Mercurial > sdl-ios-xcode
annotate docs/html/sdlseteventfilter.html @ 4040:8515468091e3 SDL-1.2
Set the error after freeing stuff, just in case one of those functions resets
the error string.
| author | Ryan C. Gordon <icculus@icculus.org> |
|---|---|
| date | Tue, 10 Jul 2007 19:03:44 +0000 |
| parents | 355632dca928 |
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| rev | line source |
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| 0 | 1 <HTML |
| 2 ><HEAD | |
| 3 ><TITLE | |
| 4 >SDL_SetEventFilter</TITLE | |
| 5 ><META | |
| 6 NAME="GENERATOR" | |
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7 CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ |
| 0 | 8 "><LINK |
| 9 REL="HOME" | |
| 10 TITLE="SDL Library Documentation" | |
| 11 HREF="index.html"><LINK | |
| 12 REL="UP" | |
| 13 TITLE="Event Functions." | |
| 14 HREF="eventfunctions.html"><LINK | |
| 15 REL="PREVIOUS" | |
| 16 TITLE="SDL_PushEvent" | |
| 17 HREF="sdlpushevent.html"><LINK | |
| 18 REL="NEXT" | |
| 19 TITLE="SDL_GetEventFilter" | |
| 20 HREF="sdlgeteventfilter.html"></HEAD | |
| 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 | |
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31 SUMMARY="Header navigation table" |
| 0 | 32 WIDTH="100%" |
| 33 BORDER="0" | |
| 34 CELLPADDING="0" | |
| 35 CELLSPACING="0" | |
| 36 ><TR | |
| 37 ><TH | |
| 38 COLSPAN="3" | |
| 39 ALIGN="center" | |
| 40 >SDL Library Documentation</TH | |
| 41 ></TR | |
| 42 ><TR | |
| 43 ><TD | |
| 44 WIDTH="10%" | |
| 45 ALIGN="left" | |
| 46 VALIGN="bottom" | |
| 47 ><A | |
| 48 HREF="sdlpushevent.html" | |
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49 ACCESSKEY="P" |
| 0 | 50 >Prev</A |
| 51 ></TD | |
| 52 ><TD | |
| 53 WIDTH="80%" | |
| 54 ALIGN="center" | |
| 55 VALIGN="bottom" | |
| 56 ></TD | |
| 57 ><TD | |
| 58 WIDTH="10%" | |
| 59 ALIGN="right" | |
| 60 VALIGN="bottom" | |
| 61 ><A | |
| 62 HREF="sdlgeteventfilter.html" | |
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63 ACCESSKEY="N" |
| 0 | 64 >Next</A |
| 65 ></TD | |
| 66 ></TR | |
| 67 ></TABLE | |
| 68 ><HR | |
| 69 ALIGN="LEFT" | |
| 70 WIDTH="100%"></DIV | |
| 71 ><H1 | |
| 72 ><A | |
| 73 NAME="SDLSETEVENTFILTER" | |
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74 ></A |
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75 >SDL_SetEventFilter</H1 |
| 0 | 76 ><DIV |
| 77 CLASS="REFNAMEDIV" | |
| 78 ><A | |
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79 NAME="AEN5575" |
| 0 | 80 ></A |
| 81 ><H2 | |
| 82 >Name</H2 | |
| 83 >SDL_SetEventFilter -- Sets up a filter to process all events before they are posted | |
| 84 to the event queue.</DIV | |
| 85 ><DIV | |
| 86 CLASS="REFSYNOPSISDIV" | |
| 87 ><A | |
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88 NAME="AEN5578" |
| 0 | 89 ></A |
| 90 ><H2 | |
| 91 >Synopsis</H2 | |
| 92 ><DIV | |
| 93 CLASS="FUNCSYNOPSIS" | |
| 94 ><A | |
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95 NAME="AEN5579" |
| 0 | 96 ></A |
| 97 ><P | |
| 98 ></P | |
| 99 ><PRE | |
| 100 CLASS="FUNCSYNOPSISINFO" | |
| 101 >#include "SDL.h"</PRE | |
| 102 ><P | |
| 103 ><CODE | |
| 104 ><CODE | |
| 105 CLASS="FUNCDEF" | |
| 106 >void <B | |
| 107 CLASS="FSFUNC" | |
| 108 >SDL_SetEventFilter</B | |
| 109 ></CODE | |
| 110 >(SDL_EventFilter filter);</CODE | |
| 111 ></P | |
| 112 ><P | |
| 113 ></P | |
| 114 ></DIV | |
| 115 ></DIV | |
| 116 ><DIV | |
| 117 CLASS="REFSECT1" | |
| 118 ><A | |
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119 NAME="AEN5585" |
| 0 | 120 ></A |
| 121 ><H2 | |
| 122 >Description</H2 | |
| 123 ><P | |
| 124 >This function sets up a filter to process all events before they are posted | |
| 125 to the event queue. This is a very powerful and flexible feature. The filter | |
| 126 is prototyped as: | |
| 127 <PRE | |
| 128 CLASS="PROGRAMLISTING" | |
| 129 >typedef int (*SDL_EventFilter)(const SDL_Event *event);</PRE | |
| 130 > | |
| 131 If the filter returns <SPAN | |
| 132 CLASS="RETURNVALUE" | |
| 133 >1</SPAN | |
| 134 >, then the event will be | |
| 135 added to the internal queue. If it returns <SPAN | |
| 136 CLASS="RETURNVALUE" | |
