[geometry fixer] overlapcheck incorectly snaps corrected feature to grid

(cherry picked from commit c97e324)
qgis · Nov 20, 2020 · 643648c · 643648c
1 parent 75a3cd7
commit 643648c
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Showing 2 changed files with 16 additions and 4 deletions.
diff --git a/src/analysis/vector/geometry_checker/qgsgeometryoverlapcheck.cpp b/src/analysis/vector/geometry_checker/qgsgeometryoverlapcheck.cpp
@@ -153,7 +153,9 @@ void QgsGeometryOverlapCheck::fixError( const QMap<QString, QgsFeaturePool *> &f
   }
   else if ( method == Subtract )
   {
-    std::unique_ptr< QgsAbstractGeometry > diff1( geomEngineA->difference( interPart, &errMsg ) );
+    std::unique_ptr< QgsGeometryEngine > geomEngineDiffA = QgsGeometryCheckerUtils::createGeomEngine( geometryA.constGet(), 0 );
+    geomEngineDiffA->prepareGeometry();
+    std::unique_ptr< QgsAbstractGeometry > diff1( geomEngineDiffA->difference( interPart, &errMsg ) );
     if ( !diff1 || diff1->isEmpty() )
     {
       diff1.reset();
@@ -162,9 +164,9 @@ void QgsGeometryOverlapCheck::fixError( const QMap<QString, QgsFeaturePool *> &f
     {
       QgsGeometryCheckerUtils::filter1DTypes( diff1.get() );
     }
-    std::unique_ptr< QgsGeometryEngine > geomEngineB = QgsGeometryCheckerUtils::createGeomEngine( geometryB.constGet(), mContext->reducedTolerance );
-    geomEngineB->prepareGeometry();
-    std::unique_ptr< QgsAbstractGeometry > diff2( geomEngineB->difference( interPart, &errMsg ) );
+    std::unique_ptr< QgsGeometryEngine > geomEngineDiffB = QgsGeometryCheckerUtils::createGeomEngine( geometryB.constGet(), 0 );
+    geomEngineDiffB->prepareGeometry();
+    std::unique_ptr< QgsAbstractGeometry > diff2( geomEngineDiffB->difference( interPart, &errMsg ) );
     if ( !diff2 || diff2->isEmpty() )
     {
       diff2.reset();

diff --git a/tests/src/geometry_checker/testqgsgeometrychecks.cpp b/tests/src/geometry_checker/testqgsgeometrychecks.cpp
@@ -1212,6 +1212,9 @@ void TestQgsGeometryChecks::testOverlapCheckToleranceBug()
 {
   // The overlap (intersection) was computed with a different tolerance when collecting errors
   // than when fixing them, leading to failures to fix the issue esp. with big coordinates.
+  //
+  // Also, it used to offset unaffected points (far from the actual overlap) on the affected
+  // feature, leading to both unwanted shifts and remaining slivers.
 
   QTemporaryDir dir;
   QMap<QString, QString> layers;
@@ -1240,7 +1243,11 @@ void TestQgsGeometryChecks::testOverlapCheckToleranceBug()
   QgsFeature f;
   testContext.second[layers["overlap_layer_tolerance_bug.shp"]]->getFeature( 0, f );
   double areaOld = f.geometry().area();
+  QgsPoint pointOld_1 = f.geometry().vertexAt( 1 );
+  QgsPoint pointOld_2 = f.geometry().vertexAt( 2 );
   QCOMPARE( areaOld, 10442.710061549426 );
+  QCOMPARE( pointOld_1, QgsPoint( 2537221.53079314017668366, 1152360.02460834058001637 ) );
+  QCOMPARE( pointOld_2, QgsPoint( 2537366.84566075634211302, 1152360.28978145681321621 ) );
 
   QgsGeometryCheck::Changes changes;
   QMap<QString, int> mergeAttrs;
@@ -1252,6 +1259,9 @@ void TestQgsGeometryChecks::testOverlapCheckToleranceBug()
   // Ensure it actually worked
   testContext.second[layers["overlap_layer_tolerance_bug.shp"]]->getFeature( 0, f );
   QVERIFY( f.geometry().area() < areaOld );
+  // And that we don't have unexpected changes on unaffected points
+  QCOMPARE( f.geometry().vertexAt( 1 ), pointOld_1 );
+  QCOMPARE( f.geometry().vertexAt( 2 ), pointOld_2 );
 
   cleanupTestContext( testContext );
 }