VB解释下这个代码

这是一个半透明窗体的代码解释下这个代码吧！

格式：Msgbox" 小伊伊" ' 弹出提示窗口

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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 GetWindowLong Lib "user32" _
Alias "GetWindowLongA" _
(ByVal hwnd As Long, _
ByVal nIndex As Long) _
As Long

Private Const GWL_EXSTYLE = (-20)
Private Const LWA_ALPHA As Long = &H2
Private Const WS_EX_LAYERED As Long = &H80000

Private Declare Function SetLayeredWindowAttributes Lib "user32" _
(ByVal hwnd As Long, _
ByVal crKey As Long, _
ByVal bAlpha As Long, _
ByVal dwFlags As Long) _
As Long

Private Sub Form_Load()
Dim p As Long
p = GetWindowLong(Me.hwnd, GWL_EXSTYLE)
Call SetWindowLong(Me.hwnd, GWL_EXSTYLE, p Or WS_EX_LAYERED)
Call SetLayeredWindowAttributes(Me.hwnd, 0, 127, LWA_ALPHA)
End Sub

p = GetWindowLong(Me.hwnd, GWL_EXSTYLE) 得到当前的扩展的窗口风格
Call SetWindowLong(Me.hwnd, GWL_EXSTYLE, p Or WS_EX_LAYERED) 设置当前窗口的具有透明效果的扩展风格
Call SetLayeredWindowAttributes(Me.hwnd, 0, 127, LWA_ALPHA) 设置当前窗口的透明度127这个数值越小越透明....

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在前面那些东西都是声明dll里的函数，都是user32.dll里的，属于windows的dll