CFolderDialog - Selecting Folders

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Introduction

As I mentioned in my other article "CIconDialog - Selecting Icons", while developing a wizard application, I needed a dialog to select an icon from executables and another one for selecting folders on multiple ones, but did not find anything about in MFC. So, CFolderDialog was written. It wraps the ::SHBrowseForFolder API.

Sample Usage

The CFolderDialog is derived from CCommonDialog and acts like any common dialog. See sample usage:

//...
#ifndef __FOLDERDLG_H__
    #include "FolderDlg.h"
#endif
// ...
void CSomeDialog::OnSomeHandler( void ) 
{ 
    m_strFolderPath = _T( "d:\\Windows" ); // Just for sample    
    m_strDisplayName.Empty();
    
    CFolderDialog dlg(  _T( "Dialog Title" ), m_strFolderPath, this );
    if( dlg.DoModal() == IDOK  )
    {    
        m_strFolderPath  = dlg.GetFolderPath();
        m_strDisplayName = dlg.GetFolderDisplayName();
        // Use folder path and display name here ...
    }    
}
//

See demo project source for more.

Setting the Root Folder

You can also set the root folder of the dialog, specifying the location of the root folder from which to start browsing. Only the specified folder and any subfolders that are beneath it in the namespace hierarchy will appear in the dialog box.

See sample usage:

//...
#ifndef __FOLDERDLG_H__
    #include "FolderDlg.h"
#endif
// ...
void CSomeDialog::OnSomeHandler( void ) 
{
    CFolderDialog dlg( _T( "Root folder is C:\" ), NULL, this );
    dlg.SetRootFolder( _T( "C:\\" );
    
    if( dlg.DoModal() == IDOK  )
    {       
        // ...
    }
}
//

Thanks to Eckhard Schwabe and Jose Insa for that sample.

Custom Filtering

Under Microsoft® Windows® XP/2003 or later, you can do custom filtering on the contents of the dialog box.

To create a custom filter, follow these steps:

1. Set the BIF_NEWDIALOGSTYLE flag in the uFlags member of the CFolderDialog constructor. Override the OnIUnknown virtual member function in the derived class. On OnIUnknown, the function's pIUnknown parameter will contain a pointer to an instance of IUnknown. Call QueryInterface on that IUnknown to obtain a pointer to an IFolderFilterSite.
2. Create an object that implements IFolderFilter - derive a class from it that implements all basic pure virtual member functions of IUnknown, and implement IFolderFilterSite::ShouldShow and IFolderFilterSite::GetEnumFlags functions, that do filtering.
3. Call IFolderFilterSite::SetFilter (pointer to which you obtained in step 1), passing it a pointer to your custom IFolderFilter derived class. IFolderFilterSite::ShouldShow and IFolderFilterSite::GetEnumFlags methods can then be used to include and exclude items from the tree.
4. Once the filter is created, the IFolderFilterSite interface is no longer needed. Call IFolderFilterSite::Release if you have no further use for it.

I have added a sample custom filtering (look at the picture, the dialog shows only "JPG/GIF/BMP" files in the tree). Thanks to Arik Poznanski for his article "C# does Shell, Part 1". For more information, please see the source code.

Class Members

Base Class

• CCommonDialog

Data Members

• m_bi - The Windows BROWSEINFO structure. Provides access to basic folder dialog box parameters.
• m_szFolPath - Contains the path of the folder selected with the dialog.
• m_szSelPath - Contains the folder path to be initially selected when the the dialog opens.

Construction

Constructs a CFolderDialog object:

CFolderDialog( IN LPCTSTR pszTitle = NULL, IN LPCTSTR pszSelPath = 
      NULL, IN CWnd* pWndParent = NULL, IN UINT uFlags = BIF_RETURNONLYFSDIRS )

• pszTitle - Title to display in the top of the dialog.
• pszSelPath - The folder path to be initially selected when the the dialog opens.
• pWndParent - A pointer to the file dialog-box object's parent or owner window.
• uFlags - A combination of one or more flags that allows you to customize the dialog box. For more information, see BROWSEINFO structure in the Platform SDK.

