Send Message API

I m using VB6.
I want to increase the maximum number of charaters that an be entered in the combo box from 256(which is the default limit) to 2048.
I think it can be done using SendMessage API but i m not able to do it.
Can anyone help...

I was just tested and

s = "A" & Space(2500) & "a"
Combo1.AddItem s

worked fine. If there's a item length limit, I've never come close to hitting it.

So I'm going to assume you meant to ask for including a horizontal scrollbar and/or autosizing.

VB Code:

' call with 
'
'Dim x As Boolean
'
'x = AutosizeCombo(Combo1)
 
Option Explicit
 
Private Const CB_SETDROPPEDWIDTH = &H160
Private Const CB_GETDROPPEDWIDTH = &H15F
Private Const DT_CALCRECT = &H400
 
Private Type RECT
   Left As Long
   Top As Long
   Right As Long
   Bottom As Long
End Type
 
Private Declare Function SendMessageLong Lib "user32" Alias _
        "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, _
        ByVal wParam As Long, ByVal lparam As Long) As Long
 
Private Declare Function DrawText Lib "user32" Alias _
    "DrawTextA" (ByVal hdc As Long, ByVal lpStr As String, _
    ByVal nCount As Long, lpRect As RECT, ByVal wFormat _
    As Long) As Long
 
Public Function AutosizeCombo(Combo As ComboBox) As Boolean
    
    'Automatically sizes a combo box to
    'hold the longest item within it
 
    Dim lngRet As Long
    Dim lngCurrentWidth As Single
    Dim rectCboText As RECT
    Dim lngParentHDC As Long
    Dim lngListCount As Long
    Dim lngCounter As Long
    Dim lngTempWidth As Long
    Dim lngWidth As Long
    Dim strSavedFont As String
    Dim sngSavedSize As Single
    Dim blnSavedBold As Boolean
    Dim blnSavedItalic As Boolean
    Dim blnSavedUnderline As Boolean
    Dim blnFontSaved As Boolean
 
On Error GoTo ErrorHandler
 
    'Grab the combo handle and list count
 
    lngParentHDC = Combo.Parent.hdc
    lngListCount = Combo.ListCount
 
    If lngParentHDC = 0 Or lngListCount = 0 Then Exit Function
 
    'Save combo box fonts, etc. to the parent
    'object (form), for testing lengths with the API
 
    With Combo.Parent
 
        strSavedFont = .FontName
        sngSavedSize = .FontSize
        blnSavedBold = .FontBold
        blnSavedItalic = .FontItalic
        blnSavedUnderline = .FontUnderline
        
        .FontName = Combo.FontName
        .FontSize = Combo.FontSize
        .FontBold = Combo.FontBold
        .FontItalic = Combo.FontItalic
        .FontUnderline = Combo.FontItalic
 
    End With
 
    blnFontSaved = True
 
    'Get the width of the widest item
 
    For lngCounter = 0 To lngListCount
       DrawText lngParentHDC, Combo.List(lngCounter), -1, rectCboText, _
            DT_CALCRECT
 
        'Add twenty to the the number as a margin
       lngTempWidth = rectCboText.Right - rectCboText.Left + 20
 
        If (lngTempWidth > lngWidth) Then
           lngWidth = lngTempWidth
        End If
 
    Next
 
    'Get current width of combo
 
    lngCurrentWidth = SendMessageLong(Combo.hwnd, CB_GETDROPPEDWIDTH, _
        0, 0)
 
    'If big enough then that's all A-OK
    If lngCurrentWidth > lngWidth Then
 
        AutosizeCombo = True
        GoTo ErrorHandler
        Exit Function
    
    End If
 
    '... but if not big enough, first calculate
    'the screen width to ensure we don't exceed it!
 
    If lngWidth > Screen.Width \ Screen.TwipsPerPixelX - 20 Then _
        lngWidth = Screen.Width \ Screen.TwipsPerPixelX - 20
 
    'Set the width of our combo
    lngRet = SendMessageLong(Combo.hwnd, CB_SETDROPPEDWIDTH, lngWidth, 0)
 
    'Set the function to True/False depending on API success
    AutosizeCombo = lngRet > 0
    
ErrorHandler:
        
    'If anything goes wrong, revert back!
    
    On Error Resume Next
    
    If blnFontSaved Then
      With Combo.Parent
        .FontName = strSavedFont
        .FontSize = sngSavedSize
        .FontUnderline = blnSavedUnderline
        .FontBold = blnSavedBold
        .FontItalic = blnSavedItalic
     End With
    End If
 
End Function

Please help urgently

I have solved it

Public Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, Param As Any) As Long

Public Const CB_LIMITTEXT = &H141



and using this statement in form Load


SendMessage combo1.hwnd, CB_LIMITTEXT, 2048, 0&