #SEG_LINETO * @see #SEG_QUADTO * @see #SEG_CUBICTO * @see #SEG_CLOSE */ public int currentSegment(float[] coords) { if (isDone()) { throw new NoSuchElementException("ellipse iterator out of bounds"); } if (index == 5) { return SEG_CLOSE; } if (index == 0) { double[] ctrls = ctrlpts[3]; coords[0] = (float) (x + ctrls[4] * w); coords[1] = (float) (y + ctrls[5] * h); if (affine != null) { affine.transform(coords, 0, coords, 0, 1); } return SEG_MOVETO; } double[] ctrls = ctrlpts[index - 1]; coords[0] = (float) (x + ctrls[0] * w); coords[1] = (float) (y + ctrls[1] * h); coords[2] = (float) (x + ctrls[2] * w); coords[3] = (float) (y + ctrls[3] * h); coords[4] = (float) (x + ctrls[4] * w); coords[5] = (float) (y + ctrls[5] * h); if (affine != null) { affine.transform(coords, 0, coords, 0, 3); } return SEG_CUBICTO; } /** * Returns the coordinates and type of the current path segment in * the iteration. * The return value is the path segment type: * SEG_MOVETO, SEG_LINETO, SEG_QUADTO, SEG_CUBICTO, or SEG_CLOSE. * A double array of length 6 must be passed in and may be used to * store the coordinates of the point(s). * Each point is stored as a pair of double x,y coordinates. * SEG_MOVETO and SEG_LINETO types will return one point, * SEG_QUADTO will return two points, * SEG_CUBICTO will return 3 points * and SEG_CLOSE will not return any points. * @see #SEG_MOVETO * @see #SEG_LINETO * @see #SEG_QUADTO * @see #SEG_CUBICTO * @see #SEG_CLOSE */ public int currentSegment(double[] coords) { if (isDone()) { throw new NoSuchElementException("ellipse iterator out of bounds"); } if (index == 5) { return SEG_CLOSE; } if (index == 0) { double[] ctrls = ctrlpts[3]; coords[0] = x + ctrls[4] * w; coords[1] = y + ctrls[5] * h; if (affine != null) { affine.transform(coords, 0, coords, 0, 1); } return SEG_MOVETO; } double[] ctrls = ctrlpts[index - 1]; coords[0] = x + ctrls[0] * w; coords[1] = y + ctrls[1] * h; coords[2] = x + ctrls[2] * w; coords[3] = y + ctrls[3] * h; coords[4] = x + ctrls[4] * w; coords[5] = y + ctrls[5] * h; if (affine != null) { affine.transform(coords, 0, coords, 0, 3); } return SEG_CUBICTO; } }