DLL Calling Example

This example writes the text hello world! into a field by calling the SendMessage DLL function from user32.dll.

DLL Declaration:

// VB .NET code
<Dll("user32.dll")> Public Interface IUserDll32Functions
  Function SendMessageW( _
    ByVal obj As TestObject,ByVal message As Integer,ByVal wParam As Integer,ByVal lParam As String) As Integer
End Interface

The following code shows how to call the declared DLL function in the AUT:

// VB .NET code
Public Sub Main()
  Dim user32Functions As IUserDll32Functions = DllCall.CreateInProcessDllCall(Of IUserDll32Functions)()
  Dim textField = _desktop.Window().TextField()
  user32Functions.SendMessageW(textField, WindowsMessages.WM_SETTEXT, 0, "my text")
End Sub

Note: You can only call DLL functions in the AUT if the first parameter of the DLL function has the C data type HWND.

The following code shows how to call the declared DLL functions in the process of the Open Agent:

// VB .NET code
Public Sub Main()
  Dim user32Functions As IUserDll32Functions = DllCall.CreateAgentDllCall(Of IUserDll32Functions)()
  Dim textField = _desktop.Window().TextField()
  user32Functions.SendMessageW(textField, WindowsMessages.WM_SETTEXT, 0, "my text")
End Sub

Note: The example code uses the WindowsMessages class that contains useful constants for usage with DLL functions that relate to Windows messaging.