Vertical transformation of features in iterators

python/PyQt6/core/auto_generated/proj/qgscoordinatetransform.sip.in

@@ -138,6 +138,9 @@ Copy constructor
 
     ~QgsCoordinateTransform();
 
+    bool operator==( const QgsCoordinateTransform &other ) const;
+    bool operator!=( const QgsCoordinateTransform &other ) const;
+
     static bool isTransformationPossible( const QgsCoordinateReferenceSystem &source, const QgsCoordinateReferenceSystem &destination );
 %Docstring
 Returns ``True`` if it is theoretically possible to transform between ``source`` and ``destination`` CRSes.
@@ -346,6 +349,14 @@ otherwise points are transformed from destination to source CRS.
     bool isShortCircuited() const;
 %Docstring
 Returns ``True`` if the transform short circuits because the source and destination are equivalent.
+%End
+
+    bool hasVerticalComponent() const;
+%Docstring
+Returns ``True`` if the transform includes a vertical component, i.e. if both the :py:func:`~QgsCoordinateTransform.sourceCrs`
+and :py:func:`~QgsCoordinateTransform.destinationCrs` have a vertical axis.
+
+.. versionadded:: 3.40
 %End
 
     QString coordinateOperation() const;

python/PyQt6/core/auto_generated/qgsfeaturerequest.sip.in

@@ -8,7 +8,6 @@
 
 
 
-
 class QgsFeatureRequest
 {
 %Docstring(signature="appended")
@@ -714,6 +713,20 @@ Set a simplification method for geometries that will be fetched.
 Returns the simplification method for geometries that will be fetched.
 
 .. seealso:: :py:func:`setSimplifyMethod`
+%End
+
+    QgsCoordinateTransform coordinateTransform() const;
+%Docstring
+Returns the coordinate transform which will be used to transform
+the feature's geometries.
+
+If this transform is valid  then it will always be used to transform
+features, regardless of the :py:func:`~QgsFeatureRequest.destinationCrs` setting or the underlying
+feature source's actual CRS.
+
+.. seealso:: :py:func:`setCoordinateTransform`
+
+.. versionadded:: 3.40
 %End
 
     QgsCoordinateReferenceSystem destinationCrs() const;
@@ -722,6 +735,14 @@ Returns the destination coordinate reference system for feature's geometries,
 or an invalid :py:class:`QgsCoordinateReferenceSystem` if no reprojection will be done
 and all features will be left with their original geometry.
 
+.. warning::
+
+   if :py:func:`~QgsFeatureRequest.coordinateTransform` returns a valid transform then the
+   :py:func:`~QgsFeatureRequest.destinationCrs` will have no effect, and the :py:func:`~QgsFeatureRequest.coordinateTransform` will
+   always be used to transform features.
+
+.. seealso:: :py:func:`calculateTransform`
+
 .. seealso:: :py:func:`setDestinationCrs`
 
 .. seealso:: :py:func:`transformContext`
@@ -735,6 +756,52 @@ and reprojection is required
 .. seealso:: :py:func:`setDestinationCrs`
 
 .. seealso:: :py:func:`destinationCrs`
+%End
+
+    QgsCoordinateTransform calculateTransform( const QgsCoordinateReferenceSystem &sourceCrs ) const;
+%Docstring
+Calculates the coordinate transform to use to transform geometries
+when they are originally in ``sourceCrs``.
+
+This method will return :py:func:`~QgsFeatureRequest.coordinateTransform` if it is set (ignoring ``sourceCrs``), otherwise
+it will calculate an appriopriate transform from ``sourceCrs`` to :py:func:`~QgsFeatureRequest.destinationCrs`.
+
+.. versionadded:: 3.40
+%End
+
+    QgsFeatureRequest &setCoordinateTransform( const QgsCoordinateTransform &transform );
+%Docstring
+Sets the coordinate ``transform`` which will be used to transform
+the feature's geometries.
+
+If this transform is valid then it will always be used to transform
+features, regardless of the :py:func:`~QgsFeatureRequest.destinationCrs` setting or the underlying
+feature source's actual CRS.
+
+When a ``transform`` is set using :py:func:`~QgsFeatureRequest.setCoordinateTransform`, then any :py:func:`~QgsFeatureRequest.filterRect`
+or :py:func:`~QgsFeatureRequest.referenceGeometry` set on the request is expected to be in the
+same CRS as the destination CRS for the ``transform``.
+
+The feature geometry transformation is performed
+after all filter expressions are tested and any virtual fields are
+calculated. Accordingly, any geometric expressions used in
+:py:func:`~QgsFeatureRequest.filterExpression` will be performed in the original
+source CRS. This ensures consistent results are returned regardless of the
+destination CRS. Similarly, virtual field values will be calculated using the
+original geometry in the source CRS, so these values are not affected by
+any destination CRS transform present in the feature request.
+
+.. warning::
+
+   This method should be used with caution, and it is recommended
+   to use the high-level :py:func:`~QgsFeatureRequest.setDestinationCrs` method instead. Setting a specific
+   transform should only be done when there is a requirement to use a particular
+   transform.
+
+.. seealso:: :py:func:`coordinateTransform`
+
+
+.. versionadded:: 3.40
 %End
 
