如何限制可以在DataGridView中选择的行数

Question

I have got a DataGridView with a MultiSelect=True in C#.

I want to limit the maximum number of simultaneously selected rows to 2, so that user can select only one or two rows at the same time. How can I achive this?

There are no events like BeforeSelectedRowsChanged or ValidatingSelectedRows.

My DataGridView is Readonly also.

** EDIT ** my SelectionMode is FullRowSelect

Answer 1

On the SelectionChanged event you can do this:

private void dataGridView1_SelectionChanged(object sender, EventArgs e)
{
    if (dataGridView1.SelectedCells.Count > 2)
    {
      dataGridView1.SelectedCells[0].Selected = false;
    }
}

This will prevent/undo selecting any more cells after selecting two.

For whole rows:

private void dataGridView1_SelectionChanged(object sender, EventArgs e)
{
    if (dataGridView1.SelectedRows.Count > 2)
    {
      dataGridView1.SelectedRows[0].Selected = false;
    }
}

Answer 2

You could try overriding SetSelectedRowCore, calling the base with adding your new limitation to the selected condition.

protected virtual void SetSelectedRowCore(int rowIndex,bool selected   )
{
    base(rowIndex, selected && currentSelection < allowedSelectionCount);
}

SetSelectedRowCore

Answer 3

This always leave selected 2 last selected rows

private void dataGridView1_SelectionChanged(object sender, EventArgs e)
    {
        if (dataGridView1.SelectedRows.Count > 2)
        {
            for (int i = 2; i < dataGridView1.SelectedRows.Count; i++)
            {
                dataGridView1.SelectedRows[i].Selected = false;

            }
        }
    }