Re: Question about VARIANT deallocation - COM Discussion Boards

Hristo-Bojilov10-Aug-09 7:12

Hristo-Bojilov

10-Aug-09 7:12

It seem's you might not correctly release the BSTR accociated with the VARIANT *p1 variable.
You might have manually to release variant accoiated with myInt variable.

GuimaSun10-Aug-09 7:27

10-Aug-09 7:27

It was my first guess, but I don't think so...each time I receive a call (from the loop) I receive the same integer VT_BYREF | VT_I2 (which is deallocated by VariantClear).
It seems that this BSTR is lost between calls, causing the leak (obviously myInt is an integer and can't reflect changes).

GuimaSun
www.nexsun.com.br
NEXSUN TechZone

Hristo-Bojilov10-Aug-09 7:45

Hristo-Bojilov

10-Aug-09 7:45

If the BSTR is lost why don't you use BSTR* as variable type instead of VARIANT.
Which version of VB are you using?

GuimaSun10-Aug-09 8:08

10-Aug-09 8:08

I can't change that interface, the real code is far more complicated, basically I need to receive a VARIANT* and change their value, and the new value comes from a c++ string.
I'm testing using VB 6.
Thanks.

GuimaSun
www.nexsun.com.br
NEXSUN TechZone

Stuart Dootson10-Aug-09 9:21

Stuart Dootson

10-Aug-09 9:21

I suspect that rather than 'new BSTR', you should use CoTaskMemAlloc[^] to allocate memory in a COM server:

BSTR *pBSTR = (BSTR*)CoTaskMemAlloc(sizeof(BSTR));

However - one other thing strikes me - why pass the BSTR back by reference? Why not use this?

VariantClear( p );
VariantInit( p );
p->vt = VT_BSTR;
p->pbstrVal = SysAllocString( L"abc" );

One less allocation, one less place to leak memory!

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

GuimaSun10-Aug-09 9:43

10-Aug-09 9:43

Hi The same happens with CoTaskMemAlloc, and using VT_BSTR instead of VT_BSTR | VT_BYREF.
Thanks anyway.

GuimaSun
www.nexsun.com.br
NEXSUN TechZone

Vi210-Aug-09 23:01

Vi2

10-Aug-09 23:01

How CallService is defined in IDL file? If it's "CallService([in] VARIANT *p1)", then you cannot change the parameter. If it's "CallService([in,out] VARIANT *p1), then you cannot receive the parameter in Integer.

IAC, VB passes myInt variable as VT_BYREF | VT_I2 to be possible to change the myInt value. It's made only during call some method. Inside VB don't store variant by this manner.

STDMETHODIMP CDCSClient::CallService( VARIANT *p )
{
VariantClear( p );
p->vt = VT_BSTR;
p->bstrVal = SysAllocString( L"abc" );
return S_OK;
}

If you desire to pass BSTR by reference, you should keep out this address and make sure to free this BSTR after using.

BSTR g_pBSTR = NULL; // global scope, so somewhere should be "if (!g_pBSTR) SysFreeString(g_pBSTR);"

STDMETHODIMP CDCSClient::CallService( VARIANT *p )
{
VariantClear( p );
p->vt = VT_BSTR | VT_BYREF;
if (!g_pBSTR) g_pBSTR = SysAllocString( L"abc" );
p->pbstrVal = &g_pBSTR;
return S_OK;
}

With best wishes,
Vita

GuimaSun12-Aug-09 5:12

12-Aug-09 5:12

The parameter is defined as [in,out,optional].

And yes, now I understand, as I suspected, I can't reallocate the VT_BYREF | VT_I2 inside my ATL code.

The only thing still not 100% clear which confused me is that I can define a VB procedure receiving a byref variant, do the same thing receiving my int, and changing it to String and no leak happens. That was my first test.
But the difference is: there's no COM in this scenario, and the pure VB allocation\dellocation mechanisms are not the same.

Thanks a lot !

