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ICustomDestinationList::AppendCategory method

Defines a custom category and the destinations that it contains, for inclusion in a custom Jump List.

Syntax


HRESULT AppendCategory(
  [in]  LPCWSTR pszCategory,
  [in]  IObjectArray *poa
);

Parameters

pszCategory [in]

Type: LPCWSTR

A pointer to a string that contains the display name of the custom category. This string is shown in the category's header in the Jump List. The string can directly hold the display name or it can be an indirect string representation, such as "@shell32.dll,-1324", to use a stored string. An indirect string enables the category header to be displayed in the user's selected language.

Note  Each custom category must have a unique name. Duplicate category names will cause presentation issues in the Jump List.

poa [in]

Type: IObjectArray*

A pointer to an IObjectArray that represents one or more IShellItem objects that represent the destinations in the category. Some destinations in the list might also be represented by IShellLink objects, although less often.

Note  Any IShellLink used here must declare an argument list through SetArguments. Adding an IShellLink object with no arguments to a custom category is not supported since a user cannot pin or unpin this type of item from a Jump List, nor can they be added or removed.

Return value

Type: HRESULT

Returns S_OK if successful, or an error value otherwise.

If the call to AppendCategory attempts to add an item that is in the removed destinations list retrieved by the call to BeginList that initiated the session, the call to AppendCategory fails.

If AppendCategory attempts to add an IShellItem that the application is not registered to handle, the call fails.

AppendCategory can fail if there is a privacy Group Policy or user privacy setting turned on. Custom categories contain user-specific items based on individual usage, which is not allowed under those privacy settings.

A privacy Group Policy or user privacy setting will not cause a failure in any other ICustomDestinationList method. Tasks are not user-specific. AppendKnownCategory will not result in the display of the Recent or Frequent categories because they will have no data, but the method call will not return a failure code.

In the case of a failure code in AppendCategory caused by privacy Group Policy or user privacy setting (E_ACCESSDENIED), the application should continue to update tasks and call CommitList.

If no file type registration was found for the associated application, AppendCategory returns HRESULT 0x80040F03. This can result from an application not registering the file type it is trying to add to the Jump List or from a problem in the registration, such as not providing the AppUserModelID when the application is using an explicit AppUserModelID.

Remarks

You must call BeginList before you call this method.

If an application provides a custom category, that application assumes responsibility for populating it. The category contents should still be user-specific and based on the user's history and actions, but by using a custom category an application can determine what it wants to track and what it wants to ignore. For instance, different scenarios could be involved when different application options are chosen. For example, an audio program might elect to include only recently played albums and ignore recently played individual tracks. An application might also simply have a usage-tracking algorithm tailored to its specific use that gives better results than the system's default algorithms.

An application can call AppendCategory more than once in a list-building session to add multiple custom categories. In this case, the categories should be designed so that their contents are mutually exclusive. Each custom category should be built around a specific scenario so that items are not duplicated between them.

Categories in a custom Jump List, including the known Recent or Frequent categories, are shown in the order that they are added, with the most recent items added to the end of the list. If there is insufficient space to show all entries, the last entries in the list disappear off the screen first. Therefore, the most important categories should be added first to ensure their best chance of being always shown. Destinations within the category are shown in the order that they are stored in the IObjectArray object pointed to by poa.

The user might decide to pin one or more of the destinations provided in the custom category to the Jump List. The list of pinned destinations is not available to the application, but duplication is prevented by the UI so no extra action is required of the application. Visually, a pinned item moves to the Pinned section of the Jump List and disappears from its original location.

A successful call to AppendCategory does not guarantee that those items will be displayed. Any number of destinations added over the value pointed to by the pcMinItems parameter in ICustomDestinationList::BeginList are not shown. The Pinned category takes priority over all other destination lists. The Pinned list is displayed, then the remaining space is allocated to the other destination lists. It is possible for a user to pin enough destinations to the Jump List to keep any other destinations from displaying. Other factors, such as a reduced screen resolution or an increased font size, can also cause application-provided destinations to be truncated from the list. The application has no way of predicting these situations and is not notified when they occur. The application must just be aware that the possibility exists. Because truncation of the destination list or lists occurs from the bottom up, the application should put its most important categories and destinations at the top of the list so that they have the best chance of being shown.

During a session started with BeginList and ending with CommitList, you might call AppendCategory more than once. If any one of those calls fails because of an attempt to add a category that contains an item in the removed items list, the call to CommitList does not clear the removed items list. For the removed items list to be cleared, all calls to AppendCategory in a session must return successfully.

IShellLink instances provided through the IObjectArray pointed to by poa must provide the following:

The display name must be set through the item's System.Title (PKEY_Title) property. The property can directly hold the display name or it can be an indirect string representation, such as "@shell32.dll,-1324", to use a stored string. An indirect string enables the item name to be displayed in the user's selected language.

Optionally, the description field (SetDescription) can be set to provide a custom tooltip for the item in the Jump List.

Requirements

Minimum supported client

Windows 7 [desktop apps only]

Minimum supported server

Windows Server 2008 R2 [desktop apps only]

Header

Shobjidl.h

IDL

Shobjidl.idl

Library

Shell32.lib

DLL

Shell32.dll (version 6.1 or later)

See also

ICustomDestinationList
ICustomDestinationList::AppendKnownCategory
ICustomDestinationList::AddUserTasks
Taskbar Extensions

 

 

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