Make qgsRound more tolerant to large values

Fixes #19844

Author: nyalldawson

src/core/qgis.h

@@ -291,8 +291,8 @@ inline bool qgsDoubleNearSig( double a, double b, int significantDigits = 10 )
  */
 inline double qgsRound( double number, double places )
 {
-  int scaleFactor = static_cast<int>( std::pow( 10, places ) );
-  return static_cast<double>( static_cast<qlonglong>( number * scaleFactor + 0.5 ) ) / scaleFactor;
+  double scaleFactor = std::pow( 10.0, places );
+  return std::trunc( number * scaleFactor + 0.5 ) / scaleFactor;
 }
 
 

tests/src/core/testqgis.cpp

@@ -44,6 +44,7 @@ class TestQgis : public QObject
     void qVariantCompare_data();
     void qVariantCompare();
     void testQgsAsConst();
+    void testQgsRound();
 
   private:
     QString mReport;
@@ -332,6 +333,30 @@ void TestQgis::testQgsAsConst()
   QCOMPARE( ct.mVal, 2 );
 }
 
+void TestQgis::testQgsRound()
+{
+  QGSCOMPARENEAR( qgsRound( 98765432198, 8 ), 98765432198, 1.0 );
+  QGSCOMPARENEAR( qgsRound( 98765432198, 9 ), 98765432198, 1.0 );
+  QGSCOMPARENEAR( qgsRound( 98765432198, 10 ), 98765432198, 1.0 );
+  QGSCOMPARENEAR( qgsRound( 98765432198, 11 ), 98765432198, 1.0 );
+  QGSCOMPARENEAR( qgsRound( 98765432198, 12 ), 98765432198, 1.0 );
+  QGSCOMPARENEAR( qgsRound( 98765432198, 13 ), 98765432198, 1.0 );
+  QGSCOMPARENEAR( qgsRound( 98765432198, 14 ), 98765432198, 1.0 );
+  QGSCOMPARENEAR( qgsRound( 98765432198765, 14 ), 98765432198765, 1.0 );
+  QGSCOMPARENEAR( qgsRound( 98765432198765432, 20 ), 98765432198765432, 1.0 );
+  QGSCOMPARENEAR( qgsRound( 9.8765432198765, 2 ), 9.88, 0.001 );
+  QGSCOMPARENEAR( qgsRound( 9.8765432198765, 3 ), 9.877, 0.0001 );
+  QGSCOMPARENEAR( qgsRound( 9.8765432198765, 4 ), 9.8765, 0.00001 );
+  QGSCOMPARENEAR( qgsRound( 9.8765432198765, 5 ), 9.87654, 0.000001 );
+  QGSCOMPARENEAR( qgsRound( 9.8765432198765, 6 ), 9.876543, 0.0000001 );
+  QGSCOMPARENEAR( qgsRound( 9.8765432198765, 7 ), 9.8765432, 0.00000001 );
+  QGSCOMPARENEAR( qgsRound( -9.8765432198765, 7 ), -9.876543, 0.000001 );
+  QGSCOMPARENEAR( qgsRound( 9876543.2198765, 5 ), 9876543.219880, 0.000001 );
+  QGSCOMPARENEAR( qgsRound( -9876543.2198765, 5 ), -9876543.219870, 0.000001 );
+
+
+}
+
 
 QGSTEST_MAIN( TestQgis )
 #include "testqgis.moc"