QgsExpressionContext QgsExpressionContextUtils::createFeatureBasedContext( const QgsFeature &feature, const QgsFields &fields )
{
QgsExpressionContextScope* scope = new QgsExpressionContextScope();
scope->setFeature( feature );
scope->setFields( fields );
return QgsExpressionContext() << scope;
}
QgsExpressionContextScope* QgsExpressionContextUtils::layerScope( const QgsMapLayer* layer )
{
QgsExpressionContextScope* scope = new QgsExpressionContextScope( QObject::tr( "Layer" ) );
if ( !layer )
return scope;
//add variables defined in layer properties
QStringList variableNames = layer->customProperty( QStringLiteral( "variableNames" ) ).toStringList();
QStringList variableValues = layer->customProperty( QStringLiteral( "variableValues" ) ).toStringList();
int varIndex = 0;
Q_FOREACH ( const QString& variableName, variableNames )
{
if ( varIndex >= variableValues.length() )
{
break;
}
QVariant varValue = variableValues.at( varIndex );
varIndex++;
scope->setVariable( variableName, varValue );
}
scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "layer_name" ), layer->name(), true ) );
scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "layer_id" ), layer->id(), true ) );
scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "layer" ), QVariant::fromValue<QPointer<QgsMapLayer> >( QPointer<QgsMapLayer>( const_cast<QgsMapLayer*>( layer ) ) ), true ) );
const QgsVectorLayer* vLayer = dynamic_cast< const QgsVectorLayer* >( layer );
if ( vLayer )
{
scope->setFields( vLayer->fields() );
}
//TODO - add functions. Possibilities include:
//is_selected
//field summary stats
return scope;
}
QgsExpressionContextScope* QgsExpressionContextUtils::atlasScope( const QgsAtlasComposition* atlas )
{
QgsExpressionContextScope* scope = new QgsExpressionContextScope( QObject::tr( "Atlas" ) );
if ( !atlas )
{
//add some dummy atlas variables. This is done so that as in certain contexts we want to show
//users that these variables are available even if they have no current value
scope->addVariable( QgsExpressionContextScope::StaticVariable( "atlas_pagename", QString(), true ) );
scope->addVariable( QgsExpressionContextScope::StaticVariable( "atlas_feature", QVariant::fromValue( QgsFeature() ), true ) );
scope->addVariable( QgsExpressionContextScope::StaticVariable( "atlas_featureid", 0, true ) );
scope->addVariable( QgsExpressionContextScope::StaticVariable( "atlas_geometry", QVariant::fromValue( QgsGeometry() ), true ) );
return scope;
}
//add known atlas variables
scope->addVariable( QgsExpressionContextScope::StaticVariable( "atlas_totalfeatures", atlas->numFeatures(), true ) );
scope->addVariable( QgsExpressionContextScope::StaticVariable( "atlas_featurenumber", atlas->currentFeatureNumber() + 1, true ) );
scope->addVariable( QgsExpressionContextScope::StaticVariable( "atlas_filename", atlas->currentFilename(), true ) );
scope->addVariable( QgsExpressionContextScope::StaticVariable( "atlas_pagename", atlas->currentPageName(), true ) );
if ( atlas->enabled() && atlas->coverageLayer() )
{
scope->setFields( atlas->coverageLayer()->fields() );
}
if ( atlas->enabled() )
{
QgsFeature atlasFeature = atlas->feature();
scope->setFeature( atlasFeature );
scope->addVariable( QgsExpressionContextScope::StaticVariable( "atlas_feature", QVariant::fromValue( atlasFeature ), true ) );
scope->addVariable( QgsExpressionContextScope::StaticVariable( "atlas_featureid", atlasFeature.id(), true ) );
scope->addVariable( QgsExpressionContextScope::StaticVariable( "atlas_geometry", QVariant::fromValue( *atlasFeature.constGeometry() ), true ) );
}
return scope;
}