qgssymbollayerv2utils.cpp

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/***************************************************************************
    qgssymbollayerv2utils.cpp
    ---------------------
    begin                : November 2009
    copyright            : (C) 2009 by Martin Dobias
    email                : wonder dot sk at gmail dot com
 ***************************************************************************
 *                                                                         *
 *   This program 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 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/

#include "qgssymbollayerv2utils.h"

#include "qgssymbollayerv2.h"
#include "qgssymbollayerv2registry.h"
#include "qgssymbolv2.h"
#include "qgsvectorcolorrampv2.h"
#include "qgsexpression.h"
#include "qgsapplication.h"
#include "qgsproject.h"
#include "qgsogcutils.h"

#include "qgsapplication.h"
#include "qgsproject.h"
#include "qgslogger.h"
#include "qgsrendercontext.h"

#include <QColor>
#include <QFont>
#include <QDomDocument>
#include <QDomNode>
#include <QDomElement>
#include <QIcon>
#include <QPainter>
#include <QSettings>

QString QgsSymbolLayerV2Utils::encodeColor( QColor color )
{
  return QString( "%1,%2,%3,%4" ).arg( color.red() ).arg( color.green() ).arg( color.blue() ).arg( color.alpha() );
}

QColor QgsSymbolLayerV2Utils::decodeColor( QString str )
{
  QStringList lst = str.split( "," );
  if ( lst.count() < 3 )
  {
    return QColor( str );
  }
  int red, green, blue, alpha;
  red = lst[0].toInt();
  green = lst[1].toInt();
  blue = lst[2].toInt();
  alpha = 255;
  if ( lst.count() > 3 )
  {
    alpha = lst[3].toInt();
  }
  return QColor( red, green, blue, alpha );
}

QString QgsSymbolLayerV2Utils::encodeSldAlpha( int alpha )
{
  return QString::number( alpha / 255.0, 'f', 2 );
}

int QgsSymbolLayerV2Utils::decodeSldAlpha( QString str )
{
  bool ok;
  double alpha = str.toDouble( &ok );
  if ( !ok || alpha > 1 )
    alpha = 255;
  else if ( alpha < 0 )
    alpha = 0;
  return alpha * 255;
}

QString QgsSymbolLayerV2Utils::encodeSldFontStyle( QFont::Style style )
{
  switch ( style )
  {
    case QFont::StyleNormal:  return "normal";
    case QFont::StyleItalic:  return "italic";
    case QFont::StyleOblique: return "oblique";
    default: return "";
  }
}

QFont::Style QgsSymbolLayerV2Utils::decodeSldFontStyle( QString str )
{
  if ( str == "normal" ) return QFont::StyleNormal;
  if ( str == "italic" ) return QFont::StyleItalic;
  if ( str == "oblique" ) return QFont::StyleOblique;
  return QFont::StyleNormal;
}

QString QgsSymbolLayerV2Utils::encodeSldFontWeight( int weight )
{
  if ( weight == 50 ) return "normal";
  if ( weight == 75 ) return "bold";

  // QFont::Weight is between 0 and 99
  // CSS font-weight is between 100 and 900
  if ( weight < 0 ) return "100";
  if ( weight > 99 ) return "900";
  return QString::number( weight * 800 / 99 + 100 );
}

int QgsSymbolLayerV2Utils::decodeSldFontWeight( QString str )
{
  bool ok;
  int weight = str.toInt( &ok );
  if ( !ok ) return ( int ) QFont::Normal;

  // CSS font-weight is between 100 and 900
  // QFont::Weight is between 0 and 99
  if ( weight > 900 ) return 99;
  if ( weight < 100 ) return 0;
  return ( weight - 100 ) * 99 / 800;
}

QString QgsSymbolLayerV2Utils::encodePenStyle( Qt::PenStyle style )
{
  switch ( style )
  {
    case Qt::NoPen:          return "no";
    case Qt::SolidLine:      return "solid";
    case Qt::DashLine:       return "dash";
    case Qt::DotLine:        return "dot";
    case Qt::DashDotLine:    return "dash dot";
    case Qt::DashDotDotLine: return "dash dot dot";
    default: return "???";
  }
}

Qt::PenStyle QgsSymbolLayerV2Utils::decodePenStyle( QString str )
{
  if ( str == "no" ) return Qt::NoPen;
  if ( str == "solid" ) return Qt::SolidLine;
  if ( str == "dash" ) return Qt::DashLine;
  if ( str == "dot" ) return Qt::DotLine;
  if ( str == "dash dot" ) return Qt::DashDotLine;
  if ( str == "dash dot dot" ) return Qt::DashDotDotLine;
  return Qt::SolidLine;
}

QString QgsSymbolLayerV2Utils::encodePenJoinStyle( Qt::PenJoinStyle style )
{
  switch ( style )
  {
    case Qt::BevelJoin: return "bevel";
    case Qt::MiterJoin: return "miter";
    case Qt::RoundJoin: return "round";
    default: return "???";
  }
}

Qt::PenJoinStyle QgsSymbolLayerV2Utils::decodePenJoinStyle( QString str )
{
  if ( str == "bevel" ) return Qt::BevelJoin;
  if ( str == "miter" ) return Qt::MiterJoin;
  if ( str == "round" ) return Qt::RoundJoin;
  return Qt::BevelJoin;
}

QString QgsSymbolLayerV2Utils::encodeSldLineJoinStyle( Qt::PenJoinStyle style )
{
  switch ( style )
  {
    case Qt::BevelJoin: return "bevel";
    case Qt::MiterJoin: return "mitre";
    case Qt::RoundJoin: return "round";
    default: return "";
  }
}

Qt::PenJoinStyle QgsSymbolLayerV2Utils::decodeSldLineJoinStyle( QString str )
{
  if ( str == "bevel" ) return Qt::BevelJoin;
  if ( str == "mitre" ) return Qt::MiterJoin;
  if ( str == "round" ) return Qt::RoundJoin;
  return Qt::BevelJoin;
}

QString QgsSymbolLayerV2Utils::encodePenCapStyle( Qt::PenCapStyle style )
{
  switch ( style )
  {
    case Qt::SquareCap: return "square";
    case Qt::FlatCap:   return "flat";
    case Qt::RoundCap:  return "round";
    default: return "???";
  }
}

Qt::PenCapStyle QgsSymbolLayerV2Utils::decodePenCapStyle( QString str )
{
  if ( str == "square" ) return Qt::SquareCap;
  if ( str == "flat" ) return Qt::FlatCap;
  if ( str == "round" ) return Qt::RoundCap;
  return Qt::SquareCap;
}

QString QgsSymbolLayerV2Utils::encodeSldLineCapStyle( Qt::PenCapStyle style )
{
  switch ( style )
  {
    case Qt::SquareCap: return "square";
    case Qt::FlatCap:   return "butt";
    case Qt::RoundCap:  return "round";
    default: return "";
  }
}

Qt::PenCapStyle QgsSymbolLayerV2Utils::decodeSldLineCapStyle( QString str )
{
  if ( str == "square" ) return Qt::SquareCap;
  if ( str == "butt" ) return Qt::FlatCap;
  if ( str == "round" ) return Qt::RoundCap;
  return Qt::SquareCap;
}

QString QgsSymbolLayerV2Utils::encodeBrushStyle( Qt::BrushStyle style )
{
  switch ( style )
  {
    case Qt::SolidPattern : return "solid";
    case Qt::HorPattern : return "horizontal";
    case Qt::VerPattern : return "vertical";
    case Qt::CrossPattern : return "cross";
    case Qt::BDiagPattern : return "b_diagonal";
    case Qt::FDiagPattern : return  "f_diagonal";
    case Qt::DiagCrossPattern : return "diagonal_x";
    case Qt::Dense1Pattern  : return "dense1";
    case Qt::Dense2Pattern  : return "dense2";
    case Qt::Dense3Pattern  : return "dense3";
    case Qt::Dense4Pattern  : return "dense4";
    case Qt::Dense5Pattern  : return "dense5";
    case Qt::Dense6Pattern  : return "dense6";
    case Qt::Dense7Pattern  : return "dense7";
    case Qt::NoBrush : return "no";
    default: return "???";
  }
}

Qt::BrushStyle QgsSymbolLayerV2Utils::decodeBrushStyle( QString str )
{
  if ( str == "solid" ) return Qt::SolidPattern;
  if ( str == "horizontal" ) return Qt::HorPattern;
  if ( str == "vertical" ) return Qt::VerPattern;
  if ( str == "cross" ) return Qt::CrossPattern;
  if ( str == "b_diagonal" ) return Qt::BDiagPattern;
  if ( str == "f_diagonal" ) return Qt::FDiagPattern;
  if ( str == "diagonal_x" ) return Qt::DiagCrossPattern;
  if ( str == "dense1" ) return Qt::Dense1Pattern;
  if ( str == "dense2" ) return Qt::Dense2Pattern;
  if ( str == "dense3" ) return Qt::Dense3Pattern;
  if ( str == "dense4" ) return Qt::Dense4Pattern;
  if ( str == "dense5" ) return Qt::Dense5Pattern;
  if ( str == "dense6" ) return Qt::Dense6Pattern;
  if ( str == "dense7" ) return Qt::Dense7Pattern;
  if ( str == "no" ) return Qt::NoBrush;
  return Qt::SolidPattern;
}

QString QgsSymbolLayerV2Utils::encodeSldBrushStyle( Qt::BrushStyle style )
{
  switch ( style )
  {
    case Qt::CrossPattern: return "cross";
    case Qt::DiagCrossPattern: return "x";

      /* The following names are taken from the presentation "GeoServer
       * Cartographic Rendering" by Andrea Aime at the FOSS4G 2010.
       * (see http://2010.foss4g.org/presentations/3588.pdf)
       */
    case Qt::HorPattern: return "horline";
    case Qt::VerPattern: return "line";
    case Qt::BDiagPattern: return "slash";
    case Qt::FDiagPattern: return "backslash";

      /* define the other names following the same pattern used above */
    case Qt::Dense1Pattern:
    case Qt::Dense2Pattern:
    case Qt::Dense3Pattern:
    case Qt::Dense4Pattern:
    case Qt::Dense5Pattern:
    case Qt::Dense6Pattern:
    case Qt::Dense7Pattern:
      return QString( "brush://%1" ).arg( encodeBrushStyle( style ) );

    default:
      return QString();
  }
}

Qt::BrushStyle QgsSymbolLayerV2Utils::decodeSldBrushStyle( QString str )
{
  if ( str == "horline" ) return Qt::HorPattern;
  if ( str == "line" ) return Qt::VerPattern;
  if ( str == "cross" ) return Qt::CrossPattern;
  if ( str == "slash" ) return Qt::BDiagPattern;
  if ( str == "backshash" ) return Qt::FDiagPattern;
  if ( str == "x" ) return Qt::DiagCrossPattern;

  if ( str.startsWith( "brush://" ) )
    return decodeBrushStyle( str.mid( 8 ) );

  return Qt::NoBrush;
}

QString QgsSymbolLayerV2Utils::encodePoint( QPointF point )
{
  return QString( "%1,%2" ).arg( point.x() ).arg( point.y() );
}

QPointF QgsSymbolLayerV2Utils::decodePoint( QString str )
{
  QStringList lst = str.split( ',' );
  if ( lst.count() != 2 )
    return QPointF( 0, 0 );
  return QPointF( lst[0].toDouble(), lst[1].toDouble() );
}

QString QgsSymbolLayerV2Utils::encodeOutputUnit( QgsSymbolV2::OutputUnit unit )
{
  switch ( unit )
  {
    case QgsSymbolV2::MM:
      return "MM";
    case QgsSymbolV2::MapUnit:
      return "MapUnit";
    default:
      return "MM";
  }
}

QgsSymbolV2::OutputUnit QgsSymbolLayerV2Utils::decodeOutputUnit( QString str )
{
  if ( str == "MM" )
  {
    return QgsSymbolV2::MM;
  }
  else if ( str == "MapUnit" )
  {
    return QgsSymbolV2::MapUnit;
  }

