C++ HWND to and from C# and Managed C++?

[=?Utf-8?B?Sm9hY2hpbQ==?=]

How can I pass a C++ HWND to and from C# and Managed C++?

[=?Utf-8?B?Sm9hY2hpbQ==?=]

Seems like you could use a void*:

C#:
MyMethod(this.H andle.ToPointer ());

C++:
public:
void MyMethod(void* handle)
{
HWND l_wnd(handle);
....
}

However, that seems to require the unsafe keyword and that the code is
compiled with the /unsafe parameter. However 2, the descriptions I have found
about how to add this compiler option (e.g.
http://forums.microsoft.com/MSDN/Sho...22815&SiteID=1) talks
about a Build subfolder under Configuration Properties. I have: General,
Debugging, C/C++, Linker, Manifest Tool, Resources, XML Document Generation,
Browse Information, Build Events, Custom Build setup, and web deployment.
Nothing called Build. Where do I find this setting?

Perhaps this is not the best / simplest way to do it. Then I would
appreciate if I could be told this.
"Joachim" wrote:

What I really want to do is to pass a C# equivalent to the HWND structure in
C++ and pass it as a pointer to a HWND in managed C++. I need to get this
window handle to a third party unmanaged C++ function to assign the third
party software to render video onto this window.

"Joachim" wrote:

How can I pass a C++ HWND to and from C# and Managed C++?

[=?Utf-8?B?Sm9hY2hpbQ==?=]

What I really want to do is to pass a C# equivalent to the HWND structure in
C++ and pass it as a pointer to a HWND in managed C++. I need to get this
window handle to a third party unmanaged C++ function to assign the third
party software to render video onto this window.

"Joachim" wrote:

How can I pass a C++ HWND to and from C# and Managed C++?

[=?Utf-8?B?Sm9hY2hpbQ==?=]

I found it.

"Joachim" wrote:

Seems like you could use a void*:

C#:
MyMethod(this.H andle.ToPointer ());

C++:
public:
void MyMethod(void* handle)
{
HWND l_wnd(handle);
...
}

However, that seems to require the unsafe keyword and that the code is
compiled with the /unsafe parameter. However 2, the descriptions I have found
about how to add this compiler option (e.g.
http://forums.microsoft.com/MSDN/Sho...22815&SiteID=1) talks
about a Build subfolder under Configuration Properties. I have: General,
Debugging, C/C++, Linker, Manifest Tool, Resources, XML Document Generation,
Browse Information, Build Events, Custom Build setup, and web deployment.
Nothing called Build. Where do I find this setting?

Perhaps this is not the best / simplest way to do it. Then I would
appreciate if I could be told this.
"Joachim" wrote:

What I really want to do is to pass a C# equivalent to the HWND structure in
C++ and pass it as a pointer to a HWND in managed C++. I need to get this
window handle to a third party unmanaged C++ function to assign the third
party software to render video onto this window.

"Joachim" wrote:

How can I pass a C++ HWND to and from C# and Managed C++?

[Willy Denoyette [MVP]]

"Joachim" <Jo*****@discus sions.microsoft .comwrote in message
news:85******** *************** ***********@mic rosoft.com...

What I really want to do is to pass a C# equivalent to the HWND structure in
C++ and pass it as a pointer to a HWND in managed C++. I need to get this
window handle to a third party unmanaged C++ function to assign the third
party software to render video onto this window.

"Joachim" wrote:

>How can I pass a C++ HWND to and from C# and Managed C++?

A HANDLE is represented by an IntPtr in the framework so you simply have to pass a reference
to the IntPtr variable holding the HWND.

IntPtr hwnd = myForm.Handle;
....
// call unmanaged function expecting a pointer to a HWND.
UnmanagedFunc(r ef hwnd);

Willy.

[=?Utf-8?B?Sm9hY2hpbQ==?=]

Thanks Willy,

However, I can't get that working:

Argument '2': cannot convert from 'ref System.IntPtr' to
'HWND__*' F:\Development\ Test\MCPP\TestA pp\Form1.cs 67 21 TestApp

Regards,
Joachim

"Willy Denoyette [MVP]" wrote:

"Joachim" <Jo*****@discus sions.microsoft .comwrote in message
news:85******** *************** ***********@mic rosoft.com...

