''' <summary>
''' The CountLinesExtensions is an example shell context menu extension,
''' implemented with SharpShell. It adds the command 'Count Lines' to text
''' files.
''' </summary>
<ComVisible(True)> _
<COMServerAssociation(AssociationType.ClassOfExtension, ".txt")> _
Public Class CountLinesExtension
  Inherits SharpContextMenu
  ''' <summary>
  ''' Determines whether this instance can a shell
  ''' context show menu, given the specified selected file list.
  ''' </summary>
  ''' <returns>
  ''' <c>true</c> if this instance should show a shell context
  ''' menu for the specified file list; otherwise, <c>false</c>.
  ''' </returns>
  Protected Overrides Function CanShowMenu() As Boolean
    '  We always show the menu.
    Return True
  End Function

  ''' <summary>
  ''' Creates the context menu. This can be a single menu item or a tree of them.
  ''' </summary>
  ''' <returns>
  ''' The context menu for the shell context menu.
  ''' </returns>
  Protected Overrides Function CreateMenu() As ContextMenuStrip
    '  Create the menu strip.
    Dim menu = New ContextMenuStrip()

    '  Create a 'count lines' item.
    Dim itemCountLines = New ToolStripMenuItem() With { _
      Key .Text = "Count Lines...", _
      Key .Image = Properties.Resources.CountLines _
    }

    '  When we click, we'll count the lines.
    itemCountLines.Click += Function(sender, args) CountLines()

    '  Add the item to the context menu.
    menu.Items.Add(itemCountLines)

    '  Return the menu.
    Return menu
  End Function

  ''' <summary>
  ''' Counts the lines in the selected files.
  ''' </summary>
  Private Sub CountLines()
    '  Builder for the output.
    Dim builder = New StringBuilder()

    '  Go through each file.
    For Each filePath As var In SelectedItemPaths
      '  Count the lines.
      builder.AppendLine(String.Format("{0} - {1} Lines", Path.GetFileName(filePath), File.ReadAllLines(filePath).Length))
    Next

    '  Show the ouput.
    MessageBox.Show(builder.ToString())
  End Sub
End Class

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