VB.NET code to find active window title.

Hi All,

I am looking for VB.NET code which can help me get the active window (the one user has got focus to) title. I know you can do this using Win 32 API like this:

VB Code:

Private Declare Function GetActiveWindow Lib "user32" () As Long
Private Declare Function GetWindowText Lib "user32" Alias "GetWindowTextA" (ByVal hwnd As Long, ByVal lpString As String, ByVal cch As Long) As Long
Private Declare Function GetWindowTextLength Lib "user32" Alias "GetWindowTextLengthA" (ByVal hwnd As Long) As Long
 
Private Sub Form_Load()
    Timer1.Interval = 5000
    Timer1.Enabled = True
End Sub
 
Private Sub Timer1_Timer()
    Dim lWnd As Long
    Dim strName As String
   
    lWnd = GetActiveWindow
    strName = String(GetWindowTextLength(lWnd) + 1, Chr$(0))
    GetWindowText lWnd, strName, Len(strName)
    Debug.Print strName
 
End Sub

but I want to use, Managed code and not API calls.
Do you know of way of achieving the same in Managed code?
Also, is there any event which tells me that Active window has been changed by user??

JD

you will need to use the api's , but you must replace the " Longs " with " Integers " and the String , with StringBuilder. here's a quick example...

VB Code:

[Color=Blue]Declare[/color] [Color=Blue]Function[/color] GetActiveWindow [Color=Blue]Lib[/color] "user32.dll" () [Color=Blue]As[/color] [Color=Blue]Integer
[/color]    [Color=Blue]Declare[/color] [Color=Blue]Function[/color] GetWindowText [Color=Blue]Lib[/color] "user32.dll" [Color=Blue]Alias[/color] "GetWindowTextA" ([Color=Blue]ByVal[/color] hwnd [Color=Blue]As[/color] [Color=Blue]Integer[/color], [Color=Blue]ByVal[/color] lpString [Color=Blue]As[/color] System.Text.StringBuilder, [Color=Blue]ByVal[/color] cch [Color=Blue]As[/color] [Color=Blue]Integer[/color]) [Color=Blue]As[/color] [Color=Blue]Integer
[/color]    [Color=Blue]Declare[/color] [Color=Blue]Function[/color] GetWindowTextLength [Color=Blue]Lib[/color] "user32.dll" [Color=Blue]Alias[/color] "GetWindowTextLengthA" ([Color=Blue]ByVal[/color] hwnd [Color=Blue]As[/color] [Color=Blue]Integer[/color]) [Color=Blue]As[/color] [Color=Blue]Integer
 
 
[/color]    [Color=Blue]Private[/color] [Color=Blue]Sub[/color] Button1_Click([Color=Blue]ByVal[/color] sender [Color=Blue]As[/color] System.Object, [Color=Blue]ByVal[/color] e [Color=Blue]As[/color] System.EventArgs) [Color=Blue]Handles[/color] Button1.Click
 
        [Color=Blue]Dim[/color] hwnd [Color=Blue]As[/color] [Color=Blue]Integer[/color] = GetActiveWindow
        [Color=Blue]Dim[/color] sBuild [Color=Blue]As[/color] [Color=Blue]New[/color] System.Text.StringBuilder(GetWindowTextLength(hwnd) + 1)
        GetWindowText(hwnd, sBuild, sBuild.Capacity)
        MessageBox.Show(sBuild.ToString)
 
    [Color=Blue]End[/color] [Color=Blue]Sub[/color]

I would think since you can get a handle to all open windows, .net or not with the below code, there should be a way to figure which one has active focus... perhaps the Management namespace contains class or classes than can extract that info.

You may have to buy a $40 book on WMI, because no one seems to post much information on the Net about it.

VB Code:

'form level variable
 Private c As Array
 
 
 Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        c = Process.GetProcesses
        Dim i As Integer
        For i = 0 To c.Length - 1
 
            ListBox1.Items.Add(c(i))
        Next
 
 
 
 
 
    End Sub
 
    Private Sub ListBox1_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles ListBox1.SelectedIndexChanged
        Dim a As Process = c(ListBox1.SelectedIndex)
        MessageBox.Show(a.MainWindowTitle & " [Handle = " _
         & a.MainWindowHandle.ToString & "]")
 
 
    End Sub

Hi

Dynamic sysop,

Thanks for suggesting the required code changes so as to make it work in .NET. But what I am really looking for is 'managed code' to achieve the same!

And nemaroller,

yes, I looked in to process class. I went through all the properties but couldnt find a property/member/method, which could tell me whether the given process has got user's focus.

and by WMI, you mean 'Windows Management I?????'

Thanks for your help,

JD

yes I meant Windows Management. There may be other ways beside using WMI, but the only thing you lose by using the API is platform independence. And at this time, .Net really only works on Windows systems.

Platform depedence?

It's not my concern anyway. We are 100% Windows shop and I am happy with it! :)

Btw, I couldnt find any namespace named 'Windows Management' , could you point me to online MSDN document which talks about it??

Thanks once again for your help!
JD