HOWTO: Support Renaming of Items in the Windows Explorer Tree

• Microsoft Win32 Software Development Kit (SDK) included with: - Microsoft Windows NT 4.0 - Microsoft Windows 95

SUMMARY

When creating a namespace extension that has multiple levels of folders, it may be necessary to allow the folders to be renamed. This article discusses how to support renaming of folders in the Windows Explorer tree. This article assumes you are already familiar with development of namespace extensions. For more information on writing namespace extensions, see David Campbell's article "Extending the Windows Explorer with Name Space Extensions" in the July, 1996 issue of the Microsoft Systems Journal. In addition, please see the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q178665
   TITLE     : SAMPLE: RegView.exe: Shell Namespace Extension Example

MORE INFORMATION

To support renaming of folders in the Windows Explorer tree, follow these steps:

1. Supply the SFGAO_CANRENAME attribute in response to your IShellFolder::GetAttributesOf method for any folders that can be renamed.

   Explorer will call your IShellFolder::GetAttributesOf with the PIDL of a folder in your namespace. If this item can be renamed, you need to add the SFGAO_CANRENAME attribute to the attributes for that item. Don't forget that you can call IShellFolder::GetAttributesOf with multiple PIDLs, so you must only return the attributes that apply to all items. When Windows Explorer detects the SFGAO_CANRENAME attribute for the selected folder in the tree, it will enable the Rename item in the File menu.

   An example of GetAttributesOf might look something like this:

   STDMETHODIMP CShellFolder::GetAttributesOf( UINT uCount,

                                                   LPCITEMIDLIST aPidls[],
                                                   LPDWORD pdwAttribs)
      {
      UINT  i;
   
      for(i = 0; i < uCount; i++)
         {
         DWORD dwAttribs = 0;
   
         // Is this item a folder?
         if(IsFolder(aPidls[i]))
            {
            dwAttribs |= SFGAO_FOLDER;
   
            // Does this folder item have any subfolders?
            if(HasSubFolders(aPidls[i]))
               dwAttribs |= SFGAO_HASSUBFOLDER;
   
            // Can this folder be renamed?
            if(CanRename(aPidls[i]))
               dwAttribs |= SFGAO_CANRENAME;
            }
   
         /*
         On entry, *pdwAttributes contains the attributes that are being
         requested, so just use it as a mask.
         */
         *pdwAttribs &= dwAttribs;
         }
   
      return S_OK;
      }
   
   

2. Add a rename item to the context menu in your IContextMenu::QueryContextMenu.

   To support renaming of tree items you must also add a rename item to the context menu supplied for a folder item in the tree. Windows Explorer calls your IShellFolder::GetUIObjectOf with IID_IContextMenu to get the IContextMenu for the folder item. When this IContextMenu's QueryContextMenu method is called, you need to add a rename item to the menu if CMF_CANRENAME is specified and then enable or disable the rename menu item based on the item's SFGAO_CANRENAME attribute. A context menu can be created for multiple items. As a result, you should disable the rename menu item if the context menu is created for more than one item because renaming of multiple items is generally not implemented. The rename menu item can have any command identifier as long as it is unique with respect to the other items in the menu. Remember that the string set for the rename menu item should be localized so that various languages can be supported.

   Following is an example of what an IContextMenu::QueryContextMenu could look like. This sample code assumes that the context menu object maintains a NULL-terminated list of the items that it was created for in its m_aPidls member variable and a pointer to the IShellFolder that created it in its m_pSFParent member variable.

Sample Code

   #define IDM_MYRENAME 0
   #define IDM_LAST     5

   STDMETHODIMP CContextMenu::QueryContextMenu( HMENU hMenu,
                                                UINT indexMenu,
                                                UINT idCmdFirst,
                                                UINT idCmdLast,
                                                UINT uFlags)
   {
   if(!(CMF_DEFAULTONLY & uFlags))
      {
      MENUITEMINFO   mii;

      // Add any other menu items here.

      if(uFlags & CMF_CANRENAME)
         {
         ZeroMemory(&mii, sizeof(mii));
         mii.cbSize = sizeof(mii);
         mii.fMask = MIIM_ID | MIIM_TYPE;
         mii.wID = 0;
         mii.fType = MFT_SEPARATOR;
         InsertMenuItem(   hMenu,
                           indexMenu++,
                           TRUE,
                           &mii);

         ZeroMemory(&mii, sizeof(mii));
         mii.cbSize = sizeof(mii);
         mii.fMask = MIIM_ID | MIIM_TYPE | MIIM_STATE;
         mii.wID = idCmdFirst + IDM_MYRENAME;
         mii.fType = MFT_STRING;
         mii.dwTypeData = TEXT("&Rename");
         mii.fState = (CanRenameItems() ? MFS_ENABLED : MFS_DISABLED);
         InsertMenuItem(   hMenu,
                           indexMenu++,
                           TRUE,
                           &mii);
         }

      // Add the following menu items here.

      return MAKE_HRESULT(SEVERITY_SUCCESS, 0, USHORT(IDM_LAST + 1));
      }

   return MAKE_HRESULT(SEVERITY_SUCCESS, 0, USHORT(0));
   }

   BOOL CContextMenu::CanRenameItems(void)
   {
   if(m_aPidls)
      {
      // Get the number of items assigned to this object.
      UINT  i;
      for(i = 0; m_aPidls[i]; i++)
         {
         }

      // You can't rename more than one item at a time.
      if(i > 1)
         return FALSE;

      DWORD dwAttributes = SFGAO_CANRENAME;
      m_pSFParent->GetAttributesOf(i, (LPCITEMIDLIST*)m_aPidls,
   &dwAttributes);

      return dwAttributes & SFGAO_CANRENAME;
      }

   return FALSE;
   }