Visual Basic 2008 in PictureBox zeichnen wie in Paint mit Stift

Public Class Form1
    Private MouseD As Boolean
    Private Col As Color
    Private NewPen As Pen
    Private bmp As Bitmap
    Private Plist As List(Of Point)
    Private Sub PictureBox1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseDown
        MouseD = True
        Plist.Add(New Point(e.X, e.Y))
        NewPen = New Pen(Col, CSng(ComboBox2.SelectedItem))
    End Sub
    Private Sub PictureBox1_MouseUp(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseUp
        If MouseD Then
            MouseD = False
            Using gr = Graphics.FromImage(bmp)

                Draw(gr)
                gr.Flush()
            End Using
            Plist.Clear()
            PictureBox1.Invalidate()
        End If
    End Sub
    Private Sub PictureBox1_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseMove
        If MouseD Then
            Plist.Add(New Point(e.X, e.Y))
            PictureBox1.Invalidate()
        End If
    End Sub
    Private Sub PictureBox1_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles PictureBox1.Paint
        If MouseD Then Draw(e.Graphics)
    End Sub
   
    Private Sub Draw(ByVal g As Graphics)
        If Plist.Count > 0 Then
            Dim bs As Byte() = New Byte(Plist.Count - 1) {}
            bs(0) = CByte(System.Drawing.Drawing2D.PathPointType.Start)
            For a = 1 To Plist.Count - 1
                bs(a) = CByte(System.Drawing.Drawing2D.PathPointType.Line)
                g.DrawPath(NewPen, New System.Drawing.Drawing2D.GraphicsPath(Plist.ToArray, bs))
            Next
        End If
    End Sub

    Private Function GetColors() As List(Of String)
        Dim colors As New List(Of String)()
        Dim colorNames As String() = [Enum].GetNames(GetType(KnownColor))
        For Each colorName As String In colorNames
            Dim knownColor As KnownColor = DirectCast([Enum].Parse(GetType(KnownColor), colorName), KnownColor)
            If knownColor > knownColor.Transparent Then
                colors.Add(colorName)
            End If
        Next
        Return colors
    End Function
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        PictureBox1.BackColor = Color.White
        bmp = New Bitmap(PictureBox1.Width, PictureBox1.Height)
        PictureBox1.Image = bmp
        Plist = New List(Of Point)
        Me.DoubleBuffered = True
        For Each c As String In GetColors()
            ComboBox1.Items.Add(c)
        Next
        For a = 1 To 25
            ComboBox2.Items.Add(a.ToString)
        Next
        ComboBox1.SelectedItem = ComboBox1.Items(0)
        ComboBox2.SelectedItem = ComboBox2.Items(0)
    End Sub
    Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox1.SelectedIndexChanged
        Col = Color.FromName(ComboBox1.SelectedItem)
    End Sub
   
End Class