IDLitData::NotifyDataChange

Syntax | Arguments | Keywords | Version History

The IDLitData::NotifyDataChange procedure method is called when a data object has been changed; it is part of the notification process that allows data updates to be reflected by visualizations that use the data. It works in conjunction with the NotifyDataComplete method to provide a two-pass change notification system that minimizes the number of operations performed when a data object changes.

When NotifyDataChange is called, the OnDataChange methods of all observers of the data object (usually visualizations) are automatically called. This causes the observers to perform any necessary updates without committing those updates. When the NotifyDataComplete method is called, the observers' OnDataComplete methods are called to commit the updates. This two-pass system allows visualizations to be notified that the data has changed without forcing an immediate redraw of the iTool window; when the NotifyDataComplete method is called, all visualizations can be redrawn at once.

Every call to the NotifyDataChange method must have an accompanying NotifyDataComplete call; without the call to NotifyDataComplete, no updates will take place.

Note
If the data object is being changed by an operation based on the IDLitDataOperation class, the call to NotifyDataChange is handled automatically. The only time you will need to call this method directly is if the operation that modifies the data is based on the more generic IDLitOperation class.

Syntax

Obj->[IDLitData::]NotifyDataChange

Arguments

None

Keywords

None

Version History