Inside Macintosh: QuickTime Components /

Chapter 11 - Clock Components / Clock Components Reference

Clock Component Functions / Using the Callback Functions

ClockCancelCallBack

Your clock component's ClockCancelCallBack function removes the specified callback event from the list of scheduled callback events for a time base.

pascal ComponentResult ClockCancelCallBack 
                                       (ComponentInstance aClock, 
                                        QTCallBack cb)

aClock

Specifies the clock for the operation. Your application obtains this identifier from the Component Manager's OpenComponent function.

cb

Specifies the callback event for the operation. The Movie Toolbox obtains this value from your component's ClockNewCallBack function (described on page 11-9).

DESCRIPTION

The Movie Toolbox calls this function when an application cancels its callback event by calling CancelCallBack. The Movie Toolbox also calls this function whenever it executes the callback event, thus removing it from the list of scheduled callback events. The application is then responsible for rescheduling the event, if appropriate.

If your clock component successfully cancels the callback event, you should call the RemoveCallBackFromTimeBase function, described on page 11-17, so that the Movie Toolbox can remove the callback event from its list of scheduled events.