Inherited from an itemsControl - How to change the type of the items?

Question

I'm trying to improve ListView. This mostly has to do with changed in the ListViewItem class. So I inherited from both, creating two costume controls:

NestedListView : ListView 
NestedListViewItem : ListViewItem

The problem is that now I want the NestedListView's <ItemsPresenter/> to present NestedListViewItems instead of regular ListViewItems. How do I achieve this?

(I pretty much have no idea how <ItemsPresenter/> works. So any explanation on that area could be helpful).

Answer 1

Override the GetContainerForItemOverride method and return the type of item container you want:

public class NestedListView : ListView
{
    protected override DependencyObject GetContainerForItemOverride()
    {
        return new NestedListViewItem();
    }

    protected override bool IsItemItsOwnContainerOverride(object item)
    {
        return item is NestedListViewItem;
    }
}

Answer 2

Becareful, the accepted answer is not enough for a TreeView if you want all the descendants to be of the overriden TreeViewItem subclass.

Here is the complete solution:

1. Override the TreeViewItem class

public class TreeViewItemEx : TreeViewItem
{
    protected override DependencyObject GetContainerForItemOverride()
    {
        return new TreeViewItemEx (); // Required to preserve the item type in all the hierarchy
    }

    protected override bool IsItemItsOwnContainerOverride(object item)
    {
        return item is TreeViewItemEx ;
    }
}

2. Override the TreeView class

public class TreeViewEx : TreeView 
{
    protected override DependencyObject GetContainerForItemOverride()
    {
        return new TreeViewItemEx();
    }

    protected override bool IsItemItsOwnContainerOverride(object item)
    {
        return item is TreeViewItemEx;
    }
}