protected virtual void HandleSelectAllItem(ItemCheckEventArgs e, ToolStripCheckedListBox checkedList, int selectAllIndex)
{
// Did they check/uncheck the "Select All"?
if (e.Index == selectAllIndex) {
if (e.NewValue == CheckState.Checked)
checkedList.CheckAll();
if (e.NewValue == CheckState.Unchecked)
checkedList.UncheckAll();
return;
}
// OK. The user didn't check/uncheck SelectAll. Now we have to update it's
// checkedness to reflect the state of everything else
// If all clusters are checked, we check the Select All.
// If no clusters are checked, the uncheck the Select All.
// For everything else, Select All is set to indeterminate.
// How many items are currenty checked?
int count = checkedList.CheckedItems.Count;
// First complication.
// The value of the Select All itself doesn't count
if (checkedList.GetItemCheckState(selectAllIndex) != CheckState.Unchecked)
count -= 1;
// Another complication.
// CheckedItems does not yet know about the item the user has just
// clicked, so we have to adjust the count of checked items to what
// it is going to be
if (e.NewValue != e.CurrentValue) {
if (e.NewValue == CheckState.Checked)
count += 1;
else
count -= 1;
}
// Update the state of the Select All item
if (count == 0)
checkedList.SetItemState(selectAllIndex, CheckState.Unchecked);
else if (count == checkedList.Items.Count - 1)
checkedList.SetItemState(selectAllIndex, CheckState.Checked);
else
checkedList.SetItemState(selectAllIndex, CheckState.Indeterminate);
}