Operations

• DoModal( void ) Displays the browse for folder dialog box and allows the user to make a selection.
• SetSelectedFolder( IN LPCTSTR pszPath ) - Sets the folder path to be initially selected when the the dialog opens.
• SetRootFolder( IN LPCTSTR pszPath ) - Sets the root folder path to show. If pszPath is NULL, the root folder is removed.
• GetRootFolder( IN OUT LPTSTR pszPath ) - Gets the root folder of the dialog. The pszPath buffer must be at least MAX_PATH characters in size.
• GetSelectedFolder( void ) const - Gets the folder path to be initially selected when the the dialog opens.
• GetFolderPath( void )const - Retrieves the path of the open folder.
• GetFolderDisplayName( void )const - Retrieves the display name of the currently open folder.
• GetFolderImageIndex( void )const - Gets the image associated with the selected folder. The image is specified as an index to the system image list.
• GetBI( void ) - Retrieves the BROWSEINFO structure of the CFolderDialog object.
• GetBI( void )const - Retrieves the BROWSEINFO structure of the CFolderDialog object.

Overridables

• OnInitialized( void ) - Called when browse dialog box has finished initializing.
• OnSelChanged( IN LPITEMIDLIST pItemIDList ) - Called when browse dialog box selection is changed.
• OnValidateFailed( IN LPCTSTR pszPath ) - Called when the user typed an invalid name into the edit box (if any) of the browse dialog box. Return zero to allow the dialog to be dismissed or nonzero to keep the dialog open.

Microsoft® Windows® XP/2003 or later:

• OnIUnknown( IN IUnknown* pIUnknown ) - Provides an IUnknown interface to the client for custom filtering of the contents of the dialog box, using IFolderFilterSite and IFolderFilter.

Functions, that are valid to be called only from Overridables:

• EnableOK( IN BOOL bEnable = TRUE ) - Enables or disables the browse dialog box's OK button.
• SetSelection( IN LPITEMIDLIST pItemIDList ) - Selects the specified folder.
• SetSelection( IN LPCTSTR pszPath ) - Selects the specified folder.
• SetStatusText( IN LPCTSTR pszText ) - Sets the dialog box status text.

Shell version 5.0 or later:

• SetExpanded( IN LPITEMIDLIST pItemIDList ) - Specifies a path to expand in the dialog box.
• SetExpanded( IN LPCTSTR pszPath ) - Specifies a path to expand in the dialog box.
• SetOKText( IN LPCTSTR pszText ) - Sets the dialog box "OK" button text.

Notes

If you convert this project to VC 7.0 or later, do not forget to add shlwapi.dll to the list of delay loaded DLLs because it uses ::StrRetToStr function of shlwapi.dll 5.0. Go to "[Project Properties]>[Configuration Properties]>[Linker]>[Input]" and add "shlwapi.dll;" to the list of "[Delay Loaded DLLs]". VC 6.0 project does this using "/DelayLoad" linker option, not supported under VC 7.0 or later.

Version History

• 27 Mar 2002
  • Posted the article.
• 30 Mar 2003
  • Some code changes.
  • Added missing in old Platform SDK new flag definitions.
  • Added support for both MFC 6.0 and 7.0.
  • Added OnIUnknown handler for Microsoft® Windows® XP folder filtration.
  • Added SetExpanded, SetOKText and GetSelectedFolder functions.
• 30 May 2003
  • Added OnSelChanged default implementation.
• 14 Jul 2003
  • Added custom filtering sample for Microsoft® Windows® XP/2003 or later.
  • Set SetExpanded and SetOKText to noinline.
• 07 Jan 2004
  • Added SetRootFolder and GetRootFolder functions.
  • Changed IFolderFilter implementation.
• 15 Feb 2005
  • Small bug fix in DoModal, thanks to WindSeven.

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)