"Group by" a certain folder in windows explorer - windows

Question

What I am trying to do is to crate a folder for my application, and to make sure each time a user enters this folder, it's grouped, like this:
except that the disks would be replaced by some folders/files.
so basically I'm trying to achieve exactly what "Group by" function does:
and I have to do this in my application with c/c++ code or a bat. I'm guessing this needs to be done in the registry, but I cannot find where. any idea?
thanks.

Answer 1

You must understand that changing of Explorer view mode with registry is dirty hack. So USE ON YOUR OWN RISK. TESTED ON WINDOWS 7 ONLY.
procedure SetFolderGroupBy(AParentWnd: HWND; const AFolder: UnicodeString; const AColumn: TPropertyKey; AAscending: Boolean);
var
Desktop: IShellFolder;
Attr: DWORD;
Eaten: DWORD;
IDList: PItemIDList;
Bag: IPropertyBag;
Direction: DWORD;
begin
OleCheck(SHGetDesktopFolder(Desktop));
try
Attr := 0;
OleCheck(Desktop.ParseDisplayName(AParentWnd, nil, PWideChar(AFolder), Eaten, IDList, Attr));
try
OleCheck(SHGetViewStatePropertyBag(IDList, 'Shell', SHGVSPB_FOLDERNODEFAULTS, IPropertyBag, Bag));
try
OleCheck(Bag.Write('SniffedFolderType', 'Generic'));
finally
Bag := nil;
end;
OleCheck(SHGetViewStatePropertyBag_(IDList, 'Shell\{5C4F28B5-F869-4E84-8E60-F11DB97C5CC7}', SHGVSPB_FOLDERNODEFAULTS, IPropertyBag, Bag));
try
if AAscending then Direction := SORT_ASCENDING
else Direction := DWORD(SORT_DESCENDING);
OleCheck(Bag.Write('GroupByDirection', Direction));
OleCheck(Bag.Write('GroupByKey:FMTID', GUIDToString(AColumn.fmtid)));
OleCheck(Bag.Write('GroupByKey:PID', AColumn.pid));
OleCheck(Bag.Write('GroupView', DWORD(-1)));
finally
Bag := nil;
end;
finally
CoTaskMemFree(IDList);
end;
finally
Desktop := nil;
end;
end;