  // milimeters are default
  return QgsSymbolV2::MM;
}

QString QgsSymbolLayerV2Utils::encodeSldUom( QgsSymbolV2::OutputUnit unit, double *scaleFactor )
{
  switch ( unit )
  {
    case QgsSymbolV2::MapUnit:
      if ( scaleFactor )
        *scaleFactor = 0.001; // from millimeters to meters
      return "http://www.opengeospatial.org/se/units/metre";

    case QgsSymbolV2::MM:
    default:
      // pixel is the SLD default uom. The "standardized rendering pixel
      // size" is defined to be 0.28mm × 0.28mm (millimeters).
      if ( scaleFactor )
        *scaleFactor = 0.28;  // from millimeters to pixels

      // http://www.opengeospatial.org/sld/units/pixel
      return QString();
  }
}

QgsSymbolV2::OutputUnit QgsSymbolLayerV2Utils::decodeSldUom( QString str, double *scaleFactor )
{
  if ( str == "http://www.opengeospatial.org/se/units/metre" )
  {
    if ( scaleFactor )
      *scaleFactor = 1000.0;  // from meters to millimeters
    return QgsSymbolV2::MapUnit;
  }
  else if ( str == "http://www.opengeospatial.org/se/units/foot" )
  {
    if ( scaleFactor )
      *scaleFactor = 304.8; // from feet to meters
    return QgsSymbolV2::MapUnit;
  }

  // pixel is the SLD default uom. The "standardized rendering pixel
  // size" is defined to be 0.28mm x 0.28mm (millimeters).
  if ( scaleFactor )
    *scaleFactor = 1 / 0.00028; // from pixels to millimeters
  return QgsSymbolV2::MM;
}

QString QgsSymbolLayerV2Utils::encodeRealVector( const QVector<qreal>& v )
{
  QString vectorString;
  QVector<qreal>::const_iterator it = v.constBegin();
  for ( ; it != v.constEnd(); ++it )
  {
    if ( it != v.constBegin() )
    {
      vectorString.append( ";" );
    }
    vectorString.append( QString::number( *it ) );
  }
  return vectorString;
}

QVector<qreal> QgsSymbolLayerV2Utils::decodeRealVector( const QString& s )
{
  QVector<qreal> resultVector;

  QStringList realList = s.split( ";" );
  QStringList::const_iterator it = realList.constBegin();
  for ( ; it != realList.constEnd(); ++it )
  {
    resultVector.append( it->toDouble() );
  }

  return resultVector;
}

QString QgsSymbolLayerV2Utils::encodeSldRealVector( const QVector<qreal>& v )
{
  QString vectorString;
  QVector<qreal>::const_iterator it = v.constBegin();
  for ( ; it != v.constEnd(); ++it )
  {
    if ( it != v.constBegin() )
    {
      vectorString.append( " " );
    }
    vectorString.append( QString::number( *it ) );
  }
  return vectorString;
}

QVector<qreal> QgsSymbolLayerV2Utils::decodeSldRealVector( const QString& s )
{
  QVector<qreal> resultVector;

  QStringList realList = s.split( " " );
  QStringList::const_iterator it = realList.constBegin();
  for ( ; it != realList.constEnd(); ++it )
  {
    resultVector.append( it->toDouble() );
  }

  return resultVector;
}

QString QgsSymbolLayerV2Utils::encodeScaleMethod( QgsSymbolV2::ScaleMethod scaleMethod )
{
  QString encodedValue;

  switch ( scaleMethod )
  {
    case QgsSymbolV2::ScaleDiameter:
      encodedValue = "diameter";
      break;
    case QgsSymbolV2::ScaleArea:
      encodedValue = "area";
      break;
  }
  return encodedValue;
}

QgsSymbolV2::ScaleMethod QgsSymbolLayerV2Utils::decodeScaleMethod( QString str )
{
  QgsSymbolV2::ScaleMethod scaleMethod;

  if ( str == "diameter" )
  {
    scaleMethod = QgsSymbolV2::ScaleDiameter;
  }
  else
  {
    scaleMethod = QgsSymbolV2::ScaleArea;
  }

  return scaleMethod;
}

QIcon QgsSymbolLayerV2Utils::symbolPreviewIcon( QgsSymbolV2* symbol, QSize size )
{
  return QIcon( symbolPreviewPixmap( symbol, size ) );
}

QPixmap QgsSymbolLayerV2Utils::symbolPreviewPixmap( QgsSymbolV2* symbol, QSize size )
{
  Q_ASSERT( symbol );

  QPixmap pixmap( size );
  pixmap.fill( Qt::transparent );
  QPainter painter;
  painter.begin( &pixmap );
  painter.setRenderHint( QPainter::Antialiasing );
  symbol->drawPreviewIcon( &painter, size );
  painter.end();
  return pixmap;
}


QIcon QgsSymbolLayerV2Utils::symbolLayerPreviewIcon( QgsSymbolLayerV2* layer, QgsSymbolV2::OutputUnit u, QSize size )
{
  QPixmap pixmap( size );
  pixmap.fill( Qt::transparent );
  QPainter painter;
  painter.begin( &pixmap );
  painter.setRenderHint( QPainter::Antialiasing );
  QgsRenderContext renderContext = createRenderContext( &painter );
  QgsSymbolV2RenderContext symbolContext( renderContext, u );
  layer->drawPreviewIcon( symbolContext, size );
  painter.end();
  return QIcon( pixmap );
}

QIcon QgsSymbolLayerV2Utils::colorRampPreviewIcon( QgsVectorColorRampV2* ramp, QSize size )
{
  return QIcon( colorRampPreviewPixmap( ramp, size ) );
}

QPixmap QgsSymbolLayerV2Utils::colorRampPreviewPixmap( QgsVectorColorRampV2* ramp, QSize size )
{
  QPixmap pixmap( size );
  pixmap.fill( Qt::transparent );
  // pixmap.fill( Qt::white ); // this makes the background white instead of transparent
  QPainter painter;
  painter.begin( &pixmap );

  //draw stippled background, for transparent images
  drawStippledBackround( &painter, QRect( 0, 0, size.width(), size.height() ) );

  // antialising makes the colors duller, and no point in antialiasing a color ramp
  // painter.setRenderHint( QPainter::Antialiasing );
  for ( int i = 0; i < size.width(); i++ )
  {
    QPen pen( ramp->color(( double ) i / size.width() ) );
    painter.setPen( pen );
    painter.drawLine( i, 0, i, size.height() - 1 );
  }
  painter.end();
  return pixmap;
}

void QgsSymbolLayerV2Utils::drawStippledBackround( QPainter* painter, QRect rect )
{
  // create a 2x2 checker-board image
  uchar pixDataRGB[] = { 255, 255, 255, 255,
                         127, 127, 127, 255,
                         127, 127, 127, 255,
                         255, 255, 255, 255
                       };
  QImage img( pixDataRGB, 2, 2, 8, QImage::Format_ARGB32 );
  // scale it to rect so at least 5 patterns are shown
  int width = ( rect.width() < rect.height() ) ?
              rect.width() / 2.5 : rect.height() / 2.5;
  QPixmap pix = QPixmap::fromImage( img.scaled( width, width ) );
  // fill rect with texture
  QBrush brush;
  brush.setTexture( pix );
  painter->fillRect( rect, brush );
}

#include <QPolygonF>

#include <cmath>
#include <cfloat>


// calculate line's angle and tangent
static bool lineInfo( QPointF p1, QPointF p2, double& angle, double& t )
{
  double x1 = p1.x(), y1 = p1.y(), x2 = p2.x(), y2 = p2.y();

  if ( x1 == x2 && y1 == y2 )
    return false;

  // tangent
  t = ( x1 == x2 ? DBL_MAX : ( y2 - y1 ) / ( x2 - x1 ) );

  // angle
  if ( t == DBL_MAX )
    angle = ( y2 > y1 ? M_PI / 2 : M_PI * 3 / 2 );  // angle is 90 or 270
  else if ( t == 0 )
    angle = ( x2 > x1 ? 0 : M_PI ); // angle is 0 or 180
  else if ( t >= 0 )
    angle = ( y2 > y1 ? atan( t ) : M_PI + atan( t ) );
  else // t < 0
    angle = ( y2 > y1 ? M_PI + atan( t ) : atan( t ) );

  return true;
}

// offset a point with an angle and distance
static QPointF offsetPoint( QPointF pt, double angle, double dist )
{
  return QPointF( pt.x() + dist * cos( angle ), pt.y() + dist * sin( angle ) );
}

// calc intersection of two (infinite) lines defined by one point and tangent
static QPointF linesIntersection( QPointF p1, double t1, QPointF p2, double t2 )
{
  // parallel lines? (or the difference between angles is less than appr. 10 degree)
  if (( t1 == DBL_MAX && t2 == DBL_MAX ) || qAbs( atan( t1 ) - atan( t2 ) ) < 0.175 )
    return QPointF();

  double x, y;
  if ( t1 == DBL_MAX || t2 == DBL_MAX )
  {
    // in case one line is with angle 90 resp. 270 degrees (tangent undefined)
    // swap them so that line 2 is with undefined tangent
    if ( t1 == DBL_MAX )
    {
      QPointF pSwp = p1; p1 = p2; p2 = pSwp;
      double  tSwp = t1; t1 = t2; t2 = tSwp;
    }

    x = p2.x();
  }
  else
  {
    // usual case
    x = (( p1.y() - p2.y() ) + t2 * p2.x() - t1 * p1.x() ) / ( t2 - t1 );
  }

  y = p1.y() + t1 * ( x - p1.x() );
  return QPointF( x, y );
}


QPolygonF offsetLine( QPolygonF polyline, double dist )
{
  QPolygonF newLine;

  if ( polyline.count() < 2 )
    return newLine;

  double angle = 0.0, t_new, t_old = 0;
  QPointF pt_old, pt_new;
  QPointF p1 = polyline[0], p2;
  bool first_point = true;

  for ( int i = 1; i < polyline.count(); i++ )
  {
    p2 = polyline[i];

    if ( !lineInfo( p1, p2, angle, t_new ) )
      continue; // not a line...

    pt_new = offsetPoint( p1, angle + M_PI / 2, dist );

    if ( ! first_point )
    {
      // if it's not the first line segment
      // calc intersection with last line (with offset)
      QPointF pt_tmp = linesIntersection( pt_old, t_old, pt_new, t_new );
      if ( !pt_tmp.isNull() )
        pt_new = pt_tmp;
    }

    newLine.append( pt_new );

    pt_old = pt_new;
    t_old = t_new;
    p1 = p2;
    first_point = false;
  }

  // last line segment:
  pt_new = offsetPoint( p2, angle + M_PI / 2, dist );
  newLine.append( pt_new );
  return newLine;
}



QgsSymbolV2* QgsSymbolLayerV2Utils::loadSymbol( QDomElement& element )
{
  QgsSymbolLayerV2List layers;
  QDomNode layerNode = element.firstChild();

  while ( !layerNode.isNull() )
  {
    QDomElement e = layerNode.toElement();
    if ( !e.isNull() )
    {
      if ( e.tagName() != "layer" )
      {
        QgsDebugMsg( "unknown tag " + e.tagName() );
      }
      else
      {
        QgsSymbolLayerV2* layer = loadSymbolLayer( e );

        if ( layer != NULL )
        {
          // Dealing with sub-symbols nested into a layer
          QDomElement s = e.firstChildElement( "symbol" );
          if ( !s.isNull() )
          {
            QgsSymbolV2* subSymbol = loadSymbol( s );
            bool res = layer->setSubSymbol( subSymbol );
            if ( !res )
            {
              QgsDebugMsg( "symbol layer refused subsymbol: " + s.attribute( "name" ) );
            }
          }
          layers.append( layer );
        }
      }
    }
    layerNode = layerNode.nextSibling();
  }

  if ( layers.count() == 0 )
  {
    QgsDebugMsg( "no layers for symbol" );
    return NULL;
  }

  QString symbolType = element.attribute( "type" );

