How do I use WithEvents?

[eyeRmonkey]

I have seen WithEvents used before and I understand it somewhat but I am looking for some clarification. How far can its use be extended? Can I declare an object WithEvents without knowing what will be in it?

I am working on making a custom control and I have an Init() method. In that method you declare which control on the form you want to link my control to. I know the control will always have a Resize event, but I don't always know what the event will be. Is there a way to use WithEvents to access the Resize event?

[eyeRmonkey]

Can anyone help me with this?

I experimented a little and found that doing WithEvents with an Object doesn't work because you have to specify a specific control. Is there any way to get access to the events of an object without knowing what object it will be, but knowing it will have a Resize event?

[penagate]

The events are part of the class's interface, so you can't declare a generic Object WithEvents. What you can do, I think, is declare an instance interface class WithEvents and make all your classes Implement that interface. Pop your events in there and it should work (assuming VB6 handles interfaces the way I think).

[brucevde]

You can create a generic event handler for ActiveX controls using the VBControlExtender object.

Private WithEvents oControlEvents As VBControlExtender
 
Private Sub Form_Load()
    Set oControlEvents = Me.MSFlexGrid1
End Sub
 
Private Sub oControlEvents_ObjectEvent(Info As EventInfo)
    Dim oParam As EventParameter
 
    Debug.Print Info.Name; 
 
    For Each oParam In Info.EventParameters
        Debug.Print , oParam.Name, oParam.Value
    Next
 
End Sub

Note that VB intrinsic controls do not implement the ControlExtender.

[Bombdrop]

Attached is a simple example of using Withevents from your own classes.

Hope this helps!!

[eyeRmonkey]

The events are part of the class's interface, so you can't declare a generic Object WithEvents. What you can do, I think, is declare an instance interface class WithEvents and make all your classes Implement that interface. Pop your events in there and it should work (assuming VB6 handles interfaces the way I think).

What is an instance interface class?

[eyeRmonkey]

You can create a generic event handler for ActiveX controls using the VBControlExtender object.

Note that VB intrinsic controls do not implement the ControlExtender.

By intrinsic control, do you mean the standard ones that are always available?

If thats the case then I am stuck again. Basically I need to be able to get the events of a PictureBox OR a custom control.

I couldn't even subclass if I wanted to because it is likely that the controls I will be dealing with don't have .hWnds.

Do I have any other options?

[rm_03]

The events are part of the class's interface, so you can't declare a generic Object WithEvents. What you can do, I think, is declare an instance interface class WithEvents and make all your classes Implement that interface. Pop your events in there and it should work (assuming VB6 handles interfaces the way I think).

As far as I understood the whole event stuff, interfaces which support events
only implement IConnectionPointContainer, but the events have their own interface.
So what you do if you want events:
get IConnectionPointContainer from the interface,
take the first IConnectionPoint returned by IConnectionPointContainer.EnumConnectionPoints,
create a new interface which implements IDispatch (event sink),
advise your event sink to IConnectionPoint,
and capture events through IDispatch.Invoke, which the interface will call everytime an event get's raised.

[eyeRmonkey]

Could I get you to post a sample project? Because I have no idea what you just said.

[penagate]

get IConnectionPointContainer from the interface

How do you do this? Is it just a matter of casting the object?

[rm_03]

How do you do this? Is it just a matter of casting the object?

Yes.
Like:

Set IConnectionPointContainer = object

Or:

IUnknown.QueryInterface IID_IConnectionPointContainer, IConnectionPointContainer

Could I get you to post a sample project? Because I have no idea what you just said.

Sure
But it's rather complicated, I didn't want to use a type library.

[eyeRmonkey]

What type library would make it easier?

[rm_03]

One which defines the interfaces used in the example (IUnk/IDisp/ICPC/ICP).
I think it would shorten the code about 40-50%. I'm just too lazy