Listing Windows / Controls of another application from .Net
I am developing a small utility application that needs to determine if one of one of its child windows has MDI (this is an out-of-the-box Win32 business application that I have no source code or control over). From my application, I would like to be able to poll or detect when a special Child MDI window is open.
It's easy to test running processes in .Net, but I haven't found an easy way to iterate through (sub) windows and controls for a given Win32 process with .Net.
Any ideas?
Update
Thanks for the answers they gave me on the right track.
I found an article with a test project that uses both EnumWindows
, and EnumChidWindows
other API calls for expanded information about the controls.
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3 answers
You must use native Win32 API.
[DllImport("user32")]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool EnumChildWindows(IntPtr window, EnumWindowProc callback, IntPtr i);
/// <summary>
/// Returns a list of child windows
/// </summary>
/// <param name="parent">Parent of the windows to return</param>
/// <returns>List of child windows</returns>
public static List<IntPtr> GetChildWindows(IntPtr parent)
{
List<IntPtr> result = new List<IntPtr>();
GCHandle listHandle = GCHandle.Alloc(result);
try
{
EnumWindowProc childProc = new EnumWindowProc(EnumWindow);
EnumChildWindows(parent, childProc, GCHandle.ToIntPtr(listHandle));
}
finally
{
if (listHandle.IsAllocated)
listHandle.Free();
}
return result;
}
/// <summary>
/// Callback method to be used when enumerating windows.
/// </summary>
/// <param name="handle">Handle of the next window</param>
/// <param name="pointer">Pointer to a GCHandle that holds a reference to the list to fill</param>
/// <returns>True to continue the enumeration, false to bail</returns>
private static bool EnumWindow(IntPtr handle, IntPtr pointer)
{
GCHandle gch = GCHandle.FromIntPtr(pointer);
List<IntPtr> list = gch.Target as List<IntPtr>;
if (list == null)
{
throw new InvalidCastException("GCHandle Target could not be cast as List<IntPtr>");
}
list.Add(handle);
// You can modify this to check to see if you want to cancel the operation, then return a null here
return true;
}
/// <summary>
/// Delegate for the EnumChildWindows method
/// </summary>
/// <param name="hWnd">Window handle</param>
/// <param name="parameter">Caller-defined variable; we use it for a pointer to our list</param>
/// <returns>True to continue enumerating, false to bail.</returns>
public delegate bool EnumWindowProc(IntPtr hWnd, IntPtr parameter);
code>
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This is an old post, but a common problem. I have a similar situation where I am trying to control the behavior of a finished software application. Mostly I was able to use Kixstart but ran into the limitations of using SETFOCUS and SENDKEYS because at certain points the finished software displays windows where the WindowTitle is empty. So I developed a little utility that identifies visible Windows by their ProcessName as well as WindowTitle (or lack thereof) and sends a message to close the window that matches.
Most of the examples I've seen in the EnumWindows callback functions ignore windows that are not visible or have empty titles, whereas this code lists all windows, including invisible ones.
This code is Visual Basic and uses a configuration file in the format
PRC=process name
WIN=window title
Hope this is helpful to someone
Imports System
Imports System.IO
Imports System.Runtime.InteropServices
Imports System.Text
Module Module1
Dim hShellWindow As IntPtr = GetShellWindow()
Dim dictWindows As New Dictionary(Of IntPtr, String)
Dim dictChildWindows As New Dictionary(Of IntPtr, String)
Dim currentProcessID As Integer = -1
<DllImport("USER32.DLL")>
Function GetShellWindow() As IntPtr
End Function
<DllImport("USER32.DLL")>
Function GetForegroundWindow() As IntPtr
End Function
<DllImport("USER32.DLL")>
Function GetWindowText(ByVal hWnd As IntPtr, ByVal lpString As StringBuilder, ByVal nMaxCount As Integer) As Integer
End Function
<DllImport("USER32.DLL")>
Function GetWindowTextLength(ByVal hWnd As IntPtr) As Integer
End Function
<DllImport("user32.dll", SetLastError:=True)>
Function GetWindowThreadProcessId(ByVal hWnd As IntPtr, <Out()> ByRef lpdwProcessId As UInt32) As UInt32
End Function
<DllImport("USER32.DLL")>
Function IsWindowVisible(ByVal hWnd As IntPtr) As Boolean
End Function
Delegate Function EnumWindowsProc(ByVal hWnd As IntPtr, ByVal lParam As Integer) As Boolean
