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Merge pull request #9063 from mhugo/fix_19355
Fix $length in labels
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Hugo Mercier committed Feb 14, 2019
2 parents 24c09d1 + e4288e5 commit 9ed5b3f
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Showing 15 changed files with 100 additions and 15 deletions.
12 changes: 10 additions & 2 deletions python/core/auto_generated/expression/qgsexpression.sip.in
Expand Up @@ -293,8 +293,12 @@ Returns calculator used for distance and area calculations
void setGeomCalculator( const QgsDistanceArea *calc );
%Docstring
Sets the geometry calculator used for distance and area calculations in expressions.
(used by $length, $area and $perimeter functions only). By default, no geometry
calculator is set and all distance and area calculations are performed using simple
(used by $length, $area and $perimeter functions only).
If the geometry calculator is set to None (default), prepare() will read variables
from the expression context ("project_ellipsoid", "_project_transform_context" and
"_layer_crs") to build a geometry calculator.
If these variables does not exist and if setGeomCalculator() is not called,
all distance and area calculations are performed using simple
Cartesian methods (ie no ellipsoidal calculations).

:param calc: geometry calculator. Ownership is not transferred. Set to a None to force
Expand All @@ -321,6 +325,8 @@ Returns the desired distance units for calculations involving geomCalculator(),
void setDistanceUnits( QgsUnitTypes::DistanceUnit unit );
%Docstring
Sets the desired distance units for calculations involving geomCalculator(), e.g., "$length" and "$perimeter".
If distance units are set to QgsUnitTypes.DistanceUnknownUnit (default), prepare() will read
variables from the expression context ("project_distance_units") to determine distance units.

.. note::

Expand Down Expand Up @@ -351,6 +357,8 @@ Returns the desired areal units for calculations involving geomCalculator(), e.g
void setAreaUnits( QgsUnitTypes::AreaUnit unit );
%Docstring
Sets the desired areal units for calculations involving geomCalculator(), e.g., "$area".
If distance units are set to QgsUnitTypes.AreaUnknownUnit (default), prepare() will read
variables from the expression context ("project_distance_units") to determine distance units.

.. note::

Expand Down
Expand Up @@ -185,6 +185,7 @@ Write the context's state to application settings.




/************************************************************************
* This file has been generated automatically from *
* *
Expand Down
42 changes: 37 additions & 5 deletions src/core/expression/qgsexpression.cpp
Expand Up @@ -102,6 +102,7 @@ void QgsExpression::setExpression( const QString &expression )
d->mRootNode = ::parseExpression( expression, d->mParserErrorString, d->mParserErrors );
d->mEvalErrorString = QString();
d->mExp = expression;
d->mIsPrepared = false;
}

QString QgsExpression::expression() const
Expand Down Expand Up @@ -313,13 +314,37 @@ bool QgsExpression::needsGeometry() const
return d->mRootNode->needsGeometry();
}

void QgsExpression::initGeomCalculator()
void QgsExpression::initGeomCalculator( const QgsExpressionContext *context )
{
if ( d->mCalc )
return;
// Set the geometry calculator from the context if it has not been set by setGeomCalculator()
if ( context && ! d->mCalc )
{
QString ellipsoid = context->variable( "project_ellipsoid" ).toString();
QgsCoordinateReferenceSystem crs = context->variable( "_layer_crs" ).value<QgsCoordinateReferenceSystem>();
QgsCoordinateTransformContext tContext = context->variable( "_project_transform_context" ).value<QgsCoordinateTransformContext>();
if ( crs.isValid() )
{
d->mCalc = std::shared_ptr<QgsDistanceArea>( new QgsDistanceArea() );
d->mCalc->setEllipsoid( ellipsoid.isEmpty() ? GEO_NONE : ellipsoid );
d->mCalc->setSourceCrs( crs, tContext );
}
}

// Set the distance units from the context if it has not been set by setDistanceUnits()
if ( context && distanceUnits() == QgsUnitTypes::DistanceUnknownUnit )
{
QString distanceUnitsStr = context->variable( "project_distance_units" ).toString();
if ( ! distanceUnitsStr.isEmpty() )
setDistanceUnits( QgsUnitTypes::stringToDistanceUnit( distanceUnitsStr ) );
}

// Use planimetric as default
d->mCalc = std::shared_ptr<QgsDistanceArea>( new QgsDistanceArea() );
// Set the area units from the context if it has not been set by setAreaUnits()
if ( context && areaUnits() == QgsUnitTypes::AreaUnknownUnit )
{
QString areaUnitsStr = context->variable( "project_area_units" ).toString();
if ( ! areaUnitsStr.isEmpty() )
setAreaUnits( QgsUnitTypes::stringToAreaUnit( areaUnitsStr ) );
}
}

void QgsExpression::detach()
Expand Down Expand Up @@ -361,6 +386,8 @@ bool QgsExpression::prepare( const QgsExpressionContext *context )
return false;
}

initGeomCalculator( context );
d->mIsPrepared = true;
return d->mRootNode->prepare( this, context );
}

