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267 lines
4.0 KiB
267 lines
4.0 KiB
<HTML |
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>SDL_SetTimer</TITLE |
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>SDL Library Documentation</TH |
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>Prev</A |
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> </TD |
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><H1 |
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><A |
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NAME="SDLSETTIMER" |
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></A |
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>SDL_SetTimer</H1 |
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><DIV |
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CLASS="REFNAMEDIV" |
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><A |
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NAME="AEN8557" |
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></A |
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><H2 |
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>Name</H2 |
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>SDL_SetTimer -- Set a callback to run after the specified number of milliseconds has |
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elapsed.</DIV |
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><DIV |
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CLASS="REFSYNOPSISDIV" |
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><A |
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NAME="AEN8560" |
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></A |
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><H2 |
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>Synopsis</H2 |
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><DIV |
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><A |
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NAME="AEN8561" |
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></A |
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><P |
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></P |
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><PRE |
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CLASS="FUNCSYNOPSISINFO" |
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>#include "SDL.h"</PRE |
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><P |
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><CODE |
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><CODE |
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CLASS="FUNCDEF" |
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>int <B |
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CLASS="FSFUNC" |
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>SDL_SetTimer</B |
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></CODE |
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>(Uint32 interval, SDL_TimerCallback callback);</CODE |
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></P |
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><P |
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></P |
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></DIV |
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></DIV |
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><DIV |
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CLASS="REFSECT1" |
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><A |
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NAME="SDLTIMERCALLBACK" |
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></A |
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><H2 |
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>Callback</H2 |
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><P |
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>/* Function prototype for the timer callback function */ |
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typedef Uint32 (*SDL_TimerCallback)(Uint32 interval);</P |
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></DIV |
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><DIV |
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CLASS="REFSECT1" |
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><A |
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NAME="AEN8570" |
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></A |
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><H2 |
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>Description</H2 |
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><P |
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>Set a callback to run after the specified number of milliseconds has |
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elapsed. The callback function is passed the current timer interval |
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and returns the next timer interval. If the returned value is the |
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same as the one passed in, the periodic alarm continues, otherwise a |
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new alarm is scheduled.</P |
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><P |
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>To cancel a currently running timer, call |
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<TT |
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CLASS="FUNCTION" |
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>SDL_SetTimer(0, NULL);</TT |
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></P |
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><P |
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>The timer callback function may run in a different thread than your |
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main constant, and so shouldn't call any functions from within itself.</P |
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><P |
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>The maximum resolution of this timer is 10 ms, which means that if |
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you request a 16 ms timer, your callback will run approximately 20 ms |
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later on an unloaded system. If you wanted to set a flag signaling |
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a frame update at 30 frames per second (every 33 ms), you might set a |
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timer for 30 ms (see example below).</P |
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><P |
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>If you use this function, you need to pass <TT |
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CLASS="LITERAL" |
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>SDL_INIT_TIMER</TT |
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> |
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to <TT |
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CLASS="FUNCTION" |
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>SDL_Init()</TT |
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>.</P |
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><DIV |
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CLASS="NOTE" |
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><BLOCKQUOTE |
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CLASS="NOTE" |
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><P |
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><B |
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>Note: </B |
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>This function is kept for compatibility but has been superseded |
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by the new timer functions |
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<A |
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HREF="sdladdtimer.html" |
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>SDL_AddTimer</A |
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> and |
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<A |
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HREF="sdlremovetimer.html" |
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>SDL_RemoveTimer</A |
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> which support |
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multiple timers.</P |
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CLASS="REFSECT1" |
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><A |
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NAME="AEN8584" |
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></A |
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><H2 |
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>Examples</H2 |
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><P |
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><PRE |
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CLASS="PROGRAMLISTING" |
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>SDL_SetTimer((33/10)*10, my_callback);</PRE |
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></P |
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><DIV |
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CLASS="REFSECT1" |
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><A |
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NAME="AEN8588" |
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></A |
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><H2 |
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>See Also</H2 |
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><P |
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><A |
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HREF="sdladdtimer.html" |
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><TT |
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CLASS="FUNCTION" |
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>SDL_AddTimer</TT |
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></A |
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>SDL_RemoveTimer</TD |
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