C++ QScopedPointer::evaluate方法代码示例

QList<double> QgsGraduatedSymbolRendererV2::getDataValues( QgsVectorLayer *vlayer )
{
  QList<double> values;
  QScopedPointer<QgsExpression> expression;
  int attrNum = vlayer->fieldNameIndex( mAttrName );

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

  QgsFeature f;
  QStringList lst;
  if ( expression.isNull() )
    lst.append( mAttrName );
  else
    lst = expression->referencedColumns();

  QgsFeatureIterator fit = vlayer->getFeatures( QgsFeatureRequest()
                           .setFlags(( expression && expression->needsGeometry() ) ?
                                     QgsFeatureRequest::NoFlags :
                                     QgsFeatureRequest::NoGeometry )
                           .setSubsetOfAttributes( lst, vlayer->pendingFields() ) );

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

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 )
//.........这里部分代码省略.........

int QgsAtlasComposition::updateFeatures()
{
  //needs to be called when layer, filter, sort changes

  if ( !mCoverageLayer )
  {
    return 0;
  }

  QgsExpressionContext expressionContext = createExpressionContext();

  updateFilenameExpression();

  // select all features with all attributes
  QgsFeatureRequest req;

  QScopedPointer<QgsExpression> filterExpression;
  if ( mFilterFeatures && !mFeatureFilter.isEmpty() )
  {
    filterExpression.reset( new QgsExpression( mFeatureFilter ) );
    if ( filterExpression->hasParserError() )
    {
      mFilterParserError = filterExpression->parserErrorString();
      return 0;
    }

    //filter good to go
    req.setFilterExpression( mFeatureFilter );
  }
  mFilterParserError = QString();

  QgsFeatureIterator fit = mCoverageLayer->getFeatures( req );

  QScopedPointer<QgsExpression> nameExpression;
  if ( !mPageNameExpression.isEmpty() )
  {
    nameExpression.reset( new QgsExpression( mPageNameExpression ) );
    if ( nameExpression->hasParserError() )
    {
      nameExpression.reset( nullptr );
    }
    else
    {
      nameExpression->prepare( &expressionContext );
    }
  }

  // We cannot use nextFeature() directly since the feature pointer is rewinded by the rendering process
  // We thus store the feature ids for future extraction
  QgsFeature feat;
  mFeatureIds.clear();
  mFeatureKeys.clear();
  int sortIdx = mCoverageLayer->fields().lookupField( mSortKeyAttributeName );

  while ( fit.nextFeature( feat ) )
  {
    expressionContext.setFeature( feat );

    QString pageName;
    if ( !nameExpression.isNull() )
    {
      QVariant result = nameExpression->evaluate( &expressionContext );
      if ( nameExpression->hasEvalError() )
      {
        QgsMessageLog::logMessage( tr( "Atlas name eval error: %1" ).arg( nameExpression->evalErrorString() ), tr( "Composer" ) );
      }
      pageName = result.toString();
    }

    mFeatureIds.push_back( qMakePair( feat.id(), pageName ) );

    if ( mSortFeatures && sortIdx != -1 )
    {
      mFeatureKeys.insert( feat.id(), feat.attributes().at( sortIdx ) );
    }
  }

  // sort features, if asked for
  if ( !mFeatureKeys.isEmpty() )
  {
    FieldSorter sorter( mFeatureKeys, mSortAscending );
    qSort( mFeatureIds.begin(), mFeatureIds.end(), sorter );
  }

  emit numberFeaturesChanged( mFeatureIds.size() );

  //jump to first feature if currently using an atlas preview
  //need to do this in case filtering/layer change has altered matching features
  if ( mComposition->atlasMode() == QgsComposition::PreviewAtlas )
  {
    firstFeature();
  }

  return mFeatureIds.size();
}

bool QgsComposerAttributeTable::getFeatureAttributes( QList<QgsAttributeMap> &attributeMaps )
{
  if ( !mVectorLayer )
  {
    return false;
  }

  QScopedPointer< QgsExpressionContext > context( createExpressionContext() );
  context->setFields( mVectorLayer->fields() );

  attributeMaps.clear();

