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Home >> Visual C++ / C++ >> COM-based Technologies >> Shell Programming


Imitating Windows Explorer
Rating: none

Leon Finker (view profile)
May 23, 2001

I wandered how I can simulate the Windows explorer listview of files. Here is what I found. It might be useful to someone. If you create a simple listview control and populate it with files/folders, you'll notice that you can't:

  • Easily detect changes to files (rename, delete, copy/move...etc) while user is viewing the list
  • Send To menu is not populated if you try to use the shell's menu for your items
  • There doesn't seem to be a way of getting the column names used in shellview (filename, size, owner, times, and many others)

(continued)




I found that Windows explorer and File Open dialog expose IShellBrowser, which is used by IShellFolder/IShellView to create the listview of files.  So, I created a simple app with WTL.  Implemented basic IShellBrowser methods and exposed it to IShellView through IShellFolder::CreateViewObject.  Finally, to create the listview I called IShellView::CreateViewWindow.  I didn't try to merge the menus.
Things I couldn't get to work:

  • Toolbar buttons (they were added to my toolbar, but bitmaps were messed up). They do function however.
  • The most important one for me was that I couldn't easily detect when user wanted to open/explore/search the selected folder so  I could sync the file tree.

The IShellBrowser::BrowseObject was never even called, so I didn't implement it, but it should be implemented because most NSEs use this method.  I did find that the shellview sends WM_DDE* messages and if you respond properly you'll get the info about the action user taken. The needed messages are WM_DDE_INITIATE, WM_DDE_EXECUTE, WM_DDE_TERMINATE.  WM_DDE_EXECUTE will give you string such as

 "[ViewFolder("C:\Documents and Settings\leon\Desktop\billing", :428:780, 1)]"

I have no idea what the 428:780 stand for, but action would be ViewFolder/ExploreFolder/FindFolder.  It would be nice if Microsoft documented this stuff so we could use it correctly.  In the MSDN they state, "You do not implement this interface directly. IShellBrowser is implemented by Windows Explorer and by the Windows File Open common dialog box." Why did they tell us about WM_GETISHELLBROWSER? Anyway, maybe it would be useful to someone, so here it is.

Some useful points:

  • To get drag drop functioning in shellview, call OleInitialize/OleUninitialize 
  • Make sure you respond properly to WM_GETISHELLBROWSER or CreateView might crash
  • Details listview seems to work only with FVM_DETAILS and FWF_SNAPTOGRID combination
  • ICommDlgBrowser can be supported to have a simple listview like in common file dialog boxes (without webview)
  • Don't name your executable as explorer.exe or unpleasant things will happen



Useful links:

EnumDesk

Sample for enumerating/navigating folders/files (comes with PSDK) I have it under
C:\Program Files\Microsoft Platform SDK\Samples\WinUI\Shell

Q157247 - PRB: IShellFolder::CreateViewObject() Causes Access Violation

IShellBrowser

IShellFolder
IShellView

Comments in the Shell Object Header File (shlobj.h) are useful.

Downloads


Explorer.zip - 14.2K

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Latest Comments:
• events and class wizard - Legacy CodeGuru (06/06/2001)
• thanx leon....another question - Legacy CodeGuru (06/06/2001)
• How to detect folder open... - Legacy CodeGuru (05/29/2001)
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