     QgsFeatureRequest &setDestinationCrs( const QgsCoordinateReferenceSystem &crs, const QgsCoordinateTransformContext &context );
@@ -758,6 +825,12 @@ destination CRS. Similarly, virtual field values will be calculated using the
 original geometry in the source CRS, so these values are not affected by
 any destination CRS transform present in the feature request.
 
+.. warning::
+
+   if :py:func:`~QgsFeatureRequest.coordinateTransform` returns a valid transform then the
+   :py:func:`~QgsFeatureRequest.destinationCrs` will have no effect, and the :py:func:`~QgsFeatureRequest.coordinateTransform` will
+   always be used to transform features.
+
 .. seealso:: :py:func:`destinationCrs`
 %End
 

python/core/auto_generated/proj/qgscoordinatetransform.sip.in

@@ -138,6 +138,9 @@ Copy constructor
 
     ~QgsCoordinateTransform();
 
+    bool operator==( const QgsCoordinateTransform &other ) const;
+    bool operator!=( const QgsCoordinateTransform &other ) const;
+
     static bool isTransformationPossible( const QgsCoordinateReferenceSystem &source, const QgsCoordinateReferenceSystem &destination );
 %Docstring
 Returns ``True`` if it is theoretically possible to transform between ``source`` and ``destination`` CRSes.
@@ -346,6 +349,14 @@ otherwise points are transformed from destination to source CRS.
     bool isShortCircuited() const;
 %Docstring
 Returns ``True`` if the transform short circuits because the source and destination are equivalent.
+%End
+
+    bool hasVerticalComponent() const;
+%Docstring
+Returns ``True`` if the transform includes a vertical component, i.e. if both the :py:func:`~QgsCoordinateTransform.sourceCrs`
+and :py:func:`~QgsCoordinateTransform.destinationCrs` have a vertical axis.
+
+.. versionadded:: 3.40
 %End
 
     QString coordinateOperation() const;

python/core/auto_generated/qgsfeaturerequest.sip.in

@@ -8,7 +8,6 @@
 
 
 
-
 class QgsFeatureRequest
 {
 %Docstring(signature="appended")
@@ -714,6 +713,20 @@ Set a simplification method for geometries that will be fetched.
 Returns the simplification method for geometries that will be fetched.
 
 .. seealso:: :py:func:`setSimplifyMethod`
+%End
+
+    QgsCoordinateTransform coordinateTransform() const;
+%Docstring
+Returns the coordinate transform which will be used to transform
+the feature's geometries.
+
+If this transform is valid  then it will always be used to transform
+features, regardless of the :py:func:`~QgsFeatureRequest.destinationCrs` setting or the underlying
+feature source's actual CRS.
+
+.. seealso:: :py:func:`setCoordinateTransform`
+
+.. versionadded:: 3.40
 %End
 
     QgsCoordinateReferenceSystem destinationCrs() const;
@@ -722,6 +735,14 @@ Returns the destination coordinate reference system for feature's geometries,
 or an invalid :py:class:`QgsCoordinateReferenceSystem` if no reprojection will be done
 and all features will be left with their original geometry.
 
+.. warning::
+
+   if :py:func:`~QgsFeatureRequest.coordinateTransform` returns a valid transform then the
+   :py:func:`~QgsFeatureRequest.destinationCrs` will have no effect, and the :py:func:`~QgsFeatureRequest.coordinateTransform` will
+   always be used to transform features.
+
+.. seealso:: :py:func:`calculateTransform`
+
 .. seealso:: :py:func:`setDestinationCrs`
 
 .. seealso:: :py:func:`transformContext`
@@ -735,6 +756,52 @@ and reprojection is required
 .. seealso:: :py:func:`setDestinationCrs`
 