  QgsSymbolV2* symbol = 0;
  if ( symbolType == "line" )
    symbol = new QgsLineSymbolV2( layers );
  else if ( symbolType == "fill" )
    symbol = new QgsFillSymbolV2( layers );
  else if ( symbolType == "marker" )
    symbol = new QgsMarkerSymbolV2( layers );
  else
  {
    QgsDebugMsg( "unknown symbol type " + symbolType );
    return NULL;
  }

  if ( element.hasAttribute( "outputUnit" ) )
  {
    symbol->setOutputUnit( decodeOutputUnit( element.attribute( "outputUnit" ) ) );
  }
  symbol->setAlpha( element.attribute( "alpha", "1.0" ).toDouble() );

  return symbol;
}

QgsSymbolLayerV2* QgsSymbolLayerV2Utils::loadSymbolLayer( QDomElement& element )
{
  QString layerClass = element.attribute( "class" );
  bool locked = element.attribute( "locked" ).toInt();
  int pass = element.attribute( "pass" ).toInt();

  // parse properties
  QgsStringMap props = parseProperties( element );

  QgsSymbolLayerV2* layer;
  layer = QgsSymbolLayerV2Registry::instance()->createSymbolLayer( layerClass, props );
  if ( layer )
  {
    layer->setLocked( locked );
    layer->setRenderingPass( pass );
    return layer;
  }
  else
  {
    QgsDebugMsg( "unknown class " + layerClass );
    return NULL;
  }
}

static QString _nameForSymbolType( QgsSymbolV2::SymbolType type )
{
  switch ( type )
  {
    case QgsSymbolV2::Line: return "line";
    case QgsSymbolV2::Marker: return "marker";
    case QgsSymbolV2::Fill: return "fill";
    default: return "";
  }
}

QDomElement QgsSymbolLayerV2Utils::saveSymbol( QString name, QgsSymbolV2* symbol, QDomDocument& doc )
{
  Q_ASSERT( symbol );
  QDomElement symEl = doc.createElement( "symbol" );
  symEl.setAttribute( "type", _nameForSymbolType( symbol->type() ) );
  symEl.setAttribute( "name", name );
  symEl.setAttribute( "alpha", QString::number( symbol->alpha() ) );
  QgsDebugMsg( "num layers " + QString::number( symbol->symbolLayerCount() ) );

  for ( int i = 0; i < symbol->symbolLayerCount(); i++ )
  {
    QgsSymbolLayerV2* layer = symbol->symbolLayer( i );

    QDomElement layerEl = doc.createElement( "layer" );
    layerEl.setAttribute( "class", layer->layerType() );
    layerEl.setAttribute( "locked", layer->isLocked() );
    layerEl.setAttribute( "pass", layer->renderingPass() );
    saveProperties( layer->properties(), doc, layerEl );
    if ( layer->subSymbol() != NULL )
    {
      QString subname = QString( "@%1@%2" ).arg( name ).arg( i );
      QDomElement subEl = saveSymbol( subname, layer->subSymbol(), doc );
      layerEl.appendChild( subEl );
    }
    symEl.appendChild( layerEl );
  }

  return symEl;
}


bool QgsSymbolLayerV2Utils::createSymbolLayerV2ListFromSld( QDomElement& element,
    QGis::GeometryType geomType,
    QgsSymbolLayerV2List &layers )
{
  QgsDebugMsg( "Entered." );

  if ( element.isNull() )
    return false;

  QgsSymbolLayerV2 *l = 0;

  QString symbolizerName = element.localName();

  if ( symbolizerName == "PointSymbolizer" )
  {
    // first check for Graphic element, nothing will be rendered if not found
    QDomElement graphicElem = element.firstChildElement( "Graphic" );
    if ( graphicElem.isNull() )
    {
      QgsDebugMsg( "Graphic element not found in PointSymbolizer" );
    }
    else
    {
      switch ( geomType )
      {
        case QGis::Polygon:
          // polygon layer and point symbolizer: draw poligon centroid
          l = QgsSymbolLayerV2Registry::instance()->createSymbolLayerFromSld( "CentroidFill", element );
          if ( l )
            layers.append( l );

          break;

        case QGis::Point:
          // point layer and point symbolizer: use markers
          l = createMarkerLayerFromSld( element );
          if ( l )
            layers.append( l );

          break;

        case QGis::Line:
          // line layer and point symbolizer: draw central point
          l = QgsSymbolLayerV2Registry::instance()->createSymbolLayerFromSld( "SimpleMarker", element );
          if ( l )
            layers.append( l );

          break;

        default:
          break;
      }
    }
  }

  if ( symbolizerName == "LineSymbolizer" )
  {
    // check for Stroke element, nothing will be rendered if not found
    QDomElement strokeElem = element.firstChildElement( "Stroke" );
    if ( strokeElem.isNull() )
    {
      QgsDebugMsg( "Stroke element not found in LineSymbolizer" );
    }
    else
    {
      switch ( geomType )
      {
        case QGis::Polygon:
        case QGis::Line:
          // polygon layer and line symbolizer: draw polygon outline
          // line layer and line symbolizer: draw line
          l = createLineLayerFromSld( element );
          if ( l )
            layers.append( l );

          break;

        case QGis::Point:
          // point layer and line symbolizer: draw a little line marker
          l = QgsSymbolLayerV2Registry::instance()->createSymbolLayerFromSld( "MarkerLine", element );
          if ( l )
            layers.append( l );

        default:
          break;
      }
    }
  }

  if ( symbolizerName == "PolygonSymbolizer" )
  {
    // get Fill and Stroke elements, nothing will be rendered if both are missing
    QDomElement fillElem = element.firstChildElement( "Fill" );
    QDomElement strokeElem = element.firstChildElement( "Stroke" );
    if ( fillElem.isNull() && strokeElem.isNull() )
    {
      QgsDebugMsg( "neither Fill nor Stroke element not found in PolygonSymbolizer" );
    }
    else
    {
      QgsSymbolLayerV2 *l = 0;

      switch ( geomType )
      {
        case QGis::Polygon:
          // polygon layer and polygon symbolizer: draw fill

          l = createFillLayerFromSld( element );
          if ( l )
          {
            layers.append( l );

            // SVGFill and SimpleFill symbolLayerV2 supports outline internally,
            // so don't go forward to create a different symbolLayerV2 for outline
            if ( l->layerType() == "SimpleFill" || l->layerType() == "SVGFill" )
              break;
          }

          // now create polygon outline
          // polygon layer and polygon symbolizer: draw polygon outline
          l = createLineLayerFromSld( element );
          if ( l )
            layers.append( l );

          break;

        case QGis::Line:
          // line layer and polygon symbolizer: draw line
          l = createLineLayerFromSld( element );
          if ( l )
            layers.append( l );

          break;

        case QGis::Point:
          // point layer and polygon symbolizer: draw a square marker
          convertPolygonSymbolizerToPointMarker( element, layers );
          break;

        default:
          break;
      }
    }
  }

  return true;
}

QgsSymbolLayerV2* QgsSymbolLayerV2Utils::createFillLayerFromSld( QDomElement &element )
{
  QDomElement fillElem = element.firstChildElement( "Fill" );
  if ( fillElem.isNull() )
  {
    QgsDebugMsg( "Fill element not found" );
    return NULL;
  }

  QgsSymbolLayerV2 *l = 0;

  if ( needLinePatternFill( element ) )
    l = QgsSymbolLayerV2Registry::instance()->createSymbolLayerFromSld( "LinePatternFill", element );
  else if ( needPointPatternFill( element ) )
    l = QgsSymbolLayerV2Registry::instance()->createSymbolLayerFromSld( "PointPatternFill", element );
  else if ( needSvgFill( element ) )
    l = QgsSymbolLayerV2Registry::instance()->createSymbolLayerFromSld( "SVGFill", element );
  else
    l = QgsSymbolLayerV2Registry::instance()->createSymbolLayerFromSld( "SimpleFill", element );

  return l;
}

QgsSymbolLayerV2* QgsSymbolLayerV2Utils::createLineLayerFromSld( QDomElement &element )
{
  QDomElement strokeElem = element.firstChildElement( "Stroke" );
  if ( strokeElem.isNull() )
  {
    QgsDebugMsg( "Stroke element not found" );
    return NULL;
  }

  QgsSymbolLayerV2 *l = 0;

  if ( needMarkerLine( element ) )
    l = QgsSymbolLayerV2Registry::instance()->createSymbolLayerFromSld( "MarkerLine", element );
  else
    l = QgsSymbolLayerV2Registry::instance()->createSymbolLayerFromSld( "SimpleLine", element );

  return l;
}

QgsSymbolLayerV2* QgsSymbolLayerV2Utils::createMarkerLayerFromSld( QDomElement &element )
{
  QDomElement graphicElem = element.firstChildElement( "Graphic" );
  if ( graphicElem.isNull() )
  {
    QgsDebugMsg( "Graphic element not found" );
    return NULL;
  }

  QgsSymbolLayerV2 *l = 0;

  if ( needFontMarker( element ) )
    l = QgsSymbolLayerV2Registry::instance()->createSymbolLayerFromSld( "FontMarker", element );
  else if ( needSvgMarker( element ) )
    l = QgsSymbolLayerV2Registry::instance()->createSymbolLayerFromSld( "SvgMarker", element );
  else if ( needEllipseMarker( element ) )
    l = QgsSymbolLayerV2Registry::instance()->createSymbolLayerFromSld( "EllipseMarker", element );
  else
    l = QgsSymbolLayerV2Registry::instance()->createSymbolLayerFromSld( "SimpleMarker", element );

  return l;
}

bool QgsSymbolLayerV2Utils::hasExternalGraphic( QDomElement &element )
{
  QDomElement graphicElem = element.firstChildElement( "Graphic" );
  if ( graphicElem.isNull() )
    return false;

  QDomElement externalGraphicElem = graphicElem.firstChildElement( "ExternalGraphic" );
  if ( externalGraphicElem.isNull() )
    return false;

  // check for format
  QDomElement formatElem = externalGraphicElem.firstChildElement( "Format" );
  if ( formatElem.isNull() )
    return false;

  QString format = formatElem.firstChild().nodeValue();
  if ( format != "image/svg+xml" )
  {
    QgsDebugMsg( "unsupported External Graphic format found: " + format );
    return false;
  }

  // check for a valid content
  QDomElement onlineResourceElem = externalGraphicElem.firstChildElement( "OnlineResource" );
  QDomElement inlineContentElem = externalGraphicElem.firstChildElement( "InlineContent" );
  if ( !onlineResourceElem.isNull() )
  {
    return true;
  }
  else if ( !inlineContentElem.isNull() )
  {
    return false; // not implemented yet
  }
  else
  {
    return false;
  }
}

bool QgsSymbolLayerV2Utils::hasWellKnownMark( QDomElement &element )
{
  QDomElement graphicElem = element.firstChildElement( "Graphic" );
  if ( graphicElem.isNull() )
    return false;

  QDomElement markElem = graphicElem.firstChildElement( "Mark" );
  if ( markElem.isNull() )
    return false;

  QDomElement wellKnownNameElem = markElem.firstChildElement( "WellKnownName" );
  if ( wellKnownNameElem.isNull() )
    return false;

  return true;
}


bool QgsSymbolLayerV2Utils::needFontMarker( QDomElement &element )
{
  QDomElement graphicElem = element.firstChildElement( "Graphic" );
  if ( graphicElem.isNull() )
    return false;

  QDomElement markElem = graphicElem.firstChildElement( "Mark" );
  if ( markElem.isNull() )
    return false;

  // check for format
  QDomElement formatElem = markElem.firstChildElement( "Format" );
  if ( formatElem.isNull() )
    return false;

  QString format = formatElem.firstChild().nodeValue();
  if ( format != "ttf" )
  {
    QgsDebugMsg( "unsupported Graphic Mark format found: " + format );
    return false;
  }

