private Tuple <IGeoTransformation, esriTransformDirection> GetPredefinedTransformation(
SpatialReferenceEnvironmentClass spatialReferenceFactory,
ISpatialReference fromSpatialReference,
ISpatialReference toSpatialReference)
{
int?fromFactoryCode = GetGCSFactoryCode(fromSpatialReference);
int?toFactoryCode = GetGCSFactoryCode(toSpatialReference);
if (!fromFactoryCode.HasValue || !toFactoryCode.HasValue)
{
return(null);
}
var geographicTransformationsSet = spatialReferenceFactory.CreatePredefinedGeographicTransformations();
geographicTransformationsSet.Reset();
var geoTransformation = geographicTransformationsSet.Next() as IGeoTransformation;
try
{
while (geoTransformation != null)
{
geoTransformation.GetSpatialReferences(
out ISpatialReference bufferForFromGeoCoordSystemSR,
out ISpatialReference bufferForToGeoCoordSystemSR);
if (bufferForFromGeoCoordSystemSR.FactoryCode == fromFactoryCode &&
bufferForToGeoCoordSystemSR.FactoryCode == toFactoryCode)
{
return(new Tuple <IGeoTransformation, esriTransformDirection>
(geoTransformation, esriTransformDirection.esriTransformForward));
}
if (bufferForFromGeoCoordSystemSR.FactoryCode == toFactoryCode &&
bufferForToGeoCoordSystemSR.FactoryCode == fromFactoryCode)
{
return(new Tuple <IGeoTransformation, esriTransformDirection>
(geoTransformation, esriTransformDirection.esriTransformReverse));
}
geoTransformation = geographicTransformationsSet.Next() as IGeoTransformation;
}
}
finally
{
Marshal.ReleaseComObject(geographicTransformationsSet);
}
return(null);
}