  //prepare filter expression
  QScopedPointer<QgsExpression> filterExpression;
  bool activeFilter = false;
  if ( mFilterFeatures && !mFeatureFilter.isEmpty() )
  {
    filterExpression.reset( new QgsExpression( mFeatureFilter ) );
    if ( !filterExpression->hasParserError() )
    {
      activeFilter = true;
    }
  }

  QgsRectangle selectionRect;
  if ( mComposerMap && mShowOnlyVisibleFeatures )
  {
    selectionRect = *mComposerMap->currentMapExtent();
    if ( mComposition->mapSettings().hasCrsTransformEnabled() )
    {
      //transform back to layer CRS
      QgsCoordinateTransform coordTransform( mVectorLayer->crs(), mComposition->mapSettings().destinationCrs() );
      try
      {
        selectionRect = coordTransform.transformBoundingBox( selectionRect, QgsCoordinateTransform::ReverseTransform );
      }
      catch ( QgsCsException &cse )
      {
        Q_UNUSED( cse );
        return false;
      }
    }
  }

  QgsFeatureRequest req;
  if ( !selectionRect.isEmpty() )
    req.setFilterRect( selectionRect );

  req.setFlags( mShowOnlyVisibleFeatures ? QgsFeatureRequest::ExactIntersect : QgsFeatureRequest::NoFlags );

  QgsFeature f;
  int counter = 0;
  QgsFeatureIterator fit = mVectorLayer->getFeatures( req );

  while ( fit.nextFeature( f ) && counter < mMaximumNumberOfFeatures )
  {
    context->setFeature( f );
    //check feature against filter
    if ( activeFilter && !filterExpression.isNull() )
    {
      QVariant result = filterExpression->evaluate( context.data() );
      // skip this feature if the filter evaluation is false
      if ( !result.toBool() )
      {
        continue;
      }
    }

    attributeMaps.push_back( QgsAttributeMap() );

    QList<QgsComposerTableColumn*>::const_iterator columnIt = mColumns.constBegin();
    int i = 0;
    for ( ; columnIt != mColumns.constEnd(); ++columnIt )
    {
      int idx = mVectorLayer->fieldNameIndex(( *columnIt )->attribute() );
      if ( idx != -1 )
      {
        attributeMaps.last().insert( i, f.attributes().at( idx ) );
      }
      else
      {
        // Lets assume it's an expression
        QgsExpression* expression = new QgsExpression(( *columnIt )->attribute() );
        context->lastScope()->setVariable( QString( "row_number" ), counter + 1 );
        expression->prepare( context.data() );
        QVariant value = expression->evaluate( context.data() );
        attributeMaps.last().insert( i, value.toString() );
      }

      i++;
    }
    ++counter;
  }

  //sort the list, starting with the last attribute
  QgsComposerAttributeTableCompare c;
  QList< QPair<int, bool> > sortColumns = sortAttributes();
  for ( int i = sortColumns.size() - 1; i >= 0; --i )
  {
    c.setSortColumn( sortColumns.at( i ).first );
//.........这里部分代码省略.........

bool QgsComposerAttributeTableV2::getTableContents( QgsComposerTableContents &contents )
{
  contents.clear();

  if (( mSource == QgsComposerAttributeTableV2::AtlasFeature || mSource == QgsComposerAttributeTableV2::RelationChildren )
      && !mComposition->atlasComposition().enabled() )
  {
    //source mode requires atlas, but atlas disabled
    return false;
  }

  QgsVectorLayer* layer = sourceLayer();

  if ( !layer )
  {
    //no source layer
    return false;
  }

  //prepare filter expression
  QScopedPointer<QgsExpression> filterExpression;
  bool activeFilter = false;
  if ( mFilterFeatures && !mFeatureFilter.isEmpty() )
  {
    filterExpression.reset( new QgsExpression( mFeatureFilter ) );
    if ( !filterExpression->hasParserError() )
    {
      activeFilter = true;
    }
  }

  QgsRectangle selectionRect;
  if ( mComposerMap && mShowOnlyVisibleFeatures )
  {
    selectionRect = *mComposerMap->currentMapExtent();
    if ( layer && mComposition->mapSettings().hasCrsTransformEnabled() )
    {
      //transform back to layer CRS
      QgsCoordinateTransform coordTransform( layer->crs(), mComposition->mapSettings().destinationCrs() );
      try
      {
        selectionRect = coordTransform.transformBoundingBox( selectionRect, QgsCoordinateTransform::ReverseTransform );
      }
      catch ( QgsCsException &cse )
      {
        Q_UNUSED( cse );
        return false;
      }
    }
  }