  // check for a valid content
  QDomElement onlineResourceElem = markElem.firstChildElement( "OnlineResource" );
  QDomElement inlineContentElem = markElem.firstChildElement( "InlineContent" );
  if ( !onlineResourceElem.isNull() )
  {
    // mark with ttf format has a markIndex element
    QDomElement markIndexElem = markElem.firstChildElement( "MarkIndex" );
    if ( !markIndexElem.isNull() )
      return true;
  }
  else if ( !inlineContentElem.isNull() )
  {
    return false; // not implemented yet
  }

  return false;
}

bool QgsSymbolLayerV2Utils::needSvgMarker( QDomElement &element )
{
  return hasExternalGraphic( element );
}

bool QgsSymbolLayerV2Utils::needEllipseMarker( QDomElement &element )
{
  QDomElement graphicElem = element.firstChildElement( "Graphic" );
  if ( graphicElem.isNull() )
    return false;

  QgsStringMap vendorOptions = QgsSymbolLayerV2Utils::getVendorOptionList( graphicElem );
  for ( QgsStringMap::iterator it = vendorOptions.begin(); it != vendorOptions.end(); ++it )
  {
    if ( it.key() == "widthHeightFactor" )
    {
      return true;
    }
  }

  return false;
}

bool QgsSymbolLayerV2Utils::needMarkerLine( QDomElement &element )
{
  QDomElement strokeElem = element.firstChildElement( "Stroke" );
  if ( strokeElem.isNull() )
    return false;

  QDomElement graphicStrokeElem = strokeElem.firstChildElement( "GraphicStroke" );
  if ( graphicStrokeElem.isNull() )
    return false;

  return hasWellKnownMark( graphicStrokeElem );
}

bool QgsSymbolLayerV2Utils::needLinePatternFill( QDomElement &element )
{
  QDomElement fillElem = element.firstChildElement( "Fill" );
  if ( fillElem.isNull() )
    return false;

  QDomElement graphicFillElem = fillElem.firstChildElement( "GraphicFill" );
  if ( graphicFillElem.isNull() )
    return false;

  QDomElement graphicElem = graphicFillElem.firstChildElement( "Graphic" );
  if ( graphicElem.isNull() )
    return false;

  // line pattern fill uses horline wellknown marker with an angle

  QString name;
  QColor fillColor, borderColor;
  double size, borderWidth;
  if ( !wellKnownMarkerFromSld( graphicElem, name, fillColor, borderColor, borderWidth, size ) )
    return false;

  if ( name != "horline" )
    return false;

  QString angleFunc;
  if ( !rotationFromSldElement( graphicElem, angleFunc ) )
    return false;

  bool ok;
  double angle = angleFunc.toDouble( &ok );
  if ( !ok || angle == 0 )
    return false;

  return true;
}

bool QgsSymbolLayerV2Utils::needPointPatternFill( QDomElement &element )
{
  Q_UNUSED( element );
  return false;
}

bool QgsSymbolLayerV2Utils::needSvgFill( QDomElement &element )
{
  QDomElement fillElem = element.firstChildElement( "Fill" );
  if ( fillElem.isNull() )
    return false;

  QDomElement graphicFillElem = fillElem.firstChildElement( "GraphicFill" );
  if ( graphicFillElem.isNull() )
    return false;

  return hasExternalGraphic( graphicFillElem );
}


bool QgsSymbolLayerV2Utils::convertPolygonSymbolizerToPointMarker( QDomElement &element, QgsSymbolLayerV2List &layerList )
{
  QgsDebugMsg( "Entered." );

  /* SE 1.1 says about PolygonSymbolizer:
     if a point geometry is referenced instead of a polygon,
     then a small, square, ortho-normal polygon should be
     constructed for rendering.
   */

  QgsSymbolLayerV2List layers;

  // retrieve both Fill and Stroke elements
  QDomElement fillElem = element.firstChildElement( "Fill" );
  QDomElement strokeElem = element.firstChildElement( "Stroke" );

  // first symbol layer
  {
    bool validFill = false, validBorder = false;

    // check for simple fill
    // Fill element can contain some SvgParameter elements
    QColor fillColor;
    Qt::BrushStyle fillStyle;

    if ( fillFromSld( fillElem, fillStyle, fillColor ) )
      validFill = true;

    // check for simple outline
    // Stroke element can contain some SvgParameter elements
    QColor borderColor;
    Qt::PenStyle borderStyle;
    double borderWidth = 1.0, dashOffset = 0.0;
    QVector<qreal> customDashPattern;

    if ( lineFromSld( strokeElem, borderStyle, borderColor, borderWidth,
                      0, 0, &customDashPattern, &dashOffset ) )
      validBorder = true;

    if ( validFill || validBorder )
    {
      QgsStringMap map;
      map["name"] = "square";
      map["color"] = encodeColor( validFill ? fillColor : Qt::transparent );
      map["color_border"] = encodeColor( validBorder ? borderColor : Qt::transparent );
      map["size"] = QString::number( 6 );
      map["angle"] = QString::number( 0 );
      map["offset"] = encodePoint( QPointF( 0, 0 ) );
      layers.append( QgsSymbolLayerV2Registry::instance()->createSymbolLayer( "SimpleMarker", map ) );
    }
  }

  // second symbol layer
  {
    bool validFill = false, validBorder = false;

    // check for graphic fill
    QString name, format;
    int markIndex = -1;
    QColor fillColor, borderColor;
    double borderWidth = 1.0, size = 0.0, angle = 0.0;
    QPointF anchor, offset;

    // Fill element can contain a GraphicFill element
    QDomElement graphicFillElem = fillElem.firstChildElement( "GraphicFill" );
    if ( !graphicFillElem.isNull() )
    {
      // GraphicFill element must contain a Graphic element
      QDomElement graphicElem = graphicFillElem.firstChildElement( "Graphic" );
      if ( !graphicElem.isNull() )
      {
        // Graphic element can contains some ExternalGraphic and Mark element
        // search for the first supported one and use it
        bool found = false;

        QDomElement graphicChildElem = graphicElem.firstChildElement();
        while ( !graphicChildElem.isNull() )
        {
          if ( graphicChildElem.localName() == "Mark" )
          {
            // check for a well known name
            QDomElement wellKnownNameElem = graphicChildElem.firstChildElement( "WellKnownName" );
            if ( !wellKnownNameElem.isNull() )
            {
              name = wellKnownNameElem.firstChild().nodeValue();
              found = true;
              break;
            }
          }

          if ( graphicChildElem.localName() == "ExternalGraphic" || graphicChildElem.localName() == "Mark" )
          {
            // check for external graphic format
            QDomElement formatElem = graphicChildElem.firstChildElement( "Format" );
            if ( formatElem.isNull() )
              continue;

            format = formatElem.firstChild().nodeValue();

            // TODO: remove this check when more formats will be supported
            // only SVG external graphics are supported in this moment
            if ( graphicChildElem.localName() == "ExternalGraphic" && format != "image/svg+xml" )
              continue;

            // TODO: remove this check when more formats will be supported
            // only ttf marks are supported in this moment
            if ( graphicChildElem.localName() == "Mark" && format != "ttf" )
              continue;

            // check for a valid content
            QDomElement onlineResourceElem = graphicChildElem.firstChildElement( "OnlineResource" );
            QDomElement inlineContentElem = graphicChildElem.firstChildElement( "InlineContent" );

            if ( !onlineResourceElem.isNull() )
            {
              name = onlineResourceElem.attributeNS( "http://www.w3.org/1999/xlink", "href" );

              if ( graphicChildElem.localName() == "Mark" && format == "ttf" )
              {
                // mark with ttf format may have a name like ttf://fontFamily
                if ( name.startsWith( "ttf://" ) )
                  name = name.mid( 6 );

                // mark with ttf format has a markIndex element
                QDomElement markIndexElem = graphicChildElem.firstChildElement( "MarkIndex" );
                if ( markIndexElem.isNull() )
                  continue;

                bool ok;
                int v = markIndexElem.firstChild().nodeValue().toInt( &ok );
                if ( !ok || v < 0 )
                  continue;

                markIndex = v;
              }

              found = true;
              break;
            }
            else if ( !inlineContentElem.isNull() )
              continue; // TODO: not implemeneted yet
            else
              continue;
          }

          // if Mark element is present but it doesn't contains neither
          // WellKnownName nor OnlineResource nor InlineContent,
          // use the default mark (square)
          if ( graphicChildElem.localName() == "Mark" )
          {
            name = "square";
            found = true;
            break;
          }
        }

        // if found a valid Mark, check for its Fill and Stroke element
        if ( found && graphicChildElem.localName() == "Mark" )
        {
          // XXX: recursive definition!?! couldn't be dangerous???
          // to avoid recursion we handle only simple fill and simple stroke

          // check for simple fill
          // Fill element can contain some SvgParameter elements
          Qt::BrushStyle markFillStyle;

          QDomElement markFillElem = graphicChildElem.firstChildElement( "Fill" );
          if ( fillFromSld( markFillElem, markFillStyle, fillColor ) )
            validFill = true;

          // check for simple outline
          // Stroke element can contain some SvgParameter elements
          Qt::PenStyle borderStyle;
          double borderWidth = 1.0, dashOffset = 0.0;
          QVector<qreal> customDashPattern;

          QDomElement markStrokeElem = graphicChildElem.firstChildElement( "Stroke" );
          if ( lineFromSld( markStrokeElem, borderStyle, borderColor, borderWidth,
                            0, 0, &customDashPattern, &dashOffset ) )
            validBorder = true;
        }

        if ( found )
        {
          // check for Opacity, Size, Rotation, AnchorPoint, Displacement
          QDomElement opacityElem = graphicElem.firstChildElement( "Opacity" );
          if ( !opacityElem.isNull() )
            fillColor.setAlpha( decodeSldAlpha( opacityElem.firstChild().nodeValue() ) );

          QDomElement sizeElem = graphicElem.firstChildElement( "Size" );
          if ( !sizeElem.isNull() )
          {
            bool ok;
            double v = sizeElem.firstChild().nodeValue().toDouble( &ok );
            if ( ok && v > 0 )
              size = v;
          }

          QString angleFunc;
          if ( rotationFromSldElement( graphicElem, angleFunc ) && !angleFunc.isEmpty() )
          {
            bool ok;
            double v = angleFunc.toDouble( &ok );
            if ( ok )
              angle = v;
          }

          displacementFromSldElement( graphicElem, offset );
        }
      }
    }

    if ( validFill || validBorder )
    {
      if ( format == "image/svg+xml" )
      {
        QgsStringMap map;
        map["name"] = name;
        map["fill"] = fillColor.name();
        map["outline"] = borderColor.name();
        map["outline-width"] = QString::number( borderWidth );
        if ( !qgsDoubleNear( size, 0.0 ) )
          map["size"] = QString::number( size );
        if ( !qgsDoubleNear( angle, 0.0 ) )
          map["angle"] = QString::number( angle );
        if ( !offset.isNull() )
          map["offset"] = encodePoint( offset );
        layers.append( QgsSymbolLayerV2Registry::instance()->createSymbolLayer( "SvgMarker", map ) );
      }
      else if ( format == "ttf" )
      {
        QgsStringMap map;
        map["font"] = name;
        map["chr"] = markIndex;
        map["color"] = encodeColor( validFill ? fillColor : Qt::transparent );
        if ( size > 0 )
          map["size"] = QString::number( size );
        if ( !qgsDoubleNear( angle, 0.0 ) )
          map["angle"] = QString::number( angle );
        if ( !offset.isNull() )
          map["offset"] = encodePoint( offset );
        layers.append( QgsSymbolLayerV2Registry::instance()->createSymbolLayer( "FontMarker", map ) );
      }
    }
  }

  if ( layers.isEmpty() )
    return false;

  layerList << layers;
  layers.clear();
  return true;
}

void QgsSymbolLayerV2Utils::fillToSld( QDomDocument &doc, QDomElement &element, Qt::BrushStyle brushStyle, QColor color )
{
  QString patternName;
  switch ( brushStyle )
  {
    case Qt::NoBrush:
      return;

    case Qt::SolidPattern:
      if ( color.isValid() )
      {
        element.appendChild( createSvgParameterElement( doc, "fill", color.name() ) );
        if ( color.alpha() < 255 )
          element.appendChild( createSvgParameterElement( doc, "fill-opacity", encodeSldAlpha( color.alpha() ) ) );
      }
      return;

    case Qt::CrossPattern:
    case Qt::DiagCrossPattern:
    case Qt::HorPattern:
    case Qt::VerPattern:
    case Qt::BDiagPattern:
    case Qt::FDiagPattern:
    case Qt::Dense1Pattern:
    case Qt::Dense2Pattern:
    case Qt::Dense3Pattern:
    case Qt::Dense4Pattern:
    case Qt::Dense5Pattern:
    case Qt::Dense6Pattern:
    case Qt::Dense7Pattern:
      patternName = encodeSldBrushStyle( brushStyle );
      break;

    default:
      element.appendChild( doc.createComment( QString( "Qt::BrushStyle '%1'' not supported yet" ).arg( brushStyle ) ) );
      return;
  }

