BM_GETCHECK and BM_SETCHECK and .NET controls

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ME - 21 Nov 2007 02:39 GMT

I have googled this quite a bit and I just can't find the answer. I need to
read the state of a radio button in another process. Not much is known
about the other process, other than the fact that it was created with .NET
controls. I have read on various forums that SendMessage(conrolhandle,
BM_GETCHECK, 0,0) does not work on .NET controls. I have found this to be
true as the code that previosly worked on a NON .net radio button returned
the state of the radio button. However the control created in .NET only
returns 0 for its state, regardless of whether it is checked or not. For
BM_SETCHECK I have found that the control simply ignores the message.

I am using VS 2005, C# (but can easily read vb). Does anyone know of a
resource or a document that can help me?

Thanks,

Matt

Here is one of the several examples I found but did not have an answer to.
This example is exactly as it occurs for me:
http://www.vb-forum.com/showthread.php?t=480772

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Juergen Thuemmler - 21 Nov 2007 05:59 GMT

> I need to read the state of a radio button in another process. Not much
> is known
> about the other process, other than the fact that it was created with .NET
> controls. I have read on various forums that SendMessage(conrolhandle,
> BM_GETCHECK, 0,0) does not work on .NET controls.

As a workaround, you can check the controls style for WS_MAXIMIZEBOX. If it
is set, the radio button is checked. I played around with Spy++ and found
this working for option button, but not for checkboxes. A better method is
to use the Active Accessibility for checking the role and state of the
control. The classic "window view" gives you only a buttonlike class for
option buttons and checkboxes, but with accessibility (see
AccessibleObjectFromWindow() function) you get the correct information about
the control and its state.

Juergen.

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ME - 21 Nov 2007 16:52 GMT

Juergen,

Thank you. The Accessiblity idea solved my GET problem completely. I
enjoyed learning a bit about that and look forward to learning more. I
managed to retrieve the value through the IAccessible interface. In my
research to get this accomplished I noticed that the Accessiblity Explorer
can "set" the value of a .net checkbox. This is also something I am not
able to do via BM_SETCHECK and I am hoping to be able to pull it off via
IAccessible. Do you know of any information that can direct me in setting
the checkbox via IAccessible as the Accessible Explorer does? Is this even
possible? As you can tell I very green to Accessiblity and could use a
little direction.

Thanks,

Matt

Accessible Explorer
http://www.microsoft.com/downloads/details.aspx?FamilyId=3755582A-A707-460A-BF21
-1373316E13F0&displaylang=en

>> I need to read the state of a radio button in another process. Not much
>> is known
[quoted text clipped - 13 lines]
>
> Juergen.

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Juergen Thuemmler - 21 Nov 2007 19:59 GMT

> IAccessible. Do you know of any information that can direct me in setting
> the checkbox via IAccessible as the Accessible Explorer does? Is this
> even possible? As you can tell I very green to Accessiblity and could use
> a little direction.

Have a look at IAccessible::get_accDefaultAction and
IAccessible::accDoDefaultAction. Depending on the state of the checkbox, the
DefaultAction will be either Check or Uncheck.

Juergen.

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Bob Butler - 21 Nov 2007 14:10 GMT

<cut>

> I am using VS 2005, C# (but can easily read vb).

You can read VB or VB.Net? They are very different languages.