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KHTML

Path.cpp

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00001 /*
00002  * Copyright (C) 2003, 2006 Apple Computer, Inc.  All rights reserved.
00003  *                     2006 Rob Buis <buis@kde.org>
00004  * Copyright (C) 2007 Eric Seidel <eric@webkit.org>
00005  *
00006  * Redistribution and use in source and binary forms, with or without
00007  * modification, are permitted provided that the following conditions
00008  * are met:
00009  * 1. Redistributions of source code must retain the above copyright
00010  *    notice, this list of conditions and the following disclaimer.
00011  * 2. Redistributions in binary form must reproduce the above copyright
00012  *    notice, this list of conditions and the following disclaimer in the
00013  *    documentation and/or other materials provided with the distribution.
00014  *
00015  * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
00016  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
00017  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
00018  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
00019  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
00020  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
00021  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
00022  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
00023  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
00024  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
00025  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
00026  */
00027 
00028 
00029 #include "config.h"
00030 #include "wtf/Platform.h"
00031 #include "Path.h"
00032 
00033 #include "FloatPoint.h"
00034 #include "FloatRect.h"
00035 #include "PathTraversalState.h"
00036 #include <math.h>
00037 #include <wtf/MathExtras.h>
00038 
00039 const float QUARTER = 0.552f; // approximation of control point positions on a bezier
00040                               // to simulate a quarter of a circle.
00041                               
00042 using namespace WebCore;
00043 
00044 namespace khtml {
00045 
00046 static void pathLengthApplierFunction(void* info, const PathElement* element)
00047 {
00048     PathTraversalState& traversalState = *static_cast<PathTraversalState*>(info);
00049     if (traversalState.m_success)
00050         return;
00051     traversalState.m_previous = traversalState.m_current;
00052     FloatPoint* points = element->points;
00053     float segmentLength = 0.0f;
00054     switch (element->type) {
00055         case PathElementMoveToPoint:
00056             segmentLength = traversalState.moveTo(points[0]);
00057             break;
00058         case PathElementAddLineToPoint:
00059             segmentLength = traversalState.lineTo(points[0]);
00060             break;
00061         case PathElementAddQuadCurveToPoint:
00062             segmentLength = traversalState.quadraticBezierTo(points[0], points[1]);
00063             break;
00064         case PathElementAddCurveToPoint:
00065             segmentLength = traversalState.cubicBezierTo(points[0], points[1], points[2]);
00066             break;
00067         case PathElementCloseSubpath:
00068             segmentLength = traversalState.closeSubpath();
00069             break;
00070     }
00071     traversalState.m_totalLength += segmentLength; 
00072     if ((traversalState.m_action == PathTraversalState::TraversalPointAtLength || 
00073          traversalState.m_action == PathTraversalState::TraversalNormalAngleAtLength) &&
00074         (traversalState.m_totalLength >= traversalState.m_desiredLength)) {
00075         FloatSize change = traversalState.m_current - traversalState.m_previous;
00076         float slope = atan2f(change.height(), change.width());
00077 
00078         if (traversalState.m_action == PathTraversalState::TraversalPointAtLength) {
00079             float offset = traversalState.m_desiredLength - traversalState.m_totalLength;
00080             traversalState.m_current.move(offset * cosf(slope), offset * sinf(slope));
00081         } else {
