How do I use WithEvents?

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?

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?

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).

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

VB Code:

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.

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

Hope this helps!!
:wave: :thumb: :wave:

Quote:

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Originally Posted by 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).

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What is an instance interface class?

Quote:

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Originally Posted by brucevde

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

Note that VB intrinsic controls do not implement the ControlExtender.

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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?

Quote:

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Originally Posted by 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).

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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.

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

Quote:

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Originally Posted by rm_03

get IConnectionPointContainer from the interface

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

Quote:

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Originally Posted by penagate

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

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Yes.
Like:

VB Code:

Set IConnectionPointContainer = object

Or:

VB Code:

IUnknown.QueryInterface IID_IConnectionPointContainer, IConnectionPointContainer

Quote:

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Originally Posted by eyeRmonkey

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

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

What type library would make it easier?

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 :)