| /* |
| * Copyright (c) 1998, 2006, 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 sun.awt.geom; |
| |
| import java.awt.geom.Rectangle2D; |
| import java.awt.geom.PathIterator; |
| import java.awt.geom.QuadCurve2D; |
| import java.util.Vector; |
| |
| final class Order2 extends Curve { |
| private double x0; |
| private double y0; |
| private double cx0; |
| private double cy0; |
| private double x1; |
| private double y1; |
| private double xmin; |
| private double xmax; |
| |
| private double xcoeff0; |
| private double xcoeff1; |
| private double xcoeff2; |
| private double ycoeff0; |
| private double ycoeff1; |
| private double ycoeff2; |
| |
| public static void insert(Vector curves, double tmp[], |
| double x0, double y0, |
| double cx0, double cy0, |
| double x1, double y1, |
| int direction) |
| { |
| int numparams = getHorizontalParams(y0, cy0, y1, tmp); |
| if (numparams == 0) { |
| // We are using addInstance here to avoid inserting horisontal |
| // segments |
| addInstance(curves, x0, y0, cx0, cy0, x1, y1, direction); |
| return; |
| } |
| // assert(numparams == 1); |
| double t = tmp[0]; |
| tmp[0] = x0; tmp[1] = y0; |
| tmp[2] = cx0; tmp[3] = cy0; |
| tmp[4] = x1; tmp[5] = y1; |
| split(tmp, 0, t); |
| int i0 = (direction == INCREASING)? 0 : 4; |
| int i1 = 4 - i0; |
| addInstance(curves, tmp[i0], tmp[i0 + 1], tmp[i0 + 2], tmp[i0 + 3], |
| tmp[i0 + 4], tmp[i0 + 5], direction); |
| addInstance(curves, tmp[i1], tmp[i1 + 1], tmp[i1 + 2], tmp[i1 + 3], |
| tmp[i1 + 4], tmp[i1 + 5], direction); |
| } |
| |
| public static void addInstance(Vector curves, |
| double x0, double y0, |
| double cx0, double cy0, |
| double x1, double y1, |
| int direction) { |
| if (y0 > y1) { |
| curves.add(new Order2(x1, y1, cx0, cy0, x0, y0, -direction)); |
| } else if (y1 > y0) { |
| curves.add(new Order2(x0, y0, cx0, cy0, x1, y1, direction)); |
| } |
| } |
| |
| /* |
| * Return the count of the number of horizontal sections of the |
| * specified quadratic Bezier curve. Put the parameters for the |
| * horizontal sections into the specified <code>ret</code> array. |
| * <p> |
| * If we examine the parametric equation in t, we have: |
| * Py(t) = C0*(1-t)^2 + 2*CP*t*(1-t) + C1*t^2 |
| * = C0 - 2*C0*t + C0*t^2 + 2*CP*t - 2*CP*t^2 + C1*t^2 |
| * = C0 + (2*CP - 2*C0)*t + (C0 - 2*CP + C1)*t^2 |
| * Py(t) = (C0 - 2*CP + C1)*t^2 + (2*CP - 2*C0)*t + (C0) |
| * If we take the derivative, we get: |
| * Py(t) = At^2 + Bt + C |
| * dPy(t) = 2At + B = 0 |
| * 2*(C0 - 2*CP + C1)t + 2*(CP - C0) = 0 |
| * 2*(C0 - 2*CP + C1)t = 2*(C0 - CP) |
| * t = 2*(C0 - CP) / 2*(C0 - 2*CP + C1) |
| * t = (C0 - CP) / (C0 - CP + C1 - CP) |
| * Note that this method will return 0 if the equation is a line, |
| * which is either always horizontal or never horizontal. |
| * Completely horizontal curves need to be eliminated by other |
| * means outside of this method. |
| */ |
| public static int getHorizontalParams(double c0, double cp, double c1, |
| double ret[]) { |
| if (c0 <= cp && cp <= c1) { |
| return 0; |
| } |
| c0 -= cp; |
| c1 -= cp; |
| double denom = c0 + c1; |
| // If denom == 0 then cp == (c0+c1)/2 and we have a line. |
| if (denom == 0) { |
| return 0; |
| } |
| double t = c0 / denom; |
| // No splits at t==0 and t==1 |
| if (t <= 0 || t >= 1) { |
| return 0; |
| } |
| ret[0] = t; |
| return 1; |
| } |
| |
| /* |
| * Split the quadratic Bezier stored at coords[pos...pos+5] representing |
| * the paramtric range [0..1] into two subcurves representing the |
| * parametric subranges [0..t] and [t..1]. Store the results back |
| * into the array at coords[pos...pos+5] and coords[pos+4...pos+9]. |
| */ |
| public static void split(double coords[], int pos, double t) { |
| double x0, y0, cx, cy, x1, y1; |
| coords[pos+8] = x1 = coords[pos+4]; |
| coords[pos+9] = y1 = coords[pos+5]; |
| cx = coords[pos+2]; |
| cy = coords[pos+3]; |
| x1 = cx + (x1 - cx) * t; |
| y1 = cy + (y1 - cy) * t; |
| x0 = coords[pos+0]; |
| y0 = coords[pos+1]; |