Expand All @@ -385,6 +412,11 @@ QVariant QgsExpression::evaluate( const QgsExpressionContext *context )
return QVariant();
}

if ( ! d->mIsPrepared )
{
qWarning( "QgsExpression::evaluate() called on an expression not yet prepared !" );
prepare( context );
}
return d->mRootNode->eval( this, context );
}

Expand Down
14 changes: 11 additions & 3 deletions src/core/expression/qgsexpression.h
Expand Up @@ -379,8 +379,12 @@ class CORE_EXPORT QgsExpression

/**
* Sets the geometry calculator used for distance and area calculations in expressions.
* (used by $length, $area and $perimeter functions only). By default, no geometry
* calculator is set and all distance and area calculations are performed using simple
* (used by $length, $area and $perimeter functions only).
* If the geometry calculator is set to nullptr (default), prepare() will read variables
* from the expression context ("project_ellipsoid", "_project_transform_context" and
* "_layer_crs") to build a geometry calculator.
* If these variables does not exist and if setGeomCalculator() is not called,
* all distance and area calculations are performed using simple
* Cartesian methods (ie no ellipsoidal calculations).
* \param calc geometry calculator. Ownership is not transferred. Set to a nullptr to force
* Cartesian calculations.
Expand All @@ -399,6 +403,8 @@ class CORE_EXPORT QgsExpression

/**
* Sets the desired distance units for calculations involving geomCalculator(), e.g., "$length" and "$perimeter".
* If distance units are set to QgsUnitTypes::DistanceUnknownUnit (default), prepare() will read
* variables from the expression context ("project_distance_units") to determine distance units.
* \note distances are only converted when a geomCalculator() has been set
* \see distanceUnits()
* \see setAreaUnits()
Expand All @@ -417,6 +423,8 @@ class CORE_EXPORT QgsExpression

/**
* Sets the desired areal units for calculations involving geomCalculator(), e.g., "$area".
* If distance units are set to QgsUnitTypes::AreaUnknownUnit (default), prepare() will read
* variables from the expression context ("project_distance_units") to determine distance units.
* \note areas are only converted when a geomCalculator() has been set
* \see areaUnits()
* \see setDistanceUnits()
Expand Down Expand Up @@ -619,7 +627,7 @@ class CORE_EXPORT QgsExpression
#endif

private:
void initGeomCalculator();
void initGeomCalculator( const QgsExpressionContext *context );

struct HelpArg SIP_SKIP
{
Expand Down
5 changes: 5 additions & 0 deletions src/core/expression/qgsexpressioncontextutils.cpp
Expand Up @@ -257,6 +257,10 @@ QgsExpressionContextScope *QgsExpressionContextUtils::projectScope( const QgsPro
QgsCoordinateReferenceSystem projectCrs = project->crs();
scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "project_crs" ), projectCrs.authid(), true, true ) );
scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "project_crs_definition" ), projectCrs.toProj4(), true, true ) );
scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "project_ellipsoid" ), project->ellipsoid(), true, true ) );
scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "project_distance_units" ), QgsUnitTypes::toString( project->distanceUnits() ), true, true ) );
scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "project_area_units" ), QgsUnitTypes::toString( project->areaUnits() ), true, true ) );
scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "_project_transform_context" ), QVariant::fromValue<QgsCoordinateTransformContext>( project->transformContext() ), true, true ) );

// metadata
scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "project_author" ), project->metadata().author(), true, true ) );
Expand Down Expand Up @@ -335,6 +339,7 @@ QgsExpressionContextScope *QgsExpressionContextUtils::layerScope( const QgsMapLa

scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "layer_name" ), layer->name(), true, true ) );
scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "layer_id" ), layer->id(), true, true ) );
scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "_layer_crs" ), QVariant::fromValue<QgsCoordinateReferenceSystem>( layer->crs() ), true, true ) );
scope->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "layer" ), QVariant::fromValue<QgsWeakMapLayerPointer >( QgsWeakMapLayerPointer( const_cast<QgsMapLayer *>( layer ) ) ), true, true ) );

const QgsVectorLayer *vLayer = qobject_cast< const QgsVectorLayer * >( layer );
Expand Down
10 changes: 6 additions & 4 deletions src/core/expression/qgsexpressionnodeimpl.cpp
Expand Up @@ -1261,16 +1261,18 @@ bool QgsExpressionNodeColumnRef::prepareNode( QgsExpression *parent, const QgsEx
QgsFields fields = qvariant_cast<QgsFields>( context->variable( QgsExpressionContext::EXPR_FIELDS ) );

mIndex = fields.lookupField( mName );
if ( mIndex >= 0 )

if ( mIndex == -1 && context->hasFeature() )
{
return true;
mIndex = context->feature().fieldNameIndex( mName );
}
else

if ( mIndex == -1 )
{
parent->setEvalErrorString( tr( "Column '%1' not found" ).arg( mName ) );
mIndex = -1;
return false;
}
return true;
}

