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Delphi Programming

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How to browse for a folder

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The following working code sample shows how to browse for a folder using "SHBrowseForFolder" (i.e. how to invoke a selection folder dialog) and also how to specify the initially selected folder:

unit BrowseForFolderU;

interface

function BrowseForFolder(const browseTitle: String;
  const initialFolder: String = '';
  mayCreateNewFolder: Boolean = False): String;

implementation

uses
  Windows, Forms, shlobj;

var
  lg_StartFolder: String;

// With later versions of Delphi you may not need these constants.
const
  BIF_NEWDIALOGSTYLE=$40;
  BIF_NONEWFOLDERBUTTON=$200;

////////////////////////////////////////////////////////////////////////
// Call back function used to set the initial browse directory.
////////////////////////////////////////////////////////////////////////
function BrowseForFolderCallBack(Wnd: HWND; uMsg: UINT; lParam,
lpData: LPARAM): Integer stdcall;
begin
  if uMsg = BFFM_INITIALIZED then
    SendMessage(Wnd,BFFM_SETSELECTION, 1, Integer(@lg_StartFolder[1]));
  result := 0;
end;

////////////////////////////////////////////////////////////////////////
// This function allows the user to browse for a folder
//
// Arguments:-
//         browseTitle : The title to display on the browse dialog.
//       initialFolder : Optional argument. Use to specify the folder
//                       initially selected when the dialog opens.
//  mayCreateNewFolder : Flag indicating whether the user can create a
//                       new folder.
//
// Returns: The empty string if no folder was selected (i.e. if the user
//          clicked cancel), otherwise the full folder path.
////////////////////////////////////////////////////////////////////////
function BrowseForFolder(const browseTitle: String;
  const initialFolder: String ='';
  mayCreateNewFolder: Boolean = False): String;
var
  browse_info: TBrowseInfo;
  folder: array[0..MAX_PATH] of char;
  find_context: PItemIDList;
begin
  //--------------------------
  // Initialise the structure.
  //--------------------------
  FillChar(browse_info,SizeOf(browse_info),#0);
  lg_StartFolder := initialFolder;
  browse_info.pszDisplayName := @folder[0];
  browse_info.lpszTitle := PChar(browseTitle);
  browse_info.ulFlags := BIF_RETURNONLYFSDIRS or BIF_NEWDIALOGSTYLE;
  if not mayCreateNewFolder then
    browse_info.ulFlags := browse_info.ulFlags or BIF_NONEWFOLDERBUTTON;

  browse_info.hwndOwner := Application.Handle;
  if initialFolder <> '' then
    browse_info.lpfn := BrowseForFolderCallBack;
  find_context := SHBrowseForFolder(browse_info);
  if Assigned(find_context) then
  begin
    if SHGetPathFromIDList(find_context,folder) then
      result := folder
    else
      result := '';
    GlobalFreePtr(find_context);
  end
  else
    result := '';
end;

end.

The initial folder can be a local path, a mapped drive or even a UNC path.

In later versions of Delphi you may find the two constants for BIF_NEWDIALOGSTYLE and BIF_NONEWFOLDERBUTTON are defined in the unit shlobj, but these were missing in Delphi 7.

I gratefully acknowledge the help of Martin Birk for suggesting the addition of the line "browse_info.hwndOwner := Application.Handle;". Without that, the browse dialog pops up in the corner of the screen, with the line the dialog pops up over the application.

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I have had it suggested that if you pass in the application handle as a parameter then you no longer need to include "forms" in the uses clause. The function signature would then become:

function BrowseForFolder(const browseTitle: String;
const initialFolder: String = '';
const appHWND: THandle;
mayCreateNewFolder: Boolean = False): String;

and the line:

   browse_info.hwndOwner := Application.Handle;

replaced with:

   browse_info.hwndOwner := appHWND;

which you prefer is down to your individual preference.

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These notes are believed to be correct for Delphi 6 and Delphi 7, and may apply to other versions as well.