程序在标题栏支持32位图标文件,是通过Sendmessage发送消息实现重绘
'模块
Option Explicit

Private Declare Function GetSystemMetrics Lib "user32" ( _
ByVal nIndex As Long _
) As Long

Private Const SM_CXICON = 11
Private Const SM_CYICON = 12

Private Const SM_CXSMICON = 49
Private Const SM_CYSMICON = 50

Private Declare Function LoadImageAsString Lib "user32" Alias "LoadImageA" ( _
ByVal hInst As Long, _
ByVal lpsz As String, _
ByVal uType As Long, _
ByVal cxDesired As Long, _
ByVal cyDesired As Long, _
ByVal fuLoad As Long _
) As Long

Private Const LR_DEFAULTCOLOR = &H0
Private Const LR_MONOCHROME = &H1
Private Const LR_COLOR = &H2
Private Const LR_COPYRETURNORG = &H4
Private Const LR_COPYDELETEORG = &H8
Private Const LR_LOADFROMFILE = &H10
Private Const LR_LOADTRANSPARENT = &H20
Private Const LR_DEFAULTSIZE = &H40
Private Const LR_VGACOLOR = &H80
Private Const LR_LOADMAP3DCOLORS = &H1000
Private Const LR_CREATEDIBSECTION = &H2000
Private Const LR_COPYFROMRESOURCE = &H4000
Private Const LR_SHARED = &H8000&

Private Const IMAGE_ICON = 1

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 Const WM_SETICON = &H80

Private Const ICON_SMALL = 0
Private Const ICON_BIG = 1

Private Declare Function GetWindow Lib "user32" (ByVal hWnd As Long, ByVal wCmd As Long) As Long
Private Const GW_OWNER = 4


Public Sub SetIcon( _
ByVal hWnd As Long, _
ByVal sIconResName As String, _
Optional ByVal bSetAsAppIcon As Boolean = True _
)
Dim lhWndTop As Long
Dim lhWnd As Long
Dim cx As Long
Dim cy As Long
Dim hIconLarge As Long
Dim hIconSmall As Long

If (bSetAsAppIcon) Then
' Find VB's hidden parent window:
lhWnd = hWnd
lhWndTop = lhWnd
Do While Not (lhWnd = 0)
lhWnd = GetWindow(lhWnd, GW_OWNER)
If Not (lhWnd = 0) Then
lhWndTop = lhWnd
End If
Loop
End If

cx = GetSystemMetrics(SM_CXICON)
cy = GetSystemMetrics(SM_CYICON)
hIconLarge = LoadImageAsString( _
App.hInstance, sIconResName, _
IMAGE_ICON, _
cx, cy, _
LR_SHARED)
If (bSetAsAppIcon) Then
SendMessageLong lhWndTop, WM_SETICON, ICON_BIG, hIconLarge
End If
SendMessageLong hWnd, WM_SETICON, ICON_BIG, hIconLarge

cx = GetSystemMetrics(SM_CXSMICON)
cy = GetSystemMetrics(SM_CYSMICON)
hIconSmall = LoadImageAsString( _
App.hInstance, sIconResName, _
IMAGE_ICON, _
cx, cy, _
LR_SHARED)
If (bSetAsAppIcon) Then
SendMessageLong lhWndTop, WM_SETICON, ICON_SMALL, hIconSmall
End If
SendMessageLong hWnd, WM_SETICON, ICON_SMALL, hIconSmall

End Sub
'窗体
Option Explicit

Private Sub Form_Load()
SetIcon Me.hWnd, "AAA"
End Sub