Fix allow fallback determination for reversed operations

nyalldawson · Feb 17, 2020 · 69950ae · 69950ae
1 parent e3b1649
commit 69950ae
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Showing 2 changed files with 17 additions and 2 deletions.
diff --git a/src/core/qgscoordinatetransformcontext.cpp b/src/core/qgscoordinatetransformcontext.cpp
@@ -205,6 +205,11 @@ bool QgsCoordinateTransformContext::allowFallbackTransform( const QgsCoordinateR
 
   d->mLock.lockForRead();
   QgsCoordinateTransformContextPrivate::OperationDetails res = d->mSourceDestDatumTransforms.value( qMakePair( srcKey, destKey ), QgsCoordinateTransformContextPrivate::OperationDetails() );
+  if ( res.operation.isEmpty() )
+  {
+    // try to reverse
+    res = d->mSourceDestDatumTransforms.value( qMakePair( destKey, srcKey ), QgsCoordinateTransformContextPrivate::OperationDetails() );
+  }
   d->mLock.unlock();
   return res.allowFallback;
 #else

diff --git a/tests/src/python/test_qgscoordinatetransformcontext.py b/tests/src/python/test_qgscoordinatetransformcontext.py
@@ -163,6 +163,8 @@ def testSourceDestinationDatumTransformsProj6(self):
                                                                QgsCoordinateReferenceSystem('EPSG:3111')))
         self.assertTrue(
             context.allowFallbackTransform(QgsCoordinateReferenceSystem('EPSG:3111'), QgsCoordinateReferenceSystem('EPSG:4283')))
+        self.assertTrue(
+            context.allowFallbackTransform(QgsCoordinateReferenceSystem('EPSG:4283'), QgsCoordinateReferenceSystem('EPSG:3111')))
 
         self.assertTrue(
             context.hasTransform(QgsCoordinateReferenceSystem('EPSG:4283'), QgsCoordinateReferenceSystem('EPSG:3111')))
@@ -186,11 +188,19 @@ def testSourceDestinationDatumTransformsProj6(self):
                                                               QgsCoordinateReferenceSystem('EPSG:3111')), proj_string_2)
         self.assertFalse(context.mustReverseCoordinateOperation(QgsCoordinateReferenceSystem('EPSG:4283'),
                                                                 QgsCoordinateReferenceSystem('EPSG:3111')))
-        self.assertFalse(
-            context.allowFallbackTransform(QgsCoordinateReferenceSystem('EPSG:4283'), QgsCoordinateReferenceSystem('EPSG:3111')))
         context.removeCoordinateOperation(QgsCoordinateReferenceSystem('EPSG:4283'),
                                           QgsCoordinateReferenceSystem('EPSG:3111'))
 
+        self.assertTrue(context.addCoordinateOperation(QgsCoordinateReferenceSystem('EPSG:4283'),
+                                                       QgsCoordinateReferenceSystem('EPSG:3113'), proj_string_2, False))
+        self.assertFalse(
+            context.allowFallbackTransform(QgsCoordinateReferenceSystem('EPSG:4283'), QgsCoordinateReferenceSystem('EPSG:3113')))
+        self.assertFalse(
+            context.allowFallbackTransform(QgsCoordinateReferenceSystem('EPSG:3113'), QgsCoordinateReferenceSystem('EPSG:4283')))
+
+        context.removeCoordinateOperation(QgsCoordinateReferenceSystem('EPSG:4283'),
+                                          QgsCoordinateReferenceSystem('EPSG:3113'))
+
         proj_string_2 = '+proj=pipeline +step +inv +proj=utm +zone=56 +south +ellps=GRS80 +step +proj=unitconvert +xy_in=rad +xy_out=deg +step +proj=axisswap +order=2,1'
         self.assertTrue(context.addCoordinateOperation(QgsCoordinateReferenceSystem('EPSG:28356'),
                                                        QgsCoordinateReferenceSystem(4283), proj_string_2))