Expose extra arguments to QgsGeometry::transform

Previously these were only available via the raw QgsAbstractGeometry
API.

Also add more unit tests for QgsGeometry::transform

Author: nyalldawson

python/core/geometry/qgsgeometry.sip.in

@@ -616,9 +616,20 @@ Translates this geometry by dx, dy, dz and dm.
 :return: OperationResult a result code: success or reason of failure
 %End
 
-    OperationResult transform( const QgsCoordinateTransform &ct );
+    OperationResult transform( const QgsCoordinateTransform &ct,
+                               QgsCoordinateTransform::TransformDirection direction = QgsCoordinateTransform::ForwardTransform,
+                               bool transformZ = false );
 %Docstring
-Transforms this geometry as described by CoordinateTransform ct
+Transforms this geometry as described by the coordinate transform ``ct``.
+
+The transformation defaults to a forward transform, but the direction can be swapped
+by setting the ``direction`` argument.
+
+By default, z-coordinates are not transformed, even if the coordinate transform
+includes a vertical datum transformation. To transform z-coordinates, set
+``transformZ`` to true. This requires that the z coordinates in the geometry represent
+height relative to the vertical datum of the source CRS (generally ellipsoidal heights)
+and are expressed in its vertical units (generally meters).
 
 :return: OperationResult a result code: success or reason of failure
 %End

src/core/geometry/qgsgeometry.cpp

@@ -2337,15 +2337,15 @@ bool QgsGeometry::requiresConversionToStraightSegments() const
   return d->geometry->hasCurvedSegments();
 }
 
-QgsGeometry::OperationResult QgsGeometry::transform( const QgsCoordinateTransform &ct )
+QgsGeometry::OperationResult QgsGeometry::transform( const QgsCoordinateTransform &ct, const QgsCoordinateTransform::TransformDirection direction, const bool transformZ )
 {
   if ( !d->geometry )
   {
     return QgsGeometry::InvalidBaseGeometry;
   }
 
   detach();
-  d->geometry->transform( ct );
+  d->geometry->transform( ct, direction, transformZ );
   return QgsGeometry::Success;
 }
 

src/core/geometry/qgsgeometry.h

@@ -659,10 +659,22 @@ class CORE_EXPORT QgsGeometry
     OperationResult translate( double dx, double dy, double dz = 0.0, double dm = 0.0 );
 
     /**
-     * Transforms this geometry as described by CoordinateTransform ct
+     * Transforms this geometry as described by the coordinate transform \a ct.
+     *
+     * The transformation defaults to a forward transform, but the direction can be swapped
+     * by setting the \a direction argument.
+     *
+     * By default, z-coordinates are not transformed, even if the coordinate transform
+     * includes a vertical datum transformation. To transform z-coordinates, set
+     * \a transformZ to true. This requires that the z coordinates in the geometry represent
+     * height relative to the vertical datum of the source CRS (generally ellipsoidal heights)
+     * and are expressed in its vertical units (generally meters).
+     *
      * \returns OperationResult a result code: success or reason of failure
      */
-    OperationResult transform( const QgsCoordinateTransform &ct );
+    OperationResult transform( const QgsCoordinateTransform &ct,
+                               QgsCoordinateTransform::TransformDirection direction = QgsCoordinateTransform::ForwardTransform,
+                               bool transformZ = false );
 
     /**
      * Transforms the x and y components of the geometry using a QTransform object \a t.

