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| >SDL_SetEventFilter</H1 |
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| NAME="AEN5575" |
| ></A |
| ><H2 |
| >Name</H2 |
| >SDL_SetEventFilter -- Sets up a filter to process all events before they are posted |
| to the event queue.</DIV |
| ><DIV |
| CLASS="REFSYNOPSISDIV" |
| ><A |
| NAME="AEN5578" |
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| >Synopsis</H2 |
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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 |
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| ><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 |
| ><DIV |
| CLASS="NOTE" |
| ><BLOCKQUOTE |
| CLASS="NOTE" |
| ><P |
| ><B |
| >Note: </B |
| >Events pushed onto the queue with <A |
| HREF="sdlpushevent.html" |
| ><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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| ><BLOCKQUOTE |
| CLASS="NOTE" |
| ><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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| ></DIV |
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| CLASS="REFSECT1" |
| ><A |
| NAME="AEN5602" |
| ></A |
| ><H2 |
| >See Also</H2 |
| ><P |
| ><A |
| HREF="sdlevent.html" |
| ><SPAN |
| CLASS="STRUCTNAME" |
| >SDL_Event</SPAN |
| ></A |
| >, |
| <A |
| HREF="sdlgeteventfilter.html" |
| ><TT |
| CLASS="FUNCTION" |
| >SDL_GetEventFilter</TT |
| ></A |
| >, |
| <A |
| HREF="sdlpushevent.html" |
| ><TT |
| CLASS="FUNCTION" |
| >SDL_PushEvent</TT |
| ></A |
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