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Fixes slow update in field calculator
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by blocking the vector signals ...
... and emitting dataChanged at
the end.

I'm a bit worried of side effects,
but I can't see any other solution.

The root of the issue here is that
for each changed field/row an attribute
valueChanged signal is emitted, and the
QgsVectorLayerCache::featureAtId
loads the feature again.
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@elpaso
elpaso committed Oct 12, 2018
1 parent 42ea216 commit d79e3ad
Showing 1 changed file with 128 additions and 120 deletions.
248 changes: 128 additions & 120 deletions src/app/qgsfieldcalculator.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -163,169 +163,177 @@ void QgsFieldCalculator::accept()
{
builder->saveToRecent( QStringLiteral( "fieldcalc" ) );

if ( !mVectorLayer )
if ( ! mVectorLayer )
{
return;
}
else // Need a scope for the blocker let's keep the else for clarity
{

// Set up QgsDistanceArea each time we (re-)calculate
QgsDistanceArea myDa;
QgsSignalBlocker<QgsVectorLayer> vectorBlocker( mVectorLayer );

myDa.setSourceCrs( mVectorLayer->crs(), QgsProject::instance()->transformContext() );
myDa.setEllipsoid( QgsProject::instance()->ellipsoid() );
// Set up QgsDistanceArea each time we (re-)calculate
QgsDistanceArea myDa;

QString calcString = builder->expressionText();
QgsExpression exp( calcString );
exp.setGeomCalculator( &myDa );
exp.setDistanceUnits( QgsProject::instance()->distanceUnits() );
exp.setAreaUnits( QgsProject::instance()->areaUnits() );
myDa.setSourceCrs( mVectorLayer->crs(), QgsProject::instance()->transformContext() );
myDa.setEllipsoid( QgsProject::instance()->ellipsoid() );

QgsExpressionContext expContext( QgsExpressionContextUtils::globalProjectLayerScopes( mVectorLayer ) );
QString calcString = builder->expressionText();
QgsExpression exp( calcString );
exp.setGeomCalculator( &myDa );
exp.setDistanceUnits( QgsProject::instance()->distanceUnits() );
exp.setAreaUnits( QgsProject::instance()->areaUnits() );

if ( !exp.prepare( &expContext ) )
{
QMessageBox::critical( nullptr, tr( "Evaluation Error" ), exp.evalErrorString() );
return;
}
QgsExpressionContext expContext( QgsExpressionContextUtils::globalProjectLayerScopes( mVectorLayer ) );

bool updatingGeom = false;
if ( !exp.prepare( &expContext ) )
{
QMessageBox::critical( nullptr, tr( "Evaluation Error" ), exp.evalErrorString() );
return;
}

// Test for creating expression field based on ! mUpdateExistingGroupBox checked rather
// than on mNewFieldGroupBox checked, as if the provider does not support adding attributes
// then mUpdateExistingGroupBox is set to not checkable, and hence is not checked. This
// is a minimum fix to resolve this - better would be some GUI redesign...
if ( ! mUpdateExistingGroupBox->isChecked() && mCreateVirtualFieldCheckbox->isChecked() )
{
mVectorLayer->addExpressionField( calcString, fieldDefinition() );
}
else
{
if ( !mVectorLayer->isEditable() )
mVectorLayer->startEditing();
bool updatingGeom = false;

// Test for creating expression field based on ! mUpdateExistingGroupBox checked rather
// than on mNewFieldGroupBox checked, as if the provider does not support adding attributes
// then mUpdateExistingGroupBox is set to not checkable, and hence is not checked. This
// is a minimum fix to resolve this - better would be some GUI redesign...
if ( ! mUpdateExistingGroupBox->isChecked() && mCreateVirtualFieldCheckbox->isChecked() )
{
mVectorLayer->addExpressionField( calcString, fieldDefinition() );
}
else
{
if ( !mVectorLayer->isEditable() )
mVectorLayer->startEditing();

QApplication::setOverrideCursor( Qt::WaitCursor );
QApplication::setOverrideCursor( Qt::WaitCursor );

mVectorLayer->beginEditCommand( QStringLiteral( "Field calculator" ) );
mVectorLayer->beginEditCommand( QStringLiteral( "Field calculator" ) );

//update existing field
if ( mUpdateExistingGroupBox->isChecked() || !mNewFieldGroupBox->isEnabled() )
{
if ( mExistingFieldComboBox->currentData().toString() == QLatin1String( "geom" ) )
//update existing field
if ( mUpdateExistingGroupBox->isChecked() || !mNewFieldGroupBox->isEnabled() )
{
//update geometry
mAttributeId = -1;
updatingGeom = true;
if ( mExistingFieldComboBox->currentData().toString() == QLatin1String( "geom" ) )
{
//update geometry
mAttributeId = -1;
updatingGeom = true;
}
else
{
QMap<QString, int>::const_iterator fieldIt = mFieldMap.constFind( mExistingFieldComboBox->currentText() );
if ( fieldIt != mFieldMap.constEnd() )
{
mAttributeId = fieldIt.value();
}
}
}
else
{
QMap<QString, int>::const_iterator fieldIt = mFieldMap.constFind( mExistingFieldComboBox->currentText() );
if ( fieldIt != mFieldMap.constEnd() )
//create new field
const QgsField newField = fieldDefinition();

if ( !mVectorLayer->addAttribute( newField ) )
{
mAttributeId = fieldIt.value();
QApplication::restoreOverrideCursor();
QMessageBox::critical( nullptr, tr( "Create New Field" ), tr( "Could not add the new field to the provider." ) );
mVectorLayer->destroyEditCommand();
return;
}
}
}
else
{
//create new field
const QgsField newField = fieldDefinition();

if ( !mVectorLayer->addAttribute( newField ) )
{
QApplication::restoreOverrideCursor();
QMessageBox::critical( nullptr, tr( "Create New Field" ), tr( "Could not add the new field to the provider." ) );
mVectorLayer->destroyEditCommand();
return;
}
//get index of the new field
const QgsFields &fields = mVectorLayer->fields();

