Timers and random numbers

Repeating timers, reading the clock, random numbers.

For the full list see "UI development". Each call below comes with a one-line usage note and an example; signatures come from Lib/c/vml_ui.h (the authoritative source).

ui_math_rand(int n)

A random number: ui_math_rand(n) gives 0..n-1 (for n <= 0 it returns 1, so it never crashes).

int n = ui_math_rand(6);      /* 0..5 */
int side = ui_math_rand(2);   /* 0 or 1 */

ui_time_get_ms(void)

Milliseconds since boot (for measuring frame intervals yourself, and for animation).

int now = ui_time_get_ms();

ui_timer_kill(int timerId)

Stops a timer. Note: the timer is repeating - relying on "a KeyUp will always arrive" to stop it is not reliable, so build in your own brake (a new key takes over / stop after two ticks with no movement / a cap on the total number of ticks).

ui_timer_kill(1);

ui_timer_set(int interval_ms, int tag)

Starts a repeating timer that posts one VML_MSG_TIMER every N milliseconds (msg[1] is the id you passed in).

ui_timer_set(1, 100);   /* one every 100ms, id=1 */