🚀 go-pugleaf

On Fri, 26 Mar 2004 22:52:41 -0800, Remy Lebeau (TeamB) wrote:

> 
> "Dave" <dave_xse@-spam-hotmail.com> wrote in message
> news:1cj24pzpnk6kq.7n0lajrj0cil$.dlg@40tude.net...
> 
>> I have done it but it just won't work yet...
> 
> It works fine when I use it in my own projects.
> 
>> The event is newer trapped by the Form's message
>> handler somehow...
> 
> That is because you did not set it up correctly.
> 
>>     hNotify = SHChangeNotifyRegister(Form1->Handle,
> 
> You are calling your register code from within TForm1's constructor.  The
> global Form1 pointer has not been assigned yet at that time.  You are lucky
> your program did not crash from referencing an invalid pointer.  To use the
> Handle from the constructor, you need to use the implicit 'this' pointer
> instead, like you did when calling SHBrowseForFolder().
> 
>> WM_USER, cItems, Mine);
> 
> The last parameter of SHChangeNotifyRegister() expects a pointer, but you
> are not passing a pointer at all.  You need to change your declaration to
> use NOTIFYREGISTER* instead, and then pass your structure instance using the
> '&' operator:
> 
> Also, the functions you are importing from Shell32 all use the __stdcall
> calling convention, but your declarations are not specifying any calling
> convention at all.  Unless your environment's default convention is
> __stdcall (__cdecl is usually the default), then you will not be able to
> call the functions correctly, and more importantly you will corrupt the
> stack and thus your program will have undefined behavior from that point on.
> 
> Use this code instead (I suggest you use typedefs for make your code
> clearer):
> 
>     typedef HANDLE (__stdcall *LPSHCNR)(HWND, DWORD, ULONG, UINT, DWORD,
> NOTIFYREGISTER*);
>     typedef BOOL (__stdcall *LPSHCND)(HWND);
> 
>     LPSHCNR lpSHChangeNotifyRegister;
>     LPSHCND lpSHChangeNotifyDeRegister;
> 
>     lpSHChangeNotifyRegister = (LPSHCNR) GetProcAddress(hShell,
> MAKEINTRESOURCE(2));
>     lpSHChangeNotifyDeRegister = (LPSHCND) GetProcAddress(hShell,
> MAKEINTRESOURCE(4));
> 
> Now, with that said, if you run your code under WinNT/2K/XP, then you need
> to use SHChangeNotification_Lock() and SHChangeNotification_Unlock() as well
> in order to get at the event information.  Under Win9x/Me, the event info is
> contained inside the wParam and lParam values directly.  But under
> WinNT/2K/XP, the OS creates a block of shared memory and then passes the
> memory address to your code rather than the original data.  So you have to
> lock the memory and then copy the desired data into your local storage, then
> you can process the same values that Win9x/Me normally give directly.
> 
> 
> Gambit

Thanks for you prompt feedback,
I did a bit of mess with the declarations, thanks for
fixing it...

Now the event gets trapped however i can't Lock it (using XP).
hLock is always NULL when i call lpSHChangeNotification_Lock.
I declared lpSHChangeNotification_Lock as follows

typedef HANDLE (__stdcall *LPSHCNL)(HWND, DWORD, LPCITEMIDLIST**, LPLONG);
LPSHCNR lpSHChangeNotifyRegister;

and here's the code involved...

void __fastcall TForm1::DirectoryHasChanged(TMessage &Msg)
{
  Edit1->Text = "Some stuff happened";

  LPCITEMIDLIST *pidls;
  LONG wEventId;
  if (bRunningWindowsNT) {
    HANDLE hLock;
    hLock = lpSHChangeNotification_Lock((HANDLE)Msg.WParam,
(DWORD)Msg.LParam, &pidls, &wEventId);
    if (hLock){
      int i = 0;
//      ProcessEvent(wEventId, pidls[0], pidls[1]);
      lpSHChangeNotification_Unlock(hLock);
    }
  }
  else {
    pidls = (LPCITEMIDLIST*)wParam;
    wEventId = (LONG)lParam;
    ProcessEvent(wEventId, pidls[0], pidls[1]);
  }
}
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