Microsoft KB Archive/112649

= How To Get a Window's Class Name and Other Window Attributes =

Article ID: 112649

Article Last Modified on 7/1/2004

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APPLIES TO


 * Microsoft Visual Basic 5.0 Learning Edition
 * Microsoft Visual Basic 5.0 Professional Edition
 * Microsoft Visual Basic 5.0 Enterprise Edition
 * Microsoft Visual Basic 4.0 Standard Edition
 * Microsoft Visual Basic 4.0 Professional Edition
 * Microsoft Visual Basic 4.0 Professional Edition
 * Microsoft Visual Basic 4.0 16-bit Enterprise Edition
 * Microsoft Visual Basic 4.0 32-Bit Enterprise Edition
 * Microsoft Visual Basic 3.0 Professional Edition
 * Microsoft Visual Basic 3.0 Professional Edition

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This article was previously published under Q112649



SUMMARY
You could use SPY.EXE, which comes with Microsoft Visual C/C++, to get information such as a window's class name. However, this article shows by example how you can create your own Visual Basic application that does the same thing; displays a window's class name along with several other attributes. For example, you might need a window's class name for use in a function in the Microsoft Windows Application Programming Interface (Windows API).



MORE INFORMATION
This example uses several functions from the Windows API to get information about the window the cursor is currently over. First, the routine calls GetCursorPos to get the current position of the cursor. Then it calls WindowFromPoint to get the handle to the window the cursor is currently over. Then it calls several other functions in the Windows API to get specific information pertaining to the window.

The example finds the following information about the window:


 * Window Handle
 * Window Text
 * Window Class Name
 * Window Style
 * Window ID Number
 * Parent Window Handle (if applicable)
 * Parent Window Text (if applicable)
 * Parent Window Class Name (if applicable)
 * Module File Name

The example can be easily expanded to get other window attributes by calling appropriate functions in the Windows API.

Step-by-Step Example
THE FOLLOWING SECTION APPLIES TO VISUAL BASIC 4.0 AND 5.0 ONLY:

This example creates a Visual Basic program that produces results similar to those produced by SPY.EXE, and makes use of conditional compilation so that the program can be run in either 16-bit or 32-bit editions of Visual Basic.

NOTE: Although the code below works in Visual Basic 5.0, it not necessary to use the conditional compilation (#If Win16, #ElseIf Win32) in Visual Basic 5.0 since it requires 32-bit. As a result, you can shorten the code below by using only the 32-bit declarations.

 Start a new project in Visual Basic. Form1 is created by default.  Add the following declarations to the general declarations section of Form1:

#If Win16 Then Private Declare Sub GetCursorPos Lib "User" (lpPoint As Long) Private Declare Function WindowFromPoint Lib "User" (ByVal ptScreen _        As Any) As Integer Private Declare Function GetModuleFileName Lib "Kernel" (ByVal _        hModule As Integer, ByVal lpFileName As String, ByVal nSize As _         Integer) As Integer Private Declare Function GetWindowWord Lib "User" (ByVal hwnd As _        Integer, ByVal nIndex As Integer) As Integer Private Declare Function GetWindowLong Lib "User" (ByVal hwnd As _        Integer, ByVal nIndex As Integer) As Long Private Declare Function GetParent Lib "User" (ByVal hwnd As _        Integer) As Integer Private Declare Function GetClassName Lib "User" (ByVal hwnd As _        Integer, ByVal lpClassName As String, ByVal nMaxCount As _         Integer) As Integer Private Declare Function GetWindowText Lib "User" (ByVal hwnd As _        Integer, ByVal lpString As String, ByVal aint As Integer) As _ Integer

#ElseIf Win32 Then Private Type POINTAPI x As Long y As Long End Type

Private Declare Function GetCursorPos Lib "User32" (lpPoint As _        POINTAPI) As Long Private Declare Function WindowFromPointXY Lib "User32" Alias _ "WindowFromPoint" (ByVal xPoint As Long, ByVal yPoint As Long) _ As Long Private Declare Function GetModuleFileName Lib "kernel32" Alias _ "GetModuleFileNameA" (ByVal hModule As Long, ByVal lpFileName As _        String, ByVal nSize As Long) As Long Private Declare Function GetWindowWord Lib "User32" (ByVal hwnd As _        Long, ByVal nIndex As Long) As Integer Private Declare Function GetWindowLong Lib "User32" Alias _ "GetWindowLongA" (ByVal hwnd As Long, ByVal nIndex As Long) As _ Long Private Declare Function GetParent Lib "User32" (ByVal hwnd 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 #End If  Const GWW_HINSTANCE = (-6) Const GWW_ID = (-12) Const GWL_STYLE = (-16)  Add a timer control (Timer1) to the form. Set the interval property of the timer to 200.  Add the following code to timer's timer event:

