Re: void* and void** [modified] - COM Discussion Boards

28-May-06 21:01

Hi,

I have created an inproc COM server dll which displays a Window. WTL has been used to create the Window. This window houses a custom built TreeView control.

I have created a client which uses this COM Server. the functions which inserts child treenodes is defined in the erver thus:

IDL

[id(3), helpstring("method InsertTreeChild"), local] HRESULT InsertTreeChild([in] BSTR Text,[in] BSTR Data,[in,unique] void* ParentItem,[out] void** ChildItem);

.h
STDMETHOD(InsertTreeChild)(BSTR Text, BSTR Data, void* ParentItem, void** ChildItem);

Now how do I set ChildItem so that the address of Child item is passed to the Client. Currently I am doine something like..

*ChildItem= (void*) treeNode ;

but the value of ChildItem is 0x000000 when the function returns to the client although it gets set in the Server.

Can anyone explain why this is happening?

---
With best regards,
A Manchester United Fan

The Genius of a true fool is that he can mess up a foolproof plan!

Re: void* and void**

Roger Stoltz28-May-06 21:33

Roger Stoltz

28-May-06 21:33

TechyMaila wrote:
IDL
[id(3), helpstring("method InsertTreeChild"), local] HRESULT InsertTreeChild([in] BSTR Text,[in] BSTR Data,[in,unique] void* ParentItem,[out] void** ChildItem);

This looks like the interface of the server is a dispatch interface since the method has an id.
If it is, you can only use data types that can be represented with a VARIANT and void is not among those data types.

If you are forced to use marshalling, e.g. due to server access from multiple threads, the marshaller don't know how to handle the unknown data type.

Hope this helps
--
Roger

It's supposed to be hard, otherwise anybody could do it!

Regarding CodeProject: "resistance is pointless; you will be assimilated"

HakunaMatada28-May-06 22:24

28-May-06 22:24

Roger Stoltz wrote:
This looks like the interface of the server is a dispatch interface since the method has an id.
If it is, you can only use data types that can be represented with a VARIANT and void is not among those data types.

Ok, so then what member of the VARIANT type can I use to store a pointer?Is it VT_PTR?

Thanks for your reply.

---
With best regards,
A Manchester United Fan

The Genius of a true fool is that he can mess up a foolproof plan!

-- modified at 4:26 Monday 29th May, 2006

Roger Stoltz28-May-06 22:42

Roger Stoltz

28-May-06 22:42

TechyMaila wrote:
Ok, so then what member of the VARIANT type can I use to store a pointer?

Well, to put it simple: you don't.
Why? Because it's a design issue. Your server should behave like a black box that solves a well defined problem. How the box looks inside should be hidden from "users" or clients. By exposing internal pointers to your client, you are putting some of the responsabilities of the server on the client which is undesirable.

I suggest you use an index instead.
You could even have an interface that enumerates the tree nodes, e.g. IEnumTreeNodes, that provides you with an interface for each tree node letting you manipulate each node, e.g. ITreeNode.

Perhaps I've misunderstood your problem. If this is the case, post again and explain it further.

Hope this helps
--
Roger

It's supposed to be hard, otherwise anybody could do it!

Regarding CodeProject: "resistance is pointless; you will be assimilated"

HakunaMatada29-May-06 0:12

29-May-06 0:12

Hi Roger,

Thanks a lot for replying. Well, I believe ITreeNode is the solution to my problem. Well actually, I gotta fill a tree view in the COM server from the client. Now that can only be done when I get the TREEITEM from the last InsertChild so that multiple levels of child nodes can be added. So to pass the pointer to a TREEITEM, I was trying using void**. If I am not allowed to use void, then what can I useto pass the address of HTREEITEM? My COM server is InProc.

Do you have anyother suggestions?

---
With best regards,
A Manchester United Fan

The Genius of a true fool is that he can mess up a foolproof plan!

Roger Stoltz29-May-06 0:48

Roger Stoltz

29-May-06 0:48

TechyMaila wrote:
what can I useto pass the address of HTREEITEM

If I've understood your problem correctly, you actually don't need to pass the address. You only need a way to keep track of the node that you got from the previous call to InsertChild(), right?

What I suggested in my previous post was to use an integer to be able to refer to the node you got from InsertChild().
An ugly solution, which I don't recommend, is to pass the address as a long and type cast it to a HTREEITEM pointer. This will work on systems that are 32-bit, but will surely fail if built for 64-bit systems, in other words not a very good solution. Dead | X|

Always design with distribution in mind. It will make your design better and protect you from unwanted surprises when your software is used where you didn't think it would be used.

A better solution is to still pass a 32-bit integer through the interface, but the integer is mapped to a HTREEITEM pointer that you keep in an internal map inside the server.
No need for overkill here, simply mask the HTREEITEM address with 0xffffffff to get the 32-bit identifier.

--
Roger

It's supposed to be hard, otherwise anybody could do it!

Regarding CodeProject: "resistance is pointless; you will be assimilated"

HakunaMatada29-May-06 1:08

How to register shell extension DLL?

29-May-06 1:08

Alright!!! Smile | :)

Thanks a lot for your help. I ahd never thought about 64 bit systems coz.. frankly, I have never seen one. Frown | :(

Anyways, thanks once again. Rose | [Rose]

---
With best regards,
A Manchester United Fan

The Genius of a true fool is that he can mess up a foolproof plan!

