PRB: System Image List Does Not Contain Overlay Images

   HIMAGELIST  himl;
   SHFILEINFO  sfi;

   himl = (HIMAGELIST)SHGetFileInfo(TEXT("C:\\"), 0, &sfi,
      sizeof(SHFILEINFO), SHGFI_SYSICONINDEX);
				

RESOLUTION

To add the standard overlay images to the process' copy of the system image list with the Desktop Update, you need to get an IShellIconOverlay interface pointer for a file system folder and call its GetOverlayIndex method for a shortcut (.lnk) file that is contained in the folder. This causes both standard overlay images to be added to the process' copy of the system image list. GetOverlayIndex also registers the overlay images using the ImageList_SetOverlayImage function.

The following function retrieves the handle of the system image list, and, if you are running under Windows NT version 4.0, it creates a temporary .lnk file. Then it gets the IShellIconOverlay interface from the parent folder and calls IShellIconOverlay::GetOverlayIndex, passing the PIDL for the temporary .lnk file. Finally, the handle to the system image list is returned from the function. The fSmall flag indicates if the small or large image list is being requested. If fSmall is zero, the system image list that contains large icons is retrieved. If fSmall is non-zero, the system image list that contains large icons is retrieved. If Internet Explorer 4.0 with the Desktop Update is not installed on your computer, the function cannot retrieve the IShellIconOverlay interface, so the function will simply return the image list handle.

   /********************************************************************

      GetSystemImageList()

   ********************************************************************/ 

   HIMAGELIST GetSystemImageList(BOOL fSmall)
   {
   HIMAGELIST  himl;
   SHFILEINFO  sfi;

   himl = (HIMAGELIST)SHGetFileInfo(TEXT("C:\\"), 0, &sfi,
      sizeof(SHFILEINFO), SHGFI_SYSICONINDEX |
         (fSmall ? SHGFI_SMALLICON : SHGFI_LARGEICON));

   /*
   Do a version check first because you only need to use this code on
   Windows NT version 4.0.
   */ 
   OSVERSIONINFO vi;
   vi.dwOSVersionInfoSize = sizeof(vi);
   GetVersionEx(&vi);
   if(VER_PLATFORM_WIN32_WINDOWS == vi.dwPlatformId)
      return himl;

   /*
   You need to create a temporary, empty .lnk file that you can use to
   pass to IShellIconOverlay::GetOverlayIndex. You could just enumerate
   down from the Start Menu folder to find an existing .lnk file, but
   there is a very remote chance that you will not find one. By creating
   your own, you know this code will always work.
   */ 
   HRESULT           hr;
   IShellFolder      *psfDesktop = NULL;
   IShellFolder      *psfTempDir = NULL;
   IMalloc           *pMalloc = NULL;
   LPITEMIDLIST      pidlTempDir = NULL;
   LPITEMIDLIST      pidlTempFile = NULL;
   TCHAR             szTempDir[MAX_PATH];
   TCHAR             szTempFile[MAX_PATH] = TEXT("");
   TCHAR             szFile[MAX_PATH];
   HANDLE            hFile;
   int               i;
   OLECHAR           szOle[MAX_PATH];
   DWORD             dwAttributes;
   DWORD             dwEaten;
   IShellIconOverlay *psio = NULL;
   int               nIndex;

   // Get the desktop folder.
   hr = SHGetDesktopFolder(&psfDesktop);
   if(FAILED(hr))
      goto exit;

   // Get the shell's allocator.
   hr = SHGetMalloc(&pMalloc);
   if(FAILED(hr))
      goto exit;

   // Get the TEMP directory.
   if(!GetTempPath(MAX_PATH, szTempDir))
      {
      /*
      There might not be a TEMP directory. If this is the case, use the
      Windows directory.
      */ 
      if(!GetWindowsDirectory(szTempDir, MAX_PATH))
         {
         hr = E_FAIL;
         goto exit;
         }
      }

   // Create a temporary .lnk file.
   if(szTempDir[lstrlen(szTempDir) - 1] != '\\')
      lstrcat(szTempDir, TEXT("\\"));
   for(i = 0, hFile = INVALID_HANDLE_VALUE;
      INVALID_HANDLE_VALUE == hFile;
      i++)
      {
      lstrcpy(szTempFile, szTempDir);
      wsprintf(szFile, TEXT("temp%d.lnk"), i);
      lstrcat(szTempFile, szFile);

      hFile = CreateFile(  szTempFile,
                           GENERIC_WRITE,
                           0,
                           NULL,
                           CREATE_NEW,
                           FILE_ATTRIBUTE_NORMAL,
                           NULL);

      // Do not try this more than 100 times.
      if(i > 100)
         {
         hr = E_FAIL;
         goto exit;
         }
      }

   // Close the file you just created.
   CloseHandle(hFile);
   hFile = INVALID_HANDLE_VALUE;

   // Get the PIDL for the directory.
   LocalToWideChar(szOle, szTempDir, MAX_PATH);
   hr = psfDesktop->ParseDisplayName(  NULL,
                                       NULL,
                                       szOle,
                                       &dwEaten,
                                       &pidlTempDir,
                                       &dwAttributes);
   if(FAILED(hr))
      goto exit;

   // Get the IShellFolder for the TEMP directory.
   hr = psfDesktop->BindToObject(   pidlTempDir,
                                    NULL,
                                    IID_IShellFolder,
                                    (LPVOID*)&psfTempDir);
   if(FAILED(hr))
      goto exit;

   /*
   Get the IShellIconOverlay interface for this folder. If this fails,
   it could indicate that you are running on a pre-Internet Explorer 4.0
   shell, which doesn't support this interface. If this is the case, the
   overlay icons are already in the system image list.
   */ 
   hr = psfTempDir->QueryInterface(IID_IShellIconOverlay, (LPVOID*)&psio);
   if(FAILED(hr))
      goto exit;

   // Get the PIDL for the temporary .lnk file.
   LocalToWideChar(szOle, szFile, MAX_PATH);
   hr = psfTempDir->ParseDisplayName(  NULL,
                                       NULL,
                                       szOle,
                                       &dwEaten,
                                       &pidlTempFile,
                                       &dwAttributes);
   if(FAILED(hr))
      goto exit;

   /*
   Get the overlay icon for the .lnk file. This causes the shell
   to put all of the standard overlay icons into your copy of the system
   image list.
   */ 
   hr = psio->GetOverlayIndex(pidlTempFile, &nIndex);

   exit:
   // Delete the temporary file.
   DeleteFile(szTempFile);

   if(psio)
      psio->Release();

   if(INVALID_HANDLE_VALUE != hFile)
      CloseHandle(hFile);

   if(psfTempDir)
      psfTempDir->Release();

   if(pMalloc)
      {
      if(pidlTempFile)
         pMalloc->Free(pidlTempFile);

      if(pidlTempDir)
         pMalloc->Free(pidlTempDir);

      pMalloc->Release();
      }

   if(psfDesktop)
      psfDesktop->Release();

   return himl;
   }