Important: The information in this document is obsolete and should not be used for new development.
Using the Vertical Retrace ManagerYou can use the Vertical Retrace Manager to install VBL task records in and remove VBL task records from system-based or slot-based vertical retrace queues. To install a task record, you must first fill in some of its fields and then call either
SlotVInstall. See the next section, "Installing a VBL Task," for information on installing VBL tasks.
If it is to be executed more than once, a VBL task must access the task record and reset the value of the task record's
vblCountfield. The section "Accessing a Task Record at Interrupt Time" on page 4-12 describes this technique. To disable a task temporarily, you can simply set the
vblCountfield of its task record to 0. To remove a VBL task from its VBL queue, call
VRemoveif you installed the task by calling
SlotVRemoveif you installed the task by calling
If your VBL task needs to access your application global variables, you can put the application's A5 value or the global variables themselves into the second field of a record whose first field contains the VBL task itself. The sections "Accessing Application Global Variables in a VBL Task," beginning on page 4-13, and "Spinning the Cursor," beginning on page 4-16, explain these techniques.
- Installing a VBL Task
- Accessing a Task Record at Interrupt Time
- Accessing Application Global Variables in a VBL Task
- Spinning the Cursor
- Installing a Persistent VBL Task