GuimaSun
www.nexsun.com.br
NEXSUN TechZone

Vi212-Aug-09 22:37

Vi2

12-Aug-09 22:37

STDMETHODIMP CDCSClient::CallService(/*[in,out]*/ VARIANT *p)
{
  if (V_VT(p) == (VT_VARIANT | VT_BYREF))
  {
     // only here you can change the type of passed variable (see VB example below)
     VARIANT *p2 = V_VARIANTREF(p);
     p2->vt = VT_BSTR;
     p2->bstrVal = SysAllocString( L"abc" );
     return S_OK;
  }
}

Dim v As Variant
v = 1
Debug.Print TypeName(v) & " " & v
Call obj.CallService(v)
Debug.Print TypeName(v) & " " & v

With best wishes,
Vita

calling messagebox funtion from a c# code

Vi213-Aug-09 1:20

Vi2

13-Aug-09 1:20

About memory leaks. VB allocation\dellocation mechanisms are the same with COM.

p->vt = VT_BSTR | VT_BYREF;
BSTR *pBSTR = new BSTR;
*pBSTR = SysAllocString( L"abc" );
p->pbstrVal = pBSTR;

There are 2 memory allocations in statements "= new BSTR" and "= SysAllocString".

The VARIANT with VT_BYREF|VT_BSTR isn't an owner of its values, so freeing of the VARIANT doesn't free neither pbstrVal nor *pbstrVal. And finally you have memory leaks.

The VARIANT with VT_BSTR (without VT_BYREF) is an owner of its values, so freeing of the VARIANT frees bstrVal.

p->vt = VT_BSTR;
p->bstrVal = SysAllocString( L"abc" );

And there are no memory leaks.

With best wishes,
Vita

nicetohaveyou8-Aug-09 9:22

nicetohaveyou

8-Aug-09 9:22

Hi,

I am trying to call the Win 32 API messagebox function from c#.
However, i finding my code not working:

could you please help me correct it:

using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;

namespace ConsoleApplication5
{
class Program
{

public const String UserReference = "user32.dll";
[DllImport(UserReference, SetLastError = true)]
private static extern Int32 MessageBox(IntPtr hWnd, String pText,
String pCaption, Int32 uType);

static void Main(string[] args)
{
IntPtr ProblemCauser = (IntPtr)(-100);
MessageBox(ProblemCauser, "hello", "check", 0);

Int32 ErrorCode = Marshal.GetLastWin32Error();
Console.WriteLine("Error Code: " + ErrorCode.ToString());

Console.ReadLine();

}
}
}

Re: calling messagebox funtion from a c# code

Hristo-Bojilov10-Aug-09 4:27

Hristo-Bojilov

10-Aug-09 4:27

Your arguments are invalid!

nicetohaveyou wrote:
IntPtr ProblemCauser = (IntPtr)(-100)

.
-100 is a number not pointer to valid window.
Call it like that
MessageBox(this.Handle,"hello", "check", 0)
into Form body or
MessageBox(IntPtr.Zero,"hello", "check", 0)

InvalidCastException by registering events on Office Add-In

maesi19808-Aug-09 6:54

maesi1980

8-Aug-09 6:54

On one side I have a C# application (WPF) from which I want to call an Office Add-In class. On my Office Add-In project I've exposed a class and an interface to COM. I'm able to call functions from my exposed Add-In object, but I'm not able to register an event, which should by fired by the exposed Add-In project.

My C# code:

officeAddIn = excel.COMAddIns.Item(ref addinName);
object obj = officeAddIn.Object;
IAddInUtilities m_excelFIMAddInUtils = (IAddInUtilities)obj;

AddInEnablingEventHandler addInEnablingEventHandler = new AddInEnablingEventHandler(m_excelFIMAddInUtils_AddInEnablingEvent);
m_excelFIMAddInUtils.EnableAddIn(true);
//Until here, it works fine

m_excelFIMAddInUtils.AddInEnablingEvent += addInEnablingEventHandler 
//Failes! --> InvalidCastException

My AddIn Project:

[ComVisible(false)]
    [Serializable()]
    public delegate void AddInEnablingEventHandler();

 public partial class ExcelFIMAddIn
    {
        private AddInFIMUtilities m_utilities;
        private Office.IRibbonExtensibility m_ribbon;     
        
        protected override object RequestComAddInAutomationService()
        {
            
            if (m_utilities == null)
            {
                m_utilities = new AddInFIMUtilities();
       
