void QgsPointDisplacementRenderer::printInfoDisplacementGroups()
{
  int nGroups = mDisplacementGroups.size();
  QgsDebugMsg( "number of displacement groups:" + QString::number( nGroups ) );
  for ( int i = 0; i < nGroups; ++i )
  {
    QgsDebugMsg( "***************displacement group " + QString::number( i ) );
    DisplacementGroup::const_iterator it = mDisplacementGroups.at( i ).constBegin();
    for ( ; it != mDisplacementGroups.at( i ).constEnd(); ++it )
    {
      QgsDebugMsg( FID_TO_STRING( it.key() ) );
    }
  }
}
void QgsPointDisplacementRenderer::drawGroup( const DisplacementGroup& group, QgsRenderContext& context )
{
  const QgsFeature& feature = group.begin().value().first;
  bool selected = mSelectedFeatures.contains( feature.id() ); // maybe we should highlight individual features instead of the whole group?



  //get list of labels and symbols
  QStringList labelAttributeList;
  QList<QgsMarkerSymbolV2*> symbolList;

  QgsMultiPointV2* groupMultiPoint = new QgsMultiPointV2();
  for ( DisplacementGroup::const_iterator attIt = group.constBegin(); attIt != group.constEnd(); ++attIt )
  {
    labelAttributeList << ( mDrawLabels ? getLabel( attIt.value().first ) : QString() );
    symbolList << dynamic_cast<QgsMarkerSymbolV2*>( attIt.value().second );
    groupMultiPoint->addGeometry( attIt.value().first.constGeometry()->geometry()->clone() );
  }

  //calculate centroid of all points, this will be center of group
  QgsGeometry groupGeom( groupMultiPoint );
  QgsGeometry* centroid = groupGeom.centroid();
  QPointF pt;
  _getPoint( pt, context, centroid->asWkb() );
  delete centroid;

  //calculate max diagonal size from all symbols in group
  double diagonal = 0;
  Q_FOREACH ( QgsMarkerSymbolV2* symbol, symbolList )
  {
    if ( symbol )
    {
      diagonal = qMax( diagonal, QgsSymbolLayerV2Utils::convertToPainterUnits( context,
                       M_SQRT2 * symbol->size(),
                       symbol->outputUnit(), symbol->mapUnitScale() ) );
    }
  }

  QgsSymbolV2RenderContext symbolContext( context, QgsSymbolV2::MM, 1.0, selected );

  QList<QPointF> symbolPositions;
  QList<QPointF> labelPositions;
  double circleRadius = -1.0;
  calculateSymbolAndLabelPositions( symbolContext, pt, symbolList.size(), diagonal, symbolPositions, labelPositions, circleRadius );

  //draw Circle
  if ( circleRadius > 0 )
    drawCircle( circleRadius, symbolContext, pt, symbolList.size() );

  //draw mid point
  if ( labelAttributeList.size() > 1 )
  {
    if ( mCenterSymbol )
    {
      mCenterSymbol->renderPoint( pt, &feature, context, -1, selected );
    }
    else
    {
      context.painter()->drawRect( QRectF( pt.x() - symbolContext.outputLineWidth( 1 ), pt.y() - symbolContext.outputLineWidth( 1 ), symbolContext.outputLineWidth( 2 ), symbolContext.outputLineWidth( 2 ) ) );
    }
  }

  //draw symbols on the circle
  drawSymbols( feature, context, symbolList, symbolPositions, selected );
  //and also the labels
  drawLabels( pt, symbolContext, labelPositions, labelAttributeList );
}
void QgsPointDisplacementRenderer::drawGroup( const DisplacementGroup& group, QgsRenderContext& context )
{
  const QgsFeature& feature = group.begin().value().first;
  bool selected = mSelectedFeatures.contains( feature.id() ); // maybe we should highlight individual features instead of the whole group?

  QPointF pt;
  _getPoint( pt, context, feature.constGeometry()->asWkb() );

  //get list of labels and symbols
  QStringList labelAttributeList;
  QList<QgsMarkerSymbolV2*> symbolList;

  for ( DisplacementGroup::const_iterator attIt = group.constBegin(); attIt != group.constEnd(); ++attIt )
  {
    labelAttributeList << ( mDrawLabels ? getLabel( attIt.value().first ) : QString() );
    symbolList << dynamic_cast<QgsMarkerSymbolV2*>( attIt.value().second );
  }

  //draw symbol
  double diagonal = 0;
  double currentWidthFactor; //scale symbol size to map unit and output resolution

  QList<QgsMarkerSymbolV2*>::const_iterator it = symbolList.constBegin();
  for ( ; it != symbolList.constEnd(); ++it )
  {
    if ( *it )
    {
      currentWidthFactor = QgsSymbolLayerV2Utils::lineWidthScaleFactor( context, ( *it )->outputUnit(), ( *it )->mapUnitScale() );
      double currentDiagonal = sqrt( 2 * (( *it )->size() * ( *it )->size() ) ) * currentWidthFactor;
      if ( currentDiagonal > diagonal )
      {
        diagonal = currentDiagonal;
      }
    }
  }


  QgsSymbolV2RenderContext symbolContext( context, QgsSymbolV2::MM, 1.0, selected );
  double circleAdditionPainterUnits = symbolContext.outputLineWidth( mCircleRadiusAddition );
  double radius = qMax(( diagonal / 2 ), labelAttributeList.size() * diagonal / 2 / M_PI ) + circleAdditionPainterUnits;

  //draw Circle
  drawCircle( radius, symbolContext, pt, symbolList.size() );

  QList<QPointF> symbolPositions;
  QList<QPointF> labelPositions;
  calculateSymbolAndLabelPositions( pt, labelAttributeList.size(), radius, diagonal, symbolPositions, labelPositions );

  //draw mid point
  if ( labelAttributeList.size() > 1 )
  {
    if ( mCenterSymbol )
    {
      mCenterSymbol->renderPoint( pt, &feature, context, -1, selected );
    }
    else
    {
      context.painter()->drawRect( QRectF( pt.x() - symbolContext.outputLineWidth( 1 ), pt.y() - symbolContext.outputLineWidth( 1 ), symbolContext.outputLineWidth( 2 ), symbolContext.outputLineWidth( 2 ) ) );
    }
  }

  //draw symbols on the circle
  drawSymbols( feature, context, symbolList, symbolPositions, selected );
  //and also the labels
  drawLabels( pt, symbolContext, labelPositions, labelAttributeList );
}