Rostfrei28-May-06 20:55

Rostfrei

28-May-06 20:55

Hello!

I came accross the article http://www.codeproject.com/tips/dirclean.asp[^] which is about some handy utility. Shell extension DLL is provided. Can somebody please tell me how to register this shell extension trough console maybe? I really don't want to learn about shell extensions right now. All I want, is to use this utility.

P.S. I'm reposting this question in this message board. I made a mistake and post it to the C++ board.

Best regards,

Rostfrei

Re: How to register shell extension DLL?

_AnsHUMAN_ 28-May-06 23:07

_AnsHUMAN_

28-May-06 23:07

aren't you able to register the dll using regsvr32 ?

Somethings seem HARD to do, until we know how to do them.
Wink | ;-)

_AnShUmAn_

Re: How to register shell extension DLL?

Michael Dunn29-May-06 7:23

Michael Dunn

29-May-06 7:23

regsvr32 C:\path\to\dirclean.dll

If regsvr32 isn't in your path, cd to the system32 directory first.

--Mike--
Visual C++ MVP Cool | :cool:

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InprocServer32 Key

Richard Andrew x6428-May-06 13:57

Richard Andrew x64

28-May-06 13:57

What does it mean when the value for the InprocServer32 key is garbled gibberish, as though it's been encrypted?

How does the system find the right component to launch when the value is scrambled like that?

I found this key in my registry:

HKEY_CLASSES_ROOT\CLSID\{0000002F-0000-0000-C000-000000000046}

Default - oleaut32.dll
InprocServer32 -

,(GnBmGFa=nZ7]6MJA+rGIANT_AntiSpyware_Files>M5KDYSUnf(HA*L[xeX)y<br />
GfXmE~Yz*@5HHM+Pw4D]AlwaysInstall>M5KDYSUnf(HA*L[xeX)y<br />
a7I{dV5R1@_YU_&e(5qUPSDK>M5KDYSUnf(HA*L[xeX)y<br />
*c4w146BQ9+]'zoDRy(dAlwaysInstall>M5KDYSUnf(HA*L[xeX)y<br />

ThreadingModel - Both

How does that work?

ø¤º°`°º¤ø,¸¸,ø¤º°`°º¤ø,¸¸,ø¤º°`°º¤ø,¸¸,ø¤º°`°º¤ø,¸¸,ø¤º°`°º¤ø,¸¸,ø¤º°`°º¤ø,¸¸,ø¤º°`°º¤ø,¸

Re: InprocServer32 Key

Michael Dunn28-May-06 18:57

Michael Dunn

28-May-06 18:57

My guesses:
1. It's not really COM data, but some other kind of data being hidden in a very simple fashion.
2. MSAS made that change at install time as part of its protection, and it has a hook that watches for DLLs being loaded by COM, and undoes the obfuscation on the fly.

--Mike--
Visual C++ MVP Cool | :cool:

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export data to Database

viji]28-May-06 2:15

viji]

28-May-06 2:15

hi,
how can we export data from Excel to Informix Database

WIA (Windows Image Acquisition) API

opl25-May-06 10:27

opl

25-May-06 10:27

Hi,

I have a Visual C++ application that controls the digital USB camera.
Currently this is done using camera's SDK.
I am looking for vendor-independent ways to communicate with digital cameras.

1. Does WIA API support viewfinder mode, i.e. can I have "live preview" from the camera in my application?
2. Can I communicate with digital camera directly through PTP (Picture Transfer Protocol) from my application, thus avoiding WIA?
Is there some kind of API available for PTP?

Thanks a lot.

Re: WIA (Windows Image Acquisition) API

Renjith Ramachandran26-May-06 4:50

Renjith Ramachandran

26-May-06 4:50

yes this is the same thing which i am also looking for....

Loka Samastha Sukhino Bhavanthu..!!!
( May all beings be happy and free )

_bstr_t and MS Security update

ChrisLang25-May-06 5:43

ChrisLang

25-May-06 5:43

I just finished another Security update and now this code throws an exception.

CString myStr(L"test");
_bstr_t t = _bstr_t(myStr);

This worked until the sercurity update. I've tried to AllocateSysString to get a BSTR as well as CComBSTR instead of CString and nothing seems to work.

Does anyone know what happened to the wrapper class and how to successfully create a _bstr_t object?

Thanks
Chris

Michael Dunn25-May-06 8:45

Michael Dunn

25-May-06 8:45

How about:
_bstr_t t = (LPCTSTR) myStr;
to explicitly pass a C-style string pointer to the _bstr_t ctor.

--Mike--
Visual C++ MVP Cool | :cool:

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ChrisLang25-May-06 10:30

ChrisLang

25-May-06 10:30

Mike,
Thanks for the response but no that doesn't work either.
All will work in MFC but in my ATL DLL everything that worked yesterday now won't!
I've tried createding a BSTR and then using that to create the _bstr_t, using a variant (_variant_t) even creating a BSTR and then using the attach method on the _bstr_t and everything throws and exception!!!!!!

It is I can't find any information in MSDN about why it isn't working either.

Chris

ChrisLang25-May-06 11:17

ChrisLang

25-May-06 11:17

Sometime I can be so stupid!!

There was no problem with _bstr_t

There was a problem were I changed the length of an integer array from 500 to 200 and FORGOT to change the init loop. The overwriting of memeory just happend to show up in the _bstr_t object.

Sorry for all the wasted time.
Chris