| 137 >0</SPAN | |
| 138 >, | |
| 139 then the event will be dropped from the queue. This allows selective | |
| 140 filtering of dynamically.</P | |
| 141 ><P | |
| 142 >There is one caveat when dealing with the <TT | |
| 143 CLASS="LITERAL" | |
| 144 >SDL_QUITEVENT</TT | |
| 145 > event type. The | |
| 146 event filter is only called when the window manager desires to close the | |
| 147 application window. If the event filter returns 1, then the window will | |
| 148 be closed, otherwise the window will remain open if possible. | |
| 149 If the quit event is generated by an interrupt signal, it will bypass the | |
| 150 internal queue and be delivered to the application at the next event poll.</P | |
| 151 ><DIV | |
| 152 CLASS="NOTE" | |
| 153 ><BLOCKQUOTE | |
| 154 CLASS="NOTE" | |
| 155 ><P | |
| 156 ><B | |
| 157 >Note: </B | |
| 158 >Events pushed onto the queue with <A | |
| 159 HREF="sdlpushevent.html" | |
| 160 ><TT | |
| 161 CLASS="FUNCTION" | |
| 162 >SDL_PushEvent</TT | |
| 163 ></A | |
| 164 > or <A | |
| 165 HREF="sdlpeepevents.html" | |
| 166 ><TT | |
| 167 CLASS="FUNCTION" | |
| 168 >SDL_PeepEvents</TT | |
| 169 ></A | |
| 170 > do not get passed through the event filter.</P | |
| 171 ></BLOCKQUOTE | |
| 172 ></DIV | |
| 173 ><DIV | |
| 174 CLASS="NOTE" | |
| 175 ><BLOCKQUOTE | |
| 176 CLASS="NOTE" | |
| 177 ><P | |
| 178 ><B | |
| 179 >Note: </B | |
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180 ><SPAN |
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181 CLASS="emphasis" |
| 0 | 182 ><I |
| 183 CLASS="EMPHASIS" | |
| 184 >Be Careful!</I | |
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185 ></SPAN |
| 0 | 186 > The event filter function may run in a different thread so be careful what you do within it.</P |
| 187 ></BLOCKQUOTE | |
| 188 ></DIV | |
| 189 ></DIV | |
| 190 ><DIV | |
| 191 CLASS="REFSECT1" | |
| 192 ><A | |
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193 NAME="AEN5602" |
| 0 | 194 ></A |
| 195 ><H2 | |
| 196 >See Also</H2 | |
| 197 ><P | |
| 198 ><A | |
| 199 HREF="sdlevent.html" | |
| 200 ><SPAN | |
| 201 CLASS="STRUCTNAME" | |
| 202 >SDL_Event</SPAN | |
| 203 ></A | |
| 204 >, | |
| 205 <A | |
| 206 HREF="sdlgeteventfilter.html" | |
| 207 ><TT | |
| 208 CLASS="FUNCTION" | |
| 209 >SDL_GetEventFilter</TT | |
| 210 ></A | |
| 211 >, | |
| 212 <A | |
| 213 HREF="sdlpushevent.html" | |
| 214 ><TT | |
| 215 CLASS="FUNCTION" | |
| 216 >SDL_PushEvent</TT | |
| 217 ></A | |
| 218 ></P | |
| 219 ></DIV | |
| 220 ><DIV | |
| 221 CLASS="NAVFOOTER" | |
| 222 ><HR | |
| 223 ALIGN="LEFT" | |
| 224 WIDTH="100%"><TABLE | |
|
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225 SUMMARY="Footer navigation table" |
| 0 | 226 WIDTH="100%" |
| 227 BORDER="0" | |
| 228 CELLPADDING="0" | |
| 229 CELLSPACING="0" | |
| 230 ><TR | |
| 231 ><TD | |
| 232 WIDTH="33%" | |
| 233 ALIGN="left" | |
| 234 VALIGN="top" | |
| 235 ><A | |
| 236 HREF="sdlpushevent.html" | |
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237 ACCESSKEY="P" |
| 0 | 238 >Prev</A |
| 239 ></TD | |
| 240 ><TD | |
| 241 WIDTH="34%" | |
| 242 ALIGN="center" | |
| 243 VALIGN="top" | |
| 244 ><A | |
| 245 HREF="index.html" | |
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246 ACCESSKEY="H" |
| 0 | 247 >Home</A |
| 248 ></TD | |
| 249 ><TD | |
| 250 WIDTH="33%" | |
| 251 ALIGN="right" | |
| 252 VALIGN="top" | |
| 253 ><A | |
| 254 HREF="sdlgeteventfilter.html" | |
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255 ACCESSKEY="N" |
| 0 | 256 >Next</A |
| 257 ></TD | |
| 258 ></TR | |
| 259 ><TR | |
| 260 ><TD | |
| 261 WIDTH="33%" | |
| 262 ALIGN="left" | |
| 263 VALIGN="top" | |
| 264 >SDL_PushEvent</TD | |
| 265 ><TD | |
| 266 WIDTH="34%" | |
| 267 ALIGN="center" | |
| 268 VALIGN="top" | |
| 269 ><A | |
| 270 HREF="eventfunctions.html" | |
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271 ACCESSKEY="U" |
| 0 | 272 >Up</A |
| 273 ></TD | |
| 274 ><TD | |
| 275 WIDTH="33%" | |
| 276 ALIGN="right" | |
| 277 VALIGN="top" | |
| 278 >SDL_GetEventFilter</TD | |
| 279 ></TR | |
| 280 ></TABLE | |
| 281 ></DIV | |
| 282 ></BODY | |
| 283 ></HTML | |
| 284 > |