Add QgsGeometry::isGeosValid option to ignore self-touching rings

python/core/auto_generated/geometry/qgsgeometry.sip.in

@@ -313,9 +313,18 @@ by equals() instead.
 .. versionadded:: 1.5
 %End
 
-    bool isGeosValid() const;
+    enum ValidityFlag
+    {
+      FlagAllowSelfTouchingHoles,
+    };
+    typedef QFlags<QgsGeometry::ValidityFlag> ValidityFlags;
+
+
+    bool isGeosValid( QgsGeometry::ValidityFlags flags = 0 ) const;
 %Docstring
-Checks validity of the geometry using GEOS
+Checks validity of the geometry using GEOS.
+
+The ``flags`` parameter indicates optional flags which control the type of validity checking performed.
 
 .. versionadded:: 1.5
 %End
@@ -2107,6 +2116,8 @@ Downgrades a point list from QgsPoint to :py:class:`QgsPointXY`
 
 }; // class QgsGeometry
 
+QFlags<QgsGeometry::ValidityFlag> operator|(QgsGeometry::ValidityFlag f1, QFlags<QgsGeometry::ValidityFlag> f2);
+
 
 
 /************************************************************************

python/core/auto_generated/geometry/qgsgeometryengine.sip.in

@@ -207,7 +207,17 @@ pattern.
 
     virtual double area( QString *errorMsg = 0 ) const = 0;
     virtual double length( QString *errorMsg = 0 ) const = 0;
-    virtual bool isValid( QString *errorMsg = 0 ) const = 0;
+
+    virtual bool isValid( QString *errorMsg = 0, bool allowSelfTouchingHoles = false ) const = 0;
+%Docstring
+Returns true if the geometry is valid.
+
+If the geometry is invalid, ``errorMsg`` will be filled with the reported geometry error.
+
+The ``allowSelfTouchingHoles`` argument specifies whether self-touching holes are permitted.
+OGC validity states that self-touching holes are NOT permitted, whilst other vendor
+validity checks (e.g. ESRI) permit self-touching holes.
+%End
 
     virtual bool isEqual( const QgsAbstractGeometry *geom, QString *errorMsg = 0 ) const = 0;
 %Docstring

src/core/geometry/qgsgeometry.cpp

@@ -2462,7 +2462,7 @@ void QgsGeometry::validateGeometry( QVector<QgsGeometry::Error> &errors, Validat
   QgsGeometryValidator::validateGeometry( *this, errors, method );
 }
 
-bool QgsGeometry::isGeosValid() const
+bool QgsGeometry::isGeosValid( const QgsGeometry::ValidityFlags flags ) const
 {
   if ( !d->geometry )
   {
@@ -2477,7 +2477,7 @@ bool QgsGeometry::isGeosValid() const
 
   QgsGeos geos( d->geometry.get() );
   mLastError.clear();
-  return geos.isValid( &mLastError );
+  return geos.isValid( &mLastError, flags & FlagAllowSelfTouchingHoles );
 }
 
 bool QgsGeometry::isSimple() const

src/core/geometry/qgsgeometry.h

@@ -345,11 +345,21 @@ class CORE_EXPORT QgsGeometry
      */
     bool isGeosEqual( const QgsGeometry & ) const;
 
+    //! Validity check flags
+    enum ValidityFlag
+    {
+      FlagAllowSelfTouchingHoles = 1 << 0, //!< Indicates that self-touching holes are permitted. OGC validity states that self-touching holes are NOT permitted, whilst other vendor validity checks (e.g. ESRI) permit self-touching holes.
+    };
+    Q_DECLARE_FLAGS( ValidityFlags, ValidityFlag )
+
     /**
-     * Checks validity of the geometry using GEOS
+     * Checks validity of the geometry using GEOS.
+     *
+     * The \a flags parameter indicates optional flags which control the type of validity checking performed.
+     *
      * \since QGIS 1.5
      */
-    bool isGeosValid() const;
+    bool isGeosValid( QgsGeometry::ValidityFlags flags = nullptr ) const;
 
     /**
      * Determines whether the geometry is simple (according to OGC definition),
@@ -2270,6 +2280,7 @@ class CORE_EXPORT QgsGeometry
 }; // class QgsGeometry
 
 Q_DECLARE_METATYPE( QgsGeometry )
+Q_DECLARE_OPERATORS_FOR_FLAGS( QgsGeometry::ValidityFlags )
 
 //! Writes the geometry to stream out. QGIS version compatibility is not guaranteed.
 CORE_EXPORT QDataStream &operator<<( QDataStream &out, const QgsGeometry &geometry );

src/core/geometry/qgsgeometryengine.h

@@ -217,7 +217,17 @@ class CORE_EXPORT QgsGeometryEngine
 
     virtual double area( QString *errorMsg = nullptr ) const = 0;
     virtual double length( QString *errorMsg = nullptr ) const = 0;
-    virtual bool isValid( QString *errorMsg = nullptr ) const = 0;
+
+    /**
+     * Returns true if the geometry is valid.
+     *
+     * If the geometry is invalid, \a errorMsg will be filled with the reported geometry error.
+     *
+     * The \a allowSelfTouchingHoles argument specifies whether self-touching holes are permitted.
+     * OGC validity states that self-touching holes are NOT permitted, whilst other vendor
+     * validity checks (e.g. ESRI) permit self-touching holes.
+     */
+    virtual bool isValid( QString *errorMsg = nullptr, bool allowSelfTouchingHoles = false ) const = 0;
 
