QgsGraduatedSymbolRendererV2* QgsGraduatedSymbolRendererV2::createRenderer(
  QgsVectorLayer* vlayer,
  QString attrName,
  int classes,
  Mode mode,
  QgsSymbolV2* symbol,
  QgsVectorColorRampV2* ramp )
{
  if ( classes < 1 )
    return NULL;

  int attrNum = vlayer->fieldNameIndex( attrName );

  double minimum = vlayer->minimumValue( attrNum ).toDouble();
  double maximum = vlayer->maximumValue( attrNum ).toDouble();
  QgsDebugMsg( QString( "min %1 // max %2" ).arg( minimum ).arg( maximum ) );

  QList<double> breaks;
  QList<int> labels;
  if ( mode == EqualInterval )
  {
    breaks = _calcEqualIntervalBreaks( minimum, maximum, classes );
  }
  else if ( mode == Pretty )
  {
    breaks = _calcPrettyBreaks( minimum, maximum, classes );
  }
  else if ( mode == Quantile || mode == Jenks || mode == StdDev )
  {
    // get values from layer
    QList<double> values;
    QgsFeature f;
    QgsAttributeList lst;
    lst.append( attrNum );

    QgsFeatureIterator fit = vlayer->getFeatures( QgsFeatureRequest().setFlags( QgsFeatureRequest::NoGeometry ).setSubsetOfAttributes( lst ) );

    // create list of non-null attribute values
    while ( fit.nextFeature( f ) )
      if ( !f.attribute( attrNum ).isNull() )
        values.append( f.attribute( attrNum ).toDouble() );

    // calculate the breaks
    if ( mode == Quantile )
    {
      breaks = _calcQuantileBreaks( values, classes );
    }
    else if ( mode == Jenks )
    {
      breaks = _calcJenksBreaks( values, classes, minimum, maximum );
    }
    else if ( mode == StdDev )
    {
      breaks = _calcStdDevBreaks( values, classes, labels );
    }
  }
  else
  {
    Q_ASSERT( false );
  }

  QgsRangeList ranges;
  double lower, upper = minimum;
  QString label;

  // "breaks" list contains all values at class breaks plus maximum as last break
  int i = 0;
  for ( QList<double>::iterator it = breaks.begin(); it != breaks.end(); ++it, ++i )
  {
    lower = upper; // upper border from last interval
    upper = *it;
    if ( mode == StdDev )
    {
      if ( i == 0 )
      {
        label = "< " + QString::number( labels[i], 'i', 0 ) + " Std Dev";
      }
      else if ( i == labels.count() - 1 )
      {
        label = ">= " + QString::number( labels[i-1], 'i', 0 ) + " Std Dev";
      }
      else
      {
        label = QString::number( labels[i-1], 'i', 0 ) + " Std Dev" + " - " + QString::number( labels[i], 'i', 0 ) + " Std Dev";
      }
    }
    else
    {
      label = QString::number( lower, 'f', 4 ) + " - " + QString::number( upper, 'f', 4 );
    }

    QgsSymbolV2* newSymbol = symbol->clone();
    double colorValue = ( breaks.count() > 1 ? ( double ) i / ( breaks.count() - 1 ) : 0 );
    newSymbol->setColor( ramp->color( colorValue ) ); // color from (0 / cl-1) to (cl-1 / cl-1)

    ranges.append( QgsRendererRangeV2( lower, upper, newSymbol, label ) );
  }

  QgsGraduatedSymbolRendererV2* r = new QgsGraduatedSymbolRendererV2( attrName, ranges );
  r->setSourceSymbol( symbol->clone() );
  r->setSourceColorRamp( ramp->clone() );
  r->setMode( mode );
  return r;
}
QgsGraduatedSymbolRendererV2* QgsGraduatedSymbolRendererV2::createRenderer(
  QgsVectorLayer* vlayer,
  QString attrName,
  int classes,
  Mode mode,
  QgsSymbolV2* symbol,
  QgsVectorColorRampV2* ramp,
  bool inverted )
{
  if ( classes < 1 )
    return NULL;

  int attrNum = vlayer->fieldNameIndex( attrName );
  double minimum;
  double maximum;

