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Introduction

The Eye4Software GPS toolkit allows software developers to add GPS functionality to their own programs without the need to have any knowledge on serial communications and GPS protocols like RS-232 and NMEA0183.

The product can be used in many programming environments, such as Visual Basic, Visual C++, Visual Studio.Net, Borland C++ Builder, Borland Delphi and VBA, but also web oriented applications such as ASP, ASP.NET and PHP, and all other programming environments that support ActiveX.

Prerequisites

First you must have Visual Basic .Net and the Eye4Software GPS Component installed on your computer. We will use Visual Basic .Net 2008 in this document, but other versions from 2002 and up can be used. You can download the Eye4Software GPS Component here.

Creating the project

Start the Visual Studio IDE, and select the "New" => "Project" option from the "File" menu. The "New Project" dialog now appears, select the "Windows Application" option to generate a Windows GUI application.

Add a reference to the ActiveX component

In order to declare and create the objects from your Visual Basic .Net application, you need to add a reference to the ActiveX object, by choosing the "Add Reference..." option from the "Project" menu. A list of components installed on the system is displayed. Just select the "COM" tab, and select the "Eye4Software GPS Toolkit 3.0", click "Select" and finally click "OK".

Declare and create the object(s)

After adding the reference to the control, you can declare the objects like this:

Private objProjection As GpsProjection
Private objDatumSrc   As GpsDatumParameters
Private objDatumDst   As GpsDatumParameters

The objects can be created in your code by double clicking on the Form you created, this will open the Formx_Load handler. Paste the following code in this function:

objProjection = New GpsProjection
objDatumSrc   = New GpsDatumParameters
objDatumDst   = New GpsDatumParameters

The source code

The following code shows how to perform a map datum conversion using the GPS Toolkit. In this example a position is transformed from WGS84 to NAD27. For a list of other supported map datums, please refer to our map datum list.

' ConvDatum Visual Basic .NET demo - Eye4Software GPS Toolkit
' This demo shows how to convert a latitude/longitude coordinate from one map datum to another.
' For more information on how to use the Eye4Software GPS Toolkit with Visual Basic .NET, 
' visit http://www.eye4software.com/products/gpstoolkit/source#vbnet

Imports GpsToolkit

Module Module1

  Private objProjection As GpsProjection

  Private objSrcDatum As GpsDatumParameters
  Private objDstDatum As GpsDatumParameters

  Sub Main()
    ' Create instances of objects
    objProjection = New GpsProjection
    objSrcDatum = New GpsDatumParameters
    objDstDatum = New GpsDatumParameters

    ' Set Source Datum ( WGS84 )
    ' The ID for WGS84 is 4326, see 'http://www.eye4software.com/resources/datums' for a full list of supported datums 
    ' To convert from another datum, just change the code below (EPSG code)
    ' To define your own datum, please have a look at the 'ConvUserGrid' Visual Basic .NET demo.
    objSrcDatum.LoadFromId(4326)

    ' Set Destination Datum ( NAD27 )
    ' The ID for NAD27 is 4267, see 'http://www.eye4software.com/resources/datums' for a full list of supported datums 
    ' To convert to another datum, just change the code below (EPSG code)
    ' To define your own datum, please have a look at the 'ConvUserGrid' Visual Basic .NET demo.
    objDstDatum.LoadFromId(4267)

    ' Set source latitude and longitude coordinates
    objProjection.Latitude = 33.59
    objProjection.Longitude = -112.15

    ' Perform datum transformation
    objProjection.TransformDatum (objSrcDatum, objDstDatum)

    ' Get and display result
    If (objProjection.LastError = 0) Then
      Console.WriteLine("(WGS84) 33.590 N, 112.15 W => (NAD27) {0} N, {1} W", 
                        objProjection.Latitude, objProjection.Longitude)
    Else
      Console.WriteLine("Error occured during datum transformation: {0} ({1})", 
                        objProjection.LastError, objProjection.LastErrorDescription)
    End If

    Console.WriteLine("Ready.")
  End Sub
End Module