| 1 | <HTML |
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| 4 | >Initializing SDL</TITLE |
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| 40 | >SDL Library Documentation</TH |
| 41 | ></TR |
| 42 | ><TR |
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| 56 | >Chapter 1. The Basics</TD |
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| 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 |
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