Imports System.IO

Public Class Form1

    Private Sub btnLOAD_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnLOAD.Click

        'Questo codice carica il file in una ListBox
        OpenFileDialog1.InitialDirectory = "c:\"
        openFileDialog1.Filter = "txt files (*.txt)|*.txt|All files (*.*)|*.*"
        openFileDialog1.FilterIndex = 2
        openFileDialog1.RestoreDirectory = True

        If openFileDialog1.ShowDialog() = System.Windows.Forms.DialogResult.OK Then
            Try
                Dim readText() As String = File.ReadAllLines(OpenFileDialog1.FileName)
                Dim s As String
                For Each s In readText
                    Me.ListBox1.Items.Add(s)
                Next
            Catch Ex As Exception
                MessageBox.Show("Cannot read file from disk. Original error: " & Ex.Message)
            End Try
        End If

    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        'Questo codice disegna le linee che trova nella ListBox in una PictureBox

        If Me.ListBox1.Items.Count > 0 Then

            Dim bmp As New Bitmap(Me.PictureBox1.Width, Me.PictureBox1.Height)
            Dim gr As Graphics = Graphics.FromImage(bmp)

            Dim blackPen As New Pen(Color.Red, 3)

            Dim x1 As Single = Nothing
            Dim y1 As Single = Nothing
            Dim x2 As Single = Nothing
            Dim y2 As Single = Nothing

            For i As Integer = 0 To Me.ListBox1.Items.Count - 1

                Dim line() As String

                line = Split(Me.ListBox1.Items(i), ";")

                x1 = line(0)
                y1 = line(1)
                x2 = line(2)
                y2 = line(3)

                gr.DrawLine(blackPen, x1, y1, x2, y2)

            Next

            Me.PictureBox1.Image = bmp
        Else
            MsgBox("Nessuna riga da processare")
        End If


    End Sub
End Class