Onrender Method in WPF

Question

i have drawingcontext object i want to show it this code:

public DrawingContext Drwc
{
   get { return drwc; }
   set
   {
      drwc = value;
      OnRender(value);
   }
}

protected override void OnRender(DrawingContext drawingContext)
{
    base.OnRender(drawingContext);
}

but donot show any element of drawingcontext