Writing Shell Namespace Extensions Krishna Kotipalli Microsoft Product Support

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Writing Shell Namespace Extensions Krishna
KotipalliMicrosoft Product Support
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Objectives

• Understand what a Shell Namespace is
• Learn how to extend the Shell Namespace
• Understand the various COM interfaces related to
  extending the Shell Namespace

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Prerequisites

• Microsoft Win32 programming
• Knowledge of COM

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Shell Namespace

• What is a Shell Namespace?
• Type of Shell Namespace
• Examples of Shell Namespace

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Extending the Shell Namespace

• Why to extend the Shell Namespace?
• What can be done?
• What cannot be done?

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PIDL

• What is a pidl?
• ITEMIDLIST
• typedef struct _ITEMIDLIST
• SHITEMID mkid
• ITEMIDLIST
• SHITEMID
• typedef struct _SHITEMID
• USHORT cb // size of the ID (including cb
  itself)
• BYTE abID1 // The item ID (variable length)
• SHITEMID

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PIDL (continued)
PIDL

• A pidl to C\Pics\MtRainier.jpg would be

Remember PIDLs are OPAQUE
PIDLs should always be allocated with Shells
Memory allocator (obtained via SHGetMalloc)
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Some Shell Namespace Related Interfaces

• IShellBrowser
• IShellFolder
• IShellView
• IEnumIDList

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IShellFolder Methods

• BindToObject retrieves IShellFolder interface
  for the specified subfolder
• BindToStorage returns the storage instance of a
  subfolder. Not implemented currently
• CompareIDs Determines relative order of two
  file/folder objects, given their item identifier
  lists
• CreateViewObject Creates a view object of the
  folder itself
• EnumObjects Enumerates the objects in a folder
• GetAttributesOf Retrieves the attributes of the
  specified file object or subfolder.
• GetDisplayNameOf Retrieves the display name of a
  file object or subfolder
• GetUIObjectOf Creates an OLE interface that can
  be used to carry out operations on a file object
  (or objects) or subfolder(s).
• ParseDisplayName Translates a display name into
  an item identifier list.
• SetNameOf Sets the display name of the specified
  file object or subfolder and changes its
  identifier accordingly.

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IShellView Methods

• AddPropertySheetPages Allows the view to add
  pages to the Options property sheet.
• CreateViewWindow Creates the view window.
• DestroyViewWindow Destroys the view window
• EnableModeless Enables or disables modeless
  dialog boxes. Not in use.
• EnableModelessSV Not in use.
• GetCurrentInfo Returns the current folder
  settings
• GetItemObject Allows callers to get an object
  that represents something in the view.
• Refresh Refreshes the display in response to
  user input.
• SaveViewState Saves the shells view setting
• SelectItem Changes the state of items within the
  shell view window
• TransalteAccelerator Translates accelerator key
  strokes when the view has the focus.
• UIActivate Called whenever the activation state
  of the view windows is changed by an event not
  caused by the shell view itself.

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IEnumIDList Methods

• Clone Creates a new item enumeration object
  identical to the current one.
• Next Retrieves the specified number of item
  identifiers.
• Reset Returns to the beginning of the
  enumeration.
• Skip Skips over the specified number of items.

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IShellBrowser Methods

• BrowseObject Tells the container to browse in
  another folder.
• EnableModelessSB Enables or disables modeless
  windows of the container.
• GetControlWindow Gets the window handle to the
  container.
• GetViewStateStream Returns a view-specific
  stream that can be used to read and write the
  persistent data for a view.
• InsertMenusSB Inserts menu items to an empty
  menu created by the view.
• OnViewWindowActive Informs that the view was
  activated.
• QueryActiveShellView Returns the currently
  activated shell view object.
• RemoveMenusSB Instructs the container to remove
  its items from a composite menu.
• SendControlMsg Sends messages to the containers
  controls.
• SetMenuSB Installs the composite menu in the
  container.
• SetStatusTextSB Sets and displays status text
  for the container.
• SetToolbarItems Adds toolbar items to the
  containers toolbar.
• TranslateAcceleratorSB reserved for future use.

