WindowFromPoint

[alexandros]

hello i used this vb6 code in order to get the handle of any window from a point.

Dim myhwnd As Long
    Dim typPt As POINTAPI
    Dim hwnd As Long
     typPt.x = MY_X
     typPt.y = MY_Y
    myhwnd = WindowFromPoint(typPt.x, typPt.y)

now the problem is that this code seems not to work with vb.net.
I could get a handle to any window even if it did not belong to the form.
Now the following code can find the handle a control that does only exist on the form ,i think. Is there a way to get a handle to any control of any windows window ?

thanks !

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim pt As System.Drawing.Point
        pt.X = 500
        pt.Y = 100
        Dim co As Control
        co = Me.GetChildAtPoint(pt)
        If Not co Is Nothing Then
            MsgBox(co.Name)
        Else
            MsgBox("NO CONTROL FOUND", MsgBoxStyle.ApplicationModal)
        End If
 
 
    End Sub

[nemaroller]

You will only be able to retrieve controls (windows or others) that are part of your application using those functions.

However, you can, just like in your vb6 code, use your WindowFromPoint function. In VB.NET, you need to change any Long variables to Integers, because Integers are 4 bytes long in .Net.

Declare Function WindowFromPoint Lib "user32" (ByVal xPoint As Integer, ByVal yPoint As Integer) As Integer
 
 
 Private Structure typPT 'public or private, up to you
        Public x As Integer
        Public y As Integer
 End Structure
 
 Private myhwnd As Integer
  typPt.x = MY_X
  typPt.y = MY_Y
  myhwnd = WindowFromPoint(typPt.x, typPt.y)

[alexandros]

did microsoft restrict this function for security reasons ?

[nemaroller]

Maybe, maybe not... I think it has more to do with how the .Net framework is designed to exist on a system, which, like Java, is designed to operate mostly system-independent. Low-level calls are not part of the framework, since they are operating system dependent.

So while you can call on Win32 API functions like WindowFromPoint on a Windows box, the .Net framework itself can run on a Linux or Unix box, which obviously has no support for WindowFromPoint.