00082             static const float rad2deg = 180.0f / piFloat;
00083             traversalState.m_normalAngle = slope * rad2deg;
00084         }
00085 
00086         traversalState.m_success = true;
00087     }
00088 }
00089 
00090 float Path::length()
00091 {
00092     PathTraversalState traversalState(PathTraversalState::TraversalTotalLength);
00093     apply(&traversalState, pathLengthApplierFunction);
00094     return traversalState.m_totalLength;
00095 }
00096 
00097 FloatPoint Path::pointAtLength(float length, bool& ok)
00098 {
00099     PathTraversalState traversalState(PathTraversalState::TraversalPointAtLength);
00100     traversalState.m_desiredLength = length;
00101     apply(&traversalState, pathLengthApplierFunction);
00102     ok = traversalState.m_success;
00103     return traversalState.m_current;
00104 }
00105 
00106 float Path::normalAngleAtLength(float length, bool& ok)
00107 {
00108     PathTraversalState traversalState(PathTraversalState::TraversalNormalAngleAtLength);
00109     traversalState.m_desiredLength = length;
00110     apply(&traversalState, pathLengthApplierFunction);
00111     ok = traversalState.m_success;
00112     return traversalState.m_normalAngle;
00113 }
00114 
00115 Path Path::createRoundedRectangle(const FloatRect& rectangle, const FloatSize& roundingRadii)
00116 {
00117     Path path;
00118     float x = rectangle.x();
00119     float y = rectangle.y();
00120     float width = rectangle.width();
00121     float height = rectangle.height();
00122     float rx = roundingRadii.width();
00123     float ry = roundingRadii.height();
00124     if (width <= 0.0f || height <= 0.0f)
00125         return path;
00126 
00127     float dx = rx, dy = ry;
00128     // If rx is greater than half of the width of the rectangle
00129     // then set rx to half of the width (required in SVG spec)
00130     if (dx > width * 0.5f)
00131         dx = width * 0.5f;
00132 
00133     // If ry is greater than half of the height of the rectangle
00134     // then set ry to half of the height (required in SVG spec)
00135     if (dy > height * 0.5f)
00136         dy = height * 0.5f;
00137 
00138     path.moveTo(FloatPoint(x + dx, y));
00139 
00140     if (dx < width * 0.5f)
00141         path.addLineTo(FloatPoint(x + width - rx, y));
00142 
00143     path.addBezierCurveTo(FloatPoint(x + width - dx * (1 - QUARTER), y), FloatPoint(x + width, y + dy * (1 - QUARTER)), FloatPoint(x + width, y + dy));
00144 
00145     if (dy < height * 0.5)
00146         path.addLineTo(FloatPoint(x + width, y + height - dy));
00147 
00148     path.addBezierCurveTo(FloatPoint(x + width, y + height - dy * (1 - QUARTER)), FloatPoint(x + width - dx * (1 - QUARTER), y + height), FloatPoint(x + width - dx, y + height));
00149 
00150     if (dx < width * 0.5)
00151         path.addLineTo(FloatPoint(x + dx, y + height));
00152 
00153     path.addBezierCurveTo(FloatPoint(x + dx * (1 - QUARTER), y + height), FloatPoint(x, y + height - dy * (1 - QUARTER)), FloatPoint(x, y + height - dy));
00154 
00155     if (dy < height * 0.5)
00156         path.addLineTo(FloatPoint(x, y + dy));
00157 
00158     path.addBezierCurveTo(FloatPoint(x, y + dy * (1 - QUARTER)), FloatPoint(x + dx * (1 - QUARTER), y), FloatPoint(x + dx, y));
00159 
00160     path.closeSubpath();
00161 
00162     return path;
00163 }
00164 
00165 Path Path::createRoundedRectangle(const FloatRect& rectangle, const FloatSize& topLeftRadius, const FloatSize& topRightRadius, const FloatSize& bottomLeftRadius, const FloatSize& bottomRightRadius)
00166 {
00167     Path path;
00168 
00169     float width = rectangle.width();
00170     float height = rectangle.height();
00171     if (width <= 0.0 || height <= 0.0)
00172         return path;
00173 
00174     if (width < topLeftRadius.width() + topRightRadius.width()
00175             || width < bottomLeftRadius.width() + bottomRightRadius.width()
00176             || height < topLeftRadius.height() + bottomLeftRadius.height()
00177             || height < topRightRadius.height() + bottomRightRadius.height())
00178         // If all the radii cannot be accommodated, return a rect.
