include/SDL_timer.h
author Eli Gottlieb <eligottlieb@gmail.com>
Sun, 23 May 2010 01:27:09 -0400
changeset 4767 dc3fd9b7fcbc
parent 3697 f7b03b6838cb
child 5111 481dabb098ef
permissions -rw-r--r--
I'm actually going to have to alter this proposed API a fair bit, but it's coming along. I want to keep it as orthogonal to the rest of SDL as possible.
     1 /*
     2     SDL - Simple DirectMedia Layer
     3     Copyright (C) 1997-2010 Sam Lantinga
     4 
     5     This library is free software; you can redistribute it and/or
     6     modify it under the terms of the GNU Lesser General Public
     7     License as published by the Free Software Foundation; either
     8     version 2.1 of the License, or (at your option) any later version.
     9 
    10     This library is distributed in the hope that it will be useful,
    11     but WITHOUT ANY WARRANTY; without even the implied warranty of
    12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    13     Lesser General Public License for more details.
    14 
    15     You should have received a copy of the GNU Lesser General Public
    16     License along with this library; if not, write to the Free Software
    17     Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
    18 
    19     Sam Lantinga
    20     slouken@libsdl.org
    21 */
    22 
    23 #ifndef _SDL_timer_h
    24 #define _SDL_timer_h
    25 
    26 /**
    27  *  \file SDL_timer.h
    28  *  
    29  *  Header for the SDL time management routines.
    30  */
    31 
    32 #include "SDL_stdinc.h"
    33 #include "SDL_error.h"
    34 
    35 #include "begin_code.h"
    36 /* Set up for C function definitions, even when using C++ */
    37 #ifdef __cplusplus
    38 /* *INDENT-OFF* */
    39 extern "C" {
    40 /* *INDENT-ON* */
    41 #endif
    42 
    43 /**
    44  *  This is the OS scheduler timeslice, in milliseconds.
    45  */
    46 #define SDL_TIMESLICE		10
    47 
    48 /**
    49  *  This is the maximum resolution of the SDL timer on all platforms.
    50  */
    51 #define TIMER_RESOLUTION	10      /**< Experimentally determined */
    52 
    53 /**
    54  *  Get the number of milliseconds since the SDL library initialization.
    55  *  
    56  *  Note that this value wraps if the program runs for more than ~49 days.
    57  */
    58 extern DECLSPEC Uint32 SDLCALL SDL_GetTicks(void);
    59 
    60 /**
    61  *  Wait a specified number of milliseconds before returning.
    62  */
    63 extern DECLSPEC void SDLCALL SDL_Delay(Uint32 ms);
    64 
    65 /**
    66  *  Function prototype for the timer callback function.
    67  */
    68 typedef Uint32(SDLCALL * SDL_TimerCallback) (Uint32 interval);
    69 
    70 /**
    71  *  Set a callback to run after the specified number of milliseconds has
    72  *  elapsed. The callback function is passed the current timer interval
    73  *  and returns the next timer interval.  If the returned value is the 
    74  *  same as the one passed in, the periodic alarm continues, otherwise a
    75  *  new alarm is scheduled.  If the callback returns 0, the periodic alarm
    76  *  is cancelled.
    77  *  
    78  *  To cancel a currently running timer, call 
    79  *  \code SDL_SetTimer(0, NULL); \endcode
    80  *  
    81  *  The timer callback function may run in a different thread than your
    82  *  main code, and so shouldn't call any functions from within itself.
    83  *  
    84  *  The maximum resolution of this timer is 10 ms, which means that if
    85  *  you request a 16 ms timer, your callback will run approximately 20 ms
    86  *  later on an unloaded system.  If you wanted to set a flag signaling
    87  *  a frame update at 30 frames per second (every 33 ms), you might set a 
    88  *  timer for 30 ms:
    89  *  \code
    90  *    SDL_SetTimer((33/10)*10, flag_update);
    91  *  \endcode
    92  *  
    93  *  If you use this function, you need to pass ::SDL_INIT_TIMER to SDL_Init().
    94  *  
    95  *  Under UNIX, you should not use raise or use SIGALRM and this function
    96  *  in the same program, as it is implemented using setitimer().  You also
    97  *  should not use this function in multi-threaded applications as signals
    98  *  to multi-threaded apps have undefined behavior in some implementations.
    99  *  
   100  *  \return 0 if successful, or -1 if there was an error.
   101  */
   102 extern DECLSPEC int SDLCALL SDL_SetTimer(Uint32 interval,
   103                                          SDL_TimerCallback callback);
   104 
   105 /**
   106  *  \name Peter timers
   107  *  New timer API, supports multiple timers
   108  *  Written by Stephane Peter <megastep@lokigames.com>
   109  */
   110 /*@{*/
   111 
   112 /**
   113  *  Function prototype for the new timer callback function.
   114  *  
   115  *  The callback function is passed the current timer interval and returns
   116  *  the next timer interval.  If the returned value is the same as the one
   117  *  passed in, the periodic alarm continues, otherwise a new alarm is
   118  *  scheduled.  If the callback returns 0, the periodic alarm is cancelled.
   119  */
   120 typedef Uint32(SDLCALL * SDL_NewTimerCallback) (Uint32 interval, void *param);
   121 
   122 /**
   123  *  Definition of the timer ID type.
   124  */
   125 typedef struct _SDL_TimerID *SDL_TimerID;
   126 
   127 /**
   128  *  Add a new timer to the pool of timers already running.
   129  *  \return A timer ID, or NULL when an error occurs.
   130  */
   131 extern DECLSPEC SDL_TimerID SDLCALL SDL_AddTimer(Uint32 interval,
   132                                                  SDL_NewTimerCallback
   133                                                  callback, void *param);
   134 
   135 /**
   136  *  Remove one of the multiple timers knowing its ID.
   137  *  \return A boolean value indicating success or failure.
   138  */
   139 extern DECLSPEC SDL_bool SDLCALL SDL_RemoveTimer(SDL_TimerID t);
   140 
   141 /*@}*//*Peter timers*/
   142 
   143 /* Ends C function definitions when using C++ */
   144 #ifdef __cplusplus
   145 /* *INDENT-OFF* */
   146 }
   147 /* *INDENT-ON* */
   148 #endif
   149 #include "close_code.h"
   150 
   151 #endif /* _SDL_timer_h */
   152 
   153 /* vi: set ts=4 sw=4 expandtab: */