WPF Folder Browser - CodeProject

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Introduction

This is a folder browser for WPF similar to the one found in Windows forms. WPF currently does not provide a Folder browser dialog and the only thing near enough is the Microsoft.Win32.OpenFileDialog class in WPF's PresentationFramework.dll assembly which lets users specify multiple files to open.

Using the Code

The code contains only one XAML file which houses different parts of the dialog. The dialog is loosely based on the Windows file/ folder dialog model as it has a commonly selected folder area and a Windows explorer style treeview. The selected folder is displayed in the textbox at the bottom of the dialog. The code uses MVVM and has a dependency on the latest prism binaries but this is for the DelegateCommand only. The main ViewModel which the dialog binds to is the BrowserViewModel, this initializes the treeview to point to all the drives on the machine. It has a SelectedFolder property & a FolderSelected DelegateCommand which is invoked when the user selects a common folder on the left.

public DelegateCommand<object> FolderSelectedCommand
     {
         get
         {
             return new DelegateCommand<object>(it => SelectedFolder = 
		Environment.GetFolderPath((Environment.SpecialFolder)it));
         }
     }

The folders themselves are expressed in terms of a FolderViewModel which takes an ObservableCollection of FolderViewModels to represent sub folders. The treeview in the folder dialog is bound to this FolderViewModel. The FolderViewModel implements IsExpanded & IsSelected properties to add functionality to the TreeViewItem state, i.e., to dynamically load sub folders on selection/expansion of a node. Selecting a node also expands it similar to the Windows Explorer.

private void LoadFolders()
     {
         try
         {
             if (Folders.Count > 0)
                 return;

             string[] dirs = null;

             string fullPath = Path.Combine(FolderPath, FolderName);

             if (FolderName.Contains(':'))//This is a drive
                 fullPath = string.Concat(FolderName, "\\");
             else
                 fullPath = FolderPath;

             dirs = Directory.GetDirectories(fullPath);

             Folders.Clear();
             
             foreach (string dir in dirs)
                 Folders.Add(new FolderViewModel 
                 { Root = this.Root, FolderName = Path.GetFileName(dir), 
                 FolderPath = Path.GetFullPath(dir), 
                 FolderIcon = "Images\\FolderClosed.png" });

             if (FolderName.Contains(":"))
                 FolderIcon = "Images\\HardDisk.ico";

             Root.SelectedFolder = FolderPath;
         }
         catch (UnauthorizedAccessException ae)
         {
             Console.WriteLine(ae.Message);
         }
         catch (IOException ie)
         {
             Console.WriteLine(ie.Message);
         }
     }

Points of Interest

One of the things I came across while creating this control was that the WPF binding for the SpecialFolder enum in the Environment class did not work. Initially I thought that this was due to the enum being nested, but actually it is due to the fact that nested types are not supported in XAML. A workaround for this was to append a '+' instead of a '.' for the nested enum (e.g.: Environment+SpecialFolder.Desktop).