Attribute VB_Name = "Module1"
Public Declare Function CreateEllipticRgn Lib "gdi32" _
( _
    ByVal X1 As Long, ByVal Y1 As Long, _
    ByVal X2 As Long, ByVal Y2 As Long _
    ) As Long

Public Declare Function CreateRectRgn Lib "gdi32" _
( _
    ByVal X1 As Long, ByVal Y1 As Long, _
    ByVal X2 As Long, ByVal Y2 As Long _
    ) As Long

Public Declare Function SetWindowRgn Lib "user32" _
( _
    ByVal hWnd As Long, ByVal hRgn As Long, _
    ByVal bRedraw As Boolean _
    ) As Long

Public Declare Function CombineRgn Lib "gdi32" _
( _
    ByVal hDestRgn As Long, ByVal hSrcRgn1 As Long, _
    ByVal hSrcRgn2 As Long, ByVal nCombineMode As Long _
    ) As Long

Public Const RGN_AND = 1
'將兩個區域相加
Public Const RGN_COPY = 5
'創建hSrcRgn1的拷貝
Public Const RGN_DIFF = 4
'將兩個區域相減
Public Const RGN_OR = 2
'將兩個區域進行或操作
Public Const RGN_XOR = 3
'將兩個區域進行異或操作
Public Const RGN_MAX = RGN_COPY
Public Const RGN_MIN = RGN_AND

Public Sub SetWindow(f1 As Form)
'該子過程實現設置窗口形狀
    Dim hSrcRgn1, hSrcRgn2, hSrcRgn3 As Long
    hSrcRgn1 = CreateEllipticRgn(5, 23, 397, 415)
    '創建最外面的大圓區域
    hSrcRgn2 = CreateEllipticRgn(90, 74, 395, 362)
    '創建中間的圓區域
    hSrcRgn3 = CreateEllipticRgn(183, 120, 395, 320)
    '創建最里層的小圓區域
    
    CombineRgn hSrcRgn1, hSrcRgn1, hSrcRgn2, RGN_DIFF
    '用大圓減去中間的圓得到的區域保存在hSrcRgn1
    CombineRgn hSrcRgn1, hSrcRgn1, hSrcRgn3, RGN_OR
    '用得到的區域加上小圓并保存在hSrcRgn1
    SetWindowRgn f1.hWnd, hSrcRgn1, True
End Sub
Public Sub Reset(f1 As Form)
'該子過程實現恢復窗口形狀為矩形
    Dim hSrcRgn4 As Long
    hSrcRgn4 = CreateRectRgn(0, 0, f1.Width, f1.Height)
    '創建矩形
    SetWindowRgn f1.hWnd, hSrcRgn4, True
    '將窗口恢復為矩形
End Sub