Sub Timer1_Timer #If Win16 Then Dim ptCursor As Long Dim sWindowText As String * 100 Dim sClassName As String * 100 Dim hWndOver As Integer Dim hWndParent As Integer Dim sParentClassName As String * 100 Dim wID As Integer Dim lWindowStyle As Long Dim hInstance As Integer Dim sParentWindowText As String * 100 Dim sModuleFileName As String * 100 Static hWndLast As Integer

Call GetCursorPos(ptCursor)              ' Get cursor position hWndOver = WindowFromPoint(ptCursor)     ' Get window cursor is over If hWndOver <> hWndLast Then             ' If changed update display hWndLast = hWndOver                   ' Save change Cls                                     ' Clear the form Print "Window Handle: &H"; Hex(hWndOver) ' Display window handle

r = GetWindowText(hWndOver, sWindowText, 100)     ' Window text Print "Window Text: " & Left(sWindowText, r)

r = GetClassName(hWndOver, sClassName, 100)        ' Window Class Print "Window Class Name: "; Left(sClassName, r)

lWindowStyle = GetWindowLong(hWndOver, GWL_STYLE)  ' Window Style Print "Window Style: &H"; Hex(lWindowStyle)

' Get handle of parent window: hWndParent = GetParent(hWndOver)

' If there is a parent get more info: If hWndParent <> 0 Then ' Get ID of window: wID = GetWindowWord(hWndOver, GWW_ID) Print "Window ID Number: &H"; Hex(wID) Print "Parent Window Handle: &H"; Hex(hWndParent)

' Get the text of the Parent window: r = GetWindowText(hWndParent, sParentWindowText, 100) Print "Parent Window Text: " & Left(sParentWindowText, r)

' Get the class name of the parent window: r = GetClassName(hWndParent, sParentClassName, 100) Print "Parent Window Class Name: "; Left(sParentClassName, r)        Else ' Update fields when no parent: Print "Window ID Number: N/A" Print "Parent Window Handle: N/A" Print "Parent Window Text : N/A" Print "Parent Window Class Name: N/A" End If

' Get window instance: hInstance = GetWindowLong(hWndOver, GWW_HINSTANCE)

' Get module file name: r = GetModuleFileName(hInstance, sModuleFileName, 100) If r = 0 then Print "Module: N/A" Else Print "Module: "; Left(sModuleFileName, r)        End If      End If

#ElseIf Win32 Then Dim pt32 As POINTAPI Dim ptx As Long Dim pty As Long Dim sWindowText As String * 100 Dim sClassName As String * 100 Dim hWndOver As Long Dim hWndParent As Long Dim sParentClassName As String * 100 Dim wID As Long Dim lWindowStyle As Long Dim hInstance As Long Dim sParentWindowText As String * 100 Dim sModuleFileName As String * 100 Static hWndLast As Long

Call GetCursorPos(pt32)              ' Get cursor position ptx = pt32.x     pty = pt32.y      hWndOver = WindowFromPointXY(ptx, pty)    ' Get window cursor is over If hWndOver <> hWndLast Then             ' If changed update display hWndLast = hWndOver                   ' Save change Cls                                     ' Clear the form Print "Window Handle: &H"; Hex(hWndOver) ' Display window handle

r = GetWindowText(hWndOver, sWindowText, 100)     ' Window text Print "Window Text: " & Left(sWindowText, r)

r = GetClassName(hWndOver, sClassName, 100)        ' Window Class Print "Window Class Name: "; Left(sClassName, r)

lWindowStyle = GetWindowLong(hWndOver, GWL_STYLE)  ' Window Style Print "Window Style: &H"; Hex(lWindowStyle)

' Get handle of parent window: hWndParent = GetParent(hWndOver)

' If there is a parent get more info: If hWndParent <> 0 Then ' Get ID of window: wID = GetWindowWord(hWndOver, GWW_ID) Print "Window ID Number: &H"; Hex(wID) Print "Parent Window Handle: &H"; Hex(hWndParent)

' Get the text of the Parent window: r = GetWindowText(hWndParent, sParentWindowText, 100) Print "Parent Window Text: " & Left(sParentWindowText, r)

' Get the class name of the parent window: r = GetClassName(hWndParent, sParentClassName, 100) Print "Parent Window Class Name: "; Left(sParentClassName, r)        Else ' Update fields when no parent: Print "Window ID Number: N/A" Print "Parent Window Handle: N/A" Print "Parent Window Text : N/A" Print "Parent Window Class Name: N/A" End If

