Option Explicit
 
Private Sub Form_Load()
Dim iIndex As Integer
 
For iIndex = 0 To 15
Combo1.AddItem "Color " & iIndex
Combo1.itemData(Combo1.NewIndex) = QBColor(iIndex)
Next
Combo1.ListIndex = 0
 
'Subclass the "Form", to Capture the Combobox Notification Messages
SubClassForm hWnd
End Sub
 
Private Sub Form_Unload(Cancel As Integer)
'Release the SubClassing, Very Import to Prevent Crashing!
RemoveSubClassing hWnd
End Sub
 
 

Option Explicit
 
Private Type RECT
Left As Long
Top As Long
Right As Long
Bottom As Long
End Type
 
Private Type DRAWITEMSTRUCT
CtlType As Long
CtlID As Long
itemID As Long
itemAction As Long
itemState As Long
hwndItem As Long
hdc As Long
rcItem As RECT
itemData As Long
End Type
 
Private Type CWPSTRUCT
lParam As Long
wParam As Long
message As Long
hWnd As Long
End Type
 
Private Type CREATESTRUCT
lpCreateParams As Long
hInstance As Long
hMenu As Long
hWndParent As Long
cy As Long
cx As Long
y As Long
x As Long
style As Long
'These next 2 are Normaly string, but need to be a fixed length
'so we know how long they are when using CopyMemory,
'We're only interested in the Style property anyway.
lpszName As Long
lpszClass As Long
ExStyle As Long
End Type
 
Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (Destination As Any, Source As Any, ByVal Length As Long)
 
Private Declare Function SetWindowLong Lib "user32" Alias "SetWindowLongA" (ByVal hWnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long
Private Declare Function CallWindowProc Lib "user32" Alias "CallWindowProcA" (ByVal lpPrevWndFunc As Long, ByVal hWnd As Long, ByVal Msg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
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 SetBkColor Lib "gdi32" (ByVal hdc As Long, ByVal crColor As Long) As Long
Private Declare Function SetTextColor Lib "gdi32" (ByVal hdc As Long, ByVal crColor As Long) As Long
Private Declare Function TextOut Lib "gdi32" Alias "TextOutA" (ByVal hdc As Long, ByVal x As Long, ByVal y As Long, ByVal lpString As String, ByVal nCount As Long) As Long
Private Declare Function GetSysColor Lib "user32" (ByVal nIndex 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 FillRect Lib "user32" (ByVal hdc As Long, lpRect As RECT, ByVal hBrush As Long) As Long
Private Declare Function GetBkColor Lib "gdi32" (ByVal hdc As Long) As Long
Private Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" (ByVal hWnd As Long, ByVal nIndex As Long) As Long
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 UnhookWindowsHookEx Lib "user32" (ByVal hHook 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 CreateSolidBrush Lib "gdi32" (ByVal crColor As Long) As Long
 
Private Const WH_CALLWNDPROC = 4
 
Private Const CBS_OWNERDRAWVARIABLE = &H20&
Private Const CB_GETLBTEXT = &H148
Private Const CB_SETITEMHEIGHT = &H153
 
Private Const COLOR_HIGHLIGHT = 13
Private Const COLOR_HIGHLIGHTTEXT = 14
Private Const COLOR_WINDOW = 5
Private Const COLOR_WINDOWTEXT = 8
 
Private Const GWL_WNDPROC = (-4)
Private Const GWL_STYLE = (-16)
 
Private Const ODS_SELECTED = &H1
 
Private Const ODT_COMBOBOX = 3
 
Private Const WM_CREATE = &H1
Private Const WM_DRAWITEM = &H2B
 
Private lPrevWndProc As Long
Private lHook As Long
Private lSubCombo As Long
 
Sub Main()
'The Combobox is a little more tricky to manipulate than a Listbox
'So we need to do a little extra work to make it an "Owner Drawn" Control.
lHook = SetWindowsHookEx(WH_CALLWNDPROC, AddressOf HookApp, App.hInstance, App.ThreadID)
Form1.Show
'Once the Control. etc are Drawn, we can release the Hook
Call UnhookWindowsHookEx(lHook)
End Sub
 
Public Sub SubClassForm(ByVal hWnd As Long)
lPrevWndProc = SetWindowLong(hWnd, GWL_WNDPROC, AddressOf SubClassedForm)
End Sub
 