  QScopedPointer<QgsExpression> expression;

  if ( attrNum == -1 )
  {
    // try to use expression
    expression.reset( new QgsExpression( attrName ) );
    if ( expression->hasParserError() || !expression->prepare( vlayer->pendingFields() ) )
      return 0; // should have a means to report errors

    QList<double> values;
    QgsFeatureIterator fit = vlayer->getFeatures();
    QgsFeature feature;
    while ( fit.nextFeature( feature ) )
    {
      values << expression->evaluate( feature ).toDouble();
    }
    qSort( values );
    minimum = values.first();
    maximum = values.last();
  }
  else
  {
    minimum = vlayer->minimumValue( attrNum ).toDouble();
    maximum = vlayer->maximumValue( attrNum ).toDouble();
  }

  QgsDebugMsg( QString( "min %1 // max %2" ).arg( minimum ).arg( maximum ) );
  QList<double> breaks;
  QList<int> labels;
  if ( mode == EqualInterval )
  {
    breaks = _calcEqualIntervalBreaks( minimum, maximum, classes );
  }
  else if ( mode == Pretty )
  {
    breaks = _calcPrettyBreaks( minimum, maximum, classes );
  }
  else if ( mode == Quantile || mode == Jenks || mode == StdDev )
  {
    // get values from layer
    QList<double> values;
    QgsFeature f;
    QStringList lst;
    if ( expression.isNull() )
      lst.append( attrName );
    else
      lst = expression->referencedColumns();

    QgsFeatureIterator fit = vlayer->getFeatures( QgsFeatureRequest().setFlags( QgsFeatureRequest::NoGeometry ).setSubsetOfAttributes( lst, vlayer->pendingFields() ) );

    // create list of non-null attribute values
    while ( fit.nextFeature( f ) )
    {
      QVariant v = expression.isNull() ? f.attribute( attrNum ) : expression->evaluate( f );
      if ( !v.isNull() )
        values.append( v.toDouble() );
    }

    // calculate the breaks
    if ( mode == Quantile )
    {
      breaks = _calcQuantileBreaks( values, classes );
    }
    else if ( mode == Jenks )
    {
      breaks = _calcJenksBreaks( values, classes, minimum, maximum );
    }
    else if ( mode == StdDev )
    {
      breaks = _calcStdDevBreaks( values, classes, labels );
    }
  }
  else
  {
    Q_ASSERT( false );
  }

  QgsRangeList ranges;
  double lower, upper = minimum;
  QString label;

  // "breaks" list contains all values at class breaks plus maximum as last break
  int i = 0;
  for ( QList<double>::iterator it = breaks.begin(); it != breaks.end(); ++it, ++i )
  {
    lower = upper; // upper border from last interval
    upper = *it;
    if ( mode == StdDev )
    {
      if ( i == 0 )
      {
        label = "< " + QString::number( labels[i], 'i', 0 ) + " Std Dev";
      }
      else if ( i == labels.count() - 1 )
      {
        label = ">= " + QString::number( labels[i-1], 'i', 0 ) + " Std Dev";
      }
      else
      {
        label = QString::number( labels[i-1], 'i', 0 ) + " Std Dev" + " - " + QString::number( labels[i], 'i', 0 ) + " Std Dev";
      }
    }
    else
    {
      label = QString::number( lower, 'f', 4 ) + " - " + QString::number( upper, 'f', 4 );
    }

