public void AddDropdownItem(IDropdownItem <T> dropdownItem)
{
if (null == dropdownItem)
{
throw new ArgumentNullException("dropdownItem");
}
dropdownItem.TransitionObject = TransitionObject;
DropdownItems.Add(dropdownItem);
}
private void SetSelectedDropdownItem(IDropdownItem <T> selectedItem)
{
if (selectedItem != SelectedDropdownItem)
{
//remove the old item
RemoveItem(SelectedDropdownItem);
if (null != selectedItem)
{
//set the new selected item
_selectedDropdownItem = selectedItem?.DeepCopy() as IDropdownItem <T>;
_selectedDropdownItem.Position = Position;
}
else
{
//set the selected item to null
_selectedDropdownItem = null;
}
//clear out the current item
Items.Clear();
//add the new item as the selected item
if (null != selectedItem)
{
AddItem(selectedItem);
}
//add the expansion button
if (null != DropButton)
{
if (null != SelectedDropdownItem)
{
DropButton.Layer = SelectedDropdownItem.Layer - 100;
}
AddItem(DropButton);
}
}
}
