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Initial revision
author Sam Lantinga <slouken@lokigames.com>
date Thu, 26 Apr 2001 16:45:43 +0000
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children 55f1f1b3e27d
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1 <HTML
2 ><HEAD
3 ><TITLE
4 >SDL_SetEventFilter</TITLE
5 ><META
6 NAME="GENERATOR"
7 CONTENT="Modular DocBook HTML Stylesheet Version 1.61
8 "><LINK
9 REL="HOME"
10 TITLE="SDL Library Documentation"
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13 TITLE="Event Functions."
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19 TITLE="SDL_GetEventFilter"
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21 ><BODY
22 CLASS="REFENTRY"
23 BGCOLOR="#FFF8DC"
24 TEXT="#000000"
25 LINK="#0000ee"
26 VLINK="#551a8b"
27 ALINK="#ff0000"
28 ><DIV
29 CLASS="NAVHEADER"
30 ><TABLE
31 WIDTH="100%"
32 BORDER="0"
33 CELLPADDING="0"
34 CELLSPACING="0"
35 ><TR
36 ><TH
37 COLSPAN="3"
38 ALIGN="center"
39 >SDL Library Documentation</TH
40 ></TR
41 ><TR
42 ><TD
43 WIDTH="10%"
44 ALIGN="left"
45 VALIGN="bottom"
46 ><A
47 HREF="sdlpushevent.html"
48 >Prev</A
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59 ><A
60 HREF="sdlgeteventfilter.html"
61 >Next</A
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64 ></TABLE
65 ><HR
66 ALIGN="LEFT"
67 WIDTH="100%"></DIV
68 ><H1
69 ><A
70 NAME="SDLSETEVENTFILTER"
71 >SDL_SetEventFilter</A
72 ></H1
73 ><DIV
74 CLASS="REFNAMEDIV"
75 ><A
76 NAME="AEN4957"
77 ></A
78 ><H2
79 >Name</H2
80 >SDL_SetEventFilter&nbsp;--&nbsp;Sets up a filter to process all events before they are posted
81 to the event queue.</DIV
82 ><DIV
83 CLASS="REFSYNOPSISDIV"
84 ><A
85 NAME="AEN4960"
86 ></A
87 ><H2
88 >Synopsis</H2
89 ><DIV
90 CLASS="FUNCSYNOPSIS"
91 ><A
92 NAME="AEN4961"
93 ></A
94 ><P
95 ></P
96 ><PRE
97 CLASS="FUNCSYNOPSISINFO"
98 >#include "SDL.h"</PRE
99 ><P
100 ><CODE
101 ><CODE
102 CLASS="FUNCDEF"
103 >void <B
104 CLASS="FSFUNC"
105 >SDL_SetEventFilter</B
106 ></CODE
107 >(SDL_EventFilter filter);</CODE
108 ></P
109 ><P
110 ></P
111 ></DIV
112 ></DIV
113 ><DIV
114 CLASS="REFSECT1"
115 ><A
116 NAME="AEN4967"
117 ></A
118 ><H2
119 >Description</H2
120 ><P
121 >This function sets up a filter to process all events before they are posted
122 to the event queue. This is a very powerful and flexible feature. The filter
123 is prototyped as:
124 <PRE
125 CLASS="PROGRAMLISTING"
126 >typedef int (*SDL_EventFilter)(const SDL_Event *event);</PRE
127 >
128 If the filter returns <SPAN
129 CLASS="RETURNVALUE"
130 >1</SPAN
131 >, then the event will be
132 added to the internal queue. If it returns <SPAN
133 CLASS="RETURNVALUE"
134 >0</SPAN
135 >,
136 then the event will be dropped from the queue. This allows selective
137 filtering of dynamically.</P
138 ><P
139 >There is one caveat when dealing with the <TT
140 CLASS="LITERAL"
141 >SDL_QUITEVENT</TT
142 > event type. The
143 event filter is only called when the window manager desires to close the
144 application window. If the event filter returns 1, then the window will
145 be closed, otherwise the window will remain open if possible.
146 If the quit event is generated by an interrupt signal, it will bypass the
147 internal queue and be delivered to the application at the next event poll.</P
148 ><DIV
149 CLASS="NOTE"
150 ><BLOCKQUOTE
151 CLASS="NOTE"
152 ><P
153 ><B
154 >Note: </B
155 >Events pushed onto the queue with <A
156 HREF="sdlpushevent.html"
157 ><TT
158 CLASS="FUNCTION"
159 >SDL_PushEvent</TT
160 ></A
161 > or <A
162 HREF="sdlpeepevents.html"
163 ><TT
164 CLASS="FUNCTION"
165 >SDL_PeepEvents</TT
166 ></A
167 > do not get passed through the event filter.</P
168 ></BLOCKQUOTE
169 ></DIV
170 ><DIV
171 CLASS="NOTE"
172 ><BLOCKQUOTE
173 CLASS="NOTE"
174 ><P
175 ><B
176 >Note: </B
177 ><I
178 CLASS="EMPHASIS"
179 >Be Careful!</I
180 > The event filter function may run in a different thread so be careful what you do within it.</P
181 ></BLOCKQUOTE
182 ></DIV
183 ></DIV
184 ><DIV
185 CLASS="REFSECT1"
186 ><A
187 NAME="AEN4984"
188 ></A
189 ><H2
190 >See Also</H2
191 ><P
192 ><A
193 HREF="sdlevent.html"
194 ><SPAN
195 CLASS="STRUCTNAME"
196 >SDL_Event</SPAN
197 ></A
198 >,
199 <A
200 HREF="sdlgeteventfilter.html"
201 ><TT
202 CLASS="FUNCTION"
203 >SDL_GetEventFilter</TT
204 ></A
205 >,
206 <A
207 HREF="sdlpushevent.html"
208 ><TT
209 CLASS="FUNCTION"
210 >SDL_PushEvent</TT
211 ></A
212 ></P
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229 HREF="sdlpushevent.html"
230 >Prev</A
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237 HREF="index.html"
238 >Home</A
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244 ><A
245 HREF="sdlgeteventfilter.html"
246 >Next</A
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251 WIDTH="33%"
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253 VALIGN="top"
254 >SDL_PushEvent</TD
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260 HREF="eventfunctions.html"
261 >Up</A
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272 ></HTML
273 >