//get index of the new field
const QgsFields &fields = mVectorLayer->fields();
for ( int idx = 0; idx < fields.count(); ++idx )
{
if ( fields.at( idx ).name() == mOutputFieldNameLineEdit->text() )
{
mAttributeId = idx;
break;
}
}

for ( int idx = 0; idx < fields.count(); ++idx )
{
if ( fields.at( idx ).name() == mOutputFieldNameLineEdit->text() )
//update expression context with new fields
expContext.setFields( mVectorLayer->fields() );
if ( ! exp.prepare( &expContext ) )
{
mAttributeId = idx;
break;
QApplication::restoreOverrideCursor();
QMessageBox::critical( nullptr, tr( "Evaluation Error" ), exp.evalErrorString() );
return;
}
}

//update expression context with new fields
expContext.setFields( mVectorLayer->fields() );
if ( ! exp.prepare( &expContext ) )
if ( mAttributeId == -1 && !updatingGeom )
{
mVectorLayer->destroyEditCommand();
QApplication::restoreOverrideCursor();
QMessageBox::critical( nullptr, tr( "Evaluation Error" ), exp.evalErrorString() );
return;
}
}

if ( mAttributeId == -1 && !updatingGeom )
{
mVectorLayer->destroyEditCommand();
QApplication::restoreOverrideCursor();
return;
}

//go through all the features and change the new attribute
QgsFeature feature;
bool calculationSuccess = true;
QString error;
//go through all the features and change the new attribute
QgsFeature feature;
bool calculationSuccess = true;
QString error;

bool useGeometry = exp.needsGeometry();
int rownum = 1;
bool useGeometry = exp.needsGeometry();
int rownum = 1;

QgsField field = !updatingGeom ? mVectorLayer->fields().at( mAttributeId ) : QgsField();
QgsField field = !updatingGeom ? mVectorLayer->fields().at( mAttributeId ) : QgsField();

bool newField = !mUpdateExistingGroupBox->isChecked();
QVariant emptyAttribute;
if ( newField )
emptyAttribute = QVariant( field.type() );
bool newField = !mUpdateExistingGroupBox->isChecked();
QVariant emptyAttribute;
if ( newField )
emptyAttribute = QVariant( field.type() );

QgsFeatureRequest req = QgsFeatureRequest().setFlags( useGeometry ? QgsFeatureRequest::NoFlags : QgsFeatureRequest::NoGeometry );
if ( mOnlyUpdateSelectedCheckBox->isChecked() )
{
req.setFilterFids( mVectorLayer->selectedFeatureIds() );
}
QgsFeatureIterator fit = mVectorLayer->getFeatures( req );
while ( fit.nextFeature( feature ) )
{
expContext.setFeature( feature );
expContext.lastScope()->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "row_number" ), rownum, true ) );

QVariant value = exp.evaluate( &expContext );
if ( exp.hasEvalError() )
QgsFeatureRequest req = QgsFeatureRequest().setFlags( useGeometry ? QgsFeatureRequest::NoFlags : QgsFeatureRequest::NoGeometry );
if ( mOnlyUpdateSelectedCheckBox->isChecked() )
{
calculationSuccess = false;
error = exp.evalErrorString();
break;
req.setFilterFids( mVectorLayer->selectedFeatureIds() );
}
else if ( updatingGeom )
QgsFeatureIterator fit = mVectorLayer->getFeatures( req );
while ( fit.nextFeature( feature ) )
{
if ( value.canConvert< QgsGeometry >() )
expContext.setFeature( feature );
expContext.lastScope()->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "row_number" ), rownum, true ) );

QVariant value = exp.evaluate( &expContext );
if ( exp.hasEvalError() )
{
calculationSuccess = false;
error = exp.evalErrorString();
break;
}
else if ( updatingGeom )
{
QgsGeometry geom = value.value< QgsGeometry >();
mVectorLayer->changeGeometry( feature.id(), geom );
if ( value.canConvert< QgsGeometry >() )
{
QgsGeometry geom = value.value< QgsGeometry >();
mVectorLayer->changeGeometry( feature.id(), geom );
}
}
else
{
( void )field.convertCompatible( value );
mVectorLayer->changeAttributeValue( feature.id(), mAttributeId, value, newField ? emptyAttribute : feature.attributes().value( mAttributeId ) );
}
}
else
{
( void )field.convertCompatible( value );
mVectorLayer->changeAttributeValue( feature.id(), mAttributeId, value, newField ? emptyAttribute : feature.attributes().value( mAttributeId ) );
}

rownum++;
}
rownum++;
}

QApplication::restoreOverrideCursor();
QApplication::restoreOverrideCursor();

if ( !calculationSuccess )
{
QMessageBox::critical( nullptr, tr( "Evaluation Error" ), tr( "An error occurred while evaluating the calculation string:\n%1" ).arg( error ) );
mVectorLayer->destroyEditCommand();
return;
if ( !calculationSuccess )
{
QMessageBox::critical( nullptr, tr( "Evaluation Error" ), tr( "An error occurred while evaluating the calculation string:\n%1" ).arg( error ) );
mVectorLayer->destroyEditCommand();
return;
}
mVectorLayer->endEditCommand();
}

mVectorLayer->endEditCommand();
}
// Vector signals unlocked! Tell the world that the layer has changed
mVectorLayer->dataChanged();
QDialog::accept();
}

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