[feature] Add support for georeferencing vector layers in georeferencer

Allows vector layers without spatial referencing to be interactively
georeferenced (or layers with referencing to be re-referenced!)

Sponsored by the Danish QGIS Usergroup

python/analysis/auto_additions/qgsvectorwarper.py

@@ -2,6 +2,6 @@
 # monkey patching scoped based enum
 QgsVectorWarperTask.Result.Success.__doc__ = "Warping completed successfully"
 QgsVectorWarperTask.Result.Canceled.__doc__ = "Task was canceled before completion"
-QgsVectorWarperTask.Result.Error.__doc__ = ""
+QgsVectorWarperTask.Result.Error.__doc__ = "An error occurred while warping"
 QgsVectorWarperTask.Result.__doc__ = 'Task results\n\n' + '* ``Success``: ' + QgsVectorWarperTask.Result.Success.__doc__ + '\n' + '* ``Canceled``: ' + QgsVectorWarperTask.Result.Canceled.__doc__ + '\n' + '* ``Error``: ' + QgsVectorWarperTask.Result.Error.__doc__
 # --

python/analysis/auto_generated/georeferencing/qgsvectorwarper.sip.in

@@ -68,6 +68,15 @@ A task for warping a vector layer in a background thread.
                          const QgsCoordinateReferenceSystem &destinationCrs,
                          QgsVectorLayer *layer,
                          const QString &fileName );
+%Docstring
+Constructor for QgsVectorWarperTask.
+
+:param method: transformation method
+:param points: GCP point list
+:param destinationCrs: destination layer CRS
+:param layer: source layer
+:param fileName: filename for destination layer
+%End
 
     virtual void cancel();
 
@@ -76,7 +85,7 @@ A task for warping a vector layer in a background thread.
     {
       Success,
       Canceled,
-      Error
+      Error,
     };
 
     Result result() const;

src/analysis/georeferencing/qgsvectorwarper.cpp

@@ -2,8 +2,8 @@
     qgsgcptransformer.cpp
      --------------------------------------
     Date                 : February 2022
-    Copyright            : (C) 2022 by Alex (roya0045)
-    Email                :
+    Copyright            : (C) 2022 by Nyall Dawson
+    Email                : nyall dot dawson at gmail dot com
  ***************************************************************************
  *                                                                         *
  *   This program is free software; you can redistribute it and/or modify  *

src/analysis/georeferencing/qgsvectorwarper.h

@@ -2,8 +2,8 @@
     qgsvectorwarper.h
      --------------------------------------
     Date                 : February 2022
-    Copyright            : (C) 2022 by Alex (roya0045)
-    Email                :
+    Copyright            : (C) 2022 by Nyall Dawson
+    Email                : nyall dot dawson at gmail dot com
  ***************************************************************************
  *                                                                         *
  *   This program is free software; you can redistribute it and/or modify  *
@@ -88,6 +88,15 @@ class ANALYSIS_EXPORT QgsVectorWarperTask : public QgsTask
 
   public:
 
+    /**
+     * Constructor for QgsVectorWarperTask.
+     *
+     * \param method transformation method
+     * \param points GCP point list
+     * \param destinationCrs destination layer CRS
+     * \param layer source layer
+     * \param fileName filename for destination layer
+     */
     QgsVectorWarperTask( QgsGcpTransformerInterface::TransformMethod method, const QList < QgsGcpPoint > &points,
                          const QgsCoordinateReferenceSystem &destinationCrs,
                          QgsVectorLayer *layer,
@@ -100,7 +109,7 @@ class ANALYSIS_EXPORT QgsVectorWarperTask : public QgsTask
     {
       Success, //!< Warping completed successfully
       Canceled, //!< Task was canceled before completion
-      Error
+      Error, //!< An error occurred while warping
     };
 
     /**

tests/src/python/CMakeLists.txt

@@ -359,6 +359,7 @@ ADD_PYTHON_TEST(PyQgsVectorLayerSelectedFeatureSource test_qgsvectorlayerselecte
 ADD_PYTHON_TEST(PyQgsVectorLayerShapefile test_qgsvectorlayershapefile.py)
 ADD_PYTHON_TEST(PyQgsVectorLayerTemporalProperties test_qgsvectorlayertemporalproperties.py)
 ADD_PYTHON_TEST(PyQgsVectorLayerUtils test_qgsvectorlayerutils.py)
+ADD_PYTHON_TEST(PyQgsVectorWarper test_qgsvectorwarper.py)
 ADD_PYTHON_TEST(PyQgsZonalStatistics test_qgszonalstatistics.py)
 ADD_PYTHON_TEST(PyQgsVirtualLayerProvider test_provider_virtual.py)
 ADD_PYTHON_TEST(PyQgsVirtualLayerTask test_qgsvirtuallayertask.py)

