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Undo for Tracks

The Movie Toolbox provides functions that allow you to capture and restore the edit state of a track. As with the functions that manipulate a movie’s edit state, you can manage a track’s edit states in order to implement an undo capability for track editing. For example, you can capture a track’s edit state before performing an editing operation, such as a cut, and later restore the old state. You can have several track edit states obtained at different times during an editing session, and you can restore to any one of them at any time. In this manner, you can provide a multilevel undo capability. This section describes the Movie Toolbox functions that work with track edit states.

Note that a track’s edit state does not save everything about the track. Most important, the edit state does not contain information about track spatial characteristics. For example, the edit state does not store the current clipping region. Consequently, edit states are best suited to supporting undo operations involving track content. You can use other Movie Toolbox functions to support undo operations for track characteristics. See “Functions That Modify Movie Properties” to learn more about these functions.

You can use the NewTrackEditState function to capture a track’s edit state. Use the UseTrackEditState function to restore the track to its condition according to a previous edit state. Your application can dispose of an edit state by calling the DisposeTrackEditState function.

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