The List Objects: 4 GenDynamicListClass

The GenDynamicListClass is a subclass of GenItemGroupClass that allows an application to pass monikers to the object as needed rather than specify a GenItem for each item in the list. In almost all cases, you will want a GenDynamicList to be a scrolling list so that not all of the list entries will be displayed at any given time. (You can, however, still choose to create a non-scrolling dynamic list.)

The GenDynamicList displays a list of monikers; this list of monikers is usually in the form of a data chunk managed by some other (application-supplied) object. For each moniker the GenDynamicList wishes to display, it will send out a query message and the position of the moniker requested. The object handling the query message will return a pointer to the moniker and will draw the moniker within the GenDynamicList. In this way, monikers for a GenDynamicList are only drawn as needed.

The dynamic list allows the following:

Long Lists
Very long lists can be stored by the application in any way it wants and as efficiently as possible. Because these lists are often scrolling lists, the UI is not cluttered up with a multitude of list entries. Only those within the scroller's bounds will be visually displayed.
Dynamic Display of Data
Applications can easily create a scrolling list from arbitrarily organized data. As long as you provide a means to convert the data into the proper moniker format, you can use any data you wish for moniker entries. You can also dynamically access this data and update the list entries.

An application specifies the number of items in the list and if desired can set up a custom size for the dynamic list. Whenever the object needs to display a moniker, it will query its destination for the visual moniker to display as an item in the list. At any time, the application can remove or add items from the dynamic list or change the total number of items and start with all new items. Because the list only queries for items as they become visible, it is more efficient than having to display a large number of entries in a long list.

Since GenDynamicListClass is a subclass of GenItemGroupClass , all of the same messages that are passed to GenItemGroups can be passed to GenDynamicList (except MSG_GEN_ITEM_GROUP_GET_ITEM_OPTR , which has no meaning for a GenDynamicList). The lists can be exclusive, exclusive-none, extended-selection, or non-exclusive. The user can select and deselect items depending on the behavior type, etc.

DynamicList Instance Data

DynamicList Basics

Altering Instance Data

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