tests/src/python/test_qgsvectorwarper.py

@@ -0,0 +1,88 @@
+# -*- coding: utf-8 -*-
+"""QGIS Unit tests for QgsVectorWarper
+
+.. note:: This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+"""
+__author__ = 'Nyall Dawson'
+__date__ = '01/03/2022'
+__copyright__ = 'Copyright 2022, The QGIS Project'
+
+import qgis  # NOQA
+from qgis.analysis import (
+    QgsVectorWarper,
+    QgsGcpPoint,
+    QgsGcpTransformerInterface
+)
+from qgis.core import (
+    QgsVectorLayer,
+    QgsFeature,
+    QgsGeometry,
+    QgsPointXY,
+    QgsFeatureStore,
+    QgsCoordinateReferenceSystem,
+    QgsProject
+)
+from qgis.testing import start_app, unittest
+
+start_app()
+
+
+class TestQgsVectorWarper(unittest.TestCase):
+
+    def testWarper(self):
+        # create source layer
+        source_layer = QgsVectorLayer("Point?field=fldtxt:string&field=fldint:integer",
+                                      "addfeat", "memory")
+        pr = source_layer.dataProvider()
+        f = QgsFeature()
+        f.setAttributes(["test", 123])
+        f.setGeometry(QgsGeometry.fromPointXY(QgsPointXY(100, 200)))
+        f2 = QgsFeature()
+        f2.setAttributes(["test2", 457])
+        f2.setGeometry(QgsGeometry.fromPointXY(QgsPointXY(200, 200)))
+        f3 = QgsFeature()
+        f3.setAttributes(["test3", 888])
+        f3.setGeometry(QgsGeometry.fromPointXY(QgsPointXY(300, 200)))
+        f4 = QgsFeature()
+        f4.setAttributes(["test4", -1])
+        f4.setGeometry(QgsGeometry.fromPointXY(QgsPointXY(400, 300)))
+        f5 = QgsFeature()
+        f5.setAttributes(["test5", 0])
+        f5.setGeometry(QgsGeometry.fromPointXY(QgsPointXY(0, 0)))
+        self.assertTrue(pr.addFeatures([f, f2, f3, f4, f5]))
+        self.assertTrue(source_layer.featureCount() == 5)
+
+        # create sink
+        sink = QgsFeatureStore()
+        warper = QgsVectorWarper(QgsGcpTransformerInterface.TransformMethod.PolynomialOrder1,
+                                 [
+                                     QgsGcpPoint(QgsPointXY(90, 210), QgsPointXY(8, 20),
+                                                 QgsCoordinateReferenceSystem('EPSG:4283'), True),
+                                     QgsGcpPoint(QgsPointXY(210, 190), QgsPointXY(20.5, 20),
+                                                 QgsCoordinateReferenceSystem('EPSG:4283'), True),
+                                     QgsGcpPoint(QgsPointXY(350, 220), QgsPointXY(30, 21),
+                                                 QgsCoordinateReferenceSystem('EPSG:4283'), True),
+                                     QgsGcpPoint(QgsPointXY(390, 290), QgsPointXY(39, 28),
+                                                 QgsCoordinateReferenceSystem('EPSG:4283'), True),
+                                 ],
+                                 QgsCoordinateReferenceSystem('EPSG:4283'))
+
+        self.assertTrue(warper.transformFeatures(source_layer.getFeatures(),
+                                                 sink,
+                                                 QgsProject.instance().transformContext()))
+
+        self.assertEqual(sink.count(), 5)
+        feature_map = {f.attributes()[0]: {'geom': f.geometry().asWkt(1),
+                                           'attributes': f.attributes()} for f in sink.features()}
+        self.assertEqual(feature_map, {'test': {'geom': 'Point (9.4 19.7)', 'attributes': ['test', 123]},
+                                       'test2': {'geom': 'Point (18 19.9)', 'attributes': ['test2', 457]},
+                                       'test3': {'geom': 'Point (26.6 20.1)', 'attributes': ['test3', 888]},
+                                       'test4': {'geom': 'Point (39.6 28.5)', 'attributes': ['test4', -1]},
+                                       'test5': {'geom': 'Point (-7.8 3)', 'attributes': ['test5', 0]}})
+
+
+if __name__ == '__main__':
+    unittest.main()