            }
            return m_utilities;
        }
    
        protected override Office.IRibbonExtensibility CreateRibbonExtensibilityObject()
        {
            RibbonExcelFIM ribbon = new RibbonExcelFIM();
            ribbon.FIMSaveEvent += new FIMSaveEventHandler(ribbon_FIMSaveEvent);
            return ribbon;
            /**
            if(this.Application == null)
            {
                m_ribbon = new RibbonExcelFIM();
            }
            else
            {
                
                m_ribbon = base.CreateRibbonExtensibilityObject();
            }
            return m_ribbon;
             */
        }      
    }

    [Guid("6CA66587-1A1E-4cd6-B55A-20F07F18C343")]
    [ComVisibleAttribute(true)]
    [InterfaceType(ComInterfaceType.InterfaceIsDual)]
    public interface IAddInUtilities
    {
        void EnableAddIn(bool isAddInEnabled);
        event AddInEnablingEventHandler AddInEnablingEvent;

    }

    [ComVisibleAttribute(true)]
    [Guid("F2FA4759-AEA0-4f4e-838B-3BBBC77837AB")]
    [ClassInterface(ClassInterfaceType.None)]
    [ProgId("AddInFIMUtilites")]
    [Serializable()]
    public class AddInFIMUtilities : StandardOleMarshalObject, IAddInUtilities
    { 
        public event AddInEnablingEventHandler AddInEnablingEvent;

        public void EnableAddIn(bool isAddInEnabled)
        {
            m_isAddInEnabled = isAddInEnabled;
            if (isAddInEnabled)
            {
                if (AddInEnablingEvent != null)
                {
                    AddInEnablingEvent();
                }
                else
                {
                }
            }
        }
    }

What I'm doing wrong? Is there a solution which someone can provide me?
Thanks in advance

Marcel

Re: InvalidCastException by registering events on Office Add-In [modified]

maesi198010-Aug-09 1:45

maesi1980

10-Aug-09 1:45

I found out a solution that works. If someone has a better working solution, please post it Smile | :)

The code snippet of my new code in C#:

 m_excelAddInUtils = (IAddInUtilities)obj;

// create a Channel with port 0 --> otherwise an Exception will be
//throwed: "This remoting proxy has no channel sink which means either 
//the server has no registered server channels that are listening, or 
//this application has no suitable client channel to talk to the server.
IpcChannel serverChannel = new IpcChannel("localhost:0");
ChannelServices.RegisterChannel(serverChannel);

//Use a second instance of the utility class. With the first instance provided by the COMAddIn.Object property, I 
//haven't found out how to marshal an event registering without throwing 
//an InvalidCastException
AddInFIMUtilities addInUtilClass = new AddInFIMUtilities();

//Register the second instance (CLR object) to the COM instance over the 
//provided utility interface
m_excelAddInUtils.AddToSaveObserverList(addInUtilClass);
//Now the event registering works without cast exceptions
addInUtilClass.AddInSaveEvent += new AddInSaveEventHandler(addInUtilClass_OnFIMSaved);

The new delegate in Add-In class:

public delegate void AddInSaveEventHandler();

On the Add-In class I created a new IDispatch Interface:

[Guid("69075652-6A6D-442c-B534-5816D5046F04")]
[ComVisibleAttribute(true)]
[InterfaceType(ComInterfaceType.InterfaceIsIDispatch)]
public interface IAddInEvents
{
    void AddInSaveEventHandler();
}

And extended the Main method interface:

[Guid("6CA66587-1A1E-4cd6-B55A-20F07F18C343")]
    [ComVisibleAttribute(true)]
    [InterfaceType(ComInterfaceType.InterfaceIsDual)]
    public interface IAddInUtilities
    {
        //Service to register the CLR client object to COM observer list
        [DispId(1)]
        void AddToSaveObserverList(IAddInUtilities addInUtils);

        [DispId(2)]
        void FireSaveEvent();
    }

The new methods in the Utility class:

public void AddToSaveObserverList(IAddInUtilities addInUtils)
{
    Globals.ExcelFIMAddIn.SaveObserverList.Add(addInUtils);
}

public void FireSaveEvent()
{
    AddInSaveEvent();
}

On the Add-In class itself, these extensions are required:

