Fix #11724 - do to not add extra geometries in union (ftools + processing)

Author: wonder-sk

python/plugins/fTools/tools/doGeoprocessing.py

@@ -1123,9 +1123,8 @@ def union( self ):
     while fitA.nextFeature( inFeatA ):
       self.emit( SIGNAL( "runStatus(PyQt_PyObject)" ), nElement )
       nElement += 1
-      found = False
+      lstIntersectingB = []
       geom = QgsGeometry( inFeatA.geometry() )
-      diff_geom = QgsGeometry( geom )
       atMapA = inFeatA.attributes()
       intersects = indexA.intersects( geom.boundingBox() )
       if len( intersects ) < 1:
@@ -1145,8 +1144,8 @@ def union( self ):
           tmpGeom = QgsGeometry( inFeatB.geometry() )
           try:
             if geom.intersects( tmpGeom ):
-              found = True
               int_geom = geom.intersection( tmpGeom )
+              lstIntersectingB.append(tmpGeom)
 
               if int_geom is None:
                 # There was a problem creating the intersection
@@ -1155,14 +1154,6 @@ def union( self ):
               else:
                 int_geom = QgsGeometry(int_geom)
 
-              if diff_geom.intersects( tmpGeom ):
-                diff_geom = diff_geom.difference( tmpGeom )
-                if diff_geom is None:
-                  # It's possible there was an error here?
-                  diff_geom = QgsGeometry()
-                else:
-                  diff_geom = QgsGeometry(diff_geom)
-
               if int_geom.wkbType() == 0:
                 # intersection produced different geometry types
                 temp_list = int_geom.asGeometryCollection()
@@ -1188,22 +1179,17 @@ def union( self ):
                     writer.addFeature( outFeat )
                   except Exception, err:
                     FEATURE_EXCEPT = False
-            else:
-              # this only happends if the bounding box
-              # intersects, but the geometry doesn't
-              try:
-                outFeat.setGeometry( geom )
-                outFeat.setAttributes( atMapA )
-                writer.addFeature( outFeat )
-              except:
-                # also shoudn't ever happen
-                FEATURE_EXCEPT = False
           except Exception, err:
             GEOS_EXCEPT = False
-            found = False
 
-        if found:
-          try:
+        try:
+            # the remaining bit of inFeatA's geometry
+            # if there is nothing left, this will just silently fail and we're good
+            diff_geom = QgsGeometry( geom )
+            if len(lstIntersectingB) != 0:
+                intB = QgsGeometry.unaryUnion(lstIntersectingB)
+                diff_geom = diff_geom.difference(intB)
+
             if diff_geom.wkbType() == 0:
               temp_list = diff_geom.asGeometryCollection()
               for i in temp_list:
@@ -1212,7 +1198,7 @@ def union( self ):
             outFeat.setGeometry( diff_geom )
             outFeat.setAttributes( atMapA )
             writer.addFeature( outFeat )
-          except Exception, err:
+        except Exception, err:
             FEATURE_EXCEPT = False
 
     length = len( vproviderA.fields() )

python/plugins/processing/algs/qgis/Union.py

@@ -65,9 +65,8 @@ def processAlgorithm(self, progress):
         for inFeatA in featuresA:
             progress.setPercentage(nElement / float(nFeat) * 50)
             nElement += 1
-            found = False
+            lstIntersectingB = []
             geom = QgsGeometry(inFeatA.geometry())
-            diff_geom = QgsGeometry(geom)
             atMapA = inFeatA.attributes()
             intersects = indexA.intersects(geom.boundingBox())
             if len(intersects) < 1:
@@ -89,8 +88,8 @@ def processAlgorithm(self, progress):
                     tmpGeom = QgsGeometry(inFeatB.geometry())
 
                     if geom.intersects(tmpGeom):
-                        found = True
                         int_geom = geom.intersection(tmpGeom)
+                        lstIntersectingB.append(tmpGeom)
 
                         if int_geom is None:
                            # There was a problem creating the intersection
@@ -100,14 +99,6 @@ def processAlgorithm(self, progress):
                         else:
                             int_geom = QgsGeometry(int_geom)
 
-                        if diff_geom.intersects(tmpGeom):
-                            diff_geom = diff_geom.difference(tmpGeom)
-                            if diff_geom is None:
-                                # It's possible there was an error here?
-                                diff_geom = QgsGeometry()
-                            else:
-                                diff_geom = QgsGeometry(diff_geom)
-
                         if int_geom.wkbType() == 0:
                             # Intersection produced different geomety types
                             temp_list = int_geom.asGeometryCollection()
@@ -124,20 +115,15 @@ def processAlgorithm(self, progress):
                         except Exception, err:
                             raise GeoAlgorithmExecutionException(
                                 self.tr('Feature exception while computing union'))
-                    else:
-                      # This only happends if the bounding box intersects,
-                      # but the geometry doesn't
-                        try:
-                            outFeat.setGeometry(geom)
-                            outFeat.setAttributes(atMapA)
-                            writer.addFeature(outFeat)
-                        except:
-                            # Also shoudn't ever happen
-                            raise GeoAlgorithmExecutionException(
-                                self.tr('Feature exception while computing union'))
 
-                if found:
-                    try:
+                try:
+                        # the remaining bit of inFeatA's geometry
+                        # if there is nothing left, this will just silently fail and we're good
+                        diff_geom = QgsGeometry( geom )
+                        if len(lstIntersectingB) != 0:
+                            intB = QgsGeometry.unaryUnion(lstIntersectingB)
+                            diff_geom = diff_geom.difference(intB)
+
                         if diff_geom.wkbType() == 0:
                             temp_list = diff_geom.asGeometryCollection()
                             for i in temp_list:
@@ -146,7 +132,7 @@ def processAlgorithm(self, progress):
                         outFeat.setGeometry(diff_geom)
                         outFeat.setAttributes(atMapA)
                         writer.addFeature(outFeat)
-                    except Exception, err:
+                except Exception, err:
                         raise GeoAlgorithmExecutionException(
                             self.tr('Feature exception while computing union'))