Visual Basic Programming Code Examples

Clicking a button on a form through code Below is a lot of code, which does very little! The code will clicks a button on a form by sending a message directly to that control. This has an advantage over SendKeys as it eliminates potential problems with user interaction. Option Explicit Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long Private Declare Function GetWindow32 Lib "user32" Alias "GetWindow" (ByVal hwnd As Long, ByVal wCmd 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 SetForegroundWindow Lib "user32" (ByVal hwnd As Long) As Long 'Purpose : Clicks a button on a form 'Inputs : sFormCaption The form caption ' sButtonCaption The button caption ' [sFormClassName] The caption of the child window 'Outputs : Returns the handle to the child window or zero if no matching ' window was found 'Notes : Pass in either sRequiredClassName or sCaption or both ' The button must have it's own window handle (VBA command buttons DO NOT) ' Example useage is ' Call FormButtonClick("Form1","Command1") 'Revisions : Function FormButtonClick(sFormCaption As String, sButtonCaption As String, Optional sFormClassName As String = vbNullString) As Boolean Const WM_LBUTTONDOWN = &H201, WM_LBUTTONUP = &H202 Dim lHwndButton As Long, lHwndForm As Long 'Find the form lHwndForm = FindWindow(sFormClassName, sFormCaption) If lHwndForm Then 'Found form, find button lHwndButton = DialogGetChildHwnd(lHwndForm, "", sButtonCaption) If lHwndButton Then 'Bring the window to the foreground Call SetForegroundWindow(lHwndForm) FormButtonClick = CBool(SendMessage(lHwndButton, WM_LBUTTONDOWN, ByVal 0&, ByVal 0&) = 0) FormButtonClick = CBool(SendMessage(lHwndButton, WM_LBUTTONUP, ByVal 0&, ByVal 0&) = 0) End If End If End Function 'Purpose : Returns the handle of a child window within a window 'Inputs : lhwndParent The handle of the parent window ' [sRequiredClassName] The class name of the child window ' [sCaption] The caption of the child window 'Outputs : Returns the handle to the child window or zero if no matching ' window was found 'Notes : Pass in either sRequiredClassName or sCaption or both 'Revisions : Function DialogGetChildHwnd(lhwndParent As Long, Optional sRequiredClassName As String, Optional sCaption As String) As Long Dim lLenClassName As Long Dim sClassName As String Dim lhWndNext As Long Const GW_CHILD As Integer = 5, GW_HWNDFIRST As Integer = 0, GW_HWNDNEXT As Integer = 2 On Error Resume Next 'Get a handle to a child window lhWndNext = GetWindow32(lhwndParent, GW_CHILD) 'Get first child window lhWndNext = GetWindow32(lhWndNext, GW_HWNDFIRST) 'Find the name of first child sClassName = DialogClassName(lhWndNext) If sClassName = sRequiredClassName Or Len(sRequiredClassName) = 0 Then 'Class names match If Len(sCaption) Then If DialogGetText(lhWndNext) = sCaption Then 'Found correct child window DialogGetChildHwnd = lhWndNext lhWndNext = 0 End If Else 'Found correct child window DialogGetChildHwnd = lhWndNext lhWndNext = 0 End If End If Do While lhWndNext <> 0 'Search all children lhWndNext = GetWindow32(lhWndNext, GW_HWNDNEXT) sClassName = DialogClassName(lhWndNext) If sClassName = sRequiredClassName Then If Len(sCaption) Then If DialogGetText(lhWndNext) = sCaption Then 'Found correct child window DialogGetChildHwnd = lhWndNext Exit Do End If Else 'Found correct child window DialogGetChildHwnd = lhWndNext Exit Do End If End If Loop End Function 'Purpose : Returns the class name specified window 'Inputs : lHwnd The handle of the window 'Outputs : Returns the window text of a specified window 'Notes : 'Revisions : Function DialogClassName(lHwnd As Long) As String Const clLenName As Long = 100 Dim sResult As String * clLenName, lRetVal As Long lRetVal = GetClassName(lHwnd, sResult, clLenName) DialogClassName = Left$(sResult, lRetVal) End Function 'Purpose : Returns the window text of a specified window 'Inputs : lHwnd The handle of the window 'Outputs : Returns the window text of a specified window 'Notes : 'Revisions : Function DialogGetText(lHwnd As Long) As String Const clStrLen As Long = 1000 Static ResString As String * clStrLen, lRet As Long lRet = GetWindowText(lHwnd, ResString, clStrLen) DialogGetText = Left$(ResString, lRet) End Function