C++ Interop - Getting String value back from ATL COM Server

[=?Utf-8?B?c3BkMzAwMQ==?=]

I have a C++/CLI app that uses a logging control in an ATL COM Server. C++
Interop seems to work just fine to pass data from the C++/CLI app to the ATL
Control but I can't seem to figure out how to get a string value back from
the ATL Control. When debugging the code seen below, I see that the VARIANT
pointed to by 'data' is updated but the String 'str' passed from the C++/CLI
app doesn't change. So the String 'str' seems to be passed by value rather
than reference but I can't seem to get anything else to work without throwing
out C++ interop. Any suggestions?
System::Void button2_Click(S ystem::Object^ sender, System::EventAr gs^ e)
{
System::String^ str("temp");

this->axLogCtl1->GetLogText(str );
richTextBox1->Text = str;
}
HRESULT LogCtl::GetLogT ext(VARIANT* data)
{
CComVariant v(m_strData);

/////////////////////////////////////////////////////////////////
// Pass the current log data to the caller.
/////////////////////////////////////////////////////////////////
if (VT_BSTR == data.vt)
v.CopyTo(&(data .bstrVal));

return (S_OK);
}
--

Paul - Consultant: C++ Application Design and Development

[=?Utf-8?B?c3BkMzAwMQ==?=]

Oops... Example should be as follows:

HRESULT LogCtl::GetLogT ext(VARIANT* data)
{
CComVariant v(m_strData);

/////////////////////////////////////////////////////////////////
// Pass the current log data to the caller.
/////////////////////////////////////////////////////////////////
if (VT_BSTR == data->vt)
v.CopyTo(&(data->bstrVal));

return (S_OK);
}

--
Consultant: C++ Application Design and Development
"spd3001" wrote:

I have a C++/CLI app that uses a logging control in an ATL COM Server. C++
Interop seems to work just fine to pass data from the C++/CLI app to the ATL
Control but I can't seem to figure out how to get a string value back from
the ATL Control. When debugging the code seen below, I see that the VARIANT
pointed to by 'data' is updated but the String 'str' passed from the C++/CLI
app doesn't change. So the String 'str' seems to be passed by value rather
than reference but I can't seem to get anything else to work without throwing
out C++ interop. Any suggestions?
System::Void button2_Click(S ystem::Object^ sender, System::EventAr gs^ e)
{
System::String^ str("temp");

this->axLogCtl1->GetLogText(str );
richTextBox1->Text = str;
}
HRESULT LogCtl::GetLogT ext(VARIANT* data)
{
CComVariant v(m_strData);

/////////////////////////////////////////////////////////////////
// Pass the current log data to the caller.
/////////////////////////////////////////////////////////////////
if (VT_BSTR == data.vt)
v.CopyTo(&(data .bstrVal));

return (S_OK);
}
--

Paul - Consultant: C++ Application Design and Development

[G Himangi]

How is the axLogCtl1->GetLogText() method defined in C++/CLI?

If you want the value back, you should define the parameter as an out or ref

---------
- G Himangi, Sky Software http://www.ssware.com
Shell MegaPack : GUI Controls For Drop-In Windows Explorer like Shell
Browsing Functionality For Your App (.Net & ActiveX Editions).
EZNamespaceExte nsions.Net : Develop namespace extensions rapidly in .Net
EZShellExtensio ns.Net : Develop all shell extensions,expl orer bars and BHOs
rapidly in .Net
---------

"spd3001" <sp*****@discus sions.microsoft .comwrote in message
news:FA******** *************** ***********@mic rosoft.com...

>I have a C++/CLI app that uses a logging control in an ATL COM Server. C++
Interop seems to work just fine to pass data from the C++/CLI app to the
ATL
Control but I can't seem to figure out how to get a string value back from
the ATL Control. When debugging the code seen below, I see that the
VARIANT
pointed to by 'data' is updated but the String 'str' passed from the
C++/CLI
app doesn't change. So the String 'str' seems to be passed by value
rather
than reference but I can't seem to get anything else to work without
throwing
out C++ interop. Any suggestions?
System::Void button2_Click(S ystem::Object^ sender, System::EventAr gs^ e)
{
System::String^ str("temp");

this->axLogCtl1->GetLogText(str );
richTextBox1->Text = str;
}
HRESULT LogCtl::GetLogT ext(VARIANT* data)
{
CComVariant v(m_strData);

/////////////////////////////////////////////////////////////////
// Pass the current log data to the caller.
/////////////////////////////////////////////////////////////////
if (VT_BSTR == data.vt)
v.CopyTo(&(data .bstrVal));

return (S_OK);
}
--

Paul - Consultant: C++ Application Design and Development

[=?Utf-8?B?c3BkMzAwMQ==?=]

Finally got it to work as follows:

System::Void toolStripButton 1_Click(System: :Object^ sender,
System::EventAr gs^ e)
{
IntPtr ip = Marshal::AllocH Global(0x00007F FF);
void * p = ip.ToPointer();
BYTE * pStr = (BYTE *) p;

this->axLogCtl1->GetLogText(*pS tr);
richTextBox1->Text = Marshal::PtrToS tringAuto(ip);

Marshal::FreeHG lobal(ip);

}

HRESULT LogCtl::GetLogT ext(BYTE * data)
{
_tcscpy_s((TCHA R *) data,
0x00007FFF/sizeof(TCHAR),
(const TCHAR *)m_strData.Get Buffer());

return (S_OK);
}

--
Consultant: C++ Application Design and Development
"G Himangi" wrote:

How is the axLogCtl1->GetLogText() method defined in C++/CLI?

If you want the value back, you should define the parameter as an out or ref

---------
- G Himangi, Sky Software http://www.ssware.com
Shell MegaPack : GUI Controls For Drop-In Windows Explorer like Shell
Browsing Functionality For Your App (.Net & ActiveX Editions).
EZNamespaceExte nsions.Net : Develop namespace extensions rapidly in .Net
EZShellExtensio ns.Net : Develop all shell extensions,expl orer bars and BHOs
rapidly in .Net
---------

"spd3001" <sp*****@discus sions.microsoft .comwrote in message
news:FA******** *************** ***********@mic rosoft.com...

I have a C++/CLI app that uses a logging control in an ATL COM Server. C++
Interop seems to work just fine to pass data from the C++/CLI app to the
ATL
Control but I can't seem to figure out how to get a string value back from
the ATL Control. When debugging the code seen below, I see that the
VARIANT
pointed to by 'data' is updated but the String 'str' passed from the
C++/CLI
app doesn't change. So the String 'str' seems to be passed by value
rather
than reference but I can't seem to get anything else to work without
throwing
out C++ interop. Any suggestions?
System::Void button2_Click(S ystem::Object^ sender, System::EventAr gs^ e)
{
System::String^ str("temp");

this->axLogCtl1->GetLogText(str );
richTextBox1->Text = str;
}
HRESULT LogCtl::GetLogT ext(VARIANT* data)
{
CComVariant v(m_strData);

/////////////////////////////////////////////////////////////////
// Pass the current log data to the caller.
/////////////////////////////////////////////////////////////////
if (VT_BSTR == data.vt)
v.CopyTo(&(data .bstrVal));

return (S_OK);
}
--

Paul - Consultant: C++ Application Design and Development