EnumDesktopWindows (C++) 大约需要 30 分钟才能在 Windows 10 上找到所需的打开窗口

Question

This problem occurs only on Windows 10. Works fine on other versions such as Windows 7.

On user action, I have following code to find out another open application window as:

void zcTarget::LocateSecondAppWindow( void )
{
    ghwndAppWindow = NULL;
    CString csQuickenTitleSearch = "MySecondApp";
    ::EnumDesktopWindows( hDesktop, MyCallback, (LPARAM)(LPCTSTR)csTitleSearch );
}

With callback functions as:

BOOL CALLBACK MyCallback( HWND hwnd, LPARAM lParam)
{
   if ( ::GetWindowTextLength( hwnd ) == 0 )
   {
      return TRUE;
   }

   CString strText;
   GetWindowText( hwnd, strText.GetBuffer( 256 ), 256 );
   strText.ReleaseBuffer();

   if ( strText.Find( (LPCTSTR)lParam ) == 0 )
   {
      // We found the desired app HWND, so save it off, and return FALSE to
      // tell EnumDesktopWindows to stopping iterating desktop HWNDs.
      ghwndAppWindow = hwnd;

      return FALSE;
   }

   return TRUE;
} // This is the line after which call is not returned for about 30 mins

This callback function mentioned above gets called for about 7 times, each time returning True. At this stage it finds own app window through which EnumDesktopWindows was invoked.

It returns True as expected, but then nothing happens for about 30 minutes. No debug points hit. The original running application is unresponsive at this point.

How to resolve this problem?

Answer 1

Found another path. Instead of going by Window name, looking for Process helps. Get process using process name, extract process id and get window handle.

void zcTarget::LocateSecondAppWindow( void )
 {
       PROCESSENTRY32 entry;
       entry.dwSize = sizeof(PROCESSENTRY32);
       HANDLE snapshot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, NULL);

       if (Process32First(snapshot, &entry) == TRUE)
       {
          while (Process32Next(snapshot, &entry) == TRUE)
          {
             if (_stricmp(entry.szExeFile, "myApp.exe") == 0)
             {  
                HANDLE hProcess = OpenProcess(PROCESS_ALL_ACCESS, FALSE, entry.th32ProcessID);               

                EnumData ed = { GetProcessId( hProcess ) };
                if ( !EnumWindows( EnumProc, (LPARAM)&ed ) &&
                   ( GetLastError() == ERROR_SUCCESS ) ) {
                      ghwndQuickenWindow = ed.hWnd;
                }
                CloseHandle(hProcess);
                break;
             }
          }
       }
       CloseHandle(snapshot);
}

       BOOL CALLBACK EnumProc( HWND hWnd, LPARAM lParam ) {
       // Retrieve storage location for communication data
       zcmTaxLinkProTarget::EnumData& ed = *(zcmTaxLinkProTarget::EnumData*)lParam;
       DWORD dwProcessId = 0x0;
       // Query process ID for hWnd
       GetWindowThreadProcessId( hWnd, &dwProcessId );
       // Apply filter - if you want to implement additional restrictions,
       // this is the place to do so.
       if ( ed.dwProcessId == dwProcessId ) {
          // Found a window matching the process ID
          ed.hWnd = hWnd;
          // Report success
          SetLastError( ERROR_SUCCESS );
          // Stop enumeration
          return FALSE;
       }
       // Continue enumeration
       return TRUE;
    }