svgparserutilities.cpp

linux下开源浏览器WebKit的源码,市面上的很多商用浏览器都是移植自WebKit

/*
   Copyright (C) 2002, 2003 The Karbon Developers
                 2006       Alexander Kellett <[e-mail]>
                 2006, 2007 Rob Buis <[e-mail]>
   Copyrigth (C) 2007, 2009 Apple, Inc.  All rights reserved.

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public
   License as published by the Free Software Foundation; either
   version 2 of the License, or (at your option) any later version.

   This library 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
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public License
   along with this library; see the file COPYING.LIB.  If not, write to
   the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
   Boston, MA 02110-1301, USA.
*/

#include "config.h"
#if ENABLE(SVG)
#include "SVGParserUtilities.h"

#include "ExceptionCode.h"
#include "FloatConversion.h"
#include "FloatPoint.h"
#include "Path.h"
#include "PlatformString.h"
#include "SVGPathSegList.h"
#include "SVGPathSegArc.h"
#include "SVGPathSegClosePath.h"
#include "SVGPathSegCurvetoCubic.h"
#include "SVGPathSegCurvetoCubicSmooth.h"
#include "SVGPathSegCurvetoQuadratic.h"
#include "SVGPathSegCurvetoQuadraticSmooth.h"
#include "SVGPathSegLineto.h"
#include "SVGPathSegLinetoHorizontal.h"
#include "SVGPathSegLinetoVertical.h"
#include "SVGPathSegList.h"
#include "SVGPathSegMoveto.h"
#include "SVGPointList.h"
#include "SVGPathElement.h"
#include <math.h>
#include <wtf/MathExtras.h>

namespace WebCore {

/* We use this generic _parseNumber function to allow the Path parsing code to work 
 * at a higher precision internally, without any unnecessary runtime cost or code
 * complexity
 */    
template <typename FloatType> static bool _parseNumber(const UChar*& ptr, const UChar* end, FloatType& number, bool skip)
{
    int integer, exponent;
    FloatType decimal, frac;
    int sign, expsign;
    const UChar* start = ptr;

    exponent = 0;
    integer = 0;
    frac = 1;
    decimal = 0;
    sign = 1;
    expsign = 1;

    // read the sign
    if (ptr < end && *ptr == '+')
        ptr++;
    else if (ptr < end && *ptr == '-') {
        ptr++;
        sign = -1;
    } 
    
    if (ptr == end || ((*ptr < '0' || *ptr > '9') && *ptr != '.'))
        // The first character of a number must be one of [0-9+-.]
        return false;

    // read the integer part
    while (ptr < end && *ptr >= '0' && *ptr <= '9')
        integer = (integer * 10) + *(ptr++) - '0';

    if (ptr < end && *ptr == '.') { // read the decimals
        ptr++;
        
        // There must be a least one digit following the .
        if (ptr >= end || *ptr < '0' || *ptr > '9')
            return false;
        
        while (ptr < end && *ptr >= '0' && *ptr <= '9')
            decimal += (*(ptr++) - '0') * (frac *= static_cast<FloatType>(0.1));
    }

    // read the exponent part
    if (ptr != start && ptr + 1 < end && (*ptr == 'e' || *ptr == 'E') 
        && (ptr[1] != 'x' && ptr[1] != 'm')) { 
        ptr++;

        // read the sign of the exponent
        if (*ptr == '+')
            ptr++;
        else if (*ptr == '-') {
            ptr++;
            expsign = -1;
        }
        
        // There must be an exponent
        if (ptr >= end || *ptr < '0' || *ptr > '9')
            return false;

        while (ptr < end && *ptr >= '0' && *ptr <= '9') {
            exponent *= 10;
            exponent += *ptr - '0';
            ptr++;
        }
    }

    number = integer + decimal;
    number *= sign * static_cast<FloatType>(pow(10.0, expsign * exponent));

    if (start == ptr)
        return false;

    if (skip)
        skipOptionalSpacesOrDelimiter(ptr, end);

    return true;
}

bool parseNumber(const UChar*& ptr, const UChar* end, float& number, bool skip) 
{
    return _parseNumber(ptr, end, number, skip);
}

