VB1010实例（4）圆形窗体

前台

代码

Imports System.Runtime.InteropServices
'我的操作系统是win7,64位，long类型是64位
'需要设置为：编译--高级编译--目标CPU--x64
'单击变椭圆，双击还原
Public Class Form1
    <DllImport("gdi32.dll", EntryPoint:="CreateEllipticRgn", CallingConvention:=CallingConvention.Cdecl, ExactSpelling:=True)> _
    Public Shared Function CreateEllipticRgn(ByVal X1 As Long, ByVal Y1 As Long, ByVal X2 As Long, ByVal Y2 As Long) As Long
    End Function

    <DllImport("gdi32.dll", EntryPoint:="CreateRectRgn", CallingConvention:=CallingConvention.Cdecl, ExactSpelling:=True)> _
    Private Shared Function CreateRectRgn(ByVal nLeftRect As Long, ByVal nTopRect As Long, ByVal nRightRect As Long, ByVal nBottomRect As Long) As IntPtr
    End Function

    <DllImport("user32.dll", EntryPoint:="SetWindowRgn", CallingConvention:=CallingConvention.Cdecl, ExactSpelling:=True)> _
    Public Shared Function SetWindowRgn(ByVal hWnd As Long, ByVal hRgn As IntPtr, ByVal bRedraw As Boolean) As Long
    End Function

    <DllImport("gdi32.dll", EntryPoint:="DeleteObject", CallingConvention:=CallingConvention.Cdecl, ExactSpelling:=True)> _
    Private Shared Function DeleteObject(ByVal hObject As IntPtr) As <MarshalAs(UnmanagedType.Bool)> Boolean
    End Function

    Dim hRgnC As Long
    Dim hRgnR As Long
    Private Sub Form1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Click
        hRgnC = CreateEllipticRgn(25, 25, 220, 220)
        SetWindowRgn(Me.Handle, hRgnC, True)
    End Sub

    Private Sub Form1_DoubleClick(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.DoubleClick
        hRgnR = CreateRectRgn(0, 0, Me.Width, Me.Height)
        SetWindowRgn(Me.Handle.ToInt64, hRgnR, True)
    End Sub

    Private Sub Form1_Leave(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Leave
        If hRgnR <> 0 Then DeleteObject(hRgnR)
        If hRgnC <> 0 Then DeleteObject(hRgnC)
    End Sub
End Class