  QgsFeatureRequest req;

  if ( mSource == QgsComposerAttributeTableV2::RelationChildren )
  {
    QgsRelation relation = QgsProject::instance()->relationManager()->relation( mRelationId );
    QgsFeature* atlasFeature = mComposition->atlasComposition().currentFeature();
    if ( atlasFeature )
    {
      req = relation.getRelatedFeaturesRequest( *atlasFeature );
    }
    else
    {
      //no atlas feature, so empty table
      return true;
    }
  }

  if ( !selectionRect.isEmpty() )
    req.setFilterRect( selectionRect );

  req.setFlags( mShowOnlyVisibleFeatures ? QgsFeatureRequest::ExactIntersect : QgsFeatureRequest::NoFlags );

  if ( mSource == QgsComposerAttributeTableV2::AtlasFeature
       && mComposition->atlasComposition().enabled() )
  {
    //source mode is current atlas feature
    QgsFeature* atlasFeature = mComposition->atlasComposition().currentFeature();
    if ( atlasFeature )
    {
      req.setFilterFid( atlasFeature->id() );
    }
    else
    {
      //no atlas feature, so empty table
      return true;
    }
  }

  QgsFeature f;
  int counter = 0;
  QgsFeatureIterator fit = layer->getFeatures( req );

  while ( fit.nextFeature( f ) && counter < mMaximumNumberOfFeatures )
  {
    //check feature against filter
    if ( activeFilter && !filterExpression.isNull() )
    {
      QVariant result = filterExpression->evaluate( &f, layer->pendingFields() );
      // skip this feature if the filter evaluation is false
//.........这里部分代码省略.........

QVariant QgsAggregateCalculator::calculate( QgsAggregateCalculator::Aggregate aggregate,
    const QString& fieldOrExpression,
    QgsExpressionContext* context, bool* ok ) const
{
  if ( ok )
    *ok = false;

  if ( !mLayer )
    return QVariant();

  QScopedPointer<QgsExpression> expression;
  QScopedPointer<QgsExpressionContext> defaultContext;
  if ( !context )
  {
    defaultContext.reset( createContext() );
    context = defaultContext.data();
  }

  int attrNum = mLayer->fieldNameIndex( fieldOrExpression );

  if ( attrNum == -1 )
  {
    Q_ASSERT( context );
    context->setFields( mLayer->fields() );
    // try to use expression
    expression.reset( new QgsExpression( fieldOrExpression ) );

    if ( expression->hasParserError() || !expression->prepare( context ) )
    {
      return QVariant();
    }
  }

  QStringList lst;
  if ( expression.isNull() )
    lst.append( fieldOrExpression );
  else
    lst = expression->referencedColumns();

  QgsFeatureRequest request = QgsFeatureRequest()
                              .setFlags(( expression.data() && expression->needsGeometry() ) ?
                                        QgsFeatureRequest::NoFlags :
                                        QgsFeatureRequest::NoGeometry )
                              .setSubsetOfAttributes( lst, mLayer->fields() );
  if ( !mFilterExpression.isEmpty() )
    request.setFilterExpression( mFilterExpression );
  if ( context )
    request.setExpressionContext( *context );

  //determine result type
  QVariant::Type resultType = QVariant::Double;
  if ( attrNum == -1 )
  {
    // evaluate first feature, check result type
    QgsFeatureRequest testRequest( request );
    testRequest.setLimit( 1 );
    QgsFeature f;
    QgsFeatureIterator fit = mLayer->getFeatures( testRequest );
    if ( !fit.nextFeature( f ) )
    {
      //no matching features
      if ( ok )
        *ok = true;
      return QVariant();
    }

    if ( context )
      context->setFeature( f );
    QVariant v = expression->evaluate( context );
    resultType = v.type();
  }
  else
  {
    resultType = mLayer->fields().at( attrNum ).type();
  }

  QgsFeatureIterator fit = mLayer->getFeatures( request );
  return calculate( aggregate, fit, resultType, attrNum, expression.data(), mDelimiter, context, ok );
}