QString QgsExpressionNodeColumnRef::dump() const
Expand Down
3 changes: 3 additions & 0 deletions src/core/qgscoordinatetransformcontext.h
Expand Up @@ -22,6 +22,7 @@
#include "qgis_sip.h"
#include "qgsdatumtransform.h"

#include <QMetaType>
#include <QExplicitlySharedDataPointer>
class QgsCoordinateReferenceSystem;
class QgsReadWriteContext;
Expand Down Expand Up @@ -275,6 +276,8 @@ class CORE_EXPORT QgsCoordinateTransformContext

};

Q_DECLARE_METATYPE( QgsCoordinateTransformContext )

#endif // QGSCOORDINATETRANSFORMCONTEXT_H


Expand Down
3 changes: 3 additions & 0 deletions src/core/qgsexpressionprivate.h
Expand Up @@ -70,6 +70,9 @@ class QgsExpressionPrivate
std::shared_ptr<QgsDistanceArea> mCalc;
QgsUnitTypes::DistanceUnit mDistanceUnit = QgsUnitTypes::DistanceUnknownUnit;
QgsUnitTypes::AreaUnit mAreaUnit = QgsUnitTypes::AreaUnknownUnit;

//! Whether prepare() has been called before evaluate()
bool mIsPrepared = false;
};
///@endcond

Expand Down
1 change: 1 addition & 0 deletions tests/src/core/testqgslayoutitem.cpp
Expand Up @@ -1421,6 +1421,7 @@ void TestQgsLayoutItem::itemVariablesFunction()
map->setId( QStringLiteral( "Map_id" ) );

c = l.createExpressionContext();
e.prepare( &c );
r = e.evaluate( &c );
QGSCOMPARENEAR( r.toDouble(), 184764103, 100 );

Expand Down
3 changes: 3 additions & 0 deletions tests/src/core/testqgsmapsettings.cpp
Expand Up @@ -261,12 +261,15 @@ void TestQgsMapSettings::testIsLayerVisible()
QCOMPARE( r.toBool(), false );

QgsProject::instance()->removeMapLayer( vlA );
e.prepare( &context );
r = e.evaluate( &context );
QCOMPARE( r.toBool(), false ); // layer is deleted
e2.prepare( &context );
r = e2.evaluate( &context );
QCOMPARE( r.toBool(), true ); // layer still exists

QgsProject::instance()->removeMapLayer( vlB );
e2.prepare( &context );
r = e2.evaluate( &context );
QCOMPARE( r.toBool(), false ); // layer is deleted

Expand Down
21 changes: 20 additions & 1 deletion tests/src/python/test_qgspallabeling_tests.py
Expand Up @@ -23,7 +23,8 @@
from qgis.PyQt.QtCore import Qt, QPointF, QSizeF
from qgis.PyQt.QtGui import QFont

from qgis.core import QgsLabelingEngineSettings, QgsPalLayerSettings, QgsUnitTypes, QgsTextBackgroundSettings
from qgis.core import QgsLabelingEngineSettings, QgsPalLayerSettings, QgsUnitTypes, QgsTextBackgroundSettings, QgsProject, QgsExpressionContextUtils, QgsExpressionContext
from qgis.core import QgsCoordinateReferenceSystem

from utilities import svgSymbolsPath

Expand Down Expand Up @@ -308,6 +309,24 @@ def test_curved_placement_below(self):
self.lyr.placementFlags = QgsPalLayerSettings.BelowLine | QgsPalLayerSettings.MapOrientation
self.checkTest()

def test_length_expression(self):
# compare length using the ellipsoid in kms and the planimetric distance in meters
self.lyr.fieldName = "round($length,5) || ' - ' || round(length($geometry),2)"
self.lyr.isExpression = True

QgsProject.instance().setCrs(QgsCoordinateReferenceSystem("EPSG:32613"))
QgsProject.instance().setEllipsoid("WGS84")
QgsProject.instance().setDistanceUnits(QgsUnitTypes.DistanceKilometers)

ctxt = QgsExpressionContext()
ctxt.appendScope(QgsExpressionContextUtils.projectScope(QgsProject.instance()))
ctxt.appendScope(QgsExpressionContextUtils.layerScope(self.layer))
self._TestMapSettings.setExpressionContext(ctxt)

self.lyr.placement = QgsPalLayerSettings.Curved
self.lyr.placementFlags = QgsPalLayerSettings.AboveLine | QgsPalLayerSettings.MapOrientation
self.checkTest()

# noinspection PyPep8Naming


Expand Down
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