VBcoders Guest

Don't have an account yet? Register

Forgot Password?

Autohighlight active control (MDI Form)

by Marcel A. Fritsch (3 Submissions)
Category: Windows API Call/Explanation
Compatability: Visual Basic 3.0
Difficulty: Intermediate
Date Added: Wed 3rd February 2021
Rating: (4 Votes)

This is a very simple and useful solution to highlight input controls without writting a function for each control. Only include a module with the code shown below (rename MDIFORM with your MDIForm) and call SetHook at the MDIForm_Load function and and Unhook at the MDIForm_QueryUnload function. Please vote, if you think its a good solution.

Side Effects
When running this progam in the IDE do not use the STOP-Button to exit the program, because the unhook function will not be executed and the IDE crashes!!!

Rate Autohighlight active control (MDI Form)

Option Explicit
' USER32 functions
Private Declare Function SetWindowsHookEx Lib "user32" Alias "SetWindowsHookExA" _
 (ByVal idHook As Long, ByVal lpfn As Long, ByVal hmod As Long, ByVal dwThreadId As Long) As Long
Private Declare Function CallNextHookEx Lib "user32" _
 (ByVal hHook As Long, ByVal ncode As Long, ByVal wParam As Long, lParam As Any) As Long
Private Declare Function UnhookWindowsHookEx Lib "user32" (ByVal hHook As Long) As Long
' KERNEL32 functions
Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" _
 (hpvDest As Any, hpvSource As Any, ByVal cbCopy As Long)
Private Const WH_CALLWNDPROC = 4
Public Const WM_SETFOCUS = &H7
Public Const WM_KILLFOCUS = &H8
Private Type CWPSTRUCT
 lParam As Long
 wParam As Long
 message As Long
 hwnd As Long
End Type
Public hHook As Long
Public Function SetHook()
If Not hHook Then
 hHook = SetWindowsHookEx(WH_CALLWNDPROC, AddressOf WndProc, App.hInstance, App.ThreadID)
End If
End Function
Private Function WndProc(ByVal idHook As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
Dim C As Control
On Local Error Resume Next
CopyMemory CWP, ByVal lParam, Len(CWP)
WndProc = CallNextHookEx(hHook, idHook, wParam, ByVal lParam)
Select Case CWP.message
  For Each C In MDIFORM.ActiveForm.Controls
  If CWP.hwnd = C.hwnd Then
   If Err.Number = 0 Then
    If CWP.message = WM_SETFOCUS Then
     If (TypeOf C Is TextBox) Or _
      (TypeOf C Is ComboBox) Then
      C.BackColor = &H80000018
     End If
     If (TypeOf C Is TextBox) Or _
      (TypeOf C Is ComboBox) Then
      C.BackColor = &H80000005
     End If
    End If
    Exit For
   End If
  End If
End Select
End Function
Public Function UnHook()
If hHook Then
 UnhookWindowsHookEx hHook
End If
End Function

Download this snippet    Add to My Saved Code

Autohighlight active control (MDI Form) Comments

No comments have been posted about Autohighlight active control (MDI Form). Why not be the first to post a comment about Autohighlight active control (MDI Form).

Post your comment

0/1000 characters