<DllImport("USER32.DLL")>
Function EnumWindows(ByVal enumFunc As EnumWindowsProc, ByVal lParam As Integer) As Boolean
End Function
<DllImport("USER32.DLL")>
Function EnumChildWindows(ByVal hWndParent As System.IntPtr, ByVal lpEnumFunc As EnumWindowsProc, ByVal lParam As Integer) As Boolean
End Function
<DllImport("USER32.DLL")>
Function PostMessage(ByVal hwnd As Integer, ByVal message As UInteger, ByVal wParam As Integer, ByVal lParam As Integer) As Boolean
End Function
<DllImport("USER32.DLL")>
Function SendMessage(ByVal hWnd As IntPtr, ByVal Msg As UInteger, ByVal wParam As IntPtr, ByVal lParam As IntPtr) As IntPtr
End Function
Function enumWindowsInternal(ByVal hWnd As IntPtr, ByVal lParam As Integer) As Boolean
Dim a As String = ""
Dim length As Integer = GetWindowTextLength(hWnd)
If (length > 0) Then
Dim stringBuilder As New System.Text.StringBuilder(length)
GetWindowText(hWnd, stringBuilder, (length + 1))
a = stringBuilder.ToString
End If
dictWindows.Add(hWnd, a)
EnumChildWindows(hWnd, AddressOf enumChildWindowsInternal, 0)
Return True
End Function
Function enumChildWindowsInternal(ByVal hWnd As IntPtr, ByVal lParam As Integer) As Boolean
Dim a As String = ""
Dim length As Integer = GetWindowTextLength(hWnd)
If (length > 0) Then
Dim stringBuilder As New System.Text.StringBuilder(length)
GetWindowText(hWnd, stringBuilder, (length + 1))
a = stringBuilder.ToString
End If
dictChildWindows.Add(hWnd, a)
Return True
End Function
Function cleanstring(ByVal a As String) As String
Dim c As String = ""
Dim b As String = ""
Dim i As Integer
Do While i < Len(a)
i = i + 1
c = Mid(a, i, 1)
If Asc(c) > 31 And Asc(c) < 128 Then
b = b & c
End If
Loop
cleanstring = b
End Function
Sub Main()
'
'
Dim a As String = ""
Dim b As String = ""
Dim c As String = ""
Dim d As String = ""
Dim f As String = "C:\FIS5\WK.txt"
Dim a1 As String = ""
Dim a2 As String = ""
Dim p As Process
Dim windows As IDictionary(Of IntPtr, String)
Dim kvp As KeyValuePair(Of IntPtr, String)
Dim windowPid As UInt32
Dim hWnd As IntPtr
Dim fhWnd As IntPtr
Dim WM_CLOSE As UInteger = &H12
Dim WM_SYSCOMMAND As UInteger = &H112
Dim SC_CLOSE As UInteger = &HF060
Dim x As Boolean = True
Dim y As IntPtr
Dim processes As Process() = Process.GetProcesses
Dim params As String = File.ReadAllText("C:\FIS5\WindowKiller.txt")
Dim words As String() = params.Split(vbCrLf)
Dim word As String
Dim myprocname As String = ""
Dim mywinname As String = ""
Dim i As Integer = 0
Dim v1 As Integer = 0
For Each word In words
word = Trim(cleanstring(word)).ToUpper
i = InStr(word, "=", CompareMethod.Text)
' a = a & word & " " & i.ToString & vbCrLf
If i = 4 And 4 < Len(word) Then
If Left(word, 4) = "PRC=" Then
myprocname = Mid(word, 5)
End If
If Left(word, 4) = "WIN=" Then
mywinname = Mid(word, 5)
End If
End If
Next
a = a & params & vbCrLf & "procname=" & myprocname & ", winname=" & mywinname & vbCrLf
fhWnd = GetForegroundWindow()
dictWindows.Clear()
dictChildWindows.Clear()
EnumWindows(AddressOf enumWindowsInternal, 0)
windows = dictChildWindows
For Each kvp In windows
hWnd = kvp.Key
GetWindowThreadProcessId(hWnd, windowPid)
b = ""
c = ""
For Each p In processes
If p.Id = windowPid Then
b = p.ProcessName
c = p.Id.ToString
End If
Next
d = "hidden"
If IsWindowVisible(hWnd) Then
d = "visible"
End If
If hWnd = fhWnd Then
d = d & ", foreground"
End If
a = a & "Child window=" & hWnd.ToString & ", processname=" & b & ", procid=" & c & ", windowname=" & kvp.Value & ", " & d & vbCrLf
Next
windows = dictWindows
For Each kvp In windows
v1 = 0
hWnd = kvp.Key
GetWindowThreadProcessId(hWnd, windowPid)
b = ""
c = ""
For Each p In processes
If p.Id = windowPid Then
b = p.ProcessName
c = p.Id.ToString
End If
Next
d = "hidden"
If IsWindowVisible(hWnd) Then
d = "visible"
v1 = 1
End If
If hWnd = fhWnd Then
d = d & ", foreground"
End If
word = kvp.Value
a = a & "Window=" & hWnd.ToString & ", processname=" & b & ", procid=" & c & ", windowname=" & word & ", " & d & vbCrLf
If Trim(cleanstring(b).ToUpper) = myprocname Then
a = a & "procname match" & vbCrLf
If Trim(cleanstring(word)).ToUpper = mywinname And v1 <> 0 Then
a = a & "ATTEMPTING To CLOSE: " & b & " # " & word & " # " & c & vbCrLf
' x = PostMessage(hWnd, WM_CLOSE, 0, 0)
'If x Then
'a = a & "PostMessage returned True" & vbCrLf
'Else
'a = a & "PostMessage returned False" & vbCrLf
'End If
y = SendMessage(hWnd, WM_SYSCOMMAND, SC_CLOSE, 0)
a = a & "SendMessage returned " & y.ToString & vbCrLf
End If
End If
Next
My.Computer.FileSystem.WriteAllText(f, a, False)
End Sub
End Module
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