Public Sub RemoveSubClassing(ByVal hWnd As Long)
Call SetWindowLong(hWnd, GWL_WNDPROC, lPrevWndProc)
End Sub
 
Public Function SubClassedForm(ByVal hWnd As Long, ByVal Msg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
Dim tItem As DRAWITEMSTRUCT
Dim sItem As String
Dim lBackBrush As Long
 
If Msg = WM_DRAWITEM Then
 
'This function only passes the Address of the DrawItem Structure, so we need to
'use the CopyMemory API to get a Copy into the Variable we setup:
Call CopyMemory(tItem, ByVal lParam, Len(tItem))
 
'If it's our Combobox..
If tItem.CtlType = ODT_COMBOBOX Then
 
'get the Item Text
sItem = Space(255)
Call SendMessage(tItem.hwndItem, CB_GETLBTEXT, tItem.itemID, ByVal sItem)
sItem = Left(sItem, InStr(sItem, Chr(0)) - 1)
 
'Select the Highlight Colors if this Item is currently selected
If (tItem.itemState And ODS_SELECTED) Then
lBackBrush = CreateSolidBrush(GetSysColor(COLOR_HIGHLIGHT))
Call SetBkColor(tItem.hdc, GetSysColor(COLOR_HIGHLIGHT))
Call SetTextColor(tItem.hdc, GetSysColor(COLOR_HIGHLIGHTTEXT))
Else
'Otherwise, use the default Colors
lBackBrush = CreateSolidBrush(GetSysColor(COLOR_WINDOW))
Call SetBkColor(tItem.hdc, GetSysColor(COLOR_WINDOW))
Call SetTextColor(tItem.hdc, tItem.itemData)
End If
 
FillRect tItem.hdc, tItem.rcItem, lBackBrush
 
'Display the Item
TextOut tItem.hdc, tItem.rcItem.Left, tItem.rcItem.Top, ByVal sItem, Len(sItem)
 
'Don't Return a Value as we've dealt with this Message ourselves
SubClassedForm = 0
Exit Function
End If
End If
 
'Not our Combobox, so just process the Message as Normal
SubClassedForm = CallWindowProc(lPrevWndProc, hWnd, Msg, wParam, lParam)
End Function
 
Private Function HookApp(ByVal lHookID As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
 
'This Function will get called when Initializing the Form
'We want to Interupt it when it tries to create our Combobox..
Dim tCWP As CWPSTRUCT
Dim sClass As String
 
Call CopyMemory(tCWP, ByVal lParam, Len(tCWP))
 
If tCWP.message = WM_CREATE Then
'get the Control Classname
sClass = Space(128)
Call GetClassName(tCWP.hWnd, ByVal sClass, 128)
sClass = Left(sClass, InStr(sClass, Chr(0)) - 1)
'If it's our Combobox, Sub-class it to Modify the Create Message..
If sClass = "ComboLBox" Then
lSubCombo = SetWindowLong(tCWP.hWnd, GWL_WNDPROC, AddressOf SubComboCreate)
End If
End If
'Continue the Hook Processing
HookApp = CallNextHookEx(lHook, lHookID, wParam, ByVal lParam)
 
End Function
 
Private Function SubComboCreate(ByVal hWnd As Long, ByVal Msg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
'This Function will be called when the Combobox is about to be created
Dim tCreate As CREATESTRUCT
 
If Msg = WM_CREATE Then
'Grab the Data that's going to be used to Create the Combobox
Call CopyMemory(tCreate, ByVal lParam, Len(tCreate))
'Alter it, to make the Combobox an "Owner Drawn" Control
tCreate.style = tCreate.style Or CBS_OWNERDRAWVARIABLE
'Copy the modified data back
Call CopyMemory(ByVal lParam, tCreate, Len(tCreate))
'Alter the Style to OwnerDrawn
Call SetWindowLong(hWnd, GWL_STYLE, tCreate.style)
'Release this Subclassing Function
Call SetWindowLong(hWnd, GWL_WNDPROC, lSubCombo)
End If
'let Windows Process the Modified Data
SubComboCreate = CallWindowProc(lSubCombo, hWnd, Msg, wParam, lParam)
 
End Function