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An Example

• Display context menu given a filesystem
  file/folder path.
• Get the parent folder.
• Obtain the IShellFolder for the parent folder.
• Get the pidl to the file name with respect to the
  parent folders IShellFolder
• Get the IContextMenu interface for the parent
  folder by calling IShellFolderGetUIObjectOf
  with riidIID_IContextMenu
• Get the HMENU by calling QueryContextMenu with
  the pidl to the (child) file/folder name
• Display the context menu using TrackPopupMenu
• More information is available in KB article
  Q198288.

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A Shell Namespace Extension

• COM in-proc server
• DllGetClassObject
• DllCanUnloadNow
• DllRegisterServer
• DllUnregisterServer
• Registry Entries
• HKEY_CLASSES_ROOT\CLSID\CLSID
• DefaultIcon
• Default REG_SZ
• ShellFolder
• Attributes REG_BIN
• Admin privileges on Windows NT,
• HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\Cur
  rentVersion\Shell Extensions\ Approved
• CLSID REG_SZ

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Junction Point

• On Desktop or My Computer
• HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\Cur
  rentVersion\Explorer
• Desktop\Namespace\CLSID
• Default REG_SZ
• MyComputer\Namespace\CLSID
• Default REG_SZ
• Folder.CLSID method
• Desktop.ini method

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An Empty Shell Namespace Extension

• Support self-registration
• IShellFolder implementation
• Return a pointer to implementation of
  IShellFolder in response to DllGetClassObject
  (with REFIID of IID_IShellFolder)
• Handle initializations via IShellFolderInitializ
  e
• Handle IShellFolderCreateViewObject by creating
  an instance of IShellView object
• IShellView implementation
• Create a window in response to IShellViewCreateV
  iewWindow

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A Basic Shell Namespace Extension

• Support self-registration
• Data structure for the items
• IEnumIDList implementation
• IShellFolder implementation
• IShellFolderInitialize
• IShellFolderEnumObjects
• IShellFolderCreateViewObject
• IShellFolderGetDisplayNameOf
• IShellView implementation
• IShellViewCreateViewWindow
• Create the view window (usually a list control),
  initialize, populate
• Delegate idlist related calls to the parent
  ShellFolder
• Handle selection, mouse events, and so forth.

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A Functional Shell Namespace Extension

• IShellFolder
• GetAttributesOf
• BindToObject
• CompareIDs
• IShellView
• UIActivate
• IShellBrowser
• SendControlMsg
• InsertMenusSB
• RemoveMenusSB
• SetToolbarItems

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Summary

• Shell Namespace Architecture
• IShellBrowser, IShellFolder, IShellView,
  IEnumIDList et al
• Data hiding using PIDLs
• IShellFolder - IShellView - IShellBrowser
  interaction

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Resources

• http//msdn.microsoft.com/library/sdkdoc/shellcc/s
  hell/namespace.htm
• http//www.microsoft.com/mind/0399/faq/faq0399.htm
  (article plus the AppWizard to generate Shell
  NameSpace Extensions)
• Knowledge Base articles
• Q198288 - HOWTO Displaying Context Menu Given
  the Path to a File
• Q216954 - HOWTO Support Common Dialog Browsing
  in a Shell Namespace Extension
• Q183860 - HOWTO Support Dropping of Items on
  Your Namespace Root
• Q179900 - HOWTO Support Renaming of Items in the
  Windows Explorer Tree
• Q182379 - HOWTO Support Toolbar Item Text in a
  Shell Namespace Extension
• Q198871 - PRB IShellFolderGetDisplayNameOf
  Returns Names with GUIDs
• Q178665 - SAMPLE RegView.exe Contains Shell
  Namespace Extension Example

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