  QDomElement graphicFillElem = doc.createElement( "se:GraphicFill" );
  element.appendChild( graphicFillElem );

  QDomElement graphicElem = doc.createElement( "se:Graphic" );
  graphicFillElem.appendChild( graphicElem );

  QColor fillColor = patternName.startsWith( "brush://" ) ? color : QColor();
  QColor borderColor = !patternName.startsWith( "brush://" ) ? color : QColor();

  /* Use WellKnownName tag to handle QT brush styles. */
  wellKnownMarkerToSld( doc, graphicElem, patternName, fillColor, borderColor );
}

bool QgsSymbolLayerV2Utils::fillFromSld( QDomElement &element, Qt::BrushStyle &brushStyle, QColor &color )
{
  QgsDebugMsg( "Entered." );

  brushStyle = Qt::SolidPattern;
  color = QColor( "#808080" );

  if ( element.isNull() )
  {
    brushStyle = Qt::NoBrush;
    color = QColor();
    return true;
  }

  QDomElement graphicFillElem = element.firstChildElement( "GraphicFill" );
  // if no GraphicFill element is found, it's a solid fill
  if ( graphicFillElem.isNull() )
  {
    QgsStringMap svgParams = getSvgParameterList( element );
    for ( QgsStringMap::iterator it = svgParams.begin(); it != svgParams.end(); ++it )
    {
      QgsDebugMsg( QString( "found SvgParameter %1: %2" ).arg( it.key() ).arg( it.value() ) );

      if ( it.key() == "fill" )
        color = QColor( it.value() );
      else if ( it.key() == "fill-opacity" )
        color.setAlpha( decodeSldAlpha( it.value() ) );
    }
  }
  else  // wellKnown marker
  {
    QDomElement graphicElem = graphicFillElem.firstChildElement( "Graphic" );
    if ( graphicElem.isNull() )
      return false; // Graphic is required within GraphicFill

    QString patternName = "square";
    QColor fillColor, borderColor;
    double borderWidth, size;
    if ( !wellKnownMarkerFromSld( graphicElem, patternName, fillColor, borderColor, borderWidth, size ) )
      return false;

    brushStyle = decodeSldBrushStyle( patternName );
    if ( brushStyle == Qt::NoBrush )
      return false; // unable to decode brush style

    QColor c = patternName.startsWith( "brush://" ) ? fillColor : borderColor;
    if ( c.isValid() )
      color = c;
  }

  return true;
}

void QgsSymbolLayerV2Utils::lineToSld( QDomDocument &doc, QDomElement &element,
                                       Qt::PenStyle penStyle, QColor color, double width,
                                       const Qt::PenJoinStyle *penJoinStyle, const Qt::PenCapStyle *penCapStyle,
                                       const QVector<qreal> *customDashPattern, double dashOffset )
{
  QVector<qreal> dashPattern;
  const QVector<qreal> *pattern = &dashPattern;

  if ( penStyle == Qt::CustomDashLine && !customDashPattern )
  {
    element.appendChild( doc.createComment( "WARNING: Custom dash pattern required but not provided. Using default dash pattern." ) );
    penStyle = Qt::DashLine;
  }

  switch ( penStyle )
  {
    case Qt::NoPen:
      return;

    case Qt::SolidLine:
      break;

    case Qt::DashLine:
      dashPattern.push_back( 4.0 );
      dashPattern.push_back( 2.0 );
      break;
    case Qt::DotLine:
      dashPattern.push_back( 1.0 );
      dashPattern.push_back( 2.0 );
      break;
    case Qt::DashDotLine:
      dashPattern.push_back( 4.0 );
      dashPattern.push_back( 2.0 );
      dashPattern.push_back( 1.0 );
      dashPattern.push_back( 2.0 );
      break;
    case Qt::DashDotDotLine:
      dashPattern.push_back( 4.0 );
      dashPattern.push_back( 2.0 );
      dashPattern.push_back( 1.0 );
      dashPattern.push_back( 2.0 );
      dashPattern.push_back( 1.0 );
      dashPattern.push_back( 2.0 );
      break;

    case Qt::CustomDashLine:
      Q_ASSERT( customDashPattern );
      pattern = customDashPattern;
      break;

    default:
      element.appendChild( doc.createComment( QString( "Qt::BrushStyle '%1'' not supported yet" ).arg( penStyle ) ) );
      return;
  }

  if ( color.isValid() )
  {
    element.appendChild( createSvgParameterElement( doc, "stroke", color.name() ) );
    if ( color.alpha() < 255 )
      element.appendChild( createSvgParameterElement( doc, "stroke-opacity", encodeSldAlpha( color.alpha() ) ) );
  }
  if ( width > 0 )
    element.appendChild( createSvgParameterElement( doc, "stroke-width", QString::number( width ) ) );
  if ( penJoinStyle )
    element.appendChild( createSvgParameterElement( doc, "stroke-linejoin", encodeSldLineJoinStyle( *penJoinStyle ) ) );
  if ( penCapStyle )
    element.appendChild( createSvgParameterElement( doc, "stroke-linecap", encodeSldLineCapStyle( *penCapStyle ) ) );

  if ( pattern->size() > 0 )
  {
    element.appendChild( createSvgParameterElement( doc, "stroke-dasharray", encodeSldRealVector( *pattern ) ) );
    if ( !qgsDoubleNear( dashOffset, 0.0 ) )
      element.appendChild( createSvgParameterElement( doc, "stroke-dashoffset", QString::number( dashOffset ) ) );
  }
}


bool QgsSymbolLayerV2Utils::lineFromSld( QDomElement &element,
    Qt::PenStyle &penStyle, QColor &color, double &width,
    Qt::PenJoinStyle *penJoinStyle, Qt::PenCapStyle *penCapStyle,
    QVector<qreal> *customDashPattern, double *dashOffset )
{
  QgsDebugMsg( "Entered." );

  penStyle = Qt::SolidLine;
  color = QColor( "#000000" );
  width = 1;
  if ( penJoinStyle )
    *penJoinStyle = Qt::BevelJoin;
  if ( penCapStyle )
    *penCapStyle = Qt::SquareCap;
  if ( customDashPattern )
    customDashPattern->clear();
  if ( dashOffset )
    *dashOffset = 0;

  if ( element.isNull() )
  {
    penStyle = Qt::NoPen;
    color = QColor();
    return true;
  }

  QgsStringMap svgParams = getSvgParameterList( element );
  for ( QgsStringMap::iterator it = svgParams.begin(); it != svgParams.end(); ++it )
  {
    QgsDebugMsg( QString( "found SvgParameter %1: %2" ).arg( it.key() ).arg( it.value() ) );

    if ( it.key() == "stroke" )
    {
      color = QColor( it.value() );
    }
    else if ( it.key() == "stroke-opacity" )
    {
      color.setAlpha( decodeSldAlpha( it.value() ) );
    }
    else if ( it.key() == "stroke-width" )
    {
      bool ok;
      double w = it.value().toDouble( &ok );
      if ( ok )
        width = w;
    }
    else if ( it.key() == "stroke-linejoin" && penJoinStyle )
    {
      *penJoinStyle = decodeSldLineJoinStyle( it.value() );
    }
    else if ( it.key() == "stroke-linecap" && penCapStyle )
    {
      *penCapStyle = decodeSldLineCapStyle( it.value() );
    }
    else if ( it.key() == "stroke-dasharray" )
    {
      QVector<qreal> dashPattern = decodeSldRealVector( it.value() );
      if ( dashPattern.size() > 0 )
      {
        // convert the dasharray to one of the QT pen style,
        // if no match is found then set pen style to CustomDashLine
        bool dashPatternFound = false;

        if ( dashPattern.count() == 2 )
        {
          if ( dashPattern.at( 0 ) == 4.0 &&
               dashPattern.at( 1 ) == 2.0 )
          {
            penStyle = Qt::DashLine;
            dashPatternFound = true;
          }
          else if ( dashPattern.at( 0 ) == 1.0 &&
                    dashPattern.at( 1 ) == 2.0 )
          {
            penStyle = Qt::DotLine;
            dashPatternFound = true;
          }
        }
        else if ( dashPattern.count() == 4 )
        {
          if ( dashPattern.at( 0 ) == 4.0 &&
               dashPattern.at( 1 ) == 2.0 &&
               dashPattern.at( 2 ) == 1.0 &&
               dashPattern.at( 3 ) == 2.0 )
          {
            penStyle = Qt::DashDotLine;
            dashPatternFound = true;
          }
        }
        else if ( dashPattern.count() == 6 )
        {
          if ( dashPattern.at( 0 ) == 4.0 &&
               dashPattern.at( 1 ) == 2.0 &&
               dashPattern.at( 2 ) == 1.0 &&
               dashPattern.at( 3 ) == 2.0 &&
               dashPattern.at( 4 ) == 1.0 &&
               dashPattern.at( 5 ) == 2.0 )
          {
            penStyle = Qt::DashDotDotLine;
            dashPatternFound = true;
          }
        }

        // default case: set pen style to CustomDashLine
        if ( !dashPatternFound )
        {
          if ( customDashPattern )
          {
            penStyle = Qt::CustomDashLine;
            *customDashPattern = dashPattern;
          }
          else
          {
            QgsDebugMsg( "custom dash pattern required but not provided. Using default dash pattern." );
            penStyle = Qt::DashLine;
          }
        }
      }
    }
    else if ( it.key() == "stroke-dashoffset" && dashOffset )
    {
      bool ok;
      double d = it.value().toDouble( &ok );
      if ( ok )
        *dashOffset = d;
    }
  }

  return true;
}

void QgsSymbolLayerV2Utils::externalGraphicToSld( QDomDocument &doc, QDomElement &element,
    QString path, QString mime,
    QColor color, double size )
{
  QDomElement externalGraphicElem = doc.createElement( "se:ExternalGraphic" );
  element.appendChild( externalGraphicElem );

  createOnlineResourceElement( doc, externalGraphicElem, path, mime );

  //TODO: missing a way to handle svg color. Should use <se:ColorReplacement>
  Q_UNUSED( color );

  if ( size >= 0 )
  {
    QDomElement sizeElem = doc.createElement( "se:Size" );
    sizeElem.appendChild( doc.createTextNode( QString::number( size ) ) );
    element.appendChild( sizeElem );
  }
}

bool QgsSymbolLayerV2Utils::externalGraphicFromSld( QDomElement &element,
    QString &path, QString &mime,
    QColor &color, double &size )
{
  QgsDebugMsg( "Entered." );
  Q_UNUSED( color );

  QDomElement externalGraphicElem = element.firstChildElement( "ExternalGraphic" );
  if ( externalGraphicElem.isNull() )
    return false;

  onlineResourceFromSldElement( externalGraphicElem, path, mime );

