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Important: The information in this document is obsolete and should not be used for new development.

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Inside Macintosh: Processes
Chapter 4 - Vertical Retrace Manager / Vertical Retrace Manager Reference
Vertical Retrace Manager Routines / System-Based Installation and Removal Routines


You can use the VInstall function to install a task record into the system-based vertical retrace queue.

FUNCTION VInstall (vblTaskPtr: QElemPtr): OSErr;
A pointer to the task record to add to the queue.
The VInstall function installs the VBL task record specified by the vblTaskPtr parameter in the system-based vertical retrace queue. The Vertical Retrace Manager executes the task at intervals determined by the task record's vblCount and vblPhase fields. The task must reset the value of the task record's vblCount field if you want the task to be executed again.

In current versions of system software, the Vertical Retrace Manager does not continue to execute tasks installed using the VInstall function when the application that installed them is switched out, unless the address in the vblAddr field of the task record points in the system partition.

The registers on entry and exit for VInstall are
Registers on entry
A0Pointer to the task record
Registers on exit
D0Result code

noErr0No error
vTypErr-2Invalid qType value (must be ORD(vType))

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© Apple Computer, Inc.
17 JUN 1996