    QgsSymbolV2* newSymbol = symbol->clone();
    double colorValue;
    if ( inverted ) colorValue = ( breaks.count() > 1 ? ( double )( breaks.count() - i - 1 ) / ( breaks.count() - 1 ) : 0 );
    else colorValue = ( breaks.count() > 1 ? ( double ) i / ( breaks.count() - 1 ) : 0 );
    newSymbol->setColor( ramp->color( colorValue ) ); // color from (0 / cl-1) to (cl-1 / cl-1)

    ranges.append( QgsRendererRangeV2( lower, upper, newSymbol, label ) );
  }

  QgsGraduatedSymbolRendererV2* r = new QgsGraduatedSymbolRendererV2( attrName, ranges );
  r->setSourceSymbol( symbol->clone() );
  r->setSourceColorRamp( ramp->clone() );
  r->setInvertedColorRamp( inverted );
  r->setMode( mode );
  return r;
}
void QgsGraduatedSymbolRendererV2::updateClasses( QgsVectorLayer *vlayer, Mode mode, int nclasses )
{
  if ( mAttrName.isEmpty() )
    return;

  setMode( mode );
  // Custom classes are not recalculated
  if ( mode == Custom )
    return;

  if ( nclasses < 1 )
    nclasses = 1;

  QList<double> values;
  bool valuesLoaded = false;
  double minimum;
  double maximum;

  int attrNum = vlayer->fieldNameIndex( mAttrName );

  bool ok;
  if ( attrNum == -1 )
  {
    values = vlayer->getDoubleValues( mAttrName, ok );
    if ( !ok || values.isEmpty() )
      return;

    qSort( values ); // vmora: is wondering if O( n log(n) ) is really necessary here, min and max are O( n )
    minimum = values.first();
    maximum = values.last();
    valuesLoaded = true;
  }
  else
  {
    minimum = vlayer->minimumValue( attrNum ).toDouble();
    maximum = vlayer->maximumValue( attrNum ).toDouble();
  }

  QgsDebugMsg( QString( "min %1 // max %2" ).arg( minimum ).arg( maximum ) );
  QList<double> breaks;
  QList<double> labels;
  if ( mode == EqualInterval )
  {
    breaks = _calcEqualIntervalBreaks( minimum, maximum, nclasses );
  }
  else if ( mode == Pretty )
  {
    breaks = QgsSymbolLayerV2Utils::prettyBreaks( minimum, maximum, nclasses );
  }
  else if ( mode == Quantile || mode == Jenks || mode == StdDev )
  {
    // get values from layer
    if ( !valuesLoaded )
    {
      values = vlayer->getDoubleValues( mAttrName, ok );
    }

    // calculate the breaks
    if ( mode == Quantile )
    {
      breaks = _calcQuantileBreaks( values, nclasses );
    }
    else if ( mode == Jenks )
    {
      breaks = _calcJenksBreaks( values, nclasses, minimum, maximum );
    }
    else if ( mode == StdDev )
    {
      breaks = _calcStdDevBreaks( values, nclasses, labels );
    }
  }
  else
  {
    Q_ASSERT( false );
  }

  double lower, upper = minimum;
  QString label;
  deleteAllClasses();

  // "breaks" list contains all values at class breaks plus maximum as last break

  int i = 0;
  for ( QList<double>::iterator it = breaks.begin(); it != breaks.end(); ++it, ++i )
  {
    lower = upper; // upper border from last interval
    upper = *it;

    // Label - either StdDev label or default label for a range
    if ( mode == StdDev )
    {
      if ( i == 0 )
      {
        label = "< " + QString::number( labels[i], 'f', 2 ) + " Std Dev";
      }
      else if ( i == labels.count() - 1 )
      {
        label = ">= " + QString::number( labels[i-1], 'f', 2 ) + " Std Dev";
      }
      else
      {
        label = QString::number( labels[i-1], 'f', 2 ) + " Std Dev" + " - " + QString::number( labels[i], 'f', 2 ) + " Std Dev";
      }
    }
    else
    {
      label = mLabelFormat.labelForRange( lower, upper );
    }
    QgsSymbolV2* newSymbol = mSourceSymbol ? mSourceSymbol->clone() : QgsSymbolV2::defaultSymbol( vlayer->geometryType() );
    addClass( QgsRendererRangeV2( lower, upper, newSymbol, label ) );
  }
  updateColorRamp( 0, mInvertedColorRamp );
}