API GetUserObjectInformation

API GetUserObjectInformation

• Bruno Denuit - MSFT

  Okay. Here is my form load and the declaration

  <DllImport("user32.dll", CharSet:=CharSet.Auto, SetLastError:=True)> _

  Public Function GetUserObjectInformation(ByVal hObj As IntPtr, ByVal nIndex As Int32, ByRef pvInfo As Byte(), ByVal nLength As Byte(), ByRef lpnLengthNeeded As Integer) As Boolean

  End Function

  Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

  Dim i As Short

  Dim tempDesktopName As String

  Dim tempDesktopHandle As Integer

  'Check to see if INI File Exists

  If System.IO.File.Exists(INIFILE) = False Then

  System.IO.File.Create(INIFILE).Close()

  End If

  GetDesktopName()

  'Get Desktop Count and Set Auto Switch to Value

  DesktopCount = GetFromINI("Main", "Desktop Count", 1, INIFILE)

  btnAutoSwitch.Checked = GetFromINI("Main", "Auto Switch", False, INIFILE)

  'Get Default Desktop Information

  Try

  tDefaultDesktop = GetThreadDesktop(GetCurrentThreadId())

  hDefaultDesktop = OpenInputDesktop(0, False, DESKTOP_SWITCHDESKTOP)

  sDefaultDesktop = "Default"

  Catch ex As Exception

  MsgBox("Error Code: " & Err.LastDllError, MsgBoxStyle.Critical, "Open Input Desktop Error")

  End Try

  'Setup Desktops

  If DesktopCount > 1 Then

  For i = 1 To DesktopCount - 1

  tempDesktopName = GetFromINI("Desktop" & i, "Desktop Name", Nothing, INIFILE)

  If tempDesktopName <> "" Then

  Try

  tempDesktopHandle = CreateDesktop(tempDesktopName, Nothing, 0, 0, GENERIC_ALL, 0)

  Catch ex As Exception

  MsgBox("Error Code: " & Err.LastDllError, MsgBoxStyle.Critical, "Create Desktop Error")

  End Try

  If tempDesktopHandle <> 0 Then

  btnToolStrip = New ToolStripButton

  With btnToolStrip

  .Text = tempDesktopName

  .ToolTipText = "Desktop" & i

  End With

  ToolStrip1.Items.Add(btnToolStrip)

  End If

  End If

  Next

  End If

  'Register Bar

  Try

  RegisterBar()

  Catch ex As Exception

  MsgBox("Error: " & ex.Message, MsgBoxStyle.Critical, "Register Bar Error")

  End Try

  'Disable btnDefaultDesktop since we always start here

  btnDefault.Enabled = False

  'Setup Current Desktop

  hCurrentDesktop = hDefaultDesktop

  sCurrentDesktop = "Default"

  End Sub

  Private Function GetDesktopName() As String

  Const ERROR_INSUFFICIENT_BUFFER& = 122

  Const ERROR_PROC_NOT_FOUND& = 127

  Dim buffer(15) As Byte

  Dim lpNeeded As Integer

  Dim threadID As Integer = GetCurrentThreadId()

  Dim desktop As IntPtr = GetThreadDesktop(threadID)

  Dim nLength() As Byte

  Try

  GetUserObjectInformation(desktop, UOI_NAME, Nothing, nLength, lpNeeded)

  Catch ex As Exception

  MsgBox(Err.LastDllError)

  End Try

  If lpNeeded <> 0 Then

  ReDim buffer(lpNeeded - 1)

  ReDim nLength(lpNeeded - 1)

  Try

  GetUserObjectInformation(desktop, UOI_NAME, buffer, nLength, lpNeeded + 1)

  Catch ex As Exception

  MsgBox(Err.LastDllError)

  End Try

  Dim i As Integer = 0

  For i = 0 To buffer.Length - 1

  MsgBox(buffer(i).ToString)

  Next

  End If

  End Function

  Now the thing is that in the GetDesktopName() Function is just a cluster. I am trying to do the best I can with it. Let me know if you need to see anymore of the code. But that is pretty much it. Basically what I need to do is get the desktopname on startup of the application since I can't move the process to a different desktop while it has hooks in a different one. So I have to Create another Process of the current application.

  Thanks.

  Jason

  
  

• SujathaJaganathan

  Mattias,

  Thank you very much. We had tried the StringBuilder method before but we left nLength as an Integer. So we kept getting an error or it returned nothing. Any who. Here is the code again how I used it.

  API Declaration
  Public Declare Function GetUserObjectInformation Lib "user32" Alias "GetUserObjectInformationA" (ByVal hObj As IntPtr, ByVal nIndex As Int32, ByVal pvInfo As System.Text.StringBuilder, ByVal nLength As Byte, ByRef lpnLengthNeeded As Integer) As Boolean
  
  
  Form1_Load Event
  
  Dim lengthNeeded As Integer
  Dim pvInfo As New System.Text.StringBuilder
  
  GetUserObjectInformation(GetThreadDesktop(GetCurrentThreadId()), UOI_NAME, pvInfo, Nothing, lengthNeeded)
  
  If lengthNeeded <> 0 Then
  GetUserObjectInformation(GetThreadDesktop(GetCurrentThreadId()), UOI_NAME, pvInfo, lengthNeeded, lengthNeeded)
  MsgBox(pvInfo.ToString)
  End If

  Thanks again. Very much appreciate it. :)

  Jason

  
  

• BPeck

  Your declaration is overly generic. If you know you're going to request UOI_NAME you may as well type the pvInfo parameter accordingly. I think this should work better

  <DllImport("user32.dll", CharSet:=CharSet.Auto, SetLastError:=True)> _

  Public Function GetUserObjectInformation(ByVal hObj As IntPtr, ByVal nIndex As Int32, ByVal pvInfo As StringBuilder, ByVal nLength As Byte, ByRef lpnLengthNeeded As Integer) As Boolean

  
  
  

• hal9000plus

  Sorry, nLength should be an Integer, I accidentally left it as Byte.

  You should also make sure your StringBuilder is large enough with the line

  pvInfo = New StringBuilder(lengthNeeded)

  
  
  

• noahmattern

  Jason,

  Can we see the code around the call to getobject and it's declaration in your project

  
  
  
• API GetUserObjectInformation