Sends a message at the specified VBL time.

TimerHandle TimerMsgAtTimeVBL (Item msgport, uint32 fields, uint32 userdata1, uint32 userdata2)

Creates a timer that notifies you by message at the specified VBL time. The timer is a one-shot; after sending a notification message the timer enters a suspended state. Use TimerReset() to reactivate the timer using new time values, or TimerCancel() to delete the timer.

The notification message is a SMALL message containing as values the userdata1 and userdata2 values specified in this call.

The TimerServices thread must be active before calling this function.

• msgport Port to which the notification message is sent.

• fields VBL field count at which the event occurs.

• userdata1 Value passed back to you in the msg_DataPtr field of the notification message.

• userdata2 Value passed back to you in the msg_DataSize field of the notification message.

A TimerHandle (a positive value) on success or a negative error code.

Library call implemented in lib3do.lib.

lib3do.lib, timerutils.h

TimerMsgAfterDelayVBL, TimerMsgHeartbeatVBL