Introduce qgsRound since std::round is available only in C++11 onwards

Author: manisandro

src/core/geometry/qgsgeos.cpp

@@ -1422,11 +1422,11 @@ GEOSCoordSequence* QgsGeos::createCoordinateSequence( const QgsCurveV2* curve, d
       for ( int i = 0; i < numPoints; ++i )
       {
         QgsPointV2 pt = line->pointN( i ); //todo: create method to get const point reference
-        GEOSCoordSeq_setX_r( geosinit.ctxt, coordSeq, i, std::round( pt.x() / precision ) * precision );
-        GEOSCoordSeq_setY_r( geosinit.ctxt, coordSeq, i, std::round( pt.y() / precision ) * precision );
+        GEOSCoordSeq_setX_r( geosinit.ctxt, coordSeq, i, qgsRound( pt.x() / precision ) * precision );
+        GEOSCoordSeq_setY_r( geosinit.ctxt, coordSeq, i, qgsRound( pt.y() / precision ) * precision );
         if ( hasZ )
         {
-          GEOSCoordSeq_setOrdinate_r( geosinit.ctxt, coordSeq, i, 2, std::round( pt.z() / precision ) * precision );
+          GEOSCoordSeq_setOrdinate_r( geosinit.ctxt, coordSeq, i, 2, qgsRound( pt.z() / precision ) * precision );
         }
         if ( hasM )
         {
@@ -1474,11 +1474,11 @@ GEOSGeometry* QgsGeos::createGeosPoint( const QgsAbstractGeometryV2* point, int
     GEOSCoordSequence* coordSeq = GEOSCoordSeq_create_r( geosinit.ctxt, 1, coordDims );
     if ( precision > 0. )
     {
-      GEOSCoordSeq_setX_r( geosinit.ctxt, coordSeq, 0, std::round( pt->x() / precision ) * precision );
-      GEOSCoordSeq_setY_r( geosinit.ctxt, coordSeq, 0, std::round( pt->y() / precision ) * precision );
+      GEOSCoordSeq_setX_r( geosinit.ctxt, coordSeq, 0, qgsRound( pt->x() / precision ) * precision );
+      GEOSCoordSeq_setY_r( geosinit.ctxt, coordSeq, 0, qgsRound( pt->y() / precision ) * precision );
       if ( pt->is3D() )
       {
-        GEOSCoordSeq_setOrdinate_r( geosinit.ctxt, coordSeq, 0, 2, std::round( pt->z() / precision ) * precision );
+        GEOSCoordSeq_setOrdinate_r( geosinit.ctxt, coordSeq, 0, 2, qgsRound( pt->z() / precision ) * precision );
       }
     }
     else

src/core/qgis.h

@@ -289,6 +289,14 @@ inline bool qgsDoubleNearSig( double a, double b, int significantDigits = 10 )
          qRound( ar * pow( 10.0, significantDigits ) ) == qRound( br * pow( 10.0, significantDigits ) );
 }
 
+//
+// a round function which returns a double to guard against overflows
+//
+inline double qgsRound( double x )
+{
+  return x < 0.0 ? std::ceil( x - 0.5 ) : std::floor( x + 0.5 );
+}
+
 bool qgsVariantLessThan( const QVariant& lhs, const QVariant& rhs );
 
 bool qgsVariantGreaterThan( const QVariant& lhs, const QVariant& rhs );