tests/src/python/test_qgsgeometry.py

@@ -36,7 +36,9 @@
     QgsCoordinateTransform,
     QgsRectangle,
     QgsWkbTypes,
-    QgsRenderChecker
+    QgsRenderChecker,
+    QgsCoordinateReferenceSystem,
+    QgsProject
 )
 from qgis.PyQt.QtCore import QDir
 from qgis.PyQt.QtGui import QImage, QPainter, QPen, QColor, QBrush, QPainterPath
@@ -1196,33 +1198,89 @@ def testTranslate(self):
 
         polygon = QgsGeometry.fromWkt("MultiPolygon (((0 0, 1 0, 1 1, 2 1, 2 2, 0 2, 0 0)),((4 0, 5 0, 5 2, 3 2, 3 1, 4 1, 4 0)))")
         self.assertEqual(polygon.translate(1, 2), 0, "Translate failed")
-        expwkt = "MultiPolygon (((1 2, 2 2, 2 3, 3 3, 3 4, 1 4, 1 2)),((5 2, 6 2, 6 2, 4 4, 4 3, 5 3, 5 2)))"
+        expwkt = "MultiPolygon (((1 2, 2 2, 2 3, 3 3, 3 4, 1 4, 1 2)),((5 2, 6 2, 6 4, 4 4, 4 3, 5 3, 5 2)))"
         wkt = polygon.asWkt()
+        assert compareWkt(expwkt, wkt), "Expected:\n%s\nGot:\n%s\n" % (expwkt, wkt)
 
+    def testTransform(self):
+        # null transform
         ct = QgsCoordinateTransform()
 
         point = QgsGeometry.fromWkt("Point (1 1)")
-        self.assertEqual(point.transform(ct), 0, "Translate failed")
+        self.assertEqual(point.transform(ct), 0, "Transform failed")
         expwkt = "Point (1 1)"
         wkt = point.asWkt()
         assert compareWkt(expwkt, wkt), "Expected:\n%s\nGot:\n%s\n" % (expwkt, wkt)
 
         point = QgsGeometry.fromWkt("MultiPoint ((1 1),(2 2),(3 3))")
-        self.assertEqual(point.transform(ct), 0, "Translate failed")
+        self.assertEqual(point.transform(ct), 0, "Transform failed")
         expwkt = "MultiPoint ((1 1),(2 2),(3 3))"
         wkt = point.asWkt()
         assert compareWkt(expwkt, wkt), "Expected:\n%s\nGot:\n%s\n" % (expwkt, wkt)
 
         linestring = QgsGeometry.fromWkt("LineString (1 0, 2 0)")
-        self.assertEqual(linestring.transform(ct), 0, "Translate failed")
+        self.assertEqual(linestring.transform(ct), 0, "Transform failed")
         expwkt = "LineString (1 0, 2 0)"
         wkt = linestring.asWkt()
         assert compareWkt(expwkt, wkt), "Expected:\n%s\nGot:\n%s\n" % (expwkt, wkt)
 
