[VB.NET]DataGridViewでのドラッグアンドドロップ

以下のサイトにあったC#のソースコードをVB.NETに修正＆一部変更しました。
http://social.msdn.microsoft.com/forums/ja-JP/csharpgeneralja/thread/e59a4043-6298-4653-809f-5c8fcf04f2e6

変更点として、
行セレクトモード⇒セルセレクトモードにして、
特定のカラム（ここではColumn0のImage）上でしかドラッグアンドドロップが起動しないようにしています。

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

        'テストの準備

        'データグリッド

        Dim objTable As New DataTable

        Dim objDR As DataRow

        objTable.Columns.Add(New DataColumn("項目1", GetType(String)))

        objTable.Columns.Add(New DataColumn("項目2", GetType(Integer)))

        For i As Integer = 0 To 10

            objDR = objTable.NewRow

            objDR("項目1") = i.ToString & i.ToString & i.ToString & i.ToString

            objDR("項目2") = i

            objTable.Rows.Add(objDR)

        Next

        Me.DataGridViewUe.DataSource = objTable

        For Each col As DataGridViewColumn In Me.DataGridViewUe.Columns

            col.SortMode = DataGridViewColumnSortMode.NotSortable

        Next

        Me.DataGridViewUe.AllowDrop = True

    End Sub

Private Sub DataGridViewUe_MouseDown(sender As System.Object, e As MouseEventArgs) Handles DataGridViewUe.MouseDown

        OwnBeginGrabRowIndex = -1

        If (e.Button <> MouseButtons.Left And MouseButtons.Left <> MouseButtons.Left) Then Return

        Dim hit As DataGridView.HitTestInfo = DataGridViewUe.HitTest(e.X, e.Y)

    If hit.ColumnIndex <> 0 Then Return

        If (hit.Type <> DataGridViewHitTestType.Cell) Then Return

        'ドラッグ＆ドロップの開始

        'クリック時などは -1 に戻らないが問題なし

        OwnBeginGrabRowIndex = hit.RowIndex

        'Me.TextBox1.Text = OwnBeginGrabRowIndex

        'Me.TextBox2.Text = "すたーと"

        DataGridViewUe.DoDragDrop(OwnBeginGrabRowIndex, DragDropEffects.Move)

    End Sub

  

 

    Private Sub DataGridViewUe_DragOver(sender As System.Object, e As DragEventArgs) Handles DataGridViewUe.DragOver

        'Integer型の場合は、エフェクトをMoveに変更（ここはカラムによるのかな？）

        If e.Data.GetDataPresent(GetType(Integer)) Then

            e.Effect = DragDropEffects.Move

        Else

            e.Effect = DragDropEffects.None

        End If

        Me.DataGridViewUe.Rows(OwnBeginGrabRowIndex).Selected = True

        Dim kara, made As Integer

        Dim tugi As Boolean

        Dim valid As Boolean = DecideDropDestinationRowIndex(DataGridViewUe, e, kara, made, tugi)

        'ドロップ先マーカーの表示・非表示の制御

        Dim needRedraw As Boolean = (valid <> DropDestinationIsValid)

        If (valid) Then

            needRedraw = (needRedraw Or (made <> DropDestinationRowIndex) Or (tugi <> DropDestinationIsNextRow))

        End If

        If (needRedraw) Then

            If (DropDestinationIsValid) Then

                DataGridViewUe.InvalidateRow(DropDestinationRowIndex)

            End If

            If (valid) Then

                DataGridViewUe.InvalidateRow(made)

            End If

        End If

        DropDestinationIsValid = valid

        DropDestinationRowIndex = made

        DropDestinationIsNextRow = tugi

    End Sub

    Private Sub DataGridViewUe_DragLeave(sender As System.Object, e As DragEventArgs) Handles DataGridViewUe.DragLeave

        If (DropDestinationIsValid) Then

            DropDestinationIsValid = False

            DataGridViewUe.InvalidateRow(DropDestinationRowIndex)

        End If

    End Sub

    Private Sub DataGridViewUe_DragDrop(sender As System.Object, e As DragEventArgs) Handles DataGridViewUe.DragDrop

        Dim kara, made As Integer

        Dim tugi As Boolean

        If (DecideDropDestinationRowIndex(DataGridViewUe, e, kara, made, tugi) = False) Then

            Return

        End If

        DropDestinationIsValid = False

        'データの移動

        made = MoveDataValue(kara, made, tugi)

        Me.DataGridViewUe.CurrentCell = Me.DataGridViewUe(Me.DataGridViewUe.CurrentCell.ColumnIndex, made)

        Me.DataGridViewUe.Invalidate()

    End Sub

    Private Sub DataGridViewUe_RowPostPaint(sender As System.Object, e As DataGridViewRowPostPaintEventArgs) Handles DataGridViewUe.RowPostPaint

        'ドロップ先のマーカーを描画

        If (DropDestinationIsValid And e.RowIndex = DropDestinationRowIndex) Then

            Using objpen As New Pen(Color.Red, 4)

                Dim y As Integer = IIf(DropDestinationIsNextRow = False, e.RowBounds.Y + 2, e.RowBounds.Bottom - 2)

                e.Graphics.DrawLine(objpen, e.RowBounds.X, y, e.RowBounds.X + 50, y)

            End Using

        End If

    End Sub

    'ドロップ先の行の決定

    Private Function DecideDropDestinationRowIndex(grid As DataGridView, e As DragEventArgs, ByRef kara As Integer, ByRef made As Integer, ByRef tugi As Boolean) As Boolean

        'If Not e.Data.GetDataPresent(GetType(Integer)) Then Return

        kara = DirectCast(e.Data.GetData(GetType(Integer)), Integer)

        '元の行が追加用の行であれば、常に false

        If (grid.NewRowIndex <> -1 And grid.NewRowIndex = kara) Then

            made = 0

            tugi = False

            Return False

        End If

        Dim clientPoint As Point = grid.PointToClient(New Point(e.X, e.Y))

        '上下のみに着目するため、横方向は無視する

        clientPoint.X = 1

        Dim hit As DataGridView.HitTestInfo = grid.HitTest(clientPoint.X, clientPoint.Y)

        made = hit.RowIndex

        If (made = -1) Then

            Dim top As Integer = IIf(grid.ColumnHeadersVisible, grid.ColumnHeadersHeight, 0)

            top += 1  '// ...

            If (top > clientPoint.Y) Then

                'ヘッダへのドロップ時は表示中の先頭行とする

                made = grid.FirstDisplayedCell.RowIndex

            Else

                '最終行へ

                made = grid.Rows.Count - 1

            End If

        End If

        '追加用の行は無視

        If (made = grid.NewRowIndex) Then

            made -= made

        End If

        'Me.NumericTextBox1.Text = made

        tugi = (made > kara)

        Return (kara <> made)

    End Function

    'データの移動

    Private Function MoveDataValue(ByVal kara As Integer, ByVal made As Integer, ByVal tugi As Boolean) As Integer

        Dim table As DataTable = DirectCast(DataGridViewUe.DataSource, DataTable)

        '移動するデータの退避（計算列があればたぶんダメ）

        Dim rowData = table.Rows(kara).ItemArray

        Dim row As DataRow = table.NewRow()

        row.ItemArray = rowData

        '移動元から削除

        table.Rows.RemoveAt(kara)

        If (made > kara) Then made = made - 1

        '移動先へ追加

        If (tugi) Then made = made + 1

        If (made <= table.Rows.Count) Then

            table.Rows.InsertAt(row, made)

        Else

            table.Rows.Add(row)

        End If

        Return table.Rows.IndexOf(row)

    End Function

End Class