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GetWindowThreadProcessId (user32)
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C# Signature:
[DllImport("user32.dll", SetLastError=true)]
static extern uint GetWindowThreadProcessId(IntPtr hWnd, out uint lpdwProcessId);
// When you don't want the ProcessId, use this overload and pass IntPtr.Zero for the second parameter
[DllImport("user32.dll")]
static extern uint GetWindowThreadProcessId(IntPtr hWnd, IntPtr ProcessId);
VB.Net Signature:
<DllImport("user32.dll", SetLastError:=True)> _
Private Shared Function GetWindowThreadProcessId(ByVal hwnd As IntPtr, _
ByRef lpdwProcessId As Integer) As Integer
End Function
''' <summary>
''' Retrieves the identifier of the thread that created the specified window and, optionally, the identifier of the process that created the window.
''' </summary>
''' <param name="hwnd">A handle to the window. </param>
''' <param name="lpdwProcessId">A pointer to a variable that receives the process identifier. If this parameter is not NULL, GetWindowThreadProcessId copies the identifier of the process to the variable; otherwise, it does not. </param>
''' <returns>The return value is the identifier of the thread that created the window. </returns>
''' <remarks>http://msdn.microsoft.com/en-us/library/ms633522%28v=vs.85%29.aspx</remarks>
Private Declare Auto Function GetWindowThreadProcessId Lib "user32.dll" (ByVal hwnd As IntPtr, _
ByRef lpdwProcessId As Integer) As Integer
Return Value
The return value is the identifier of the thread that created the window.
Notes:
You can use Integer / Int32 when dealing with handles, but using IntPtr is much more flexible. If you need an Integer, just call IntPtr.ToInt32.
Tips & Tricks:
We can use this API to get ProcessID from Window's Title by combining this function with EnumWindows.
Sample Code (VB):
If objAcc Is Nothing Then
objAcc = New Application
Dim lngPid As Integer
Dim lngAccessHwnd As IntPtr = New IntPtr(objAcc.hWndAccessApp)
GetWindowThreadProcessId(lngAccessHwnd, lngPid)
End If
The following sample retrieves the System.Diagnostics.Process the currently "owns" the Clipboard, and outputs the process and file name.
Public Declare Unicode Function GetClipboardOwner Lib "user32" () As IntPtr
Public Declare Auto Function GetWindowThreadProcessId Lib "user32" (ByVal hwnd As IntPtr, ByRef lpdwProcessId As IntPtr) As IntPtr
Public Function GetClipboardProcess() As Process
Dim oResult As Process = Nothing
GetWindowThreadProcessId returns the id of the thread that created the target window. To get the process id of a window, use the first c# signature above, and:
Sample Code (C#):
int processID = 0;
int threadID = GetWindowThreadProcessId(hWnd, out processID);
Alternative Managed API:
Do you know one? Please contribute it!
The GetWindowThreadProcessId API
8/29/2011 5:20:18 AM - -71.187.199.49
An IntPtr is a pointer to a memory location (unmanaged) that adapts to the platform it is running on (64-bit, etc.) UNLIKE a standard int/Integer. You should always use this type for unmanaged calls that require it, even though an int will appear to work on your development machine.
1/13/2008 4:00:13 AM - Damon Carr-72.43.165.29
The EnumWindows API
3/20/2019 10:44:34 AM - -98.152.226.218
The GetWindowThreadProcessId API
8/29/2011 5:20:18 AM - -71.187.199.49
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