Pitney Bowes MapXtreme - Manual (Page 307)

Chapter 16: Spatial Objects and Coordinate Systems
Coordinate Systems
MapXtreme v7.1 314 Developer Guide
Changing the Coordinate System of a Geometry Object
The next example illustrates how to convert a Geometry object from one coordinate system to
another.
VB example:
Public Shared Sub MapInfoGeomeTryCoordSys(ByRef coordSys As _
CoordSys, ByRef points() As DPoint, ByRef alternateCoordSys _
as CoordSys
' All Geometry constructors require a CoordSys parameter
' Note that the points array is assumed to be in coordSys
Dim lineString As LineString = New _
LineString(coordSys,points)
' The Geometry has a reference to the CoordSys used during
' construction. Unlike the coordinate data represented by the
' points array, the CoordSys' is not copied
If ReferenceEquals(coordSys, lineString.CoordSys) Then
Console.WriteLine("Geometry objects hold a reference to _
the CoordSys used during construction")
End If
' if you want to convert the object to another coordinate
' system, you need to make a new copy using one of the copy methods
If Not coordSys.Equals(alternateCoordSys) Then
Dim newGeometry as MapInfo.Geometry.Geometry = _
lineString.Copy(alternateCoordSys)
End If
End Sub
Determining the Coordinate System of a Map in MapControl
The following code examples shows how to determine the coordinate system for a Map object.
VB example:
Public Shared Sub _
MapInfo_Mapping_FeatureViewerGetDisplayCoordSys(ByVal map As Map)
’Load the Default Projection File so that we can get the name.
MapInfo.Engine.Session.Current.CoordSysFactory.LoadDefault_
ProjectionFile()
’Get the Coordinate System object for current map in the MapControl
Dim mapCoordSys As MapInfo.Geometry.CoordSys = _
map.GetDisplayCoordSys()
’Assign the name of the Coordinate System to a string variable.
’note: the CoordSysName function will return a blank string if the
’Coordinate System is not found in the current CoordinateSystemSet
’(loaded by the LoadDefaultProjectionFile above).