Working With Progress and Cover Functions(IM:Q)

Chapter 2 - Movie Toolbox / Movie Toolbox Reference

Functions for Getting and Playing Movies

Working With Progress and Cover Functions
The Movie Toolbox allows your application to assign two types of custom functions: progress functions and cover functions. These functions allow you to perform special processing under certain circumstances.
Some Movie Toolbox functions can take a long time to execute. For example, if you call the FlattenMovie function and specify a large movie, the Movie Toolbox must read and write all the sample data for the movie. During such operations you may wish to display some kind of progress indicator to the user.
A progress function is an application-defined function that you can use to track the progress of time-consuming activities, and thereby keep the user informed about that progress.
The Movie Toolbox allows your application to perform custom processing whenever one of your movie's tracks covers a screen region or reveals a region that was previously covered. You perform this processing in cover functions.
There are two types of cover functions: those that are called when your movie covers a screen region, and those that are called when your movie uncovers a screen region that was previously covered. Cover functions that are called when your movie covers a screen region are responsible for erasing the region--you may choose to save the hidden region in an offscreen buffer. Cover functions that are called when your movie reveals a hidden screen region must redisplay the hidden region.

Note
The Movie Toolbox does not call your cover function in response to changes to the movie's transformation matrix (for example, changing the matrix by calling the SetMovieBox function, which is described on page 2-146, does not cause your cover function to be invoked).
For a complete discussion of progress and cover functions, see "Application-Defined Functions," which begins on page 2-332.
The SetMovieProgressProc function helps your application work with progress functions and the SetMovieCoverProcs function helps your application work with cover functions.

Subtopics

SetMovieProgressProc

SetMovieCoverProcs