C#/WPF CollectionView - How to Add Items at Specific Position

I'm working with ListCollectionView objects to display lists of items. Currently, I'm building a screen that has two of these lists - one, completeList, holds all available items, the other one, sortedList, holds a subset of them with the item order being relevant. Possible actions here are

• add or remove any of completeList's items to/from sortedList
• move items up or down in sortedList
• save the content of sortedList.

Now, my question is this: is there any possibility to 开发者_如何转开发insert items into sortedList at a defined position?

Right now, they will always be added at the end of the list, regardless of the currently marked item, and I didn't find a way around it - apart from the obvious dirty hack, which would have me store all items after the desired position, remove them from the list, add the new item, then re-add all stored items in the correct order.

Does ListCollectionView offer any such functionality, or is there another CollectionView class that would do the trick?

You're actually asking for something that's a logical contradiction. Suppose I have a ListCollectionViewsorted alphabetically:

American
Continental
Festival
Imperial
Tower
Worldwide

Should I be able to insert Luxor between American and Continental? Not if the view is sorted. There's only one place that item can go. And where it appears in the view is independent of where it might appear in the underlying list.

Without knowing more about your application, it's hard to know exactly what to suggest. But if a collection view is sorted, the way to make an item appear at a specific place in the view is to assign its sort key(s) a value that will, once the view is refreshed, cause it to appear in the desired location.

A fairly trivial (and generic) way of doing this is to add a DateTime property to the data item class, set it to DateTime.Now in the item's constructor, and make it the last sort key that the view uses. Then, when adding a new item, set its other sort key properties to the value of the currently selected item. If you do this, new items will always appear in the appropriate place, so long as you don't change the values of any of the sort key properties.

Having said that, from the other features you want to support, I believe that you shouldn't be using a ListCollectionView at all for what you're calling sortedList. This list isn't sorted. It's ordered, which is not at all the same thing. When the user moves an item up in the list, you actually want to change its position.

What you probably want to do is implement the list as an ObservableCollection, and wrap it in a view model class that exposes Items, SelectedItem, AddNewCommand, MoveUpCommand, MoveDownCommand, and SaveCommand properties. Then you can bind the ItemsSource and SelectedItem properties of a ListBox or ListView to Items and SelectedItem properties in the class, and bind buttons or hyperlinks or whatever in the UI to the commands. The commands will manipulate the Items property, using Remove and Insert, and since the Items is an ObservableCollection, the UI will stay in sync.