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1 <HTML
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2 ><HEAD
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3 ><TITLE
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4 >SDL_AddTimer</TITLE
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5 ><META
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6 NAME="GENERATOR"
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7 CONTENT="Modular DocBook HTML Stylesheet Version 1.61
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8 "><LINK
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9 REL="HOME"
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10 TITLE="SDL Library Documentation"
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11 HREF="index.html"><LINK
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12 REL="UP"
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13 TITLE="Time"
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14 HREF="time.html"><LINK
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15 REL="PREVIOUS"
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16 TITLE="SDL_Delay"
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17 HREF="sdldelay.html"><LINK
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18 REL="NEXT"
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19 TITLE="SDL_RemoveTimer"
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20 HREF="sdlremovetimer.html"></HEAD
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21 ><BODY
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22 CLASS="REFENTRY"
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23 BGCOLOR="#FFF8DC"
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24 TEXT="#000000"
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25 LINK="#0000ee"
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26 VLINK="#551a8b"
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27 ALINK="#ff0000"
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28 ><DIV
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29 CLASS="NAVHEADER"
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30 ><TABLE
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31 WIDTH="100%"
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32 BORDER="0"
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33 CELLPADDING="0"
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34 CELLSPACING="0"
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35 ><TR
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36 ><TH
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37 COLSPAN="3"
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38 ALIGN="center"
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39 >SDL Library Documentation</TH
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40 ></TR
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41 ><TR
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42 ><TD
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43 WIDTH="10%"
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44 ALIGN="left"
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45 VALIGN="bottom"
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46 ><A
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47 HREF="sdldelay.html"
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48 >Prev</A
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49 ></TD
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50 ><TD
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51 WIDTH="80%"
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52 ALIGN="center"
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53 VALIGN="bottom"
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54 ></TD
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55 ><TD
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56 WIDTH="10%"
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57 ALIGN="right"
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58 VALIGN="bottom"
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59 ><A
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60 HREF="sdlremovetimer.html"
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61 >Next</A
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62 ></TD
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63 ></TR
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64 ></TABLE
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65 ><HR
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66 ALIGN="LEFT"
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67 WIDTH="100%"></DIV
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68 ><H1
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69 ><A
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70 NAME="SDLADDTIMER"
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71 >SDL_AddTimer</A
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72 ></H1
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73 ><DIV
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74 CLASS="REFNAMEDIV"
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75 ><A
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76 NAME="AEN7854"
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77 ></A
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78 ><H2
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79 >Name</H2
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80 >SDL_AddTimer -- Add a timer which will call a callback after the specified number of milliseconds has
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81 elapsed.</DIV
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82 ><DIV
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83 CLASS="REFSYNOPSISDIV"
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84 ><A
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85 NAME="AEN7857"
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86 ></A
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87 ><H2
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88 >Synopsis</H2
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89 ><DIV
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90 CLASS="FUNCSYNOPSIS"
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91 ><A
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92 NAME="AEN7858"
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93 ></A
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94 ><P
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95 ></P
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96 ><PRE
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97 CLASS="FUNCSYNOPSISINFO"
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98 >#include "SDL.h"</PRE
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99 ><P
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100 ><CODE
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101 ><CODE
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102 CLASS="FUNCDEF"
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103 >SDL_TimerID <B
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104 CLASS="FSFUNC"
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105 >SDL_AddTimer</B
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106 ></CODE
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107 >(Uint32 interval, SDL_NewTimerCallback callback, void *param);</CODE
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108 ></P
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109 ><P
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110 ></P
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111 ></DIV
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112 ></DIV
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113 ><DIV
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114 CLASS="REFSECT1"
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115 ><A
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116 NAME="SDLNEWTIMERCALLBACK"
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117 ></A
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118 ><H2
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119 >Callback</H2
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120 ><PRE
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121 CLASS="PROGRAMLISTING"
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122 >/* type definition for the "new" timer callback function */
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123 typedef Uint32 (*SDL_NewTimerCallback)(Uint32 interval, void *param);</PRE
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124 ></DIV
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125 ><DIV
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126 CLASS="REFSECT1"
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127 ><A
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128 NAME="AEN7867"
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129 ></A
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130 ><H2
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131 >Description</H2
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132 ><P
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133 >Adds a callback function to be run after the specified number of
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134 milliseconds has elapsed. The callback function is passed the current
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135 timer interval and the user supplied parameter from the
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136 <TT
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137 CLASS="FUNCTION"
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138 >SDL_AddTimer</TT
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139 > call and returns the next timer
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140 interval. If the returned value from the callback is the same as the one
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141 passed in, the periodic alarm continues, otherwise a new alarm is
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142 scheduled.</P
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143 ><P
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144 >To cancel a currently running timer call
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145 <A
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146 HREF="sdlremovetimer.html"
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147 >SDL_RemoveTimer</A
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148 > with the
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149 timer ID returned from
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150 <TT
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151 CLASS="FUNCTION"
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152 >SDL_AddTimer</TT
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153 >.</P
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154 ><P
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155 >The timer callback function may run in a different thread than your
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156 main program, and so shouldn't call any functions from within itself.</P
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157 ><P
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158 >The maximum resolution of this timer is 10 ms, which means that if
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159 you request a 16 ms timer, your callback will run approximately 20 ms
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160 later on an unloaded system. If you wanted to set a flag signaling
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161 a frame update at 30 frames per second (every 33 ms), you might set a
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162 timer for 30 ms (see example below).
