1 <HTML 2 ><HEAD 3 ><TITLE 4 >Initializing SDL</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="The Basics" 14 HREF="guidethebasics.html"><LINK 15 REL="PREVIOUS" 16 TITLE="The Basics" 17 HREF="guidethebasics.html"><LINK 18 REL="NEXT" 19 TITLE="Graphics and Video" 20 HREF="guidevideo.html"></HEAD 21 ><BODY 22 CLASS="SECT1" 23 BGCOLOR="#FFF8DC" 24 TEXT="#000000" 25 LINK="#0000ee" 26 VLINK="#551a8b" 27 ALINK="#ff0000" 28 ><DIV 29 CLASS="NAVHEADER" 30 ><TABLE 31 SUMMARY="Header navigation table" 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="guidethebasics.html" 49 ACCESSKEY="P" 50 >Prev</A 51 ></TD 52 ><TD 53 WIDTH="80%" 54 ALIGN="center" 55 VALIGN="bottom" 56 >Chapter 1. The Basics</TD 57 ><TD 58 WIDTH="10%" 59 ALIGN="right" 60 VALIGN="bottom" 61 ><A 62 HREF="guidevideo.html" 63 ACCESSKEY="N" 64 >Next</A 65 ></TD 66 ></TR 67 ></TABLE 68 ><HR 69 ALIGN="LEFT" 70 WIDTH="100%"></DIV 71 ><DIV 72 CLASS="SECT1" 73 ><H1 74 CLASS="SECT1" 75 ><A 76 NAME="GUIDEBASICSINIT" 77 ></A 78 >Initializing SDL</H1 79 ><P 80 >SDL is composed of eight subsystems - Audio, CDROM, Event Handling, File I/O, Joystick Handling, Threading, Timers and Video. Before you can use any of these subsystems they must be initialized by calling <A 81 HREF="sdlinit.html" 82 ><TT 83 CLASS="FUNCTION" 84 >SDL_Init</TT 85 ></A 86 > (or <A 87 HREF="sdlinitsubsystem.html" 88 ><TT 89 CLASS="FUNCTION" 90 >SDL_InitSubSystem</TT 91 ></A 92 >). <TT 93 CLASS="FUNCTION" 94 >SDL_Init</TT 95 > must be called before any other SDL function. It automatically initializes the Event Handling, File I/O and Threading subsystems and it takes a parameter specifying which other subsystems to initialize. So, to initialize the default subsystems and the Video subsystems you would call: 96 <PRE 97 CLASS="PROGRAMLISTING" 98 > SDL_Init ( SDL_INIT_VIDEO );</PRE 99 > 100 To initialize the default subsystems, the Video subsystem and the Timers subsystem you would call: 101 <PRE 102 CLASS="PROGRAMLISTING" 103 > SDL_Init ( SDL_INIT_VIDEO | SDL_INIT_TIMER );</PRE 104 ></P 105 ><P 106 ><TT 107 CLASS="FUNCTION" 108 >SDL_Init</TT 109 > is complemented by <A 110 HREF="sdlquit.html" 111 ><TT 112 CLASS="FUNCTION" 113 >SDL_Quit</TT 114 ></A 115 > (and <A 116 HREF="sdlquitsubsystem.html" 117 ><TT 118 CLASS="FUNCTION" 119 >SDL_QuitSubSystem</TT 120 ></A 121 >). <TT 122 CLASS="FUNCTION" 123 >SDL_Quit</TT 124 > shuts down all subsystems, including the default ones. It should always be called before a SDL application exits.</P 125 ><P 126 >With <TT 127 CLASS="FUNCTION" 128 >SDL_Init</TT 129 > and <TT 130 CLASS="FUNCTION" 131 >SDL_Quit</TT 132 > firmly embedded in your programmers toolkit you can write your first and most basic SDL application. However, we must be prepare to handle errors. Many SDL functions return a value and indicates whether the function has succeeded or failed, <TT 133 CLASS="FUNCTION" 134 >SDL_Init</TT 135 >, for instance, returns -1 if it could not initialize a subsystem. SDL provides a useful facility that allows you to determine exactly what the problem was, every time an error occurs within SDL an error message is stored which can be retrieved using <TT 136 CLASS="FUNCTION" 137 >SDL_GetError</TT 138 >. Use this often, you can never know too much about an error.</P 139 ><DIV 140 CLASS="EXAMPLE" 141 ><A 142 NAME="AEN60" 143 ></A 144 ><P 145 ><B 146 >Example 1-1. Initializing SDL</B 147 ></P 148 ><PRE 149 CLASS="PROGRAMLISTING" 150 >#include "SDL.h" /* All SDL App's need this */ 151 #include <stdio.h> 152 153 int main(int argc, char *argv[]) { 154 155 printf("Initializing SDL.\n"); 156 157 /* Initialize defaults, Video and Audio */ 158 if((SDL_Init(SDL_INIT_VIDEO|SDL_INIT_AUDIO)==-1)) { 159 printf("Could not initialize SDL: %s.\n", SDL_GetError()); 160 exit(-1); 161 } 162 163 printf("SDL initialized.\n"); 164 165 printf("Quiting SDL.\n"); 166 167 /* Shutdown all subsystems */ 168 SDL_Quit(); 169 170 printf("Quiting....\n"); 171 172 exit(0); 173 } </PRE 174 ></DIV 175 ></DIV 176 ><DIV 177 CLASS="NAVFOOTER" 178 ><HR 179 ALIGN="LEFT" 180 WIDTH="100%"><TABLE 181 SUMMARY="Footer navigation table" 182 WIDTH="100%" 183 BORDER="0" 184 CELLPADDING="0" 185 CELLSPACING="0" 186 ><TR 187 ><TD 188 WIDTH="33%" 189 ALIGN="left" 190 VALIGN="top" 191 ><A 192 HREF="guidethebasics.html" 193 ACCESSKEY="P" 194 >Prev</A 195 ></TD 196 ><TD 197 WIDTH="34%" 198 ALIGN="center" 199 VALIGN="top" 200 ><A 201 HREF="index.html" 202 ACCESSKEY="H" 203 >Home</A 204 ></TD 205 ><TD 206 WIDTH="33%" 207 ALIGN="right" 208 VALIGN="top" 209 ><A 210 HREF="guidevideo.html" 211 ACCESSKEY="N" 212 >Next</A 213 ></TD 214 ></TR 215 ><TR 216 ><TD 217 WIDTH="33%" 218 ALIGN="left" 219 VALIGN="top" 220 >The Basics</TD 221 ><TD 222 WIDTH="34%" 223 ALIGN="center" 224 VALIGN="top" 225 ><A 226 HREF="guidethebasics.html" 227 ACCESSKEY="U" 228 >Up</A 229 ></TD 230 ><TD 231 WIDTH="33%" 232 ALIGN="right" 233 VALIGN="top" 234 >Graphics and Video</TD 235 ></TR 236 ></TABLE 237 ></DIV 238 ></BODY 239 ></HTML 240 >
