Public Class frmHex2
    Const gridlines As Integer = 20
    Const rowcolumns As Integer = 16
    Dim inputlength As Integer = gridlines * rowcolumns
    Dim filelength, topposition As Long
    Const ShowHex As Boolean = True
 
    Dim fsin As IO.FileStream, br As IO.BinaryReader, bw As IO.BinaryWriter
    Dim WithEvents dgv As New DataGridView With {.Parent = Me, .Dock = _
      DockStyle.Fill}
 
    Private Sub frmHex_FormClosing(sender As Object, _
        e As FormClosingEventArgs) Handles Me.FormClosing
        br.Close() : bw.Close() : fsin.Close()
    End Sub
 
    Private Sub frmHex_Load(sender As System.Object, e As EventArgs) Handles _
      MyBase.Load
        'Formular einrichten
        Me.Width = 740 : Me.Height = 470
        Me.FormBorderStyle = Windows.Forms.FormBorderStyle.FixedSingle
 
        'Datei laden
        Dim infile As String = "F:\Daten\bytes.bin"
        fsin = New IO.FileStream(infile, IO.FileMode.Open, _
          IO.FileAccess.ReadWrite)
        filelength = fsin.Length
        br = New IO.BinaryReader(fsin)
        bw = New IO.BinaryWriter(fsin)
 
        'Datagridview einrichten
        With dgv
            For i As Integer = 0 To rowcolumns - 1
                .Columns.Add("SP" & CStr(i), "SP" & CStr(i))
                .Columns(i).Width = 30
                .Columns(i).DefaultCellStyle.Alignment = _
                    DataGridViewContentAlignment.BottomRight
                If i = rowcolumns \ 2 Then
                    .Columns(i).Width = 70
                Else
                    .Columns(i).Width = 40
                End If
            Next i
            .Font = New Font("Arial", 10)
            .Rows.Add(gridlines)
            .ColumnHeadersVisible = False
            .AllowUserToAddRows = False : .AllowUserToDeleteRows = False
            .AllowUserToResizeColumns = False : .AllowUserToOrderColumns = False
            .AllowUserToResizeRows = False : .RowHeadersVisible = False
            .MultiSelect = False
            .SelectionMode = DataGridViewSelectionMode.FullRowSelect
            .CellBorderStyle = DataGridViewCellBorderStyle.None
        End With
 
        'Anzeige aktualisieren
        topposition = 0 : Showbytes(0)
        dgv.Focus()
    End Sub
 
    Private Sub Showbytes(ByVal RowSelected As Integer)
        fsin.Position = topposition
        Dim byt As Byte() = br.ReadBytes(inputlength)
        Dim r, c As Integer
        dgv.SuspendLayout()
        r = 0 : c = -1
        For i As Integer = 0 To byt.Length - 1
            c += 1 : If c = rowcolumns Then r += 1 : c = 0
            If Not ShowHex Then
                dgv.Rows(r).Cells(c).Value = CStr(byt(i))
            Else
                dgv.Rows(r).Cells(c).Value = Hex(byt(i))
            End If
        Next i
        For i As Integer = byt.Length To inputlength - 1
            c += 1 : If c = rowcolumns Then r += 1 : c = 0
            dgv.Rows(r).Cells(c).Value = String.Empty
        Next i
        dgv.ResumeLayout()
        dgv.Rows(RowSelected).Selected = True
    End Sub
 
    Private Sub dgv_CellEndEdit(sender As Object, _
        e As System.Windows.Forms.DataGridViewCellEventArgs) _
        Handles dgv.CellEndEdit
 
        Dim c As DataGridViewCell = dgv.CurrentCell
        Try
            Dim byt As Byte
            If ShowHex Then
                byt = CByte(Convert.ToInt32(c.Value.ToString, 16))
            Else
                byt = CByte(c.Value)
            End If
            Dim fileposition As Long = topposition + e.RowIndex * rowcolumns + _
              e.ColumnIndex
            If fileposition < filelength Then
                fsin.Position = fileposition : bw.Write(byt)
            Else
                dgv.CurrentCell.Value = String.Empty
            End If
        Catch
        Finally
            Dim ex As New KeyEventArgs(Keys.Down)
            Showbytes(e.RowIndex)
            dgv_KeyDown(dgv, ex)
        End Try
    End Sub