FindWindow API helper

[bushmobile]

I came up with something similar to this for a scripting language I was messing around with. It outputted the code on a single line in manner that my parser would understand, so I've modified it to output VB code instead - it can handle windows with the same classname & caption:

Private Declare Function FindWindowEx Lib "user32" Alias "FindWindowExA" ( _
    ByVal hWnd1 As Long, ByVal hWnd2 As Long, ByVal lpsz1 As String, ByVal lpsz2 As String) As Long
 
Private Declare Function GetAncestor Lib "user32.dll" ( _
    ByVal hwnd As Long, ByVal gaFlags As Long) As Long
 
Private Declare Function GetClassName Lib "user32" Alias "GetClassNameA" ( _
    ByVal hwnd As Long, ByVal lpClassName As String, ByVal nMaxCount As Long) 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 Declare Function GetDesktopWindow Lib "user32" () As Long
 
Private Const GA_PARENT As Long = 1
 
Private Function WindowCode(ByVal lhWnd As Long) As String
    Dim lParent As Long, lChild As Long, lLen As Long, lCount As Long
    Dim sClass As String, sCaption As String
 
    Do
        ' ClassName
        sClass = Space$(256)
        lLen = GetClassName(lhWnd, sClass, 256)
        sClass = Left$(sClass, lLen)
 
        ' Caption
        sCaption = String$(GetWindowTextLength(lhWnd), vbNullChar)
        GetWindowText lhWnd, sCaption, Len(sCaption) + 1
 
        ' Find Window
        lParent = GetAncestor(lhWnd, GA_PARENT)
        
        lCount = 1: lChild = 0
        WindowCode = "lhWnd = lChild: lChild = 0" & vbCrLf & WindowCode
        Do
            lChild = FindWindowEx(lParent, lChild, sClass, sCaption)
            WindowCode = "lChild = FindWindowEx(lhWnd, lChild, """ & sClass & """, """ & sCaption & """)" & vbCrLf & WindowCode
            If lChild = lhWnd Then Exit Do
            lCount = lCount + 1
        Loop Until lChild = lhWnd
        lhWnd = lParent
    Loop Until lhWnd = GetDesktopWindow
    
    WindowCode = "Dim lChild As Long, lhWnd As Long" & vbCrLf & vbCrLf & WindowCode & vbCrLf & "Debug.Print Hex(lhWnd)"
End Function

example output (the "=" button on the calculator):

Dim lChild As Long, lhWnd As Long

lChild = FindWindowEx(lhWnd, lChild, "SciCalc", "Calculator")
lhWnd = lChild: lChild = 0
lChild = FindWindowEx(lhWnd, lChild, "Button", "=")
lhWnd = lChild: lChild = 0

Debug.Print Hex(lhWnd)

you could use GetAsyncKeyState to get the hWnd to pass to the function as Rob showed above, or you could also use the MouseDown / MouseUp events of a picturebox, e.g.:

Private Type POINTAPI
    X As Long
    Y As Long
End Type
 
Private Declare Function ClientToScreen Lib "user32" ( _
    ByVal hwnd As Long, lpPoint As POINTAPI) As Long
 
Private Declare Function WindowFromPoint Lib "user32" ( _
    ByVal xPoint As Long, ByVal yPoint As Long) As Long
 
Private bFinding As Boolean
 
Private Sub Picture1_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
    If Button = vbLeftButton Then
        Me.MousePointer = vbSizePointer
        bFinding = True
    End If
End Sub
 
Private Sub Picture1_MouseUp(Button As Integer, Shift As Integer, X As Single, Y As Single)
    Dim pt As POINTAPI
    If bFinding Then
        pt.X = X \ Screen.TwipsPerPixelX
        pt.Y = Y \ Screen.TwipsPerPixelY
        ClientToScreen Picture1.hwnd, pt
        Debug.Print WindowCode(WindowFromPoint(pt.X, pt.Y))
    End If
    Me.MousePointer = vbNormal
    bFinding = False
End Sub

Left-Click on the picturebox, hold it down and then move the mouse over the window of interest, release the left button and it'll find the window's hWnd (just like Spy++)