ATL / WTL / STL

21-Oct-03 16:02

Hi All,

I am in the process of developing an ATL/COM extension for an application in which I have embedded the Windows Media Player ocx COM Control into an ATLDialog object. How do I get control of this object so that I can change the video being displayed? I guess if it was a CDialog I could use the appwizard to map the control to member variable. How do I do this for an ATL Dialog?

Do I get the handle and then ......

You help would be greatly appreciated

cheers
Bryce

Abhishek Srivastava21-Oct-03 19:20

Abhishek Srivastava

21-Oct-03 19:20

Hi ,

U can use GetDlgItem(IDC_MEDIACONTROL1) , this will return u the handle of the media control window
now create a CWnd object attach this media control handle .

HWND hwn=GetDlgItem(IDC_MEDIACONTROL1)

CWnd * wnd=new CWnd();l

wnd->Attach(hwn);

then call wnd->GetControlUnknown()..this will return u the IUnknown Pointer.
Using this pointer query for other media control interfaces..and enjoy coding

byee..hope this solves ur problem

Smile | :)

'

Abhishek Srivastava
Software Engg (VC++)
India ,Noida
Mobile no 9891492921 Smile | :)

bryces22-Oct-03 0:06

22-Oct-03 0:06

Hi Abhishek,

Thankyou for your help.

I have done what you said above, but need a little more guidance. When you say at the end "Using this pointer query for other media control interfaces..and enjoy coding"... what is the other media control interfaces? What interfaces/objects should I be aiming to query too...?

I want to be able to do something like....

HWND hwn=GetDlgItem(IDC_MEDIACONTROL1)
CWnd * wnd=new CWnd();
wnd->Attach(hwn);
IUnknownPtr pUnknown;
pUnknown = GetControlUnknown();

//.......
//Query interface to some type of MediaPlayer object
IMediaPlayerPtr pMyPretendMediaPlayerObject; //any ideas on the correct interface?

pMyPretendMediaPlayerObject->Open("The path to the file I want");
pMyPretendMediaPlayerObject->Play();
//.......

Does the logic for this seem ok.... or could you point me to somewhere I could read up on this.

thanks for your help

cheers
Bryce

Abhishek Srivastava22-Oct-03 1:50

Abhishek Srivastava

22-Oct-03 1:50

Hi once again, sorry for not making myself so clear..
actually i mean
using that IUnknown Pointer

like
IUnknown *unk=wnd->GetControlUnknown();

Query for other interfaces like this
IMediaPlayer *mediaplayer
unk->QueryInterface(IID_IMediaPlayer,(void **)&mediaplayer);

in the same way all other interfaces that Windows Media Control Supports ..u can see supported interface in VB Object Browser(by addding Control in a VB and browse that object .using utility object browser).

So ...tell me if it worked..and i am making myself clear!!
Smile | :)

Abhishek Srivastava
Software Engg (VC++)
India ,Noida
Mobile no 9891492921 Smile | :)

bryces22-Oct-03 20:30

22-Oct-03 20:30

Hi Abhishek,

Yep looking at the VB object browser was a good idea.

I have foudn one reason why it was not possible working.... I forgot to import the ocx object definition for the MediaPlayer (msdxm.ocx).

However, when I define the IMediaPlayer the compiler doesn't have a clue about what to do.

C:\DEVELOPMENT\VideoTool\SelectedWin.cpp(18) : error C2065: 'IMediaPlayer' : undeclared identifier
C:\DEVELOPMENT\VideoTool\SelectedWin.cpp(18) : error C2065: 'mediaplayer' : undeclared identifier
C:\DEVELOPMENT\VideoTool\SelectedWin.cpp(18) : warning C4552: '*' : operator has no effect; expected operator with side-effect

I getting pretty frustrated why it seems so complex to something that should be simple.

I am relatively new to ATL MFC etc.... but this should be a walk in the park.

thanks for your help

cheers
Bryce

Michael Dunn22-Oct-03 12:48

Michael Dunn

22-Oct-03 12:48

Check out WTL for MFC Programmers, Part VI - Hosting ActiveX Controls[^]

--Mike--
Ericahist | CP SearchBar v2.0.2 | Homepage | RightClick-Encrypt | 1ClickPicGrabber
Kosh reminded me of some of the prima-donna programmers I've worked with. Knew everything but when you asked them a question; never gave you a straight answer.
-- Michael P. Butler in the Lounge

bryces22-Oct-03 17:16

22-Oct-03 17:16

Hi Michael,

Thanks for the pointer to your articles! nice to read the background info on why certain things have to be done.