| x0 = x0 + (cx - x0) * t; |
| y0 = y0 + (cy - y0) * t; |
| cx = x0 + (x1 - x0) * t; |
| cy = y0 + (y1 - y0) * t; |
| coords[pos+2] = x0; |
| coords[pos+3] = y0; |
| coords[pos+4] = cx; |
| coords[pos+5] = cy; |
| coords[pos+6] = x1; |
| coords[pos+7] = y1; |
| } |
| |
| public Order2(double x0, double y0, |
| double cx0, double cy0, |
| double x1, double y1, |
| int direction) |
| { |
| super(direction); |
| // REMIND: Better accuracy in the root finding methods would |
| // ensure that cy0 is in range. As it stands, it is never |
| // more than "1 mantissa bit" out of range... |
| if (cy0 < y0) { |
| cy0 = y0; |
| } else if (cy0 > y1) { |
| cy0 = y1; |
| } |
| this.x0 = x0; |
| this.y0 = y0; |
| this.cx0 = cx0; |
| this.cy0 = cy0; |
| this.x1 = x1; |
| this.y1 = y1; |
| xmin = Math.min(Math.min(x0, x1), cx0); |
| xmax = Math.max(Math.max(x0, x1), cx0); |
| xcoeff0 = x0; |
| xcoeff1 = cx0 + cx0 - x0 - x0; |
| xcoeff2 = x0 - cx0 - cx0 + x1; |
| ycoeff0 = y0; |
| ycoeff1 = cy0 + cy0 - y0 - y0; |
| ycoeff2 = y0 - cy0 - cy0 + y1; |
| } |
| |
| public int getOrder() { |
| return 2; |
| } |
| |
| public double getXTop() { |
| return x0; |
| } |
| |
| public double getYTop() { |
| return y0; |
| } |
| |
| public double getXBot() { |
| return x1; |
| } |
| |
| public double getYBot() { |
| return y1; |
| } |
| |
| public double getXMin() { |
| return xmin; |
| } |
| |
| public double getXMax() { |
| return xmax; |
| } |
| |
| public double getX0() { |
| return (direction == INCREASING) ? x0 : x1; |
| } |
| |
| public double getY0() { |
| return (direction == INCREASING) ? y0 : y1; |
| } |
| |
| public double getCX0() { |
| return cx0; |
| } |
| |
| public double getCY0() { |
| return cy0; |
| } |
| |
| public double getX1() { |
| return (direction == DECREASING) ? x0 : x1; |
| } |
| |
| public double getY1() { |
| return (direction == DECREASING) ? y0 : y1; |
| } |
| |
| public double XforY(double y) { |
| if (y <= y0) { |
| return x0; |
| } |
| if (y >= y1) { |
| return x1; |
| } |
| return XforT(TforY(y)); |
| } |
| |
| public double TforY(double y) { |
| if (y <= y0) { |
| return 0; |
| } |
| if (y >= y1) { |
| return 1; |
| } |
| return TforY(y, ycoeff0, ycoeff1, ycoeff2); |
| } |
| |
| public static double TforY(double y, |
| double ycoeff0, double ycoeff1, double ycoeff2) |
| { |
| // The caller should have already eliminated y values |
| // outside of the y0 to y1 range. |
| ycoeff0 -= y; |
| if (ycoeff2 == 0.0) { |
| // The quadratic parabola has degenerated to a line. |
| // ycoeff1 should not be 0.0 since we have already eliminated |
| // totally horizontal lines, but if it is, then we will generate |
| // infinity here for the root, which will not be in the [0,1] |
| // range so we will pass to the failure code below. |
| double root = -ycoeff0 / ycoeff1; |
| if (root >= 0 && root <= 1) { |
| return root; |
| } |
| } else { |
| // From Numerical Recipes, 5.6, Quadratic and Cubic Equations |
| double d = ycoeff1 * ycoeff1 - 4.0 * ycoeff2 * ycoeff0; |
| // If d < 0.0, then there are no roots |
| if (d >= 0.0) { |
| d = Math.sqrt(d); |
| // For accuracy, calculate one root using: |
| // (-ycoeff1 +/- d) / 2ycoeff2 |
| // and the other using: |
| // 2ycoeff0 / (-ycoeff1 +/- d) |
| // Choose the sign of the +/- so that ycoeff1+d |
| // gets larger in magnitude |
| if (ycoeff1 < 0.0) { |
| d = -d; |
| } |
| double q = (ycoeff1 + d) / -2.0; |
| // We already tested ycoeff2 for being 0 above |
| double root = q / ycoeff2; |
| if (root >= 0 && root <= 1) { |
| return root; |
| } |
| if (q != 0.0) { |
| root = ycoeff0 / q; |
| if (root >= 0 && root <= 1) { |
| return root; |
| } |
| } |
| } |
| } |
| /* We failed to find a root in [0,1]. What could have gone wrong? |
| * First, remember that these curves are constructed to be monotonic |
| * in Y and totally horizontal curves have already been eliminated. |
| * Now keep in mind that the Y coefficients of the polynomial form |
| * of the curve are calculated from the Y coordinates which define |
