Legacy Document

Inside Macintosh: Processes

Chapter 4 - Vertical Retrace Manager / Vertical Retrace Manager Reference

Vertical Retrace Manager Routines / Utility Routines

GetVBLQHdr

You can obtain the header of the system-based vertical retrace queue by calling the GetVBLQHdr function.

FUNCTION GetVBLQHdr: QHdrPtr;

DESCRIPTION

The GetVBLQHdr function returns a pointer to the header of the system-based vertical retrace queue. In general, you need to call this function only if you want to manipulate the contents of the system-based vertical retrace queue directly or if you want to read the information stored in the queue header.

ASSEMBLY-LANGUAGE INFORMATION

The global variable VBLQueue contains the header of the system-based vertical retrace queue.

The global variable ScrnVBLPtr contains a pointer to the header of the vertical retrace queue associated with the slot for the primary monitor.