1 <HTML 2 ><HEAD 3 ><TITLE 4 >Events</TITLE 5 ><META 6 NAME="GENERATOR" 7 CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ 8 "><LINK 9 REL="HOME" 10 TITLE="SDL Library Documentation" 11 HREF="index.html"><LINK 12 REL="UP" 13 TITLE="SDL Reference" 14 HREF="reference.html"><LINK 15 REL="PREVIOUS" 16 TITLE="SDL_WM_GrabInput" 17 HREF="sdlwmgrabinput.html"><LINK 18 REL="NEXT" 19 TITLE="SDL Event Structures." 20 HREF="eventstructures.html"><META 21 NAME="KEYWORD" 22 CONTENT="events"><META 23 NAME="KEYWORD" 24 CONTENT="function"></HEAD 25 ><BODY 26 CLASS="CHAPTER" 27 BGCOLOR="#FFF8DC" 28 TEXT="#000000" 29 LINK="#0000ee" 30 VLINK="#551a8b" 31 ALINK="#ff0000" 32 ><DIV 33 CLASS="NAVHEADER" 34 ><TABLE 35 SUMMARY="Header navigation table" 36 WIDTH="100%" 37 BORDER="0" 38 CELLPADDING="0" 39 CELLSPACING="0" 40 ><TR 41 ><TH 42 COLSPAN="3" 43 ALIGN="center" 44 >SDL Library Documentation</TH 45 ></TR 46 ><TR 47 ><TD 48 WIDTH="10%" 49 ALIGN="left" 50 VALIGN="bottom" 51 ><A 52 HREF="sdlwmgrabinput.html" 53 ACCESSKEY="P" 54 >Prev</A 55 ></TD 56 ><TD 57 WIDTH="80%" 58 ALIGN="center" 59 VALIGN="bottom" 60 ></TD 61 ><TD 62 WIDTH="10%" 63 ALIGN="right" 64 VALIGN="bottom" 65 ><A 66 HREF="eventstructures.html" 67 ACCESSKEY="N" 68 >Next</A 69 ></TD 70 ></TR 71 ></TABLE 72 ><HR 73 ALIGN="LEFT" 74 WIDTH="100%"></DIV 75 ><DIV 76 CLASS="CHAPTER" 77 ><H1 78 ><A 79 NAME="EVENT" 80 ></A 81 >Chapter 8. Events</H1 82 ><DIV 83 CLASS="TOC" 84 ><DL 85 ><DT 86 ><B 87 >Table of Contents</B 88 ></DT 89 ><DT 90 ><A 91 HREF="event.html#AEN3691" 92 >Introduction</A 93 ></DT 94 ><DT 95 ><A 96 HREF="eventstructures.html" 97 >SDL Event Structures.</A 98 ></DT 99 ><DT 100 ><A 101 HREF="eventfunctions.html" 102 >Event Functions.</A 103 ></DT 104 ></DL 105 ></DIV 106 ><DIV 107 CLASS="SECT1" 108 ><H1 109 CLASS="SECT1" 110 ><A 111 NAME="AEN3691" 112 ></A 113 >Introduction</H1 114 ><P 115 >Event handling allows your application to receive input from the user. Event handling is initalised (along with video) with a call to: 116 <PRE 117 CLASS="PROGRAMLISTING" 118 >SDL_Init(SDL_INIT_VIDEO);</PRE 119 > 120 Internally, SDL stores all the events waiting to be handled in an event queue. Using functions like <A 121 HREF="sdlpollevent.html" 122 ><TT 123 CLASS="FUNCTION" 124 >SDL_PollEvent</TT 125 ></A 126 > and <A 127 HREF="sdlpeepevents.html" 128 ><TT 129 CLASS="FUNCTION" 130 >SDL_PeepEvents</TT 131 ></A 132 > you can observe and handle waiting input events.</P 133 ><P 134 >The key to event handling in SDL is the <A 135 HREF="sdlevent.html" 136 ><SPAN 137 CLASS="STRUCTNAME" 138 >SDL_Event</SPAN 139 ></A 140 > union. The event queue itself is composed of a series of <SPAN 141 CLASS="STRUCTNAME" 142 >SDL_Event</SPAN 143 > unions, one for each waiting event. <SPAN 144 CLASS="STRUCTNAME" 145 >SDL_Event</SPAN 146 > unions are read from the queue with the <TT 147 CLASS="FUNCTION" 148 >SDL_PollEvent</TT 149 > function and it is then up to the application to process the information stored with them.</P 150 ></DIV 151 ></DIV 152 ><DIV 153 CLASS="NAVFOOTER" 154 ><HR 155 ALIGN="LEFT" 156 WIDTH="100%"><TABLE 157 SUMMARY="Footer navigation table" 158 WIDTH="100%" 159 BORDER="0" 160 CELLPADDING="0" 161 CELLSPACING="0" 162 ><TR 163 ><TD 164 WIDTH="33%" 165 ALIGN="left" 166 VALIGN="top" 167 ><A 168 HREF="sdlwmgrabinput.html" 169 ACCESSKEY="P" 170 >Prev</A 171 ></TD 172 ><TD 173 WIDTH="34%" 174 ALIGN="center" 175 VALIGN="top" 176 ><A 177 HREF="index.html" 178 ACCESSKEY="H" 179 >Home</A 180 ></TD 181 ><TD 182 WIDTH="33%" 183 ALIGN="right" 184 VALIGN="top" 185 ><A 186 HREF="eventstructures.html" 187 ACCESSKEY="N" 188 >Next</A 189 ></TD 190 ></TR 191 ><TR 192 ><TD 193 WIDTH="33%" 194 ALIGN="left" 195 VALIGN="top" 196 >SDL_WM_GrabInput</TD 197 ><TD 198 WIDTH="34%" 199 ALIGN="center" 200 VALIGN="top" 201 ><A 202 HREF="reference.html" 203 ACCESSKEY="U" 204 >Up</A 205 ></TD 206 ><TD 207 WIDTH="33%" 208 ALIGN="right" 209 VALIGN="top" 210 >SDL Event Structures.</TD 211 ></TR 212 ></TABLE 213 ></DIV 214 ></BODY 215 ></HTML 216 >
