Conditionally Allow Focus in a Cell in C1TrueDbGrid

Many of our customers have asked if C1TrueDbGrid offers conditionally enabling/ disabling a cell focus. This blog explains an approach to do the same. That is to allow or disallow focus when user navigates the grid either with the Arrow keys, the TAB key, or clicking with the mouse. The process used for this approach is : 1. Bind C1TrueDbgrid with a DataSouce having a boolean column. The boolean column will be displayed as a checkbox. 2. Conditionally allow focus in a column based on the CheckedState of the boolean column in BeforeRowColChange event.

Binding C1TrueDbGrid

For simplicity we are binding C1TrueDbGrid with a DataTable with a boolean 'Allow Focus' column that will be displayed as a checkbox.

Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load  
        Dim table As New DataTable  
        With table.Columns  
            .Add(New DataColumn("A", GetType(Boolean)))  
            .Add(New DataColumn("B", GetType(String)))  
            .Add(New DataColumn("C", GetType(String)))  
            .Add(New DataColumn("D", GetType(String)))  
        End With  
        C1TrueDBGrid1.SetDataBinding(table, "", True)  
        C1TrueDBGrid1.Row = 0  
        C1TrueDBGrid1.Col = 0  
        C1TrueDBGrid1.Focus()  
End Sub

Conditionally Focus a cell in BeforeRowColChange event

The CheckedState of the 'Allow Focus' column will determine whether the 'If Checked' column will be allowed focus or not as follows :

1. If 'Allow Focus' is checked, focus will be allowed in 'If Checked' column.
2. If 'Allow Focus' is unchecked, focus will not be allowed in 'If Checked' column.

This will be handled in the BeforeRowColChange event which occurs before moving onto the another cell.

Private Sub C1TrueDBGrid1_BeforeRowColChange(ByVal sender As Object, ByVal e As C1.Win.C1TrueDBGrid.CancelEventArgs) Handles C1TrueDBGrid1.BeforeRowColChange  
        ' Fetches current row index  
        Dim curRow As Integer = C1TrueDBGrid1.Row  
        ' Fetches destination row index  
        Dim desRow As Integer = C1TrueDBGrid1.DestinationRow  
        ' Fetches current column index  
        Dim curCol As Integer = C1TrueDBGrid1.Col  
        ' Fetches destination column index  
        Dim desCol As Integer = C1TrueDBGrid1.DestinationCol  

        ' Checks before moving into Column(2) if the value in Column(0) is true/false  
        If desCol = 2 Then  
            If C1TrueDBGrid1.Columns(0).CellValue(desRow).ToString() = "False" Then  
                e.Cancel = True  
                If curRow = desRow Then  
                    If curCol < desCol Then  
                        C1TrueDBGrid1.Col = desCol + 1  
                    Else  
                        C1TrueDBGrid1.Col = desCol - 1  
                    End If  
                Else  
                    If curRow < desRow Then  
                        C1TrueDBGrid1.Row = desRow + 1  
                    Else  
                        C1TrueDBGrid1.Row = desRow - 1  
                    End If  
                End If  
            End If  
        End If  
End Sub

Download the sample for detailed implementation of the above code. Download Sample