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163
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164 If you use this function, you need to pass <TT
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165 CLASS="LITERAL"
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166 >SDL_INIT_TIMER</TT
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167 >
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168 to <A
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169 HREF="sdlinit.html"
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170 >SDL_Init</A
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171 >.</P
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172 ></DIV
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173 ><DIV
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174 CLASS="REFSECT1"
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175 ><A
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176 NAME="AEN7878"
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177 ></A
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178 ><H2
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179 >Return Value</H2
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180 ><P
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181 >Returns an ID value for the added timer or
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182 <SPAN
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183 CLASS="RETURNVALUE"
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184 >NULL</SPAN
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185 > if there was an error.</P
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186 ></DIV
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187 ><DIV
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188 CLASS="REFSECT1"
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189 ><A
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190 NAME="AEN7882"
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191 ></A
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192 ><H2
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193 >Examples</H2
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194 ><P
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195 ><PRE
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196 CLASS="PROGRAMLISTING"
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197 >my_timer_id = SDL_AddTimer((33/10)*10, my_callbackfunc, my_callback_param);</PRE
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198 ></P
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199 ></DIV
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200 ><DIV
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201 CLASS="REFSECT1"
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202 ><A
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203 NAME="AEN7886"
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204 ></A
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205 ><H2
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206 >See Also</H2
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207 ><P
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208 ><A
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209 HREF="sdlremovetimer.html"
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210 ><TT
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211 CLASS="FUNCTION"
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212 >SDL_RemoveTimer</TT
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213 ></A
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214 ></P
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215 ></DIV
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216 ><DIV
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217 CLASS="NAVFOOTER"
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218 ><HR
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219 ALIGN="LEFT"
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220 WIDTH="100%"><TABLE
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221 WIDTH="100%"
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222 BORDER="0"
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223 CELLPADDING="0"
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224 CELLSPACING="0"
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225 ><TR
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226 ><TD
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227 WIDTH="33%"
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228 ALIGN="left"
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229 VALIGN="top"
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230 ><A
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231 HREF="sdldelay.html"
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232 >Prev</A
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233 ></TD
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234 ><TD
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235 WIDTH="34%"
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236 ALIGN="center"
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237 VALIGN="top"
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238 ><A
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239 HREF="index.html"
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240 >Home</A
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241 ></TD
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242 ><TD
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243 WIDTH="33%"
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244 ALIGN="right"
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245 VALIGN="top"
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246 ><A
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247 HREF="sdlremovetimer.html"
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248 >Next</A
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249 ></TD
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250 ></TR
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251 ><TR
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252 ><TD
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253 WIDTH="33%"
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254 ALIGN="left"
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255 VALIGN="top"
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256 >SDL_Delay</TD
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257 ><TD
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258 WIDTH="34%"
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259 ALIGN="center"
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260 VALIGN="top"
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261 ><A
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262 HREF="time.html"
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263 >Up</A
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264 ></TD
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265 ><TD
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266 WIDTH="33%"
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267 ALIGN="right"
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268 VALIGN="top"
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269 >SDL_RemoveTimer</TD
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270 ></TR
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271 ></TABLE
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272 ></DIV
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273 ></BODY
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274 ></HTML
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275 > |