What I really want to do is to pass a C# equivalent to the HWND structure in
C++ and pass it as a pointer to a HWND in managed C++. I need to get this
window handle to a third party unmanaged C++ function to assign the third
party software to render video onto this window.

"Joachim" wrote:

How can I pass a C++ HWND to and from C# and Managed C++?

A HANDLE is represented by an IntPtr in the framework so you simply have to pass a reference
to the IntPtr variable holding the HWND.

IntPtr hwnd = myForm.Handle;
....
// call unmanaged function expecting a pointer to a HWND.
UnmanagedFunc(r ef hwnd);

Willy.

[=?Utf-8?B?Sm9hY2hpbQ==?=]

That was for a HWND and not a HWND*. But for HWND the error is similar:

Argument '2': cannot convert from 'ref System.IntPtr' to
'HWND__**' F:\Development\ Test\MCPP\TestA pp\Form1.cs 67 21 TestApp
"Joachim" wrote:

Thanks Willy,

However, I can't get that working:

Argument '2': cannot convert from 'ref System.IntPtr' to
'HWND__*' F:\Development\ Test\MCPP\TestA pp\Form1.cs 67 21 TestApp

Regards,
Joachim

"Willy Denoyette [MVP]" wrote:

"Joachim" <Jo*****@discus sions.microsoft .comwrote in message
news:85******** *************** ***********@mic rosoft.com...

What I really want to do is to pass a C# equivalent to the HWND structure in
C++ and pass it as a pointer to a HWND in managed C++. I need to get this
window handle to a third party unmanaged C++ function to assign the third
party software to render video onto this window.
>
"Joachim" wrote:
>
>How can I pass a C++ HWND to and from C# and Managed C++?

A HANDLE is represented by an IntPtr in the framework so you simply have to pass a reference
to the IntPtr variable holding the HWND.

IntPtr hwnd = myForm.Handle;
....
// call unmanaged function expecting a pointer to a HWND.
UnmanagedFunc(r ef hwnd);

Willy.

[Barry Kelly]

Joachim wrote:

That was for a HWND and not a HWND*. But for HWND the error is similar:

Argument '2': cannot convert from 'ref System.IntPtr' to
'HWND__**' F:\Development\ Test\MCPP\TestA pp\Form1.cs 67 21 TestApp

Can you show us the prototype you're using?

Where is this function you're calling, whose second argument you can't
find the type for?

To get that HWND__** in C#, you'd need to use an unsafe block. Where did
the function come from?

-- Barry

--
http://barrkel.blogspot.com/

[Willy Denoyette [MVP]]

"Joachim" <Jo*****@discus sions.microsoft .comwrote in message
news:C5******** *************** ***********@mic rosoft.com...

Thanks Willy,

However, I can't get that working:

Argument '2': cannot convert from 'ref System.IntPtr' to
'HWND__*' F:\Development\ Test\MCPP\TestA pp\Form1.cs 67 21 TestApp

Regards,
Joachim

Please show us your "DllImport" declaration, your C function prototype and how you declared
HWND__ in C#.

Willy.

[=?Utf-8?B?Sm9hY2hpbQ==?=]

// This is the main DLL file.

#include "stdafx.h"
#include "MCPP.h"

namespace MCPP
{
/*static */ bool MyManagedCPPCla ss::Test(
HWND* parent_wnd,
HWND* overlay)
{
//Some code...
}
}
//From C#: (I included the reference dll)

IntPtr l_parent_hwnd = Handle;
IntPtr l_hwnd = m_panel1.Handle ;
if (!MyManagedCPPC lass.Test(
0,
ref l_parent_hwnd,
ref l_hwnd,


"Willy Denoyette [MVP]" wrote:

"Joachim" <Jo*****@discus sions.microsoft .comwrote in message
news:C5******** *************** ***********@mic rosoft.com...

Thanks Willy,

However, I can't get that working:

Argument '2': cannot convert from 'ref System.IntPtr' to
'HWND__*' F:\Development\ Test\MCPP\TestA pp\Form1.cs 67 21 TestApp

Regards,
Joachim

Please show us your "DllImport" declaration, your C function prototype and how you declared
HWND__ in C#.

Willy.