 .. seealso:: :py:func:`destinationCrs`
+%End
+
+    QgsCoordinateTransform calculateTransform( const QgsCoordinateReferenceSystem &sourceCrs ) const;
+%Docstring
+Calculates the coordinate transform to use to transform geometries
+when they are originally in ``sourceCrs``.
+
+This method will return :py:func:`~QgsFeatureRequest.coordinateTransform` if it is set (ignoring ``sourceCrs``), otherwise
+it will calculate an appriopriate transform from ``sourceCrs`` to :py:func:`~QgsFeatureRequest.destinationCrs`.
+
+.. versionadded:: 3.40
+%End
+
+    QgsFeatureRequest &setCoordinateTransform( const QgsCoordinateTransform &transform );
+%Docstring
+Sets the coordinate ``transform`` which will be used to transform
+the feature's geometries.
+
+If this transform is valid then it will always be used to transform
+features, regardless of the :py:func:`~QgsFeatureRequest.destinationCrs` setting or the underlying
+feature source's actual CRS.
+
+When a ``transform`` is set using :py:func:`~QgsFeatureRequest.setCoordinateTransform`, then any :py:func:`~QgsFeatureRequest.filterRect`
+or :py:func:`~QgsFeatureRequest.referenceGeometry` set on the request is expected to be in the
+same CRS as the destination CRS for the ``transform``.
+
+The feature geometry transformation is performed
+after all filter expressions are tested and any virtual fields are
+calculated. Accordingly, any geometric expressions used in
+:py:func:`~QgsFeatureRequest.filterExpression` will be performed in the original
+source CRS. This ensures consistent results are returned regardless of the
+destination CRS. Similarly, virtual field values will be calculated using the
+original geometry in the source CRS, so these values are not affected by
+any destination CRS transform present in the feature request.
+
+.. warning::
+
+   This method should be used with caution, and it is recommended
+   to use the high-level :py:func:`~QgsFeatureRequest.setDestinationCrs` method instead. Setting a specific
+   transform should only be done when there is a requirement to use a particular
+   transform.
+
+.. seealso:: :py:func:`coordinateTransform`
+
+
+.. versionadded:: 3.40
 %End
 
     QgsFeatureRequest &setDestinationCrs( const QgsCoordinateReferenceSystem &crs, const QgsCoordinateTransformContext &context );
@@ -758,6 +825,12 @@ destination CRS. Similarly, virtual field values will be calculated using the
 original geometry in the source CRS, so these values are not affected by
 any destination CRS transform present in the feature request.
 
+.. warning::
+
+   if :py:func:`~QgsFeatureRequest.coordinateTransform` returns a valid transform then the
+   :py:func:`~QgsFeatureRequest.destinationCrs` will have no effect, and the :py:func:`~QgsFeatureRequest.coordinateTransform` will
+   always be used to transform features.
+
 .. seealso:: :py:func:`destinationCrs`
 %End
 

src/core/proj/qgscoordinatetransform.cpp

@@ -174,6 +174,20 @@ QgsCoordinateTransform &QgsCoordinateTransform::operator=( const QgsCoordinateTr
 
 QgsCoordinateTransform::~QgsCoordinateTransform() {} //NOLINT
 
+bool QgsCoordinateTransform::operator==( const QgsCoordinateTransform &other ) const
+{
+  return d->mSourceCRS == other.d->mSourceCRS
+         && d->mDestCRS == other.d->mDestCRS
+         && mBallparkTransformsAreAppropriate == other.mBallparkTransformsAreAppropriate
+         && d->mProjCoordinateOperation == other.d->mProjCoordinateOperation
+         && instantiatedCoordinateOperationDetails().proj == other.instantiatedCoordinateOperationDetails().proj;
+}
+
+bool QgsCoordinateTransform::operator!=( const QgsCoordinateTransform &other ) const
+{
+  return !( *this == other );
+}
+
 bool QgsCoordinateTransform::isTransformationPossible( const QgsCoordinateReferenceSystem &source, const QgsCoordinateReferenceSystem &destination )
 {
   if ( !source.isValid() || !destination.isValid() )
@@ -921,6 +935,11 @@ bool QgsCoordinateTransform::isShortCircuited() const
   return !d->mIsValid || d->mShortCircuit;
 }
 
+bool QgsCoordinateTransform::hasVerticalComponent() const
+{
+  return d->mIsValid && d->mHasVerticalComponent;
+}
+
 QString QgsCoordinateTransform::coordinateOperation() const
 {
   return d->mProjCoordinateOperation;

src/core/proj/qgscoordinatetransform.h

@@ -147,6 +147,9 @@ class CORE_EXPORT QgsCoordinateTransform
 
     ~QgsCoordinateTransform();
 
+    bool operator==( const QgsCoordinateTransform &other ) const;
+    bool operator!=( const QgsCoordinateTransform &other ) const;
+
     /**
      * Returns TRUE if it is theoretically possible to transform between \a source and \a destination CRSes.
      *
@@ -378,6 +381,14 @@ class CORE_EXPORT QgsCoordinateTransform
      */
     bool isShortCircuited() const;
 
