Package io.github.libsdl4j.api.timer

Class SdlTimer

  • public final class SdlTimer
extends Object
    Definitions from file SDL_timer.h

    Header for the SDL time management routines.

    • Method Detail

      • SDL_GetTicks

        public static int SDL_GetTicks()
        Get the number of milliseconds since SDL library initialization.

        This value wraps if the program runs for more than ~49 days.

        This function is not recommended as of SDL 2.0.18; use SDL_GetTicks64() instead, where the value doesn't wrap every ~49 days. There are places in SDL where we provide a 32-bit timestamp that can not change without breaking binary compatibility, though, so this function isn't officially deprecated.

        Returns:
        an unsigned 32-bit value representing the number of milliseconds since the SDL library initialized.
        Since:
        This function is available since SDL 2.0.0.
        See Also:
        SDL_TICKS_PASSED(int, int)

      • SDL_GetTicks64

        public static long SDL_GetTicks64()
        Get the number of milliseconds since SDL library initialization.

        Note that you should not use the SDL_TICKS_PASSED macro with values returned by this function, as that macro does clever math to compensate for the 32-bit overflow every ~49 days that SDL_GetTicks() suffers from. 64-bit values from this function can be safely compared directly.

        For example, if you want to wait 100 ms, you could do this:

         long timeout = SDL_GetTicks64() + 100L;
 while (SDL_GetTicks64() < timeout) {
     // ... do work until timeout has elapsed
 }
        Returns:
        a 64-bit value representing the number of milliseconds since the SDL library initialized.
        Since:
        This function is available since SDL 2.0.18.

      • SDL_TICKS_PASSED

        public static boolean SDL_TICKS_PASSED​(int ticksCountA,
                                       int ticksCountB)
        Compare 32-bit SDL ticks values, and return true if A has passed B.

        This should be used with results from SDL_GetTicks(), as this macro attempts to deal with the 32-bit counter wrapping back to zero every ~49 days, but should _not_ be used with SDL_GetTicks64(), which does not have that problem.

        For example, with SDL_GetTicks(), if you want to wait 100 ms, you could do this:

         int timeout = SDL_GetTicks() + 100;
 while (!SDL_TICKS_PASSED(SDL_GetTicks(), timeout)) {
     // ... do work until timeout has elapsed
 }

        Note that this does not handle tick differences greater than 2^31 so take care when using the above kind of code with large timeout delays (tens of days).

      • SDL_GetPerformanceCounter

        public static long SDL_GetPerformanceCounter()
        Get the current value of the high resolution counter.

        This function is typically used for profiling.

        The counter values are only meaningful relative to each other. Differences between values can be converted to times by using SDL_GetPerformanceFrequency().

        Returns:
        the current counter value.
        Since:
        This function is available since SDL 2.0.0.
        See Also:
        SDL_GetPerformanceFrequency()

      • SDL_GetPerformanceFrequency

        public static long SDL_GetPerformanceFrequency()
        Get the count per second of the high resolution counter.
        Returns:
        a platform-specific count per second.
        Since:
        This function is available since SDL 2.0.0.
        See Also:
        SDL_GetPerformanceCounter()

      • SDL_Delay

        public static void SDL_Delay​(int ms)
        Wait a specified number of milliseconds before returning.

        This function waits a specified number of milliseconds before returning. It waits at least the specified time, but possibly longer due to OS scheduling.

        Parameters:
        ms - the number of milliseconds to delay
        Since:
        This function is available since SDL 2.0.0.

      • SDL_AddTimer

        public static SDL_TimerID SDL_AddTimer​(int interval,
                                       SDL_TimerCallback callback,
                                       com.sun.jna.Pointer param)
        Call a callback function at a future time.

        If you use this function, you must pass SDL_INIT_TIMER to SDL_Init().

        The callback function is passed the current timer interval and the user supplied parameter from the SDL_AddTimer() call and should return the next timer interval. If the value returned from the callback is 0, the timer is canceled.

        The callback is run on a separate thread.

        Timers take into account the amount of time it took to execute the callback. For example, if the callback took 250 ms to execute and returned 1000 (ms), the timer would only wait another 750 ms before its next iteration.

        Timing may be inexact due to OS scheduling. Be sure to note the current time with SDL_GetTicks() or SDL_GetPerformanceCounter() in case your callback needs to adjust for variances.

        Parameters:
        interval - the timer delay, in milliseconds, passed to callback
        callback - the SDL_TimerCallback function to call when the specified interval elapses
        param - a pointer that is passed to callback
        Returns:
        a timer ID or 0 if an error occurs; call SDL_GetError() for more information.
        Since:
        This function is available since SDL 2.0.0.
        See Also:
        SDL_RemoveTimer(SDL_TimerID)

      • SDL_RemoveTimer

        public static boolean SDL_RemoveTimer​(SDL_TimerID id)
        Remove a timer created with SDL_AddTimer().
        Parameters:
        id - the ID of the timer to remove
        Returns:
        true if the timer is removed or false if the timer wasn't found.
        Since:
        This function is available since SDL 2.0.0.
        See Also:
        SDL_AddTimer(int, SDL_TimerCallback, Pointer)