  QDomElement sizeElem = element.firstChildElement( "Size" );
  if ( !sizeElem.isNull() )
  {
    bool ok;
    double s = sizeElem.firstChild().nodeValue().toDouble( &ok );
    if ( ok )
      size = s;
  }

  return true;
}

void QgsSymbolLayerV2Utils::externalMarkerToSld( QDomDocument &doc, QDomElement &element,
    QString path, QString format, int *markIndex,
    QColor color, double size )
{
  QDomElement markElem = doc.createElement( "se:Mark" );
  element.appendChild( markElem );

  createOnlineResourceElement( doc, markElem, path, format );

  if ( markIndex )
  {
    QDomElement markIndexElem = doc.createElement( "se:MarkIndex" );
    markIndexElem.appendChild( doc.createTextNode( QString::number( *markIndex ) ) );
    markElem.appendChild( markIndexElem );
  }

  // <Fill>
  QDomElement fillElem = doc.createElement( "se:Fill" );
  fillToSld( doc, fillElem, Qt::SolidPattern, color );
  markElem.appendChild( fillElem );

  // <Size>
  if ( !qgsDoubleNear( size, 0.0 ) && size > 0 )
  {
    QDomElement sizeElem = doc.createElement( "se:Size" );
    sizeElem.appendChild( doc.createTextNode( QString::number( size ) ) );
    element.appendChild( sizeElem );
  }
}

bool QgsSymbolLayerV2Utils::externalMarkerFromSld( QDomElement &element,
    QString &path, QString &format, int &markIndex,
    QColor &color, double &size )
{
  QgsDebugMsg( "Entered." );

  color = QColor();
  markIndex = -1;
  size = -1;

  QDomElement markElem = element.firstChildElement( "Mark" );
  if ( markElem.isNull() )
    return false;

  onlineResourceFromSldElement( markElem, path, format );

  QDomElement markIndexElem = markElem.firstChildElement( "MarkIndex" );
  if ( !markIndexElem.isNull() )
  {
    bool ok;
    int i = markIndexElem.firstChild().nodeValue().toInt( &ok );
    if ( ok )
      markIndex = i;
  }

  // <Fill>
  QDomElement fillElem = markElem.firstChildElement( "Fill" );
  Qt::BrushStyle b = Qt::SolidPattern;
  fillFromSld( fillElem, b, color );
  // ignore brush style, solid expected

  // <Size>
  QDomElement sizeElem = element.firstChildElement( "Size" );
  if ( !sizeElem.isNull() )
  {
    bool ok;
    double s = sizeElem.firstChild().nodeValue().toDouble( &ok );
    if ( ok )
      size = s;
  }

  return true;
}

void QgsSymbolLayerV2Utils::wellKnownMarkerToSld( QDomDocument &doc, QDomElement &element,
    QString name, QColor color, QColor borderColor,
    double borderWidth, double size )
{
  QDomElement markElem = doc.createElement( "se:Mark" );
  element.appendChild( markElem );

  QDomElement wellKnownNameElem = doc.createElement( "se:WellKnownName" );
  wellKnownNameElem.appendChild( doc.createTextNode( name ) );
  markElem.appendChild( wellKnownNameElem );

  // <Fill>
  if ( color.isValid() )
  {
    QDomElement fillElem = doc.createElement( "se:Fill" );
    fillToSld( doc, fillElem, Qt::SolidPattern, color );
    markElem.appendChild( fillElem );
  }

  // <Stroke>
  if ( borderColor.isValid() )
  {
    QDomElement strokeElem = doc.createElement( "se:Stroke" );
    lineToSld( doc, strokeElem, Qt::SolidLine, borderColor, borderWidth );
    markElem.appendChild( strokeElem );
  }

  // <Size>
  if ( !qgsDoubleNear( size, 0.0 ) && size > 0 )
  {
    QDomElement sizeElem = doc.createElement( "se:Size" );
    sizeElem.appendChild( doc.createTextNode( QString::number( size ) ) );
    element.appendChild( sizeElem );
  }
}

bool QgsSymbolLayerV2Utils::wellKnownMarkerFromSld( QDomElement &element,
    QString &name, QColor &color, QColor &borderColor,
    double &borderWidth, double &size )
{
  QgsDebugMsg( "Entered." );

  name = "square";
  color = QColor();
  borderColor = QColor( "#000000" );
  borderWidth = 1;
  size = 6;

  QDomElement markElem = element.firstChildElement( "Mark" );
  if ( markElem.isNull() )
    return false;

  QDomElement wellKnownNameElem = markElem.firstChildElement( "WellKnownName" );
  if ( !wellKnownNameElem.isNull() )
  {
    name = wellKnownNameElem.firstChild().nodeValue();
    QgsDebugMsg( "found Mark with well known name: " + name );
  }

  // <Fill>
  QDomElement fillElem = markElem.firstChildElement( "Fill" );
  Qt::BrushStyle b = Qt::SolidPattern;
  fillFromSld( fillElem, b, color );
  // ignore brush style, solid expected

  // <Stroke>
  QDomElement strokeElem = markElem.firstChildElement( "Stroke" );
  Qt::PenStyle p = Qt::SolidLine;
  lineFromSld( strokeElem, p, borderColor, borderWidth );
  // ignore border style, solid expected

  // <Size>
  QDomElement sizeElem = element.firstChildElement( "Size" );
  if ( !sizeElem.isNull() )
  {
    bool ok;
    double s = sizeElem.firstChild().nodeValue().toDouble( &ok );
    if ( ok )
      size = s;
  }

  return true;
}

void QgsSymbolLayerV2Utils::createRotationElement( QDomDocument &doc, QDomElement &element, QString rotationFunc )
{
  if ( !rotationFunc.isEmpty() )
  {
    QDomElement rotationElem = doc.createElement( "se:Rotation" );
    createFunctionElement( doc, rotationElem, rotationFunc );
    element.appendChild( rotationElem );
  }
}

bool QgsSymbolLayerV2Utils::rotationFromSldElement( QDomElement &element, QString &rotationFunc )
{
  QDomElement rotationElem = element.firstChildElement( "Rotation" );
  if ( !rotationElem.isNull() )
  {
    return functionFromSldElement( rotationElem, rotationFunc );
  }
  return true;
}


void QgsSymbolLayerV2Utils::createOpacityElement( QDomDocument &doc, QDomElement &element, QString alphaFunc )
{
  if ( !alphaFunc.isEmpty() )
  {
    QDomElement opacityElem = doc.createElement( "se:Opacity" );
    createFunctionElement( doc, opacityElem, alphaFunc );
    element.appendChild( opacityElem );
  }
}

bool QgsSymbolLayerV2Utils::opacityFromSldElement( QDomElement &element, QString &alphaFunc )
{
  QDomElement opacityElem = element.firstChildElement( "Opacity" );
  if ( !opacityElem.isNull() )
  {
    return functionFromSldElement( opacityElem, alphaFunc );
  }
  return true;
}

void QgsSymbolLayerV2Utils::createDisplacementElement( QDomDocument &doc, QDomElement &element, QPointF offset )
{
  if ( offset.isNull() )
    return;

  QDomElement displacementElem = doc.createElement( "se:Displacement" );
  element.appendChild( displacementElem );

  QDomElement dispXElem = doc.createElement( "se:DisplacementX" );
  dispXElem.appendChild( doc.createTextNode( QString::number( offset.x() ) ) );

  QDomElement dispYElem = doc.createElement( "se:DisplacementY" );
  dispYElem.appendChild( doc.createTextNode( QString::number( offset.y() ) ) );

  displacementElem.appendChild( dispXElem );
  displacementElem.appendChild( dispYElem );
}

bool QgsSymbolLayerV2Utils::displacementFromSldElement( QDomElement &element, QPointF &offset )
{
  offset = QPointF( 0, 0 );

  QDomElement displacementElem = element.firstChildElement( "Displacement" );
  if ( displacementElem.isNull() )
    return true;

  QDomElement dispXElem = displacementElem.firstChildElement( "DisplacementX" );
  if ( !dispXElem.isNull() )
  {
    bool ok;
    double offsetX = dispXElem.firstChild().nodeValue().toDouble( &ok );
    if ( ok )
      offset.setX( offsetX );
  }

  QDomElement dispYElem = displacementElem.firstChildElement( "DisplacementY" );
  if ( !dispYElem.isNull() )
  {
    bool ok;
    double offsetY = dispYElem.firstChild().nodeValue().toDouble( &ok );
    if ( ok )
      offset.setY( offsetY );
  }

  return true;
}

void QgsSymbolLayerV2Utils::labelTextToSld( QDomDocument &doc, QDomElement &element,
    QString label, QFont font,
    QColor color, double size )
{
  QDomElement labelElem = doc.createElement( "se:Label" );
  labelElem.appendChild( doc.createTextNode( label ) );
  element.appendChild( labelElem );

  QDomElement fontElem = doc.createElement( "se:Font" );
  element.appendChild( fontElem );

  fontElem.appendChild( createSvgParameterElement( doc, "font-family", font.family() ) );
#if 0
  fontElem.appendChild( createSldParameterElement( doc, "font-style", encodeSldFontStyle( font.style() ) ) );
  fontElem.appendChild( createSldParameterElement( doc, "font-weight", encodeSldFontWeight( font.weight() ) ) );
#endif
  fontElem.appendChild( createSvgParameterElement( doc, "font-size", QString::number( size ) ) );

  // <Fill>
  if ( color.isValid() )
  {
    QDomElement fillElem = doc.createElement( "Fill" );
    fillToSld( doc, fillElem, Qt::SolidPattern, color );
    element.appendChild( fillElem );
  }
}

QString QgsSymbolLayerV2Utils::ogrFeatureStylePen( double width, double mmScaleFactor, double mapUnitScaleFactor, const QColor& c,
    Qt::PenJoinStyle joinStyle,
    Qt::PenCapStyle capStyle,
    double offset,
    const QVector<qreal>* dashPattern )
{
  QString penStyle;
  penStyle.append( "PEN(" );
  penStyle.append( "c:" );
  penStyle.append( c.name() );
  penStyle.append( ",w:" );
  //dxf driver writes ground units as mm? Should probably be changed in ogr
  penStyle.append( QString::number( width * mmScaleFactor ) );
  penStyle.append( "mm" );

  //dash dot vector
  if ( dashPattern && dashPattern->size() > 0 )
  {
    penStyle.append( ",p:\"" );
    QVector<qreal>::const_iterator pIt = dashPattern->constBegin();
    for ( ; pIt != dashPattern->constEnd(); ++pIt )
    {
      if ( pIt != dashPattern->constBegin() )
      {
        penStyle.append( " " );
      }
      penStyle.append( QString::number( *pIt * mapUnitScaleFactor ) );
      penStyle.append( "g" );
    }
    penStyle.append( "\"" );
  }

  //cap
  penStyle.append( ",cap:" );
  switch ( capStyle )
  {
    case Qt::SquareCap:
      penStyle.append( "p" );
      break;
    case Qt::RoundCap:
      penStyle.append( "r" );
      break;
    case Qt::FlatCap:
    default:
      penStyle.append( "b" );
  }

  //join
  penStyle.append( ",j:" );
  switch ( joinStyle )
  {
    case Qt::BevelJoin:
      penStyle.append( "b" );
      break;
    case Qt::RoundJoin:
      penStyle.append( "r" );
      break;
    case Qt::MiterJoin:
    default:
      penStyle.append( "m" );
  }

  //offset
  if ( !qgsDoubleNear( offset, 0.0 ) )
  {
    penStyle.append( ",dp:" );
    penStyle.append( QString::number( offset * mapUnitScaleFactor ) );
    penStyle.append( "g" );
  }

  penStyle.append( ")" );
  return penStyle;
}

QString QgsSymbolLayerV2Utils::ogrFeatureStyleBrush( const QColor& fillColor )
{
  QString brushStyle;
  brushStyle.append( "BRUSH(" );
  brushStyle.append( "fc:" );
  brushStyle.append( fillColor.name() );
  brushStyle.append( ")" );
  return brushStyle;
}

void QgsSymbolLayerV2Utils::createGeometryElement( QDomDocument &doc, QDomElement &element, QString geomFunc )
{
  if ( geomFunc.isEmpty() )
    return;

  QDomElement geometryElem = doc.createElement( "Geometry" );
  element.appendChild( geometryElem );