         polygon = QgsGeometry.fromWkt("MultiPolygon(((0 0,1 0,1 1,2 1,2 2,0 2,0 0)),((4 0,5 0,5 2,3 2,3 1,4 1,4 0)))")
-        self.assertEqual(polygon.transform(ct), 0, "Translate failed")
+        self.assertEqual(polygon.transform(ct), 0, "Transform failed")
         expwkt = "MultiPolygon (((0 0, 1 0, 1 1, 2 1, 2 2, 0 2, 0 0)),((4 0, 5 0, 5 2, 3 2, 3 1, 4 1, 4 0)))"
         wkt = polygon.asWkt()
+        assert compareWkt(expwkt, wkt), "Expected:\n%s\nGot:\n%s\n" % (expwkt, wkt)
+
+        # valid transform
+        ct = QgsCoordinateTransform(QgsCoordinateReferenceSystem(4326), QgsCoordinateReferenceSystem(3857), QgsProject.instance())
+
+        point = QgsGeometry.fromWkt("Point (1 1)")
+        self.assertEqual(point.transform(ct), 0, "Transform failed")
+        expwkt = "Point (111319 111325)"
+        wkt = point.asWkt()
+        assert compareWkt(expwkt, wkt, tol=100), "Expected:\n%s\nGot:\n%s\n" % (expwkt, wkt)
+
+        point = QgsGeometry.fromWkt("MultiPoint ((1 1),(2 2),(3 3))")
+        self.assertEqual(point.transform(ct), 0, "Transform failed")
+        expwkt = "MultiPoint ((111319 111325),(222638 222684),(333958 334111))"
+        wkt = point.asWkt()
+        assert compareWkt(expwkt, wkt, tol=100), "Expected:\n%s\nGot:\n%s\n" % (expwkt, wkt)
+
+        linestring = QgsGeometry.fromWkt("LineString (1 0, 2 0)")
+        self.assertEqual(linestring.transform(ct), 0, "Transform failed")
+        expwkt = "LineString (111319 0, 222638 0)"
+        wkt = linestring.asWkt()
+        assert compareWkt(expwkt, wkt, tol=100), "Expected:\n%s\nGot:\n%s\n" % (expwkt, wkt)
+
+        polygon = QgsGeometry.fromWkt("MultiPolygon(((0 0,1 0,1 1,2 1,2 2,0 2,0 0)),((4 0,5 0,5 2,3 2,3 1,4 1,4 0)))")
+        self.assertEqual(polygon.transform(ct), 0, "Transform failed")
+        expwkt = "MultiPolygon (((0 0, 111319 0, 111319 111325, 222638 111325, 222638 222684, 0 222684, 0 0)),((445277 0, 556597 0, 556597 222684, 333958 222684, 333958 111325, 445277 111325, 445277 0)))"
+        wkt = polygon.asWkt()
+        assert compareWkt(expwkt, wkt, tol=100), "Expected:\n%s\nGot:\n%s\n" % (expwkt, wkt)
+
+        # reverse transform
+        point = QgsGeometry.fromWkt("Point (111319 111325)")
+        self.assertEqual(point.transform(ct, QgsCoordinateTransform.ReverseTransform), 0, "Transform failed")
+        expwkt = "Point (1 1)"
+        wkt = point.asWkt()
+        assert compareWkt(expwkt, wkt, tol=0.01), "Expected:\n%s\nGot:\n%s\n" % (expwkt, wkt)
+
+        point = QgsGeometry.fromWkt("MultiPoint ((111319 111325),(222638 222684),(333958 334111))")
+        self.assertEqual(point.transform(ct, QgsCoordinateTransform.ReverseTransform), 0, "Transform failed")
+        expwkt = "MultiPoint ((1 1),(2 2),(3 3))"
+        wkt = point.asWkt()
+        assert compareWkt(expwkt, wkt, tol=0.01), "Expected:\n%s\nGot:\n%s\n" % (expwkt, wkt)
+
+        linestring = QgsGeometry.fromWkt("LineString (111319 0, 222638 0)")
+        self.assertEqual(linestring.transform(ct, QgsCoordinateTransform.ReverseTransform), 0, "Transform failed")
+        expwkt = "LineString (1 0, 2 0)"
+        wkt = linestring.asWkt()
+        assert compareWkt(expwkt, wkt, tol=0.01), "Expected:\n%s\nGot:\n%s\n" % (expwkt, wkt)
+
+        polygon = QgsGeometry.fromWkt("MultiPolygon (((0 0, 111319 0, 111319 111325, 222638 111325, 222638 222684, 0 222684, 0 0)),((445277 0, 556597 0, 556597 222684, 333958 222684, 333958 111325, 445277 111325, 445277 0)))")
+        self.assertEqual(polygon.transform(ct, QgsCoordinateTransform.ReverseTransform), 0, "Transform failed")
+        expwkt = "MultiPolygon(((0 0,1 0,1 1,2 1,2 2,0 2,0 0)),((4 0,5 0,5 2,3 2,3 1,4 1,4 0)))"
+        wkt = polygon.asWkt()
+        assert compareWkt(expwkt, wkt, tol=0.01), "Expected:\n%s\nGot:\n%s\n" % (expwkt, wkt)
 
     def testExtrude(self):
         # test with empty geometry