00179         return createRectangle(rectangle);
00180 
00181     float x = rectangle.x();
00182     float y = rectangle.y();
00183 
00184     path.moveTo(FloatPoint(x + topLeftRadius.width(), y));
00185 
00186     path.addLineTo(FloatPoint(x + width - topRightRadius.width(), y));
00187 
00188     path.addBezierCurveTo(FloatPoint(x + width - topRightRadius.width() * (1 - QUARTER), y), FloatPoint(x + width, y + topRightRadius.height() * (1 - QUARTER)), FloatPoint(x + width, y + topRightRadius.height()));
00189 
00190     path.addLineTo(FloatPoint(x + width, y + height - bottomRightRadius.height()));
00191 
00192     path.addBezierCurveTo(FloatPoint(x + width, y + height - bottomRightRadius.height() * (1 - QUARTER)), FloatPoint(x + width - bottomRightRadius.width() * (1 - QUARTER), y + height), FloatPoint(x + width - bottomRightRadius.width(), y + height));
00193 
00194     path.addLineTo(FloatPoint(x + bottomLeftRadius.width(), y + height));
00195 
00196     path.addBezierCurveTo(FloatPoint(x + bottomLeftRadius.width() * (1 - QUARTER), y + height), FloatPoint(x, y + height - bottomLeftRadius.height() * (1 - QUARTER)), FloatPoint(x, y + height - bottomLeftRadius.height()));
00197 
00198     path.addLineTo(FloatPoint(x, y + topLeftRadius.height()));
00199 
00200     path.addBezierCurveTo(FloatPoint(x, y + topLeftRadius.height() * (1 - QUARTER)), FloatPoint(x + topLeftRadius.width() * (1 - QUARTER), y), FloatPoint(x + topLeftRadius.width(), y));
00201 
00202     path.closeSubpath();
00203 
00204     return path;
00205 }
00206 
00207 Path Path::createRectangle(const FloatRect& rectangle)
00208 {
00209     Path path;
00210     float x = rectangle.x();
00211     float y = rectangle.y();
00212     float width = rectangle.width();
00213     float height = rectangle.height();
00214     if (width <= 0.0f || height <= 0.0f)
00215         return path;
00216     
00217     path.moveTo(FloatPoint(x, y));
00218     path.addLineTo(FloatPoint(x + width, y));
00219     path.addLineTo(FloatPoint(x + width, y + height));
00220     path.addLineTo(FloatPoint(x, y + height));
00221     path.closeSubpath();
00222 
00223     return path;
00224 }
00225 
00226 Path Path::createEllipse(const FloatPoint& center, float rx, float ry)
00227 {
00228     float cx = center.x();
00229     float cy = center.y();
00230     Path path;
00231     if (rx <= 0.0f || ry <= 0.0f)
00232         return path;
00233 
00234     float x = cx;
00235     float y = cy;
00236 
00237     unsigned step = 0, num = 100;
00238     bool running = true;
00239     while (running)
00240     {
00241         if (step == num)
00242         {
00243             running = false;
00244             break;
00245         }
00246 
00247         float angle = static_cast<float>(step) / static_cast<float>(num) * 2.0f * piFloat;
00248         x = cx + cosf(angle) * rx;
00249         y = cy + sinf(angle) * ry;
00250 
00251         step++;
00252         if (step == 1)
00253             path.moveTo(FloatPoint(x, y));
00254         else
00255             path.addLineTo(FloatPoint(x, y));
00256     }
00257 
00258     path.closeSubpath();
00259 
00260     return path;
00261 }
00262 
00263 Path Path::createCircle(const FloatPoint& center, float r)
00264 {
00265     return createEllipse(center, r, r);
00266 }
00267 
00268 Path Path::createLine(const FloatPoint& start, const FloatPoint& end)
00269 {
00270     Path path;
00271     if (start.x() == end.x() && start.y() == end.y())
00272         return path;
00273 
00274     path.moveTo(start);
00275     path.addLineTo(end);
00276 
00277     return path;
00278 }
00279 
00280 }

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