How to create a Custom Routed Event ? WPF c#

Question

I followed this tutorial but I couldn't apply what I learned to my project.

I have a LineGraph object (Dynamic Data Display) and I want to create an event that is raised when the thickness of the LineGraph is equal to 0.

How am I supposed to write it following this tutorial ?

Answer 1

Here is how I would do it with a RoutedEvent:

1. Create a class that derives from LineGraph, let's say CustomLineGraph:

   public class CustomLineGraph : LineGraph {
   }
   

2. Create our routed event like this:

   public class CustomLineGraph : LineGraph {
   
       public static readonly RoutedEvent ThicknessEvent = EventManager.RegisterRoutedEvent("Thickness", RoutingStrategy.Bubble, typeof(RoutedEventHandler, typeof(CustomLineGraph));
   
       // .NET event wrapper
       public event RoutedEventHandler Thickness
       {
           add { AddHandler(CustomLineGraph.ThicknessEvent, value); } 
           remove { RemoveHandler(CustomLineGraph.ThicknessEvent, value); }
       }
   }
   

3. Now we override the StrokeThickness property so we can raise our custom routed event when the value of that property is 0.

   public class CustomLineGraph : LineGraph {
   
       public static readonly RoutedEvent ThicknessEvent = EventManager.RegisterRoutedEvent("Thickness", RoutingStrategy.Bubble, typeof(RoutedEventHandler, typeof(CustomLineGraph));
   
       // .NET event wrapper
       public event RoutedEventHandler Thickness
       {
           add { AddHandler(CustomLineGraph.ThicknessEvent, value); } 
           remove { RemoveHandler(CustomLineGraph.ThicknessEvent, value); }
       }
   
       public override double StrokeThickness {
           get { return base.StrokeThickness; }
           set
           {
               base.StrokeThickness = value;
               if (value == 0)
                   RaiseEvent(new RoutedEventArgs(CustomLineGraph.ThicknessEvent, this));
           }
       }
   }
   

4. We are done !