Add method to determine whether a QgsCoordinateTransform has a vertical

component

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

@@ -349,6 +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/proj/qgscoordinatetransform.sip.in

@@ -349,6 +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;

src/core/proj/qgscoordinatetransform.cpp

@@ -935,6 +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

@@ -381,6 +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;
 

tests/src/python/test_qgscoordinatetransform.py

@@ -161,6 +161,53 @@ class TestQgsCoordinateTransform(QgisTestCase):
         self.assertAlmostEqual(transformedExtent.xMaximum(), 20037508.343, delta=1e-3)
         self.assertAlmostEqual(transformedExtent.yMaximum(), 44927335.427, delta=1e-3)
 
+    def test_has_vertical_component(self):
+        transform = QgsCoordinateTransform()
+        self.assertFalse(transform.hasVerticalComponent())
+
+        # 2d to 2d
+        transform = QgsCoordinateTransform(
+            QgsCoordinateReferenceSystem('EPSG:4326'),
+            QgsCoordinateReferenceSystem('EPSG:3857'),
+            QgsCoordinateTransformContext()
+        )
+        self.assertFalse(transform.hasVerticalComponent())
+
+        # 2d to 3d
+        transform = QgsCoordinateTransform(
+            QgsCoordinateReferenceSystem('EPSG:4326'),
+            QgsCoordinateReferenceSystem('EPSG:7843'),
+            QgsCoordinateTransformContext()
+        )
+        self.assertFalse(transform.hasVerticalComponent())
+
+        # 3d to 2d
+        transform = QgsCoordinateTransform(
+            QgsCoordinateReferenceSystem('EPSG:7843'),
+            QgsCoordinateReferenceSystem('EPSG:4326'),
+            QgsCoordinateTransformContext()
+        )
+        self.assertFalse(transform.hasVerticalComponent())
+
+        # 3d to 3d
+        transform = QgsCoordinateTransform(
+            QgsCoordinateReferenceSystem('EPSG:7843'),
+            QgsCoordinateReferenceSystem.createCompoundCrs(
+                QgsCoordinateReferenceSystem('EPSG:7844'),
+                QgsCoordinateReferenceSystem('EPSG:9458'))[0],
+            QgsCoordinateTransformContext()
+        )
+        self.assertTrue(transform.hasVerticalComponent())
+
+        transform = QgsCoordinateTransform(
+            QgsCoordinateReferenceSystem.createCompoundCrs(
+                QgsCoordinateReferenceSystem('EPSG:7844'),
+                QgsCoordinateReferenceSystem('EPSG:5711'))[0],
+            QgsCoordinateReferenceSystem('EPSG:7843'),
+            QgsCoordinateTransformContext()
+        )
+        self.assertTrue(transform.hasVerticalComponent())
+
 
 if __name__ == '__main__':
     unittest.main()