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Inside Macintosh: Macintosh Toolbox Essentials /

Chapter 2 - Event Manager / Event Manager Reference

Event Manager Routines / Receiving Events

SystemTask

In a multiple-application environment, the WaitNextEvent function is responsible for giving time to each open desk accessory or driver to perform any periodic action. You should not call SystemTask if your application calls WaitNextEvent.

If your application calls GetNextEvent, your application should call the SystemTask procedure.

PROCEDURE SystemTask;

DESCRIPTION

The SystemTask procedure gives time to each open desk accessory or driver to
perform the periodic action defined for it. A desk accessory or device driver specifies how often the periodic action should occur, and SystemTask gives time to the desk accessory or device driver at the appropriate interval.

If your application calls GetNextEvent, your application should call SystemTask at least every sixtieth of a second. This usually corresponds to calling SystemTask once each time through your event loop. If your application does a large amount of processing, you may need to call SystemTask more than once in your event loop.

SEE ALSO

For a description of the WaitNextEvent function and the GetNextEvent function, see page 2-85 and page 2-89, respectively.