How can I pass a C++ HWND to and from C# and Managed C++?
Mar 6 '07
15  30112 
"Joachim" <Jo*****@discus sions.microsoft .comwrote in message
news:55******** *************** ***********@mic rosoft.com...
// 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,
I'm still missing the PInvoke declaration, anyway you need something like this:
[DllImport("some dll")]
...... Test(ref IntPtr parent_wnd, ref IntPtr overlay);
but the point is, do you nee to pass a pointer to a HWND or do you need a HWND? guess not!
Note that a HWND (a HANDLE) itself is a pointer to a void. So, IMO you need to declare your
C++ function as taking two HWND, and in C# you simply need to pass an IntPtr instead of a
ref IntPtr.
Willy.
Thats odd. I can use the function without that declaration...
"Willy Denoyette [MVP]" wrote:
"Joachim" <Jo*****@discus sions.microsoft .comwrote in message
news:55******** *************** ***********@mic rosoft.com...
// 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,
I'm still missing the PInvoke declaration, anyway you need something like this:
[DllImport("some dll")]
...... Test(ref IntPtr parent_wnd, ref IntPtr overlay);
but the point is, do you nee to pass a pointer to a HWND or do you need a HWND? guess not!
Note that a HWND (a HANDLE) itself is a pointer to a void. So, IMO you need to declare your
C++ function as taking two HWND, and in C# you simply need to pass an IntPtr instead of a
ref IntPtr.
Willy.
How would that declaration look like when I have a class?
Regards,
Joachim
"Joachim" wrote:
Thats odd. I can use the function without that declaration...
"Willy Denoyette [MVP]" wrote:
"Joachim" <Jo*****@discus sions.microsoft .comwrote in message
news:55******** *************** ***********@mic rosoft.com...
// 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,
>
>
I'm still missing the PInvoke declaration, anyway you need something like this:
[DllImport("some dll")]
...... Test(ref IntPtr parent_wnd, ref IntPtr overlay);
but the point is, do you nee to pass a pointer to a HWND or do you need a HWND? guess not!
Note that a HWND (a HANDLE) itself is a pointer to a void. So, IMO you need to declare your
C++ function as taking two HWND, and in C# you simply need to pass an IntPtr instead of a
ref IntPtr.
Willy.
If I remove the class declaration and only have static functions I get the
following error
"Unable to find an entry point named 'Test' in DLL 'MCPP.dll'."
[DllImport(DllNa me, CallingConventi on = CallingConventi on.Winapi,
CharSet = CharSet.Ansi)]
static extern bool Test(
ref IntPtr one, ref IntPtr two);
//The managed cpp header
#pragma once
#include "windows.h"
#include "Common.h"
namespace MCPP
{
static bool Test(
HWND parent_wnd,
HWND overlay);
}
"Joachim" wrote:
How would that declaration look like when I have a class?
Regards,
Joachim
"Joachim" wrote:
Thats odd. I can use the function without that declaration...
"Willy Denoyette [MVP]" wrote:
"Joachim" <Jo*****@discus sions.microsoft .comwrote in message
news:55******** *************** ***********@mic rosoft.com...
// 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,
>
>
>
I'm still missing the PInvoke declaration, anyway you need something like this:
>
[DllImport("some dll")]
...... Test(ref IntPtr parent_wnd, ref IntPtr overlay);
>
but the point is, do you nee to pass a pointer to a HWND or do you need a HWND? guess not!
Note that a HWND (a HANDLE) itself is a pointer to a void. So, IMO you need to declare your
C++ function as taking two HWND, and in C# you simply need to pass an IntPtr instead of a
ref IntPtr.
>
Willy.
>
>
>
>
When I use
__declspec(dlle xport)
inf front of a function which handles any kind of System::String^ I get a
compilation error. Will it do this to all managed c++ specific constructs?
What am I doing wrong? Is there another way to export functions in Managed
C++?
"Joachim" wrote:
If I remove the class declaration and only have static functions I get the
following error
"Unable to find an entry point named 'Test' in DLL 'MCPP.dll'."
[DllImport(DllNa me, CallingConventi on = CallingConventi on.Winapi,
CharSet = CharSet.Ansi)]
static extern bool Test(
ref IntPtr one, ref IntPtr two);
//The managed cpp header
#pragma once
#include "windows.h"
#include "Common.h"
namespace MCPP
{
static bool Test(
HWND parent_wnd,
HWND overlay);
}
"Joachim" wrote:
How would that declaration look like when I have a class?
Regards,
Joachim
"Joachim" wrote:
Thats odd. I can use the function without that declaration...
>
"Willy Denoyette [MVP]" wrote:
>
"Joachim" <Jo*****@discus sions.microsoft .comwrote in message
news:55******** *************** ***********@mic rosoft.com...
// 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,
>
>
I'm still missing the PInvoke declaration, anyway you need something like this:
[DllImport("some dll")]
...... Test(ref IntPtr parent_wnd, ref IntPtr overlay);
but the point is, do you nee to pass a pointer to a HWND or do you need a HWND? guess not!
Note that a HWND (a HANDLE) itself is a pointer to a void. So, IMO you need to declare your
C++ function as taking two HWND, and in C# you simply need to pass an IntPtr instead of a
ref IntPtr.
Willy.
"Joachim" <Jo*****@discus sions.microsoft .comwrote in message
news:64******** *************** ***********@mic rosoft.com...
Thats odd. I can use the function without that declaration...
Sorry, got confused by the C++ method signature, now I see that this is managed C++, note
that you should specify which dialect of C++ you are talking about when posting, we have
MC++ (you shouldn't use any longer) and C++/CLI.
Anyway, you don't need the DllImport in your C# code, your C++/CLI method should take an
IntPtr.
When passing the IntPtr to umanaged code you need to convert the IntPtr to a point to void,
using IntPtr::ToPoint er()
C#
MyManagedCPPCla ss c = new MyManagedCPPCla ss();
c.Test(IntPtr parent, IntPtr overlay-);
//C++/CLI
/*static */ bool MyManagedCPPCla ss::Test(
System::IntPtr parent_wnd,
System::IntPtr overlay)
....
// make it an HWND
HWND hwnd = parent_wnd.ToPo inter();
// call native function expecting a HWND param..
Func(HWND hwnd..)
...
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