view docs/html/sdlseteventfilter.html @ 2197:2ff40f30af31

Merged r3261:3262 from branches/SDL-1.2: MMX/YUV with __OPTIMIZE__. "Mac OS X/x86 won't build the MMX/YUV inline assembly without optimizations enabled (not enough registers), so for now, we only build it if we see the __OPTIMIZE__ #define, which GCC provides when you build at -O1 or higher."
author Ryan C. Gordon <icculus@icculus.org>
date Sat, 14 Jul 2007 07:28:45 +0000
parents 355632dca928
children
line wrap: on
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>SDL_SetEventFilter</TITLE
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><H1
><A
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>SDL_SetEventFilter</H1
><DIV
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><A
NAME="AEN5575"
></A
><H2
>Name</H2
>SDL_SetEventFilter&nbsp;--&nbsp;Sets up a filter to process all events before they are posted 
to the event queue.</DIV
><DIV
CLASS="REFSYNOPSISDIV"
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><H2
>Synopsis</H2
><DIV
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><P
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><PRE
CLASS="FUNCSYNOPSISINFO"
>#include "SDL.h"</PRE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>void <B
CLASS="FSFUNC"
>SDL_SetEventFilter</B
></CODE
>(SDL_EventFilter filter);</CODE
></P
><P
></P
></DIV
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><DIV
CLASS="REFSECT1"
><A
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></A
><H2
>Description</H2
><P
>This function sets up a filter to process all events before they are posted 
to the event queue.  This is a very powerful and flexible feature.  The filter 
is prototyped as:
<PRE
CLASS="PROGRAMLISTING"
>typedef int (*SDL_EventFilter)(const SDL_Event *event);</PRE
>
If the filter returns <SPAN
CLASS="RETURNVALUE"
>1</SPAN
>, then the event will be 
added to the internal queue.  If it returns <SPAN
CLASS="RETURNVALUE"
>0</SPAN
>, 
then the event will be dropped from the queue.  This allows selective
filtering of dynamically.</P
><P
>There is one caveat when dealing with the <TT
CLASS="LITERAL"
>SDL_QUITEVENT</TT
> event type.  The
event filter is only called when the window manager desires to close the
application window.  If the event filter returns 1, then the window will
be closed, otherwise the window will remain open if possible.
If the quit event is generated by an interrupt signal, it will bypass the
internal queue and be delivered to the application at the next event poll.</P
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><P
><B
>Note: </B
>Events pushed onto the queue with <A
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><TT
CLASS="FUNCTION"
>SDL_PushEvent</TT
></A
> or <A
HREF="sdlpeepevents.html"
><TT
CLASS="FUNCTION"
>SDL_PeepEvents</TT
></A
> do not get passed through the event filter.</P
></BLOCKQUOTE
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><P
><B
>Note: </B
><SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>Be Careful!</I
></SPAN
> The event filter function may run in a different thread so be careful what you do within it.</P
></BLOCKQUOTE
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><H2
>See Also</H2
><P
><A
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><SPAN
CLASS="STRUCTNAME"
>SDL_Event</SPAN
></A
>,
<A
HREF="sdlgeteventfilter.html"
><TT
CLASS="FUNCTION"
>SDL_GetEventFilter</TT
></A
>,
<A
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><TT
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>SDL_PushEvent</TT
></A
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