Fix area calculation when OTF active and no ellipsoid (fix #13601)

Author: nyalldawson

python/core/geometry/qgsgeometry.sip

@@ -701,6 +701,18 @@ class QgsGeometry
 
     /** Creates and returns a new geometry engine*/
     static QgsGeometryEngine* createGeometryEngine( const QgsAbstractGeometryV2* geometry ) /Factory/;
+    
+    /** Upgrades a point list from QgsPoint to QgsPointV2
+     * @param input list of QgsPoint objects to be upgraded
+     * @param output destination for list of points converted to QgsPointV2
+     */
+    static void convertPointList( const QList<QgsPoint>& input, QList<QgsPointV2>& output );
+
+    /** Downgrades a point list from QgsPointV2 to QgsPoint
+     * @param input list of QgsPointV2 objects to be downgraded
+     * @param output destination for list of points converted to QgsPoint
+     */
+    static void convertPointList( const QList<QgsPointV2>& input, QList<QgsPoint>& output );    
 
 }; // class QgsGeometry
 

src/core/geometry/qgsgeometry.h

@@ -746,8 +746,16 @@ class CORE_EXPORT QgsGeometry
      */
     static QgsGeometryEngine* createGeometryEngine( const QgsAbstractGeometryV2* geometry );
 
-    //convert point list from v1 to v2
+    /** Upgrades a point list from QgsPoint to QgsPointV2
+     * @param input list of QgsPoint objects to be upgraded
+     * @param output destination for list of points converted to QgsPointV2
+     */
     static void convertPointList( const QList<QgsPoint>& input, QList<QgsPointV2>& output );
+
+    /** Downgrades a point list from QgsPointV2 to QgsPoint
+     * @param input list of QgsPointV2 objects to be downgraded
+     * @param output destination for list of points converted to QgsPoint
+     */
     static void convertPointList( const QList<QgsPointV2>& input, QList<QgsPoint>& output );
 
   private:

src/core/qgsdistancearea.cpp

@@ -276,8 +276,9 @@ double QgsDistanceArea::measure( const QgsAbstractGeometryV2* geomV2 ) const
     return 0.0;
   }
 
-  if ( !mEllipsoidalMode )
+  if ( !mEllipsoidalMode || mEllipsoid == GEO_NONE )
   {
+    //no transform required
     if ( geomDimension == 1 )
     {
       return geomV2->length();
@@ -296,6 +297,8 @@ double QgsDistanceArea::measure( const QgsAbstractGeometryV2* geomV2 ) const
       double sum = 0;
       for ( int i = 0; i < collection->numGeometries(); ++i )
       {
+        //hmm... this is a bit broken. What if a collection consists of both lines and polygons?
+        //the sum will be a mash of both areas and lengths
         sum += measure( collection->geometryN( i ) );
       }
       return sum;
@@ -596,15 +599,9 @@ double QgsDistanceArea::measurePolygon( const QgsCurveV2* curve ) const
 
   QList<QgsPointV2> linePointsV2;
   curve->points( linePointsV2 );
-
   QList<QgsPoint> linePoints;
-  QList<QgsPointV2>::const_iterator ptIt = linePointsV2.constBegin();
-  for ( ; ptIt != linePointsV2.constEnd(); ++ptIt )
-  {
-    linePoints.append( mCoordTransform->transform( QPoint( ptIt->x(), ptIt->y() ) ) );
-  }
-
-  return computePolygonArea( linePoints );
+  QgsGeometry::convertPointList( linePointsV2, linePoints );
+  return measurePolygon( linePoints );
 }
 
 

tests/src/core/testqgsdistancearea.cpp

@@ -23,6 +23,8 @@
 #include <qgsdistancearea.h>
 #include <qgspoint.h>
 #include "qgslogger.h"
+#include "qgsgeometryfactory.h"
+#include "qgsgeometry.h"
 
 class TestQgsDistanceArea: public QObject
 {
@@ -34,6 +36,7 @@ class TestQgsDistanceArea: public QObject
     void basic();
     void test_distances();
     void unit_conversions();
+    void regression13601();
 };
 
 void TestQgsDistanceArea::initTestCase()
@@ -163,7 +166,18 @@ void TestQgsDistanceArea::unit_conversions()
   QString myTxt = QgsDistanceArea::textUnit( inputValue, 7, inputUnit, true, false );
   QString expectedTxt = QLocale::system().toString( 2.4710538146717, 'g', 1 + 7 );
   QVERIFY( myTxt.startsWith( expectedTxt ) ); // Ignore units for now.
-};
+}
+
+void TestQgsDistanceArea::regression13601()
+{
+  //test regression #13601
+  QgsDistanceArea calc;
+  calc.setEllipsoidalMode( true );
+  calc.setEllipsoid( "NONE" );
+  calc.setSourceCrs( 1108L );
+  QgsGeometry geom( QgsGeometryFactory::geomFromWkt("Polygon ((252000 1389000, 265000 1389000, 265000 1385000, 252000 1385000, 252000 1389000))") );
+  QVERIFY( qgsDoubleNear( calc.measure( &geom ), 52000000, 0.0001 ) );
+}
 
 QTEST_MAIN( TestQgsDistanceArea )
 #include "testqgsdistancearea.moc"