  /* About using a function withing the Geometry tag.
   *
   * The SLD specification <= 1.1 is vague:
   * "In principle, a fixed geometry could be defined using GML or
   * operators could be defined for computing the geometry from
   * references or literals. However, using a feature property directly
   * is by far the most commonly useful method."
   *
   * Even if it seems that specs should take care all the possible cases,
   * looking at the XML schema fragment that encodes the Geometry element,
   * it has to be a PropertyName element:
   *   <xsd:element name="Geometry">
   *       <xsd:complexType>
   *           <xsd:sequence>
   *               <xsd:element ref="ogc:PropertyName"/>
   *           </xsd:sequence>
   *       </xsd:complexType>
   *   </xsd:element>
   *
   * Anyway we will use a ogc:Function to handle geometry transformations
   * like offset, centroid, ...
   */

  createFunctionElement( doc, geometryElem, geomFunc );
}

bool QgsSymbolLayerV2Utils::geometryFromSldElement( QDomElement &element, QString &geomFunc )
{
  QDomElement geometryElem = element.firstChildElement( "Geometry" );
  if ( geometryElem.isNull() )
    return true;

  return functionFromSldElement( geometryElem, geomFunc );
}

bool QgsSymbolLayerV2Utils::createFunctionElement( QDomDocument &doc, QDomElement &element, QString function )
{
  // let's use QgsExpression to generate the SLD for the function
  QgsExpression expr( function );
  if ( expr.hasParserError() )
  {
    element.appendChild( doc.createComment( "Parser Error: " + expr.parserErrorString() + " - Expression was: " + function ) );
    return false;
  }
  QDomElement filterElem = QgsOgcUtils::expressionToOgcFilter( expr, doc );
  if ( !filterElem.isNull() )
    element.appendChild( filterElem );
  return true;
}

bool QgsSymbolLayerV2Utils::functionFromSldElement( QDomElement &element, QString &function )
{
  QgsDebugMsg( "Entered." );

  QgsExpression *expr = QgsOgcUtils::expressionFromOgcFilter( element );
  if ( !expr )
    return false;

  bool valid = !expr->hasParserError();
  if ( !valid )
  {
    QgsDebugMsg( "parser error: " + expr->parserErrorString() );
  }
  else
  {
    function = expr->dump();
  }

  delete expr;
  return valid;
}

void QgsSymbolLayerV2Utils::createOnlineResourceElement( QDomDocument &doc, QDomElement &element,
    QString path, QString format )
{
  QString relpath = symbolPathToName( path );

  // convert image path to url
  QUrl url( relpath );
  if ( !url.isValid() || url.scheme().isEmpty() )
  {
    url.setUrl( QUrl::fromLocalFile( relpath ).toString() );
  }

  QDomElement onlineResourceElem = doc.createElement( "se:OnlineResource" );
  onlineResourceElem.setAttribute( "xlink:type", "simple" );
  onlineResourceElem.setAttribute( "xlink:href", url.toString() );
  element.appendChild( onlineResourceElem );

  QDomElement formatElem = doc.createElement( "se:Format" );
  formatElem.appendChild( doc.createTextNode( format ) );
  element.appendChild( formatElem );
}

bool QgsSymbolLayerV2Utils::onlineResourceFromSldElement( QDomElement &element, QString &path, QString &format )
{
  QgsDebugMsg( "Entered." );

  QDomElement onlineResourceElem = element.firstChildElement( "OnlineResource" );
  if ( onlineResourceElem.isNull() )
    return false;

  path = onlineResourceElem.attributeNS( "http://www.w3.org/1999/xlink", "href" );

  QDomElement formatElem = element.firstChildElement( "Format" );
  if ( formatElem.isNull() )
    return false; // OnlineResource requires a Format sibling element

  format = formatElem.firstChild().nodeValue();
  return true;
}


QDomElement QgsSymbolLayerV2Utils::createSvgParameterElement( QDomDocument &doc, QString name, QString value )
{
  QDomElement nodeElem = doc.createElement( "se:SvgParameter" );
  nodeElem.setAttribute( "name", name );
  nodeElem.appendChild( doc.createTextNode( value ) );
  return nodeElem;
}

QgsStringMap QgsSymbolLayerV2Utils::getSvgParameterList( QDomElement &element )
{
  QgsStringMap params;

  QDomElement paramElem = element.firstChildElement();
  while ( !paramElem.isNull() )
  {
    if ( paramElem.localName() == "SvgParameter" || paramElem.localName() == "CssParameter" )
    {
      QString name = paramElem.attribute( "name" );
      QString value = paramElem.firstChild().nodeValue();

      if ( !name.isEmpty() && !value.isEmpty() )
        params[ name ] = value;
    }

    paramElem = paramElem.nextSiblingElement();
  }

  return params;
}

QDomElement QgsSymbolLayerV2Utils::createVendorOptionElement( QDomDocument &doc, QString name, QString value )
{
  QDomElement nodeElem = doc.createElement( "VendorOption" );
  nodeElem.setAttribute( "name", name );
  nodeElem.appendChild( doc.createTextNode( value ) );
  return nodeElem;
}

QgsStringMap QgsSymbolLayerV2Utils::getVendorOptionList( QDomElement &element )
{
  QgsStringMap params;

  QDomElement paramElem = element.firstChildElement( "VendorOption" );
  while ( !paramElem.isNull() )
  {
    QString name = paramElem.attribute( "name" );
    QString value = paramElem.firstChild().nodeValue();

    if ( !name.isEmpty() && !value.isEmpty() )
      params[ name ] = value;

    paramElem = paramElem.nextSiblingElement( "VendorOption" );
  }

  return params;
}


QgsStringMap QgsSymbolLayerV2Utils::parseProperties( QDomElement& element )
{
  QgsStringMap props;
  QDomElement e = element.firstChildElement();
  while ( !e.isNull() )
  {
    if ( e.tagName() != "prop" )
    {
      QgsDebugMsg( "unknown tag " + e.tagName() );
    }
    else
    {
      QString propKey = e.attribute( "k" );
      QString propValue = e.attribute( "v" );
      props[propKey] = propValue;
    }
    e = e.nextSiblingElement();
  }
  return props;
}


void QgsSymbolLayerV2Utils::saveProperties( QgsStringMap props, QDomDocument& doc, QDomElement& element )
{
  for ( QgsStringMap::iterator it = props.begin(); it != props.end(); ++it )
  {
    QDomElement propEl = doc.createElement( "prop" );
    propEl.setAttribute( "k", it.key() );
    propEl.setAttribute( "v", it.value() );
    element.appendChild( propEl );
  }
}

QgsSymbolV2Map QgsSymbolLayerV2Utils::loadSymbols( QDomElement& element )
{
  // go through symbols one-by-one and load them

  QgsSymbolV2Map symbols;
  QDomElement e = element.firstChildElement();

  while ( !e.isNull() )
  {
    if ( e.tagName() == "symbol" )
    {
      QgsSymbolV2* symbol = QgsSymbolLayerV2Utils::loadSymbol( e );
      if ( symbol != NULL )
        symbols.insert( e.attribute( "name" ), symbol );
    }
    else
    {
      QgsDebugMsg( "unknown tag: " + e.tagName() );
    }
    e = e.nextSiblingElement();
  }


  // now walk through the list of symbols and find those prefixed with @
  // these symbols are sub-symbols of some other symbol layers
  // e.g. symbol named "@foo@1" is sub-symbol of layer 1 in symbol "foo"
  QStringList subsymbols;

  for ( QMap<QString, QgsSymbolV2*>::iterator it = symbols.begin(); it != symbols.end(); ++it )
  {
    if ( it.key()[0] != '@' )
      continue;

    // add to array (for deletion)
    subsymbols.append( it.key() );

    QStringList parts = it.key().split( "@" );
    if ( parts.count() < 3 )
    {
      QgsDebugMsg( "found subsymbol with invalid name: " + it.key() );
      delete it.value(); // we must delete it
      continue; // some invalid syntax
    }
    QString symname = parts[1];
    int symlayer = parts[2].toInt();

    if ( !symbols.contains( symname ) )
    {
      QgsDebugMsg( "subsymbol references invalid symbol: " + symname );
      delete it.value(); // we must delete it
      continue;
    }

    QgsSymbolV2* sym = symbols[symname];
    if ( symlayer < 0 || symlayer >= sym->symbolLayerCount() )
    {
      QgsDebugMsg( "subsymbol references invalid symbol layer: " + QString::number( symlayer ) );
      delete it.value(); // we must delete it
      continue;
    }

    // set subsymbol takes ownership
    bool res = sym->symbolLayer( symlayer )->setSubSymbol( it.value() );
    if ( !res )
    {
      QgsDebugMsg( "symbol layer refused subsymbol: " + it.key() );
    }


  }

  // now safely remove sub-symbol entries (they have been already deleted or the ownership was taken away)
  for ( int i = 0; i < subsymbols.count(); i++ )
    symbols.take( subsymbols[i] );

  return symbols;
}

QDomElement QgsSymbolLayerV2Utils::saveSymbols( QgsSymbolV2Map& symbols, QString tagName, QDomDocument& doc )
{
  QDomElement symbolsElem = doc.createElement( tagName );

  // save symbols
  for ( QMap<QString, QgsSymbolV2*>::iterator its = symbols.begin(); its != symbols.end(); ++its )
  {
    QDomElement symEl = saveSymbol( its.key(), its.value(), doc );
    symbolsElem.appendChild( symEl );
  }

  return symbolsElem;
}

void QgsSymbolLayerV2Utils::clearSymbolMap( QgsSymbolV2Map& symbols )
{
  foreach ( QString name, symbols.keys() )
  {
    delete symbols.value( name );
  }
  symbols.clear();
}


QgsVectorColorRampV2* QgsSymbolLayerV2Utils::loadColorRamp( QDomElement& element )
{
  QString rampType = element.attribute( "type" );

  // parse properties
  QgsStringMap props = QgsSymbolLayerV2Utils::parseProperties( element );

  if ( rampType == "gradient" )
    return QgsVectorGradientColorRampV2::create( props );
  else if ( rampType == "random" )
    return QgsVectorRandomColorRampV2::create( props );
  else if ( rampType == "colorbrewer" )
    return QgsVectorColorBrewerColorRampV2::create( props );
  else if ( rampType == "cpt-city" )
    return QgsCptCityColorRampV2::create( props );
  else
  {
    QgsDebugMsg( "unknown colorramp type " + rampType );
    return NULL;
  }
}


QDomElement QgsSymbolLayerV2Utils::saveColorRamp( QString name, QgsVectorColorRampV2* ramp, QDomDocument& doc )
{
  QDomElement rampEl = doc.createElement( "colorramp" );
  rampEl.setAttribute( "type", ramp->type() );
  rampEl.setAttribute( "name", name );

  QgsSymbolLayerV2Utils::saveProperties( ramp->properties(), doc, rampEl );
  return rampEl;
}

// parse color definition with format "rgb(0,0,0)" or "0,0,0"
// should support other formats like FFFFFF
QColor QgsSymbolLayerV2Utils::parseColor( QString colorStr )
{
  if ( colorStr.startsWith( "rgb(" ) )
  {
    colorStr = colorStr.mid( 4, colorStr.size() - 5 ).trimmed();
  }
  QStringList p = colorStr.split( QChar( ',' ) );
  if ( p.count() != 3 )
    return QColor();
  return QColor( p[0].toInt(), p[1].toInt(), p[2].toInt() );
}

double QgsSymbolLayerV2Utils::lineWidthScaleFactor( const QgsRenderContext& c, QgsSymbolV2::OutputUnit u )
{

  if ( u == QgsSymbolV2::MM )
  {
    return c.scaleFactor();
  }
  else //QgsSymbol::MapUnit
  {
    double mup = c.mapToPixel().mapUnitsPerPixel();
    if ( mup > 0 )
    {
      return 1.0 / mup;
    }
    else
    {
      return 1.0;
    }
  }
}

double QgsSymbolLayerV2Utils::pixelSizeScaleFactor( const QgsRenderContext& c, QgsSymbolV2::OutputUnit u )
{
  if ( u == QgsSymbolV2::MM )
  {
    return ( c.scaleFactor() * c.rasterScaleFactor() );
  }
  else //QgsSymbol::MapUnit
  {
    double mup = c.mapToPixel().mapUnitsPerPixel();
    if ( mup > 0 )
    {
      return c.rasterScaleFactor() / c.mapToPixel().mapUnitsPerPixel();
    }
    else
    {
      return 1.0;
    }
  }
}