<pre>private List<IAddInUtilities> m_saveObserverList = new List<IAddInUtilities>();

public List<IAddInUtilities> SaveObserverList
{
get { return m_saveObserverList; }
}

And eventually firing the event:

foreach (IAddInUtilities addInFIMUtil in this.SaveObserverList)
{
    try
    {
        ((AddInFIMUtilities)addInUtil).FireSaveEvent();
    }
    catch
    {
                    
    }
}

modified on Monday, August 10, 2009 6:52 AM

Com Component

sekannak7-Aug-09 0:58

sekannak

7-Aug-09 0:58

Hi,

I am new to COM Component development. I dont have that much idea. So plz give me sample code or sample program. Thanks in Advance..

regards,
kannak....

kannak

Re: Com Component

Randor 9-Aug-09 10:53

Randor

9-Aug-09 10:53

Hi kannak,

Codeproject has a very large collection of COM samples perhaps you should look there:

http://www.codeproject.com/KB/COM/[^]

Best Wishes,
-David Delaune

Re: Com Component

sekannak9-Aug-09 19:57

sekannak

9-Aug-09 19:57

Hi David...
Thanks for responding..i will go through ....
Regards,
kannak......

kannak

WMP loop playing - black between each play

pimb26-Aug-09 3:46

pimb2

6-Aug-09 3:46

When I try to play an .avi file in a Windows Media Player component, it is like 1 second black between each new play. It says 'Media has been found' (a translation of myswlf of the Dutch version). Is this solvable? The avi file is a copy of the Vista copy file dialog which musn't be black between every loop.

Thanks.

Re: WMP loop playing - black between each play --- found a solution

pimb26-Aug-09 3:53

pimb2

6-Aug-09 3:53

Sorry for asking this question too fast - I found out that this component can play without any black pause in between!

Thanks.

invoke output parameters to javascript?

Hongjun Ge5-Aug-09 7:11

Hongjun Ge

5-Aug-09 7:11

How to set output parameter value to javascript use invoke function's pDispParams.

in javascript

<script type="text/javascript"><br />
var fVal; // Want a float value<br />
external.GetFloat(fVal);<br />
</script>

How do it in Invoke function???

STDMETHODIMP CImpIDispatch::Invoke(<br />
/* [in] */ DISPID dispIdMember,<br />
/* [in] */ REFIID /*riid*/,<br />
/* [in] */ LCID /*lcid*/,<br />
/* [in] */ WORD wFlags,<br />
/* [out][in] */ DISPPARAMS* pDispParams,<br />
/* [out] */ VARIANT* pVarResult,<br />
/* [out] */ EXCEPINFO* /*pExcepInfo*/,<br />
/* [out] */ UINT* puArgErr)<br />
{<br />
return S_OK;<br />
}

Hongjun Ge

Vi25-Aug-09 21:49

Vi2

5-Aug-09 21:49

You have no chance to transmit any value to javascript by parameter in parameter's list of GetFloat function. Only by [out,retval] parameter of one. I.e. by syntax "fVal = external.GetFloat();". For this action, you should assign right value to pVarResult parameter of CImpIDispatch::Invoke.

With best wishes,
Vita

Hongjun Ge6-Aug-09 4:54

Hongjun Ge

6-Aug-09 4:54

Thanks for your reply.

In msdn document descriptions like below.Why they can implement the oCustCalenderObj parameter as out.
http://msdn.microsoft.com/en-us/library/aa770041(VS.85).aspx[^]

<SCRIPT language="JScript"><br />
function MyFunc(iSomeData)<br />
{<br />
    var oCustCalendarObj;<br />
    external.GetCustomCalender(oCustCalenderObj);<br />
    oCustCalerdarObj.doStuffWithIt();<br />
    .<br />
    .<br />
    .<br />
}<br />
</SCRIPT>

Hongjun Ge

Vi26-Aug-09 21:24

Vi2

6-Aug-09 21:24

I don't know, but all I said is correct. I didn't meet with GetCustomCalender declaration, but "Get" prefix requires [out,retval] parameter.

AFAIK JScript passes all arguments by value, so server doesn't have a way to modify them. And there is only one case - VARIANT* pVarResult parameter of Invoke.

You can assign some value to this parameter and view the result.

With best wishes,
Vita