How to get the main forM handle in .NET

[Fred Hebert]

I am trying to use a 3rd party DLL that requires the main window handle as
a parameter.

e.g. MyFunc(WHND MyHandle);

The example looks something like this:

Result = MyFunc(Handle);

Where "Handle" is the Win32 handle.

Trying to use the example as written results in a compiler error:
cannot convert parameter 5 from 'int' to 'HWND'

First isn't the HWND basically an unsigned integer? I have tried type
casting and several other things, but nothing the compiler likes.

Does anyone know how to make this work?

[William DePalo [MVP VC++]]

"Fred Hebert" <fh*****@hotmai l.com> wrote in message
news:Xn******** *************** ********@207.46 .248.16...

I am trying to use a 3rd party DLL that requires the main window handle as
a parameter.

e.g. MyFunc(WHND MyHandle);
Typo? You mean this?

MyFunc(HWND MyHandle);

The example looks something like this:

Result = MyFunc(Handle);

Where "Handle" is the Win32 handle.

Trying to use the example as written results in a compiler error:
cannot convert parameter 5 from 'int' to 'HWND'
First, it is always a good idea to post code exactly as written; the devil
is in the details.

This is a guess: If you must, cast the 5th parameter:

change ...(... x, ...);

to

...(... (HWND) x, ...);
First isn't the HWND basically an unsigned integer?
Using Von Neumann machines, everything is basically an integer. So, what?
:-)
I have tried type casting and several other things,
but nothing the compiler likes.

As I said, show the bad code, the exact text of the error message and what
you have tried.

Regards,
Will

[Fred Hebert]

Sorry about the typo, was just trying to simplify.

It's pulled from various places, but here is the actual code:

typedef int (_stdcall *pOmniConnect) (char * IpAddress,
unsigned int Port,
unsigned int Timeout,
unsigned char EncryptionKey[16],
HWND NotifyWindow);
....
pOmniConnect OmniConnect;
....
The dll is loaded and addresses resolved (not relevant to problem)
....
OmniConnect(IpE dit->Text,
PortEdit->Text->ToInt32,
TimeoutEdit->Text->ToInt32,
BinKey,
Handle); // this line is the problem
As Written:
error C2664: 'int(... the func template ...)': cannot convert parameter 5
from 'int' to 'HWND'

Tried type casting e.g. (HWND)Handle);
error C2440" 'type cast' : cannot convert from 'System::IntPtr ' to 'HWND'

Tried various this->Handle, and Handle->xxx conversions but similar
problems.

[William DePalo [MVP VC++]]

"Fred Hebert" <fh*****@hotmai l.com> wrote in message
news:Xn******** *************** ********@207.46 .248.16...

Sorry about the typo, was just trying to simplify.

It's pulled from various places, but here is the actual code:

typedef int (_stdcall *pOmniConnect) (char * IpAddress,
unsigned int Port,
unsigned int Timeout,
unsigned char EncryptionKey[16],
HWND NotifyWindow);
...
pOmniConnect OmniConnect;
...
The dll is loaded and addresses resolved (not relevant to problem)
...
OmniConnect(IpE dit->Text,
PortEdit->Text->ToInt32,
TimeoutEdit->Text->ToInt32,
BinKey,
Handle); // this line is the problem
As Written:
error C2664: 'int(... the func template ...)': cannot convert parameter 5
from 'int' to 'HWND'

Tried type casting e.g. (HWND)Handle);
error C2440" 'type cast' : cannot convert from 'System::IntPtr ' to 'HWND'

Tried various this->Handle, and Handle->xxx conversions but similar
problems.

How is Handle declared?

Regards,
Will

[Fred Hebert]

"William DePalo [MVP VC++]" <wi***********@ mvps.org> wrote in
news:uC******** ******@TK2MSFTN GP14.phx.gbl:

How is Handle declared?

Regards,
Will

It's not in my code. It should be the handle of the main form.

According to the docs:
[C++]
public: __property virtual IntPtr get_Handle();

Property Value
An IntPtr that contains the window handle (HWND) of the control.

Implements
IWin32Window.Ha ndle

Remarks
The value of the Handle property is a Windows HWND. If the handle has not
yet been created, referencing this property will force the handle to be
created.

----

And Handle.get_Hand le() doesn't work either.

[William DePalo [MVP VC++]]

"Fred Hebert" <fh*****@hotmai l.com> wrote in message
news:Xn******** *************** ********@207.46 .248.16...

"William DePalo [MVP VC++]" <wi***********@ mvps.org> wrote in
news:uC******** ******@TK2MSFTN GP14.phx.gbl:
According to the docs:
[C++]
public: __property virtual IntPtr get_Handle();

Property Value
An IntPtr that contains the window handle (HWND) of the control.

Implements
IWin32Window.Ha ndle

Remarks
The value of the Handle property is a Windows HWND. If the handle has not
yet been created, referencing this property will force the handle to be
created.

I have no idea why a window handle should be returned as an IntPtr. <Sigh>

Does this IntPtr have a ToInt32() method? If so, can you use it to get
yourself an integer and cast that to a window handle?

Regards,
Will

[Tomas Restrepo \(MVP\)]

Hi Will,

I have no idea why a window handle should be returned as an IntPtr. <Sigh>
Because IntPtr represents a platform-specific pointer size (meaning, it
holds a 64-bit value on 64-bit platforms with the 64-bit version of the
framework).
Does this IntPtr have a ToInt32() method? If so, can you use it to get
yourself an integer and cast that to a window handle?

It does, but a better option is to use IntPtr::ToPoint er() which returns a
void* :)

So you can just do (HWND)Handle.To Pointer();

--
Tomas Restrepo
to****@mvps.org

[William DePalo [MVP VC++]]

Hi Tomas,

Because IntPtr represents a platform-specific pointer size (meaning, it
holds a 64-bit value on 64-bit platforms with the 64-bit version of the
framework).

Oh. :-)

Geez, just what I need, something else new to get up to speed on.

Regards,
Will

[Tomas Restrepo \(MVP\)]

Hi Will,

Oh. :-)

Geez, just what I need, something else new to get up to speed on.

Jajajajaa. Well, in that sense, it's not all that different (source code
wise) from using ULONG_PTR and friends instead of ULONG :)
--
Tomas Restrepo
to****@mvps.org
http://www.winterdom.com/

[Fred Hebert]

"Tomas Restrepo \(MVP\)" <to****@mvps.or g> wrote in
news:us******** ******@TK2MSFTN GP15.phx.gbl:

So you can just do (HWND)Handle.To Pointer();

Sounds good, but neither ToInt32 or ToPointer works, and in fact they both
return EXACTLY the same error.

error C3374: managed function 'System::IConve rtible::ToInt32 ' requires
argument list

Any more ideas? This is really frustrating because I am sure it is
something simple.