     /**
      * Checks if this is equal to \a geom.

src/core/geometry/qgsgeos.cpp

@@ -1658,7 +1658,7 @@ QgsAbstractGeometry *QgsGeos::convexHull( QString *errorMsg ) const
   CATCH_GEOS_WITH_ERRMSG( nullptr );
 }
 
-bool QgsGeos::isValid( QString *errorMsg ) const
+bool QgsGeos::isValid( QString *errorMsg, const bool allowSelfTouchingHoles ) const
 {
   if ( !mGeos )
   {
@@ -1667,7 +1667,14 @@ bool QgsGeos::isValid( QString *errorMsg ) const
 
   try
   {
-    return GEOSisValid_r( geosinit.ctxt, mGeos.get() );
+    GEOSGeometry *g1 = nullptr;
+    char *r = nullptr;
+    char res = GEOSisValidDetail_r( geosinit.ctxt, mGeos.get(), allowSelfTouchingHoles ? GEOSVALID_ALLOW_SELFTOUCHING_RING_FORMING_HOLE : 0, &r, &g1 );
+    const bool invalid = res != 1;
+
+    if ( invalid && errorMsg )
+      *errorMsg = QString( r );
+    return !invalid;
   }
   CATCH_GEOS_WITH_ERRMSG( false );
 }

src/core/geometry/qgsgeos.h

@@ -218,7 +218,7 @@ class CORE_EXPORT QgsGeos: public QgsGeometryEngine
     bool relatePattern( const QgsAbstractGeometry *geom, const QString &pattern, QString *errorMsg = nullptr ) const override;
     double area( QString *errorMsg = nullptr ) const override;
     double length( QString *errorMsg = nullptr ) const override;
-    bool isValid( QString *errorMsg = nullptr ) const override;
+    bool isValid( QString *errorMsg = nullptr, bool allowSelfTouchingHoles = false ) const override;
     bool isEqual( const QgsAbstractGeometry *geom, QString *errorMsg = nullptr ) const override;
     bool isEmpty( QString *errorMsg = nullptr ) const override;
     bool isSimple( QString *errorMsg = nullptr ) const override;

tests/src/python/test_qgsgeometry.py

@@ -5040,6 +5040,27 @@ def testForceRHR(self):
             self.assertEqual(res.asWkt(1), t[1],
                              "mismatch for {}, expected:\n{}\nGot:\n{}\n".format(t[0], t[1], res.asWkt(1)))
 
+    def testIsGeosValid(self):
+        tests = [
+            ["", False, False, ''],
+            ["Point (100 100)", True, True, ''],
+            ["MultiPoint (100 100, 100 200)", True, True, ''],
+            ["LINESTRING (0 0, 0 100, 100 100)", True, True, ''],
+            ["POLYGON((-1 -1, 4 0, 4 2, 0 2, -1 -1))", True, True, ''],
+            ["MULTIPOLYGON(Polygon((-1 -1, 4 0, 4 2, 0 2, -1 -1)),Polygon((100 100, 200 100, 200 200, 100 200, 100 100)))", True, True, ''],
+            ['MultiPolygon (((159865.14786298031685874 6768656.31838363595306873, 159858.97975336571107619 6769211.44824895076453686, 160486.07089751763851382 6769211.44824895076453686, 160481.95882444124436006 6768658.37442017439752817, 160163.27316101978067309 6768658.37442017439752817, 160222.89822062765597366 6769116.87056819349527359, 160132.43261294672265649 6769120.98264127038419247, 160163.27316101978067309 6768658.37442017439752817, 159865.14786298031685874 6768656.31838363595306873)))', False, True, 'Ring Self-intersection']
+        ]
+        for t in tests:
+            g1 = QgsGeometry.fromWkt(t[0])
+            res = g1.isGeosValid()
+            self.assertEqual(res, t[1],
+                             "mismatch for {}, expected:\n{}\nGot:\n{}\n".format(t[0], t[1], res))
+            if not res:
+                self.assertEqual(g1.lastError(), t[3], t[0])
+            res = g1.isGeosValid(QgsGeometry.FlagAllowSelfTouchingHoles)
+            self.assertEqual(res, t[2],
+                             "mismatch for {}, expected:\n{}\nGot:\n{}\n".format(t[0], t[2], res))
+
     def renderGeometry(self, geom, use_pen, as_polygon=False, as_painter_path=False):
         image = QImage(200, 200, QImage.Format_RGB32)
         image.fill(QColor(0, 0, 0))