/// <summary>
/// Adds a tree view item to the multi-selection without going through
/// the normal event chain. Used only by TreeViewItemMultiSelect.
/// </summary>
/// <param name="newItem"></param>
internal void AddTreeViewItemToSelection(TreeViewItemMultiSelect newItem)
{
if (!selectedTreeViewItems.Contains(newItem))
{
selectedTreeViewItems.Add(newItem);
}
previousItem = newItem;
}
/// <summary>
/// Removes the item passed in to from the selected items
/// </summary>
/// <param name="userItemToDeselect"></param>
public void DeselectItem(object itemToDeselect)
{
if (itemToTreeViewItem.ContainsKey(itemToDeselect))
{
TreeViewItemMultiSelect treeViewItem = itemToTreeViewItem[itemToDeselect];
treeViewItem.IsSelected = false;
if (selectedTreeViewItems.Contains(treeViewItem))
{
selectedTreeViewItems.Remove(treeViewItem);
}
}
}
/// <summary>
/// Handles when the selected item changes. Handles the multi-select functionality.
/// </summary>
/// <param name="e"></param>
protected override void OnSelectedItemChanged(RoutedPropertyChangedEventArgs <object> e)
{
TreeViewItemMultiSelect newItem = (TreeViewItemMultiSelect)typeof(TreeView).GetField("_selectedContainer", BindingFlags.NonPublic | BindingFlags.Instance).GetValue((TreeView)this);
// Turn off updating from TreeViewItems
isSelectionChangeActiveProperty.SetValue((TreeView)this, true, null);
if ((Keyboard.Modifiers & ModifierKeys.Control) == ModifierKeys.Control)
{
// We are either :
// a ) Adding a new item so newItem!=null & !selectedTreeViewItems.Contains(newItem)
// b ) Removing the last selection so newItem==null;
// c ) Removing a previous selection selectedTreeViewItems.Contains(newItem)
if (newItem != null && !selectedTreeViewItems.Contains(newItem))
{
// Adding a new item
if (previousItem != null)
{
previousItem.IsSelected = true;
}
selectedTreeViewItems.Add(newItem);
previousItem = newItem;
}
else if (newItem == null && previousItem != null)
{
// Removing the last selected item
selectedTreeViewItems.Remove(previousItem);
previousItem = null;
}
else if (selectedTreeViewItems.Contains(newItem))
{
// Removing a previously selected item
newItem.IsSelected = false;
selectedTreeViewItems.Remove(newItem);
// The selection needs to be put back on the last selected item
if (previousItem != null)
{
previousItem.IsSelected = true;
}
previousItem = null;
}
}
else
{
while (selectedTreeViewItems.Count > 0)
{
TreeViewItemMultiSelect firstItem = selectedTreeViewItems[0];
if (firstItem.IsSelected && firstItem != newItem)
{
firstItem.IsSelected = false;
}
selectedTreeViewItems.RemoveAt(0);
}
if (newItem != null)
{
selectedTreeViewItems.Add(newItem);
}
previousItem = newItem;
}
// Turn back on updating from TreeViewItems
isSelectionChangeActiveProperty.SetValue((TreeView)this, false, null);
// when the newItem is null that's when the last item was deselected.
base.OnSelectedItemChanged(e);
}