VB.Net 未处理的异常：System.Runtime.InteropServices.ExternalException：“GDI+ 中发生一般错误

问：

我正在尝试将我在 Vb.Net 6.0 （Visual Studio 2022） 上编写的绘图保存到 .png 文件中。

bmp.Save("C:\graph.png", System.Drawing.Imaging.ImageFormat.Png)

但是，在上面的代码段中，我收到以下异常未处理消息：

VB.Net 异常未处理：

System.Runtime.InteropServices.ExternalException：“GDI+ 中发生一般错误

这是代码段所属的脚本的其余部分

Imports System.Security
Imports System.Security.Permissions
Imports System.Drawing.Bitmap
Imports System.Drawing.Imaging



Public Class Form1
    Dim m, i As Integer
    Dim h, Pi, Pi2, u, v, x, y As Single
    Dim left As Integer = Me.left

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load

    End Sub

    Dim top As Integer = Me.top
    Dim centerX As Integer = Me.left + (Me.Width / 2)
    Dim centerY As Integer = Me.top + (Me.Height / 2)
    Dim bmp As New Bitmap(Me.Width, Me.Height)
    Dim path As String = "C:\graph.png"
    Dim perm As FileIOPermission = New FileIOPermission(FileIOPermissionAccess.Write, path)



    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim g As Graphics = Graphics.FromImage(bmp)
        m = 1000
        h = 1 / 100
        Pi = 3.14
        Pi2 = 3.14 * 2
        x = 150
        y = 150

        For i = 1 To m
            u = x * Cos(h * Pi2) + y * Sin(h * Pi2)
            v = y * Cos(h * Pi2) - x * Sin(h * Pi2)
            x = u
            y = v
            g.FillRectangle(New SolidBrush(Color.FromArgb(255, 0, 0)), x, y, 1, 1)
        Next i
        Try
            perm.Demand()
            ' The application has permission to write to the file
            bmp.Save("C:\graph.png", System.Drawing.Imaging.ImageFormat.Png)
        Catch ex As SecurityException
            ' The application does not have permission to write to the file
        End Try

    End Sub
End Class