PROBLEM SOLVED-(HOWTO)Dynamically Disable/Enable Component events!

[Joe Mamma]

Works for most components, a similar approach can be used on third party controls where this doesnt work.

 

Typical Usage (assumes project appropriate references):

 

 ArrayList eventData = new ArrayList(); 
EventDescriptorCollection events = 
TypeDescriptor.GetEvents(myComponent);
foreach (EventDescriptor myEvent in events) 
{
// Unwire the events . . . 
EventDatum ed = EventDatum.Create(myComponent, myEvent);
if (ed == null) continue;
EventData.Add(ed);
ed.Unwire(myComponent);
}

//Do something with component here . . .

// now rewire . . .
foreach(EventDatum ed in EventData)
if (ed != null)
ed.Wire(myComponent);
EventData.Clear();

 

EventDatum listing (assumes project appropriate references)

 

 public class EventDatum 
{
private EventDescriptor _eventDesc;
private Delegate _event;
private static MethodInfo GetEventsMethod(Type objType)
{
MethodInfo mi = objType.GetMethod("get_Events",All);
if ((mi ==null)& (objType.BaseType!=null))
mi = GetEventsMethod(objType.BaseType);
return mi;
}

private static EventHandlerList GetEvents(object obj)
{
MethodInfo mi = GetEventsMethod(obj.GetType());
if (mi == null) return null; 
return (EventHandlerList) mi.Invoke(obj, new object[]{});
}

private static FieldInfo GetEventIDField(Type objType, string eventName)
{
FieldInfo fi = objType.GetField("Event"+eventName,All);
if ((fi ==null)& (objType.BaseType!=null))
fi = GetEventIDField(objType.BaseType,eventName);
return fi;
}

private static object GetEventID(object obj, string eventName)
{
FieldInfo fi = GetEventIDField(obj.GetType(), eventName);
if (fi ==null) return null;
return fi.GetValue(obj);
}

private static BindingFlags All
{ 
get
{ 
return
BindingFlags.Public | BindingFlags.NonPublic |
BindingFlags.Instance| BindingFlags.IgnoreCase|
BindingFlags.Static;
} 
}

internal EventDatum(EventDescriptor desc, Delegate aEvent)
{ 
_eventDesc = desc;
_event = aEvent;
}

public static EventDatum Create(object obj, EventDescriptor desc)
{
EventHandlerList list = GetEvents(obj);
if (list==null) return null;
object key = GetEventID(obj, desc.Name);
if (key==null) return null;
Delegate evnt = list[key];
if (evnt == null) return null;
return new EventDatum(desc, evnt);
}

public void Wire(object obj)
{ 
_eventDesc.AddEventHandler(obj, _event);
}

public void Unwire(object obj)
{
_eventDesc.RemoveEventHandler(obj, _event);
}
}