Inside Macintosh: QuickTime Components /

Chapter 11 - Clock Components / Clock Components Reference

Movie Toolbox Clock Support Functions /

GetFirstCallBack

The GetFirstCallBack function returns the first callback event associated with a specified time base. Your component can use this function, along with the GetNextCallBack function (described in the next section), to scan all callback events associated with a time base.

pascal QTCallBack GetFirstCallBack (TimeBase tb);

tb

Specifies the time base for the operation. Your component can obtain the time base reference from your ClockSetTimeBase function (described on page 11-15) or from the Movie Toolbox's GetCallBackTimeBase function.

DESCRIPTION

The GetFirstCallBack function returns the first callback event in the list managed
for the specified time base. If there are no callback events associated with the time base, the QTCallBack result is set to nil. Your component cannot assume that the Movie Toolbox maintains the callback list in any particular order.

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