QgsRenderContext QgsSymbolLayerV2Utils::createRenderContext( QPainter* p )
{
  QgsRenderContext context;
  context.setPainter( p );
  context.setRasterScaleFactor( 1.0 );
  if ( p && p->device() )
  {
    context.setScaleFactor( p->device()->logicalDpiX() / 25.4 );
  }
  else
  {
    context.setScaleFactor( 3.465 ); //assume 88 dpi as standard value
  }
  return context;
}

void QgsSymbolLayerV2Utils::multiplyImageOpacity( QImage* image, qreal alpha )
{
  if ( !image )
  {
    return;
  }

  QRgb myRgb;
  QImage::Format format = image->format();
  if ( format != QImage::Format_ARGB32_Premultiplied && format != QImage::Format_ARGB32 )
  {
    QgsDebugMsg( "no alpha channel." );
    return;
  }

  //change the alpha component of every pixel
  for ( int heightIndex = 0; heightIndex < image->height(); ++heightIndex )
  {
    QRgb* scanLine = ( QRgb* )image->scanLine( heightIndex );
    for ( int widthIndex = 0; widthIndex < image->width(); ++widthIndex )
    {
      myRgb = scanLine[widthIndex];
      if ( format == QImage::Format_ARGB32_Premultiplied )
        scanLine[widthIndex] = qRgba( alpha * qRed( myRgb ), alpha * qGreen( myRgb ), alpha * qBlue( myRgb ), alpha * qAlpha( myRgb ) );
      else
        scanLine[widthIndex] = qRgba( qRed( myRgb ), qGreen( myRgb ), qBlue( myRgb ), alpha * qAlpha( myRgb ) );
    }
  }
}

void QgsSymbolLayerV2Utils::blurImageInPlace( QImage& image, const QRect& rect, int radius, bool alphaOnly )
{
  // culled from Qt's qpixmapfilter.cpp, see: http://www.qtcentre.org/archive/index.php/t-26534.html
  int tab[] = { 14, 10, 8, 6, 5, 5, 4, 3, 3, 3, 3, 2, 2, 2, 2, 2, 2 };
  int alpha = ( radius < 1 )  ? 16 : ( radius > 17 ) ? 1 : tab[radius-1];

  if ( image.format() != QImage::Format_ARGB32_Premultiplied
       && image.format() != QImage::Format_RGB32 )
  {
    image = image.convertToFormat( QImage::Format_ARGB32_Premultiplied );
  }

  int r1 = rect.top();
  int r2 = rect.bottom();
  int c1 = rect.left();
  int c2 = rect.right();

  int bpl = image.bytesPerLine();
  int rgba[4];
  unsigned char* p;

  int i1 = 0;
  int i2 = 3;

  if ( alphaOnly ) // this seems to only work right for a black color
    i1 = i2 = ( QSysInfo::ByteOrder == QSysInfo::BigEndian ? 0 : 3 );

  for ( int col = c1; col <= c2; col++ )
  {
    p = image.scanLine( r1 ) + col * 4;
    for ( int i = i1; i <= i2; i++ )
      rgba[i] = p[i] << 4;

    p += bpl;
    for ( int j = r1; j < r2; j++, p += bpl )
      for ( int i = i1; i <= i2; i++ )
        p[i] = ( rgba[i] += (( p[i] << 4 ) - rgba[i] ) * alpha / 16 ) >> 4;
  }

  for ( int row = r1; row <= r2; row++ )
  {
    p = image.scanLine( row ) + c1 * 4;
    for ( int i = i1; i <= i2; i++ )
      rgba[i] = p[i] << 4;

    p += 4;
    for ( int j = c1; j < c2; j++, p += 4 )
      for ( int i = i1; i <= i2; i++ )
        p[i] = ( rgba[i] += (( p[i] << 4 ) - rgba[i] ) * alpha / 16 ) >> 4;
  }

  for ( int col = c1; col <= c2; col++ )
  {
    p = image.scanLine( r2 ) + col * 4;
    for ( int i = i1; i <= i2; i++ )
      rgba[i] = p[i] << 4;

    p -= bpl;
    for ( int j = r1; j < r2; j++, p -= bpl )
      for ( int i = i1; i <= i2; i++ )
        p[i] = ( rgba[i] += (( p[i] << 4 ) - rgba[i] ) * alpha / 16 ) >> 4;
  }

  for ( int row = r1; row <= r2; row++ )
  {
    p = image.scanLine( row ) + c2 * 4;
    for ( int i = i1; i <= i2; i++ )
      rgba[i] = p[i] << 4;

    p -= 4;
    for ( int j = c1; j < c2; j++, p -= 4 )
      for ( int i = i1; i <= i2; i++ )
        p[i] = ( rgba[i] += (( p[i] << 4 ) - rgba[i] ) * alpha / 16 ) >> 4;
  }
}

#if 0
static bool _QVariantLessThan( const QVariant& lhs, const QVariant& rhs )
{
  switch ( lhs.type() )
  {
    case QVariant::Int:
      return lhs.toInt() < rhs.toInt();
    case QVariant::UInt:
      return lhs.toUInt() < rhs.toUInt();
    case QVariant::LongLong:
      return lhs.toLongLong() < rhs.toLongLong();
    case QVariant::ULongLong:
      return lhs.toULongLong() < rhs.toULongLong();
    case QVariant::Double:
      return lhs.toDouble() < rhs.toDouble();
    case QVariant::Char:
      return lhs.toChar() < rhs.toChar();
    case QVariant::Date:
      return lhs.toDate() < rhs.toDate();
    case QVariant::Time:
      return lhs.toTime() < rhs.toTime();
    case QVariant::DateTime:
      return lhs.toDateTime() < rhs.toDateTime();
    default:
      return QString::localeAwareCompare( lhs.toString(), rhs.toString() ) < 0;
  }
}

static bool _QVariantGreaterThan( const QVariant& lhs, const QVariant& rhs )
{
  return ! _QVariantLessThan( lhs, rhs );
}
#endif

void QgsSymbolLayerV2Utils::sortVariantList( QList<QVariant>& list, Qt::SortOrder order )
{
  if ( order == Qt::AscendingOrder )
  {
    //qSort( list.begin(), list.end(), _QVariantLessThan );
    qSort( list.begin(), list.end(), qgsVariantLessThan );
  }
  else // Qt::DescendingOrder
  {
    //qSort( list.begin(), list.end(), _QVariantGreaterThan );
    qSort( list.begin(), list.end(), qgsVariantGreaterThan );
  }
}

QPointF QgsSymbolLayerV2Utils::pointOnLineWithDistance( const QPointF& startPoint, const QPointF& directionPoint, double distance )
{
  double dx = directionPoint.x() - startPoint.x();
  double dy = directionPoint.y() - startPoint.y();
  double length = sqrt( dx * dx + dy * dy );
  double scaleFactor = distance / length;
  return QPointF( startPoint.x() + dx * scaleFactor, startPoint.y() + dy * scaleFactor );
}


QStringList QgsSymbolLayerV2Utils::listSvgFiles()
{
  // copied from QgsMarkerCatalogue - TODO: unify
  QStringList list;
  QStringList svgPaths = QgsApplication::svgPaths();

  for ( int i = 0; i < svgPaths.size(); i++ )
  {
    QDir dir( svgPaths[i] );
    foreach ( QString item, dir.entryList( QDir::Dirs | QDir::NoDotAndDotDot ) )
    {
      svgPaths.insert( i + 1, dir.path() + "/" + item );
    }

    foreach ( QString item, dir.entryList( QStringList( "*.svg" ), QDir::Files ) )
    {
      // TODO test if it is correct SVG
      list.append( dir.path() + "/" + item );
    }
  }
  return list;
}

// Stripped down version of listSvgFiles() for specified directory
QStringList QgsSymbolLayerV2Utils::listSvgFilesAt( QString directory )
{
  // TODO anything that applies for the listSvgFiles() applies this also

  QStringList list;
  QStringList svgPaths;
  svgPaths.append( directory );

  for ( int i = 0; i < svgPaths.size(); i++ )
  {
    QDir dir( svgPaths[i] );
    foreach ( QString item, dir.entryList( QDir::Dirs | QDir::NoDotAndDotDot ) )
    {
      svgPaths.insert( i + 1, dir.path() + "/" + item );
    }

    foreach ( QString item, dir.entryList( QStringList( "*.svg" ), QDir::Files ) )
    {
      list.append( dir.path() + "/" + item );
    }
  }
  return list;

}

QString QgsSymbolLayerV2Utils::symbolNameToPath( QString name )
{
  // copied from QgsSymbol::setNamedPointSymbol - TODO: unify

  // we might have a full path...
  if ( QFile( name ).exists() )
    return QFileInfo( name ).canonicalFilePath();

  // or it might be an url...
  if ( name.contains( "://" ) )
  {
    QUrl url( name );
    if ( url.isValid() && !url.scheme().isEmpty() )
    {
      if ( url.scheme().compare( "file", Qt::CaseInsensitive ) == 0 )
      {
        // it's a url to a local file
        name = url.toLocalFile();
        if ( QFile( name ).exists() )
        {
          return QFileInfo( name ).canonicalFilePath();
        }
      }
      else
      {
        // it's a url pointing to a online resource
        return name;
      }
    }
  }

  // SVG symbol not found - probably a relative path was used

  QStringList svgPaths = QgsApplication::svgPaths();
  for ( int i = 0; i < svgPaths.size(); i++ )
  {
    QString svgPath = svgPaths[i];
    if ( svgPath.endsWith( QString( "/" ) ) )
    {
      svgPath.chop( 1 );
    }

    QgsDebugMsg( "SvgPath: " + svgPath );
    QFileInfo myInfo( name );
    QString myFileName = myInfo.fileName(); // foo.svg
    QString myLowestDir = myInfo.dir().dirName();
    QString myLocalPath = svgPath + QString( myLowestDir.isEmpty() ? "" : "/" + myLowestDir ) + "/" + myFileName;

    QgsDebugMsg( "Alternative svg path: " + myLocalPath );
    if ( QFile( myLocalPath ).exists() )
    {
      QgsDebugMsg( "Svg found in alternative path" );
      return QFileInfo( myLocalPath ).canonicalFilePath();
    }
    else if ( myInfo.isRelative() )
    {
      QFileInfo pfi( QgsProject::instance()->fileName() );
      QString alternatePath = pfi.canonicalPath() + QDir::separator() + name;
      if ( pfi.exists() && QFile( alternatePath ).exists() )
      {
        QgsDebugMsg( "Svg found in alternative path" );
        return QFileInfo( alternatePath ).canonicalFilePath();
      }
      else
      {
        QgsDebugMsg( "Svg not found in project path" );
      }
    }
    else
    {
      //couldnt find the file, no happy ending :-(
      QgsDebugMsg( "Computed alternate path but no svg there either" );
    }
  }
  return QString();
}

QString QgsSymbolLayerV2Utils::symbolPathToName( QString path )
{
  // copied from QgsSymbol::writeXML

  QFileInfo fi( path );
  if ( !fi.exists() )
    return path;

  path = fi.canonicalFilePath();

  QStringList svgPaths = QgsApplication::svgPaths();

  bool isInSvgPathes = false;
  for ( int i = 0; i < svgPaths.size(); i++ )
  {
    QString dir = QFileInfo( svgPaths[i] ).canonicalFilePath();

    if ( !dir.isEmpty() && path.startsWith( dir ) )
    {
      path = path.mid( dir.size() );
      isInSvgPathes = true;
      break;
    }
  }

  if ( isInSvgPathes )
    return path;

  return QgsProject::instance()->writePath( path );
}