// Only used for parsing Paths
static bool parseNumber(const UChar*& ptr, const UChar* end, double& number, bool skip = true) 
{
    return _parseNumber(ptr, end, number, skip);
}

bool parseNumberOptionalNumber(const String& s, float& x, float& y)
{
    if (s.isEmpty())
        return false;
    const UChar* cur = s.characters();
    const UChar* end = cur + s.length();

    if (!parseNumber(cur, end, x))
        return false;

    if (cur == end)
        y = x;
    else if (!parseNumber(cur, end, y, false))
        return false;

    return cur == end;
}

bool pointsListFromSVGData(SVGPointList* pointsList, const String& points)
{
    if (points.isEmpty())
        return true;
    const UChar* cur = points.characters();
    const UChar* end = cur + points.length();

    skipOptionalSpaces(cur, end);

    bool delimParsed = false;
    while (cur < end) {
        delimParsed = false;
        float xPos = 0.0f;
        if (!parseNumber(cur, end, xPos))
           return false;

        float yPos = 0.0f;
        if (!parseNumber(cur, end, yPos, false))
            return false;

        skipOptionalSpaces(cur, end);

        if (cur < end && *cur == ',') {
            delimParsed = true;
            cur++;
        }
        skipOptionalSpaces(cur, end);

        ExceptionCode ec = 0;
        pointsList->appendItem(FloatPoint(xPos, yPos), ec);
    }
    return cur == end && !delimParsed;
}

    /**
     * Parser for svg path data, contained in the d attribute.
     *
     * The parser delivers encountered commands and parameters by calling
     * methods that correspond to those commands. Clients have to derive
     * from this class and implement the abstract command methods.
     *
     * There are two operating modes. By default the parser just delivers unaltered
     * svg path data commands and parameters. In the second mode, it will convert all
     * relative coordinates to absolute ones, and convert all curves to cubic beziers.
     */
    class SVGPathParser {
    public:
        virtual ~SVGPathParser() { }
        bool parseSVG(const String& d, bool process = false);

    protected:
        virtual void svgMoveTo(double x1, double y1, bool closed, bool abs = true) = 0;
        virtual void svgLineTo(double x1, double y1, bool abs = true) = 0;
        virtual void svgLineToHorizontal(double, bool /*abs*/ = true) { }
        virtual void svgLineToVertical(double /*y*/, bool /*abs*/ = true) { }
        virtual void svgCurveToCubic(double x1, double y1, double x2, double y2, double x, double y, bool abs = true) = 0;
        virtual void svgCurveToCubicSmooth(double /*x*/, double /*y*/, double /*x2*/, double /*y2*/, bool /*abs*/ = true) { }
        virtual void svgCurveToQuadratic(double /*x*/, double /*y*/, double /*x1*/, double /*y1*/, bool /*abs*/ = true) { }
        virtual void svgCurveToQuadraticSmooth(double /*x*/, double /*y*/, bool /*abs*/ = true) { }
        virtual void svgArcTo(double /*x*/, double /*y*/, double /*r1*/, double /*r2*/, double /*angle*/, bool /*largeArcFlag*/, bool /*sweepFlag*/, bool /*abs*/ = true) { }
        virtual void svgClosePath() = 0;

    private:
        void calculateArc(bool relative, double& curx, double& cury, double angle, double x, double y, double r1, double r2, bool largeArcFlag, bool sweepFlag);
    };
    
bool SVGPathParser::parseSVG(const String& s, bool process)
{
    const UChar* ptr = s.characters();
    const UChar* end = ptr + s.length();

    double contrlx, contrly, curx, cury, subpathx, subpathy, tox, toy, x1, y1, x2, y2, xc, yc;
    double px1, py1, px2, py2, px3, py3;
    bool closed = true;
    
    if (!skipOptionalSpaces(ptr, end)) // skip any leading spaces
        return false;
    
    char command = *(ptr++), lastCommand = ' ';
    if (command != 'm' && command != 'M') // path must start with moveto
        return false;

    subpathx = subpathy = curx = cury = contrlx = contrly = 0.0;
    while (1) {
        skipOptionalSpaces(ptr, end); // skip spaces between command and first coord

        bool relative = false;

        switch(command)
        {
            case 'm':
                relative = true;
            case 'M':
            {
                if (!parseNumber(ptr, end, tox) || !parseNumber(ptr, end, toy))
                    return false;

                if (process) {
                    subpathx = curx = relative ? curx + tox : tox;
                    subpathy = cury = relative ? cury + toy : toy;

                    svgMoveTo(narrowPrecisionToFloat(curx), narrowPrecisionToFloat(cury), closed);
                } else
                    svgMoveTo(narrowPrecisionToFloat(tox), narrowPrecisionToFloat(toy), closed, !relative);
                closed = false;
                break;
            }
            case 'l':
                relative = true;
            case 'L':
            {
                if (!parseNumber(ptr, end, tox) || !parseNumber(ptr, end, toy))
                    return false;

                if (process) {
                    curx = relative ? curx + tox : tox;
                    cury = relative ? cury + toy : toy;

                    svgLineTo(narrowPrecisionToFloat(curx), narrowPrecisionToFloat(cury));
                }
                else
                    svgLineTo(narrowPrecisionToFloat(tox), narrowPrecisionToFloat(toy), !relative);
                break;
            }
            case 'h':
            {
                if (!parseNumber(ptr, end, tox))
                    return false;