+    /**
+     * Returns TRUE if the transform includes a vertical component, i.e. if both the sourceCrs()
+     * and destinationCrs() have a vertical axis.
+     *
+     * \since QGIS 3.40
+     */
+    bool hasVerticalComponent() const;
+
     /**
      * Returns a Proj string representing the coordinate operation which will be used to transform
      * coordinates.

src/core/proj/qgscoordinatetransform_p.cpp

@@ -84,6 +84,7 @@ QgsCoordinateTransformPrivate::QgsCoordinateTransformPrivate( const QgsCoordinat
   , mIsValid( other.mIsValid )
   , mShortCircuit( other.mShortCircuit )
   , mGeographicToWebMercator( other.mGeographicToWebMercator )
+  , mHasVerticalComponent( other.mHasVerticalComponent )
   , mSourceCRS( other.mSourceCRS )
   , mDestCRS( other.mDestCRS )
   , mSourceDatumTransform( other.mSourceDatumTransform )
@@ -163,6 +164,8 @@ bool QgsCoordinateTransformPrivate::initialize()
     mSourceCRS.isGeographic() &&
     mDestCRS.authid() == QLatin1String( "EPSG:3857" );
 
+  mHasVerticalComponent = mSourceCRS.hasVerticalAxis() && mDestCRS.hasVerticalAxis();
+
   mSourceIsDynamic = mSourceCRS.isDynamic();
   mSourceCoordinateEpoch = mSourceCRS.coordinateEpoch();
   mDestIsDynamic = mDestCRS.isDynamic();

src/core/proj/qgscoordinatetransform_p.h

@@ -91,6 +91,9 @@ class QgsCoordinateTransformPrivate : public QSharedData
     //! Flag to indicate EPSG:4326 to EPSG:3857 reprojection
     bool mGeographicToWebMercator = false;
 
+    //! Flag to indicate whether the transform has a vertical component
+    bool mHasVerticalComponent = false;
+
     //! QgsCoordinateReferenceSystem of the source (layer) coordinate system
     QgsCoordinateReferenceSystem mSourceCRS;
 

src/core/providers/memory/qgsmemoryfeatureiterator.cpp

@@ -28,10 +28,8 @@
 QgsMemoryFeatureIterator::QgsMemoryFeatureIterator( QgsMemoryFeatureSource *source, bool ownSource, const QgsFeatureRequest &request )
   : QgsAbstractFeatureIteratorFromSource<QgsMemoryFeatureSource>( source, ownSource, request )
 {
-  if ( mRequest.destinationCrs().isValid() && mRequest.destinationCrs() != mSource->mCrs )
-  {
-    mTransform = QgsCoordinateTransform( mSource->mCrs, mRequest.destinationCrs(), mRequest.transformContext() );
-  }
+  mTransform = mRequest.calculateTransform( mSource->mCrs );
+
   try
   {
     mFilterRect = filterRectToSourceCrs( mTransform );

src/core/providers/ogr/qgsogrfeatureiterator.cpp

@@ -123,10 +123,7 @@ QgsOgrFeatureIterator::QgsOgrFeatureIterator( QgsOgrFeatureSource *source, bool
   }
   QMutexLocker locker( mSharedDS ? &mSharedDS->mutex() : nullptr );
 
-  if ( mRequest.destinationCrs().isValid() && mRequest.destinationCrs() != mSource->mCrs )
-  {
-    mTransform = QgsCoordinateTransform( mSource->mCrs, mRequest.destinationCrs(), mRequest.transformContext() );
-  }
+  mTransform = mRequest.calculateTransform( mSource->mCrs );
   try
   {
     mFilterRect = filterRectToSourceCrs( mTransform );

src/core/providers/sensorthings/qgssensorthingsfeatureiterator.cpp

@@ -48,10 +48,7 @@ QgsSensorThingsFeatureIterator::QgsSensorThingsFeatureIterator( QgsSensorThingsF
   : QgsAbstractFeatureIteratorFromSource<QgsSensorThingsFeatureSource>( source, ownSource, request )
   , mInterruptionChecker( request.feedback() )
 {
-  if ( mRequest.destinationCrs().isValid() && mRequest.destinationCrs() != mSource->sharedData()->crs() )
-  {
-    mTransform = QgsCoordinateTransform( mSource->sharedData()->crs(), mRequest.destinationCrs(), mRequest.transformContext() );
-  }
+  mTransform = mRequest.calculateTransform( mSource->sharedData()->crs() );
   try
   {
     mFilterRect = filterRectToSourceCrs( mTransform );