LVM_SORTITEMS

Urgent!

Can anybody help me call the LVM_SORTITEMS windows message in .NET?
I'm trying to make a call to the Win32 API directly through using SendMessage. Does anyone know how to do this?

Greatly appreciated.
maloriopoliumAsked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

jkrCommented:
You can do that// =============================================================
// Comparison routine for sorting ListView on a column
// =============================================================
int CALLBACK ListViewCompareProc(LPARAM lParam1, LPARAM lParam2,
LPARAM lParamSort )
{
      int iResult;

   // MessageBox( hwnd, "Doing sort compare", "SortMsg", MB_OK );
   
      switch( lParamSort )
   {
         case 0:                                                // sub-item 0; file name
            iResult = 0;
            break;

      case 1:                                                // sub-item 1; folder size
      case 2:                                                // sub-item 2; number of files
            if ( lParam1 > lParam2 )
               iResult = 1;
         else
         if ( lParam1 < lParam2 )
               iResult = -1;
         else
               iResult = 0;
         break;
   }


   
   return iResult;
}


SendMessage( hwndList, LVM_SORTITEMS,(WPARAM)(LPARAM)(nSomeId),(LPARAM)(PFNLVCOMPARE)ListViewCompareProc );
 like
0
maloriopoliumAuthor Commented:
Hi jkr,

I am trying to do this in C# .NET. Can this be done? I know you can make various other Win32 API calls in C# but just not sure how to go about this one since one of the parameters is a pointer to a function (PFNLVCOMPARE)

Thanks.
0
jkrCommented:
Hm, I doubt that you'll be able to pass a function pointer to a C# function. What you could do is creating a "native" Win32 DLL that contains such a sor function and call it via P/Invoke. See http://www.codeproject.com/dotnet/PInvoke.asp ("Using Platform Invoke")
0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
Cloud Class® Course: Certified Penetration Testing

This CPTE Certified Penetration Testing Engineer course covers everything you need to know about becoming a Certified Penetration Testing Engineer. Career Path: Professional roles include Ethical Hackers, Security Consultants, System Administrators, and Chief Security Officers.

alb66Commented:
If you are using a ListView you can call the Sort() method.
See MSDN documentation at http://msdn2.microsoft.com/en-us/library/system.windows.forms.listview.sort(VS.71).aspx
0
maloriopoliumAuthor Commented:
Thanks jkr,

I just read that article you linked, it sys,
"Callback functions and passing arrays as parameters involve some more complications and can be the subject for the next article."

which sort of implies that it IS possible to pass function pointers to C#?
Do you know or can anyone point me to something that discusses the passing of callback functions or function pointers as a parameter to a Win32 API function??

Much appreciated
0
jkrCommented:
No, function pointer require native Win32 modules. Since C# is a P-code language (which means that it is interpreted to some extent), there are no memory addresses that resemble assembly code which could serve as a function pointer. That's why you need P/Invoke as an intermediate layer that provides these.
0
maloriopoliumAuthor Commented:
Can you explain what it means by using P/Invoke? It seems that all I have to do is declare the attribute:
[DllImport("user32.dll")]

and then declare a
static extern int SendMessage(....)
function which should be that of the Win32 API function.
Is that all there is to using P/Invoke?

0
jkrCommented:
Yes, that pretty much is it. However, I'd suggest to have the DLL that exposes the callback function itself call 'SendMessage()', since you need to have a native module pass that function pointer, managed modules won't be able to get that one.
0
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
System Programming

From novice to tech pro — start learning today.

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.