C# と VB.NET の質問掲示板

■No88633 (まっさん さん) に返信

すみません。↑は間違って投稿してしまいました。
(c)以外は以下で、一応希望通りに動作しているように思います。

    '編集中セルの行番号、列番号、EditingControl
    Private _textbox As Tuple(Of Integer, Integer, DataGridViewTextBoxEditingControl)
    Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
        Dim dt As New DataTable
        dt.Columns.Add("C1", GetType(Integer))
        dt.Rows.Add(1)
        dt.AcceptChanges()
        DataGridView1.DataSource = dt
    End Sub

    Private Sub DataGridView1_DataError(sender As Object, e As System.Windows.Forms.DataGridViewDataErrorEventArgs) Handles DataGridView1.DataError
        DataGridView1.Rows(e.RowIndex).ErrorText = "セルの値を確認してください。"
        '念の為、行番号、列番号も照合する
        If _textbox IsNot Nothing AndAlso _textbox.Item1 = e.RowIndex AndAlso _textbox.Item2 = e.ColumnIndex Then
            _textbox.Item3.SelectAll()
        End If
        e.Cancel = True
    End Sub
    Private Sub DataGridView1_CellValidating(sender As Object, e As System.Windows.Forms.DataGridViewCellValidatingEventArgs) Handles DataGridView1.CellValidating
        If DataGridView1.Rows(e.RowIndex).ErrorText IsNot String.Empty Then
            DataGridView1.Rows(e.RowIndex).ErrorText = String.Empty
        End If
    End Sub
    Private Sub DataGridView1_EditingControlShowing(ByVal sender As Object, _
        ByVal e As DataGridViewEditingControlShowingEventArgs) _
        Handles DataGridView1.EditingControlShowing
        If TypeOf e.Control Is DataGridViewTextBoxEditingControl Then
            Dim tbox = DirectCast(e.Control, DataGridViewTextBoxEditingControl)
            Dim cell = DataGridView1.CurrentCell
            _textbox = Tuple.Create(cell.RowIndex, cell.ColumnIndex, tbox)
        Else
            _textbox = Nothing
        End If
    End Sub
    Private Sub DataGridView1_CellEndEdit(sender As Object, e As System.Windows.Forms.DataGridViewCellEventArgs) Handles DataGridView1.CellEndEdit
        DataGridView1.CurrentCell = Nothing
        DataGridView1.CurrentCell = DataGridView1(e.ColumnIndex, e.RowIndex)
    End Sub

■No88637 (まっさん さん) に返信

編集中のTextBoxにアイコンを表示するのは力技になりそうなので以下のように
ToolTipでエラー表示するようにしました。
独り相撲で申し訳ありませんでした。

  '編集中セルの行番号、列番号、EditingControl
    Private _textbox As Tuple(Of Integer, Integer, DataGridViewTextBoxEditingControl)
    Private _toolTip As New ToolTip
    Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
        Dim dt As New DataTable
        dt.Columns.Add("C1", GetType(Integer))
        dt.Rows.Add(1)
        dt.AcceptChanges()
        DataGridView1.DataSource = dt
    End Sub
    Private Sub DataGridView1_DataError(sender As Object, e As System.Windows.Forms.DataGridViewDataErrorEventArgs) Handles DataGridView1.DataError
        '念の為、行番号、列番号も照合する
        If _textbox IsNot Nothing AndAlso _textbox.Item1 = e.RowIndex AndAlso _textbox.Item2 = e.ColumnIndex Then
            _textbox.Item3.SelectAll()
            'ツールチップを表示
            _toolTip.SetToolTip(_textbox.Item3, "セルの値を確認してください。")
            _toolTip.ToolTipIcon = ToolTipIcon.Error
            _toolTip.Active = True
        End If
        e.Cancel = True
    End Sub
    Private Sub DataGridView1_EditingControlShowing(ByVal sender As Object, _
        ByVal e As DataGridViewEditingControlShowingEventArgs) _
        Handles DataGridView1.EditingControlShowing
        If TypeOf e.Control Is DataGridViewTextBoxEditingControl Then
            Dim tbox = DirectCast(e.Control, DataGridViewTextBoxEditingControl)
            Dim cell = DataGridView1.CurrentCell
            _textbox = Tuple.Create(cell.RowIndex, cell.ColumnIndex, tbox)
        Else
            _textbox = Nothing
        End If
    End Sub
    Private Sub DataGridView1_CellEndEdit(sender As Object, e As System.Windows.Forms.DataGridViewCellEventArgs) Handles DataGridView1.CellEndEdit
        _toolTip.Active = False
    End Sub