QGIS » QGIS Application

diff -r 17e0ba522478 src/core/pal/pointset.cpp

--- a/src/core/pal/pointset.cpp	Thu Mar 29 16:58:30 2012 +0300

+++ b/src/core/pal/pointset.cpp	Thu Mar 29 17:06:29 2012 +0300

@@ -966,14 +966,14 @@

     for ( i = 0; i < nbPoints; i++ )

     {

       j = i + 1; if ( j == nbPoints ) j = 0;

-      tmp = ( x[i] * y[j] - x[j] * y[i] );

-      cx += ( x[i] + x[j] ) * tmp;

-      cy += ( y[i] + y[j] ) * tmp;

+      tmp = ( ( x[i] - x[0] ) * ( y[j] - y[0] ) - ( x[j] - x[0] ) * ( y[i] - y[0] ) );

+      cx += ( x[i] + x[j] - 2 * x[0] ) * tmp;

+      cy += ( y[i] + y[j] - 2 * y[0] ) * tmp;

       A += tmp;

     }

-    px = cx / ( 3 * A );

-    py = cy / ( 3 * A );

+    px = x[0] + cx / ( 3 * A );

+    py = y[0] + cy / ( 3 * A );

   }

 } // end namespace

diff -r 17e0ba522478 src/core/qgscentralpointpositionmanager.cpp

--- a/src/core/qgscentralpointpositionmanager.cpp	Thu Mar 29 16:58:30 2012 +0300

+++ b/src/core/qgscentralpointpositionmanager.cpp	Thu Mar 29 17:06:29 2012 +0300

@@ -232,17 +232,17 @@

   for ( i = numberOfPoints - 1, j = 0; j < numberOfPoints; i = j, j++ )

   {

-    ai = x[i] * y[j] - x[j] * y[i];

+    ai = ( x[i] - x[0] ) * ( y[j] - y[0] ) - ( x[j] - x[0] ) * ( y[i] - y[0] );

     atmp += ai;

-    xtmp += ( x[j] + x[i] ) * ai;

-    ytmp += ( y[j] + y[i] ) * ai;

+    xtmp += ( x[j] + x[i] - 2 * x[0] ) * ai;

+    ytmp += ( y[j] + y[i] - 2 * y[0] ) * ai;

   }

   if ( atmp == 0 )

   {

     return 2;

   }

-  centroidX = xtmp / ( 3 * atmp );

-  centroidY = ytmp / ( 3 * atmp );

+  centroidX = x[0] + xtmp / ( 3 * atmp );

+  centroidY = y[0] + ytmp / ( 3 * atmp );

   return 0;

 }