The following sections describe the grid's default navigation and scrolling behavior. You always have complete control over the behavior of the TAB and arrow keys as well as the position of the current cell when a row or split boundary is reached.

Mouse Interaction

When the user clicks a non-current cell, the grid fires the BeforeRowColChange event. Unless this event is cancelled, the clicked cell becomes current and the grid subsequently fires the RowColChange event after any pending update operations have completed. The only exceptions to this are:

• If the user clicks a cell in a column or split that has the AllowFocus property set to False, and the cell belongs to the current row, then the current cell does not change.
• If the user clicks a cell in a column or split that has the AllowFocus property set to False, and the cell does not belong to the current row, then the current row changes, but the column with the focus retains it.
• If the current cell has been modified, and the BeforeColUpdate event is canceled, then the current cell does not change.
• If the current row has been modified, and the user clicks a cell in a different row, and the BeforeUpdate event is canceled, then the current cell does not change.

The user can also use the mouse to manipulate the grid's scroll bars, bringing cells that lie outside the grid's display area into view. The vertical scroll bar governs rows; the horizontal scroll bar governs columns. The HScrollBar property controls whether the horizontal scroll bars are displayed, while the VscrollBar property controls the vertical scroll bar.

Note that the scroll bars do not change the current cell. Therefore, the current cell may not always be visible.

To respond to vertical scrolling operations in code, use the FirstRowChange event. To respond to horizontal scrolling operations in code, use the LeftColChange event.

Clicking the Rightmost Column

The grid always displays the leftmost column (the first visible column) in its entirety. The rightmost column, however, is usually clipped. The behavior of the last partially visible column when clicked by the user is controlled by the grid's ExposeCellMode property.

The default value for the ExposeCellMode property is ExposeCellModeEnum.ScrollOnSelect. If the user clicks the rightmost column when it is partially visible, the grid will scroll to the left to display this column in its entirety. This may be less desirable for users who commonly click on the grid to begin editing, as the grid will always shift to the left when the user clicks on a partially visible rightmost column.

If ExposeCellMode is set to ExposeCellModeEnum.ScrollOnEdit, the grid will not scroll when the rightmost visible column is clicked. However, if the user attempts to edit the cell, then the grid will scroll to the left to display the column in its entirety. This is how Microsoft Excel works and is probably the most familiar setting to users.

If ExposeCellMode is set to ExposeCellModeEnum.ScrollNever, the grid will not scroll to make the rightmost column visible, even if the user subsequently attempts to edit the cell. Note that editing may be difficult if only a small portion of the column is visible. The chief reason to use this setting is to ensure enough space is available for editing (or if editing is disallowed) and to prevent the grid from shifting accidentally.

Note that the ExposeCellMode property controls the behavior of the rightmost visible column only when the user clicks it with the mouse. If the rightmost column becomes visible by code (setting the grid's Col property) or by keyboard navigation, then the grid will always scroll to make it totally visible.

Keyboard Interaction

True DBGrid for WinForms includes several keyboard shortcuts that can improve users' run-time interaction experience.

In Grid View

By default, the user can navigate the grid with the arrow keys, the ENTER key, the TAB key, the Page Up and Page DOwn keys, and the HOME and END keys.

Navigation at Row Boundaries

At row boundaries, namely the first and last column, grid navigation depends on the WrapCellPointer property. The following explanation assumes that the AllowArrows property is True, and that the TabAction property is set to either ColumnNavigation or GridNavigation.

Navigation at Split Boundaries

At split boundaries, grid navigation depends on the TabAcrossSplits property as follows:

Restricting Cell Navigation

The BeforeRowColChange event can be used to prevent the user from moving to a different cell, regardless of whether the current cell is modified. Set the Cancel argument to True to keep another cell from becoming current.

If the current cell has been modified, use the BeforeColUpdate event to examine its value before moving to another grid cell. If the value entered is invalid, set the Cancel argument to True to prevent the current cell from changing, and optionally beep or display an error message for the user. The BeforeColUpdate event provides a flexible way to validate user input and restrict cell navigation.

To write code in Visual Basic

Private Sub C1TrueDBGrid1_BeforeColUpdate(ByVal sender As Object, ByVal e As C1.Win.C1TrueDBGrid.BeforeColUpdateEventArgs) Handles C1TrueDBGrid1.BeforeColUpdate
    Dim CharCode As Integer
    If e.ColIndex = 1 Then
 
        ' Data in Column 1 must start with upper case.
        CharCode = Asc(Me.C1TrueDBGrid1.Columns(1).Text)
        If CharCode > 64 And CharCode < 91 Then Exit Sub
        
        ' Display warning message for user.
        MessageBox.Show("Last name must start with upper case")
    
        ' Data validation fails, prohibit user from moving to another cell.
        e.Cancel = True
    End If
End Sub

To write code in C#

private void c1TrueDBGrid1_BeforeColUpdate(object sender, C1.Win.C1TrueDBGrid.BeforeColUpdateEventArgs e) {
    int CharCode;
    if ( e.ColIndex == 1 ) 
    {
        // Data in Column 1 must start with upper case.
        CharCode = this.c1TrueDBGrid1.Columns[1].Text[0];
        if ( CharCode > 64 && CharCode < 91 ) return;
 
        // Display warning message for user.
        MessageBox.Show("Last name must start with upper case");
 
        // Data validation fails, prohibit user from moving to another cell.
        e.Cancel = true;
    }
}