从面板的绘制形状调整窗体大小- VB.NET

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    Me.FormBorderStyle = FormBorderStyle.None ' 设置窗体边框为无
    Me.DoubleBuffered = True ' 启用双缓冲，减少闪烁
    Me.SetStyle(ControlStyles.ResizeRedraw, True) ' 启用重绘
End Sub

Private Const HTLEFT As Integer = 10 ' 左边界
Private Const HTRIGHT As Integer = 11 ' 右边界
Private Const HTTOP As Integer = 12 ' 上边界
Private Const HTTOPLEFT As Integer = 13 ' 左上角
Private Const HTTOPRIGHT As Integer = 14 ' 右上角
Private Const HTBOTTOM As Integer = 15 ' 下边界
Private Const HTBOTTOMLEFT As Integer = 16 ' 左下角
Private Const HTBOTTOMRIGHT As Integer = 17 ' 右下角

Private Sub Form1_MouseDown(sender As Object, e As MouseEventArgs) Handles MyBase.MouseDown
    If e.Button = MouseButtons.Left Then
        ReleaseCapture()
        Dim msg As Message = Message.Create(Me.Handle, &HA1, New IntPtr(2), IntPtr.Zero)
        Me.DefWndProc(msg)
    End If
End Sub

Private Sub Form1_MouseMove(sender As Object, e As MouseEventArgs) Handles MyBase.MouseMove
    If e.Button = MouseButtons.Left Then
        Dim cursorPos As Point = Me.PointToClient(Cursor.Position)
        If cursorPos.X < 5 AndAlso cursorPos.Y < 5 Then
            Me.Cursor = Cursors.SizeNWSE ' 左上角
            Return
        ElseIf cursorPos.X > Me.Width - 5 AndAlso cursorPos.Y < 5 Then
            Me.Cursor = Cursors.SizeNESW ' 右上角
            Return
        ElseIf cursorPos.X < 5 AndAlso cursorPos.Y > Me.Height - 5 Then
            Me.Cursor = Cursors.SizeNESW ' 左下角
            Return
        ElseIf cursorPos.X > Me.Width - 5 AndAlso cursorPos.Y > Me.Height - 5 Then
            Me.Cursor = Cursors.SizeNWSE ' 右下角
            Return
        ElseIf cursorPos.X < 5 Then
            Me.Cursor = Cursors.SizeWE ' 左边界
            Return
        ElseIf cursorPos.X > Me.Width - 5 Then
            Me.Cursor = Cursors.SizeWE ' 右边界
            Return
        ElseIf cursorPos.Y < 5 Then
            Me.Cursor = Cursors.SizeNS ' 上边界
            Return
        ElseIf cursorPos.Y > Me.Height - 5 Then
            Me.Cursor = Cursors.SizeNS ' 下边界
            Return
        Else
            Me.Cursor = Cursors.Default
        End If
    End If
End Sub

Private Sub Form1_MouseUp(sender As Object, e As MouseEventArgs) Handles MyBase.MouseUp
    Me.Cursor = Cursors.Default
End Sub

Private Sub Form1_Paint(sender As Object, e As PaintEventArgs) Handles MyBase.Paint
    Dim path As New Drawing2D.GraphicsPath()
    path.AddEllipse(0, 0, Me.Width, Me.Height) ' 绘制椭圆形状
    Me.Region = New Region(path) ' 设置窗体的区域为椭圆形状
End Sub