送你一个放大镜:
Option Explicit
Private Type POINTAPI
x As Long
y As Long
End Type

Const Srccopy = &HCC0020
Const Swp_nomove = &H2
Const Swp_nosize = &H1
Const Flags = Swp_nomove Or Swp_nosize
Const hwnd_topmost = -1

Private Declare Function SetWindowPos Lib "user32" (ByVal hWnd As Long, _
ByVal hWndInsertAfter As Long, ByVal x As Long, ByVal y As Long, _
ByVal cx As Long, ByVal cy As Long, ByVal wFlags As Long) As Long

Private Declare Function GetCursorPos Lib "user32" (lpPoint As POINTAPI) As Long

Private Declare Function GetDC Lib "user32" (ByVal hWnd As Long) As Long

Private Declare Function StretchBlt Lib "gdi32" (ByVal hdc As Long, ByVal x As Long, _
ByVal y As Long, ByVal nWidth As Long, ByVal nHeight As Long, ByVal hSrcDC As Long, _
ByVal xSrc As Long, ByVal ySrc As Long, ByVal nSrcWidth As Long, ByVal nSrcHeight As Long, _
ByVal dwRop As Long) As Long

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

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

Dim pos As POINTAPI
Dim i As Long
Dim sx As Long
Dim sy As Long

Private Sub file_Click()

End Sub

Private Sub Form_Load()
setwindow
i = 2
sx = 100
sy = 100
End Sub
Private Sub Form_Click() '鼠标单击窗体

End Sub
Private Sub setwindow()
SetWindowPos hWnd, hwnd_topmost, 0, 0, 0, 0, Flags
Dim hr&, dl&
Dim usew&, useh&
usew& = Me.Width / Screen.TwipsPerPixelX
useh& = Me.Height / Screen.TwipsPerPixelY
hr& = CreateEllipticRgn(0, 0, usew, useh)
dl& = SetWindowRgn(Me.hWnd, hr, True)
End Sub

Private Sub Timer1_Timer() '窗体放大效果
Dim wx As Integer
Dim wy As Integer
GetCursorPos pos
wx = IIf(pos.x < 50 Or pos.x > 900, IIf(pos.x < 50, 0, 900), pos.x - 50)
wy = IIf(pos.y < 20 Or pos.y > 900, IIf(pos.y < 20, 0, 900), pos.y - 20)
Caption = " 坐标" & wx & "," & wy & "放大倍数=" & i
StretchBlt hdc, 0, 0, sx * i, sy * i, GetDC(0), wx, wy, sx, sy, Srccopy
End Sub

Private Sub one_Click() '放大1倍
Timer1.Interval = 0
i = 1
Timer1.Interval = 50
End Sub

Private Sub onewin_Click() '窗口大小
Timer1.Interval = 0
Me.Height = 3000
Me.Width = 3000
sx = 100
sy = 100
setwindow
Timer1.Interval = 50
End Sub

Private Sub threewin_Click() '窗口大小
Timer1.Interval = 0
Me.Height = 3000 * 3
Me.Width = 3000 * 3
sx = 300
sy = 300
setwindow
Timer1.Interval = 50
End Sub

Private Sub two_Click() '放大2倍
Timer1.Interval = 0
i = 2
Timer1.Interval = 50
End Sub

Private Sub twowin_Click() '窗口大小
Timer1.Interval = 0
Me.Height = 3000 * 2
Me.Width = 3000 * 2
sx = 200
sy = 200
SetWindowPos hWnd, hwnd_topmost, 0, 0, 0, 0, Flags
Dim hr&, dl&
Dim usew&, useh&
usew& = Me.Width / Screen.TwipsPerPixelX
useh& = Me.Height / Screen.TwipsPerPixelY
hr& = CreateEllipticRgn(0, 0, usew, useh)
dl& = SetWindowRgn(Me.hWnd, hr, True)
Timer1.Interval = 50
End Sub

Private Sub three_Click() '放大3倍
Timer1.Interval = 0
i = 3
Timer1.Interval = 50
End Sub

Private Sub four_Click() '放大4倍
Timer1.Interval = 0
i = 4
Timer1.Interval = 50
End Sub

Private Sub exit_Click()
End
End Sub