The WTL example that you posted was with a com server (.exe). Does having my extension with activex control change many things if it is in a DLL?

Cheers
Bryce

Michael Dunn22-Oct-03 20:29

Michael Dunn

22-Oct-03 20:29

Nothing comes to mind... as long as you can create a CAxDialogImpl you can host controls.

--Mike--
Ericahist | CP SearchBar v2.0.2 | Homepage | RightClick-Encrypt | 1ClickPicGrabber
Pinky, are you pondering what I'm pondering?
I think so Brain, but how will we fit the hamster inside the accordion?

Collections and containers.

rbeckett16-Nov-03 14:40

rbeckett

16-Nov-03 14:40

The Windows Media Player SDK has an example of this called "WMPML" which can be downloaded with the SDK at www.windowsmedia.com
It implements a big CAxDialog, but it doesn't compile! I haven't bothered trying to fix it, but it's probably what you're looking for.
Ryan

WREY20-Oct-03 5:30

WREY

20-Oct-03 5:30

Are collections and containers created on the heap or the stack? IOW, do they persist or do they disappear after leaving the function in which they were created (understood that they weren't written out to a file or a database, etc.)?

If I need to defined more explicitly what I mean by "created", it would have to combine them being instantiated and populated.

Thanks for any insight.

Smile | :)

William

Fortes in fide et opere!

ZoogieZork20-Oct-03 5:44

ZoogieZork

20-Oct-03 5:44

In STL, the base container is allocated as you would expect, either on the stack or on the heap. The elements, however, are allocated on the heap (usually from a memory pool, but you can supply your own allocator).

When the destructor for an STL container is called, it calls the destructor for all contained elements and frees the memory. Note that this does not mean that if you have a collection of pointers that the memory they point to will be deleted; you'll need to delete those yourself.

- Mike

WREY20-Oct-03 6:07

WREY

20-Oct-03 6:07

Thanks for replying.

When is the destructor for the container called? Is it an automatic thing, or would you have to purposely call it (other than when it's done automatically for you upon exiting the program)?

If the elements are on the heap, then by doing an "erase()" you would purposely be deleting the elements (etc.), but if no such function were used, then the container and its elements should persist.

Both the vector and the map containers are defined in the same class, and instantiated in the same function. However, they were populated in different functions, but when they met back up together, the "size()" of the map showed zero (even though the class object in which they reside was still alive and no "erase()" function was used).

Confused | :confused:

William

Fortes in fide et opere!

ZoogieZork20-Oct-03 7:01

ZoogieZork

20-Oct-03 7:01

WREY wrote:
When is the destructor for the container called? Is it an automatic thing, or would you have to purposely call it (other than when it's done automatically for you upon exiting the program)?

The destructor for any type in C++ is called (implicitly):

For stack-allocated objects, it's called when the object goes out of scope.
For heap-allocated objects, it's called when you use delete on it.

So, for example:

void foo() {
  std::vector<MyClass> myvec;
  myvec.push_back(MyClass());
  myvec.push_back(MyClass());
  myvec.push_back(MyClass());
} // myvec and all elements are destroyed here.

myvec is destroyed at the end of the function since it is allocated on the stack. Each of its elements is also destroyed since they are not pointers. (Also I should note that when adding items to an STL container, the items are always added by copying, so each of those calls to push_back() is actually creating a new instance of MyClass, adding a copy of that instance, then destroying the original instance).

A couple more examples to illustrate the point:

void foo() {
  std::vector<MyClass*> myvec;
  myvec.push_back(new MyClass());
  myvec.push_back(new MyClass());
  myvec.push_back(new MyClass());
} // myvec is destroyed, but the instances of
  // MyClass persist on the heap.

void foo() {
  std::vector<MyClass> *myvec =
    new std::vector<MyClass>();
  myvec->push_back(MyClass());
  myvec->push_back(MyClass());
  myvec->push_back(MyClass());
} // myvec and the elements persist on the heap.

WREY wrote:
Both the vector and the map containers are defined in the same class, and instantiated in the same function. However, they were populated in different functions, but when they met back up together, the "size()" of the map showed zero (even though the class object in which they reside was still alive and no "erase()" function was used).

I'd have to see the code, or at least a minimal test case that illustrates the problem.

- Mike