glk_request_timer_events ()

void
glk_request_timer_events (glui32 millisecs);

Initially, there is no timer and you get no timer events. If you call glk_request_timer_events(<emphasis>N</emphasis>), with N not 0, you will get timer events about every N milliseconds thereafter. (Assuming that they are supported — if not, glk_request_timer_events() has no effect.) Unlike keyboard and mouse events, timer events will continue until you shut them off. You do not have to re-request them every time you get one. Call glk_request_timer_events(0) to stop getting timer events.

The rule is that when you call glk_select() or glk_select_poll(), if it has been more than N milliseconds since the last timer event, and (for glk_select()) if there is no player input, you will receive an event whose type is evtype_Timer. (win , val1 , and val2 will all be 0.)

Timer events do not stack up. If you spend 10N milliseconds doing computation, and then call glk_select(), you will not get ten timer events in a row. The library will simply note that it has been more than N milliseconds, and return a timer event right away. If you call glk_select() again immediately, it will be N milliseconds before the next timer event.

This means that the timing of timer events is approximate, and the library will err on the side of being late. If there is a conflict between player input events and timer events, the player input takes precedence.