Question

I would like to redefine a class of the core wpf API (UIElement), I don’t want to inherit a class.

In have a project on the MS Kinect, I’ve re-implemented cursors mapped with the user’s skeleton’s hand. I’ve implemented similar event to those that the mouse raised (enter an elements, leave an element…). I want that all elements inheriting from UIElement to get some attached properties:

  KinectCursorEnter, KinectCursorMove...

and some Properties:

    public bool IsKinectLeftCursorOver { get; set; }
    public bool IsKinectLeftCursorDirectlyOver { get; set; }
    public bool IsKinectRightCursorOver { get; set; }
    public bool IsKinectRightCursorDirectlyOver { get; set; }
    public bool IsKinectLeftCursorCaptured { get; set; }
        ...

I know there’s a lot ways to mess things up if I change such a class, but that’s at this level that I want to add thoses properties. (UIElement already implement stuff such as MouseEnter, StylusEnter…). The Kinect is an input device as any other (mouse, stylus, keyboard…)

I’ve try:

• To inherit UIElement and add the feature , but then I would have to
  reimplement all the Classes.

I’ve take a look:

• If there’s such a thing as Ruby’s open classes
• If I can use extension (link)
• If I can use in any way Adapter pattern

So far I’m using use:

• An interface and I redefine all element: I have a KinectButton that
  inherit from Button and implements IKinectInputElement but I can’t do that for some class which are sealed (Rectangle, Ellipse…)

I thing I a few months (years?) MSFT will implement those kind a Properties and method in Wpf API. But for now I need a way around.

PS: I don’t want to control the mouse with one of the hand of the user. there is one mouse, I want to have two cursors. and I have events such as : KinectLeftCursorEnter, KinectRightCursorEnter and so on..

Answer 1

You can use Extension Methods to extend the class.