Programming

Some programming notes and source code.

• Templates for deriving C++ COM classes from IDropSource and IDropTarget are generally available on the web. Here's how to obtain a COM object using IShellFolder::GetUIObjectOf() without much PIDL-ing around, the only drawback is being restricted to file and folder objects.

• UIObjectFromPath() — Obtains an interface pointer to a COM shell object given a path. Relatively simple function illustrating the basic moves. Suitable for a single folder. Useful for getting a basic drop target. Used as follows:

  #include <shlobj.h>
  
  LPDROPTARGET droptarget;
  bool ok = UIObjectFromPath (targetpath, IID_IDropTarget, (void**)&droptarget);
  ...
  droptarget->Release();
  

• UIObjectFromPaths() — Obtains an interface pointer to a COM shell object given a vector of paths. Suitable for single or multiple files and folders. Useful for getting a drop source, drop target or context menu. Example usage:

  #include <vector>
  #include <string>
  typedef std::basic_string<wchar_t> wstring;
  
  LPDATAOBJECT dataobject;
  if (UIObjectFromPaths (paths, IID_IDataObject, (void**)&dataobject))
  {
          ...
          dataobject->Release();
  }
  

• For invaluable background on shell programming, see here.