| * our curve. They should theoretically define the same curve, |
| * but they can be off by a couple of bits of precision after the |
| * math is done and so can represent a slightly modified curve. |
| * This is normally not an issue except when we have solutions near |
| * the endpoints. Since the answers we get from solving the polynomial |
| * may be off by a few bits that means that they could lie just a |
| * few bits of precision outside the [0,1] range. |
| * |
| * Another problem could be that while the parametric curve defined |
| * by the Y coordinates has a local minima or maxima at or just |
| * outside of the endpoints, the polynomial form might express |
| * that same min/max just inside of and just shy of the Y coordinate |
| * of that endpoint. In that case, if we solve for a Y coordinate |
| * at or near that endpoint, we may be solving for a Y coordinate |
| * that is below that minima or above that maxima and we would find |
| * no solutions at all. |
| * |
| * In either case, we can assume that y is so near one of the |
| * endpoints that we can just collapse it onto the nearest endpoint |
| * without losing more than a couple of bits of precision. |
| */ |
| // First calculate the midpoint between y0 and y1 and choose to |
| // return either 0.0 or 1.0 depending on whether y is above |
| // or below the midpoint... |
| // Note that we subtracted y from ycoeff0 above so both y0 and y1 |
| // will be "relative to y" so we are really just looking at where |
| // zero falls with respect to the "relative midpoint" here. |
| double y0 = ycoeff0; |
| double y1 = ycoeff0 + ycoeff1 + ycoeff2; |
| return (0 < (y0 + y1) / 2) ? 0.0 : 1.0; |
| } |
| |
| public double XforT(double t) { |
| return (xcoeff2 * t + xcoeff1) * t + xcoeff0; |
| } |
| |
| public double YforT(double t) { |
| return (ycoeff2 * t + ycoeff1) * t + ycoeff0; |
| } |
| |
| public double dXforT(double t, int deriv) { |
| switch (deriv) { |
| case 0: |
| return (xcoeff2 * t + xcoeff1) * t + xcoeff0; |
| case 1: |
| return 2 * xcoeff2 * t + xcoeff1; |
| case 2: |
| return 2 * xcoeff2; |
| default: |
| return 0; |
| } |
| } |
| |
| public double dYforT(double t, int deriv) { |
| switch (deriv) { |
| case 0: |
| return (ycoeff2 * t + ycoeff1) * t + ycoeff0; |
| case 1: |
| return 2 * ycoeff2 * t + ycoeff1; |
| case 2: |
| return 2 * ycoeff2; |
| default: |
| return 0; |
| } |
| } |
| |
| public double nextVertical(double t0, double t1) { |
| double t = -xcoeff1 / (2 * xcoeff2); |
| if (t > t0 && t < t1) { |
| return t; |
| } |
| return t1; |
| } |
| |
| public void enlarge(Rectangle2D r) { |
| r.add(x0, y0); |
| double t = -xcoeff1 / (2 * xcoeff2); |
| if (t > 0 && t < 1) { |
| r.add(XforT(t), YforT(t)); |
| } |
| r.add(x1, y1); |
| } |
| |
| public Curve getSubCurve(double ystart, double yend, int dir) { |
| double t0, t1; |
| if (ystart <= y0) { |
| if (yend >= y1) { |
| return getWithDirection(dir); |
| } |
| t0 = 0; |
| } else { |
| t0 = TforY(ystart, ycoeff0, ycoeff1, ycoeff2); |
| } |
| if (yend >= y1) { |
| t1 = 1; |
| } else { |
| t1 = TforY(yend, ycoeff0, ycoeff1, ycoeff2); |
| } |
| double eqn[] = new double[10]; |
| eqn[0] = x0; |
| eqn[1] = y0; |
| eqn[2] = cx0; |
| eqn[3] = cy0; |
| eqn[4] = x1; |
| eqn[5] = y1; |
| if (t1 < 1) { |
| split(eqn, 0, t1); |
| } |
| int i; |
| if (t0 <= 0) { |
| i = 0; |
| } else { |
| split(eqn, 0, t0 / t1); |
| i = 4; |
| } |
| return new Order2(eqn[i+0], ystart, |
| eqn[i+2], eqn[i+3], |
| eqn[i+4], yend, |
| dir); |
| } |
| |
| public Curve getReversedCurve() { |
| return new Order2(x0, y0, cx0, cy0, x1, y1, -direction); |
| } |
| |
| public int getSegment(double coords[]) { |
| coords[0] = cx0; |
| coords[1] = cy0; |
| if (direction == INCREASING) { |
| coords[2] = x1; |
| coords[3] = y1; |
| } else { |
| coords[2] = x0; |
| coords[3] = y0; |
| } |
| return PathIterator.SEG_QUADTO; |
| } |
| |
| public String controlPointString() { |
| return ("("+round(cx0)+", "+round(cy0)+"), "); |
| } |
| } |