' Get window instance: hInstance = GetWindowWord(hWndOver, GWW_HINSTANCE)

' Get module file name: r = GetModuleFileName(hInstance, sModuleFileName, 100) Print "Module: "; Left(sModuleFileName, r)     End If   #End If   End Sub  Save the project files. Run the program, and move the mouse over different windows. You will see the field values change as you move the mouse over different windows.</li></ol>

Step-by-Step Example
THE FOLLOWING SECTION APPLIES TO VISUAL BASIC 3.0 ONLY:

This example creates a Visual Basic program that produces results similar to those produced by SPY.EXE.

<ol> Start a new project in Visual Basic. Form1 is created by default.</li>  Add the following declarations to the general declarations section of Form1:

'VB3Line: Enter the following lines as one line Declare Sub GetCursorPos Lib "User" (lpPoint As Long) Declare Function WindowFromPoint Lib "User" (ByVal ptScreen As Any) As     Integer Declare Function GetModuleFileName Lib "Kernel" (ByVal hModule As     Integer, ByVal lpFilename As String, ByVal nSize As Integer) As      Integer Declare Function GetWindowWord Lib "User" (ByVal hWnd As Integer, ByVal     nIndex As Integer) As Integer Declare Function GetWindowLong Lib "User" (ByVal hWnd As Integer, ByVal     nIndex As Integer) As Long Declare Function GetParent Lib "User" (ByVal hWnd As Integer) As Integer Declare Function GetClassName Lib "User" (ByVal hWnd As Integer, ByVal     lpClassName As String, ByVal nMaxCount As Integer) As Integer Declare Function GetWindowText Lib "User" (ByVal hWnd As Integer, ByVal     lpString As String, ByVal aint As Integer) As Integer Const GWW_HINSTANCE = (-6) Const GWW_ID = (-12) Const GWL_STYLE = (-16) </li> Add a timer control (Timer1) to the form.</li> Set the interval property of the timer to 200.</li>  Add the following code to timer's timer event:

Sub Timer1_Timer Dim ptCursor As Long Dim sWindowText As String * 100 Dim sClassName As String * 100 Dim hWndOver As Integer Dim hWndParent As Integer Dim sParentClassName As String * 100 Dim wID As Integer Dim lWindowStyle As Long Dim hInstance As Integer Dim sParentWindowText As String * 100 Dim sModuleFileName As String * 100 Static hWndLast As Integer

Call GetCursorPos(ptCursor)              ' Get cursor position hWndOver = WindowFromPoint(ptCursor)     ' Get window cursor is over If hWndOver <> hWndLast Then             ' If changed update display hWndLast = hWndOver                   ' Save change Cls                                     ' Clear the form Print "Window Handle: &H"; Hex(hWndOver) ' Display window handle

r = GetWindowText(hWndOver, sWindowText, 100)     ' Window text Print "Window Text: " & Left(sWindowText, r)

r = GetClassName(hWndOver, sClassName, 100)        ' Window Class Print "Window Class Name: "; Left(sClassName, r)

lWindowStyle = GetWindowLong(hWndOver, GWL_STYLE)  ' Window Style Print "Window Style: &H"; Hex(lWindowStyle)

' Get handle of parent window: hWndParent = GetParent(hWndOver)

' If there is a parent get more info: If hWndParent <> 0 Then ' Get ID of window: wID = GetWindowWord(hWndOver, GWW_ID) Print "Window ID Number: &H"; Hex(wID) Print "Parent Window Handle: &H"; Hex(hWndParent)

' Get the text of the Parent window: r = GetWindowText(hWndParent, sParentWindowText, 100) Print "Parent Window Text: " & Left(sParentWindowText, r)

' Get the class name of the parent window: r = GetClassName(hWndParent, sParentClassName, 100) Print "Parent Window Class Name: "; Left(sParentClassName, r)        Else ' Update fields when no parent: Print "Window ID Number: N/A" Print "Parent Window Handle: N/A" Print "Parent Window Text : N/A" Print "Parent Window Class Name: N/A" End If

' Get window instance: hInstance = GetWindowWord(hWndOver, GWW_HINSTANCE)

' Get module file name: r = GetModuleFileName(hInstance, sModuleFileName, 100) Print "Module: "; Left(sModuleFileName, r)     End If   End Sub </li> Save the project files.</li> Run the program, and move the mouse over different windows. You will see the field values change as you move the mouse over different windows.</li></ol>

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