Unusual Events

[Echilon]

I'm trying to create an HTML editing control in C# using the technique at

http://www.codeproject.com/KB/IP/WYSIWYG_netHTML2.aspx

. The control works fine, but there's a nagging thing I'd like it to do.

Usually in a text editor, when you change the selection, if the selected text is bold or underlined, the bold/underline buttons appear selected in the toolbar. I need to update the buttons when the selection or caret position changes. I think I need to hook into the onselect method at

http://msdn.microsoft.com/en-us/library/ms533051(VS.85).aspx

, but I have no idea how to hook into an event of type "object". Is what I want possible?

 

[jmeckley]

object has no events. it only has Equals(object); GetHashCode(); and ToString();

you will need to determine what type of object it is and the process. you could do

if (obj.GetType() is typeof(a specific object))
{
  //do something with the specific object
}
else if(obj.GetType() is typeof(a different object))
{
}
else
{
}

but this gets messy real fast instead I would do something like this

class Exeucte
{
    private IEnumerable<IAction> actions

    public Execute(IEnumerable<IAction> actions)
    {
       this.actions = actions;
    }
    
    public void RequestOn(object subject)
    {
        foreach(IAction action in actions)
        {
            if(action.CanHandle(subject))
            {
               action.Handle(subject);
               break;
            }
        }
    }
}

have 1 action for each process. examples:

class BoldTextAction : IAction
{
   public bool CanHandel(object subject)
   {
   }
   public bool Handel(object subject)
   {
   }
}

class HyperLinkAction : IAction
{
   public bool CanHandel(object subject)
   {
   }
   public bool Handel(object subject)
   {
   }
}

class ChangeColorAction : IAction
{
   public bool CanHandel(object subject)
   {
   }
   public bool Handel(object subject)
   {
   }
}

a simple implementation would be

class DoSomeAction : IAction
{
   public bool CanHandel(object subject)
   {
      return subject as ISomeInterface != null;
   }
   public bool Handel(object subject)
   {
      ISomeInterface specificSubject = subject as ISomeInterface;
      if(specificSubject == null) return;

      specificSubject.DoSomething();
   }
}

Jason Meckley
Programmer
Specialty Bakers, Inc.

 

[KDavie]

You can achieve this using reflection.... Here is a partial example...

System.Reflection.EventInfo ei = obj.GetType().GetEvent("Select");
ei.AddEventHandler(obj, handler);

For a full example check out the following article:

http://msdn.microsoft.com/en-us/library/system.reflection.eventinfo.addeventhandler.aspx

Hope this helps