Get window handlle from process ID
A module for retrieving the handle number (hWnd) of a window providing only the process id number (PID).
This code is seeking handles that match the given PID and returns the hanlde that refers to a visible window. But, since not all the processes running are windowed or some processes may have multiple windows, may not work for every case.
Option Explicit
Private Const GWL_STYLE = (-16)
Private Const GWL_EXSTYLE = (-20)
Private Const WS_VISIBLE = &H10000000
Private Const WS_EX_APPWINDOW = &H40000
Private Type HWND_TEXT
Window_Handle As Long
Window_Title As String
End Type
Private ColCounter As Long
Private HandleTextCollection() As HWND_TEXT
Private Declare Function EnumWindows Lib "user32" _
(ByVal lpEnumFunc As Long, ByVal lParam As Long) As Boolean
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 Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" _
(ByVal Hwnd As Long, ByVal wIndx As Long) As Long
Private Declare Function GetWindowThreadProcessId Lib "user32" _
(ByVal Hwnd As Long, lpdwProcessId As Long) As Long
Private Function EnumWindowsProc(ByVal Hwnd As Long, ByVal lParam As Long) As Boolean
Dim Title As String
Dim r As Long
r = GetWindowTextLength(Hwnd)
Title = Space(r)
GetWindowText Hwnd, Title, r + 1
'Add to type array
ColCounter = ColCounter + 1
ReDim Preserve HandleTextCollection(ColCounter)
HandleTextCollection(ColCounter).Window_Handle = Hwnd
HandleTextCollection(ColCounter).Window_Title = Title
EnumWindowsProc = True
End Function
Private Sub EnumAllWindows()
ColCounter = 0
ReDim HandleTextCollection(0)
EnumWindows AddressOf EnumWindowsProc, ByVal 0&
'At this point, HandleTextCollection() array holds the handles and window titles
'of all windows enumerated
End Sub
Public Function GetWindowHandleFromPID(ByVal AppPID As Long) As Long
Dim AppPID_HWND() As HWND_TEXT 'Will store only handles related to AppPID
Dim CNT As Long
Dim HND As Long
Dim n As Long
Dim r As Long
Dim i As Long
Dim TaskID As Long
Dim TheHandle As Long
'STEP 1: Find all window handles currently running
'and put them into HandleTextCollection() array
Call EnumAllWindows
'STEP 2: Filter handles and keep only theese tha match with AppPID pid number
'and put them into AppPID_HWND() array
'GetWindowThreadProcessId returns by reference the PID for each handle given
CNT = 0
ReDim AppPID_HWND(0)
For i = 1 To UBound(HandleTextCollection())
HND = HandleTextCollection(i).Window_Handle
n = GetWindowThreadProcessId(HND, TaskID)
If TaskID = AppPID Then
'Handle matches AppPID
CNT = CNT + 1
ReDim Preserve AppPID_HWND(CNT)
AppPID_HWND(CNT).Window_Handle = HND
AppPID_HWND(CNT).Window_Title = HandleTextCollection(i).Window_Title
End If
Next i
'STEP 3: From all the handles related to AppPID, search for the handle
'that refers to a window that is visible.
For i = 1 To UBound(AppPID_HWND())
'Must be a visible window
n = GetWindowLong(AppPID_HWND(i).Window_Handle, GWL_STYLE)
'And a top-level window onto the taskbar since the window is visible
r = GetWindowLong(AppPID_HWND(i).Window_Handle, GWL_EXSTYLE)
If (n) And (WS_VISIBLE) Then
If (r) And (WS_EX_APPWINDOW) Then
'Is it the right hWnd ?
'TODO: GetTitleBarInfo
TheHandle = AppPID_HWND(i).Window_Handle
Exit For
End If
End If
Next i
GetWindowHandleFromPID = TheHandle
End Function
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