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1 <HTML
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2 ><HEAD
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3 ><TITLE
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4 >Video Examples</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="Examples"
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14 HREF="guideexamples.html"><LINK
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15 REL="PREVIOUS"
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16 TITLE="Examples"
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17 HREF="guideexamples.html"><LINK
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18 REL="NEXT"
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19 TITLE="Event Examples"
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20 HREF="guideeventexamples.html"></HEAD
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21 ><BODY
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22 CLASS="SECT1"
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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="guideexamples.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 >Chapter 4. Examples</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="guideeventexamples.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 ><DIV
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69 CLASS="SECT1"
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70 ><H1
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71 CLASS="SECT1"
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72 ><A
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73 NAME="GUIDEVIDEOEXAMPLES"
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74 >Video Examples</A
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75 ></H1
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76 ><P
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77 ></P
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78 ><DIV
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79 CLASS="SECT2"
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80 ><H2
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81 CLASS="SECT2"
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82 ><A
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83 NAME="AEN303"
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84 >Initializing the video display</A
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85 ></H2
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86 ><P
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87 ><PRE
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88 CLASS="PROGRAMLISTING"
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89 > SDL_Surface *screen;
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90
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91 /* Initialize the SDL library */
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92 if( SDL_Init(SDL_INIT_VIDEO) < 0 ) {
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93 fprintf(stderr,
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94 "Couldn't initialize SDL: %s\n", SDL_GetError());
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95 exit(1);
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96 }
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97
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98 /* Clean up on exit */
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99 atexit(SDL_Quit);
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100
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101 /* Initialize the display in a 640x480 8-bit palettized mode */
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102 screen = SDL_SetVideoMode(640, 480, 8, SDL_SWSURFACE);
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103 if ( screen == NULL ) {
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104 fprintf(stderr, "Couldn't set 640x480x8 video mode: %s\n",
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105 SDL_GetError());
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106 exit(1);
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107 }</PRE
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108 ></P
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109 ></DIV
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110 ><DIV
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111 CLASS="SECT2"
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112 ><H2
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113 CLASS="SECT2"
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114 ><A
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115 NAME="AEN307"
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116 >Initializing the best video mode</A
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117 ></H2
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118 ><P
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119 ><PRE
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120 CLASS="PROGRAMLISTING"
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121 > /* Have a preference for 8-bit, but accept any depth */
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122 screen = SDL_SetVideoMode(640, 480, 8, SDL_SWSURFACE|SDL_ANYFORMAT);
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123 if ( screen == NULL ) {
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124 fprintf(stderr, "Couldn't set 640x480x8 video mode: %s\n",
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125 SDL_GetError());
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126 exit(1);
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127 }
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128 printf("Set 640x480 at %d bits-per-pixel mode\n",
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129 screen->format->BitsPerPixel);</PRE
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130 ></P
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131 ></DIV
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132 ><DIV
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133 CLASS="SECT2"
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134 ><H2
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135 CLASS="SECT2"
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136 ><A
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137 NAME="AEN311"
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138 >Loading and displaying a BMP file</A
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139 ></H2
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140 ><P
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141 ><PRE
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142 CLASS="PROGRAMLISTING"
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143 > SDL_Surface *image;
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144 SDL_Rect dest;
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145 int ncolors, i;
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146 SDL_Color *colors;
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147
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148 /* Load the BMP file into a surface */
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149 image = SDL_LoadBMP("sample.bmp");
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150 if ( image == NULL ) {
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151 fprintf(stderr, "Couldn't load sample.bmp: %s\n",
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152 SDL_GetError());
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153 return;
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154 }
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155
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156 /* Set the display colors -- SDL_SetColors() only does something on
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157 palettized displays, but it doesn't hurt anything on HiColor or
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158 TrueColor displays.
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159 If the display colors have already been set, this step can be
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160 skipped, and the library will automatically map the image to
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161 the current display colors.
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162 */
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163 if ( image->format->palette ) {
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164 ncolors = image->format->palette->ncolors;
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165 colors = (SDL_Color *)malloc(ncolors*sizeof(SDL_Color));
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166 memcpy(colors, image->format->palette->colors, ncolors);
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167 }
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168 else {
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169 int r, g, b;
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170
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171 /* Allocate 256 color palette */
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172 ncolors = 256;
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173 colors = (SDL_Color *)malloc(ncolors*sizeof(SDL_Color));
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174
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175 /* Set a 3,3,2 color cube */
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176 for ( r=0; r<8; ++r ) {
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177 for ( g=0; g<8; ++g ) {
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178 for ( b=0; b<4; ++b ) {
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179 i = ((r<<5)|(g<<2)|b);
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180 colors[i].r = r<<5;
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181 colors[i].g = g<<5;
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182 colors[i].b = b<<6;
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183 }
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184 }
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185 }
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186 /* Note: A better way of allocating the palette might be
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187 to calculate the frequency of colors in the image
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188 and create a palette based on that information.
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189 */
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190 }
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191 /* Set colormap, try for all the colors, but don't worry about it */
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192 SDL_SetColors(screen, colors, 0, ncolors);
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193 free(colors);
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194
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195 /* Blit onto the screen surface */
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196 dest.x = 0;
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197 dest.y = 0;
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198 dest.w = image->w;
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199 dest.h = image->h;
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200 SDL_BlitSurface(image, NULL, screen, &dest);
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201
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202 SDL_UpdateRects(screen, 1, &dest);
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203
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204 /* Free the allocated BMP surface */
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205 SDL_FreeSurface(image);
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206 return;</PRE
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207 ></P
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208 ></DIV
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209 ><DIV
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210 CLASS="SECT2"
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211 ><H2
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212 CLASS="SECT2"
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213 ><A
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214 NAME="AEN315"
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215 >Drawing directly to the display</A
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216 ></H2
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217 ><P
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218 ><PRE
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219 CLASS="PROGRAMLISTING"
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220 > /* Code to set a yellow pixel at the center of the screen */
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221
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222 Sint32 X, Y;
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223 Uint32 pixel;
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224 Uint8 *bits, bpp;
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225
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226 /* Map the color yellow to this display (R=0xFF, G=0xFF, B=0x00)
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227 Note: If the display is palettized, you must set the palette first.
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228 */
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229 pixel = SDL_MapRGB(screen->format, 0xFF, 0xFF, 0x00);
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230
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231 /* Calculate the framebuffer offset of the center of the screen */
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232 if ( SDL_MUSTLOCK(screen) ) {
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233 if ( SDL_LockSurface(screen) < 0 )
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234 return;
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235 }
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236 bpp = screen->format->BytesPerPixel;
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237 X = screen->w/2;
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238 Y = screen->h/2;
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239 bits = ((Uint8 *)screen->pixels)+Y*screen->pitch+X*bpp;
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240
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241 /* Set the pixel */
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242 switch(bpp) {
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243 case 1:
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244 *((Uint8 *)(bits)) = (Uint8)pixel;
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245 break;
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246 case 2:
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247 *((Uint16 *)(bits)) = (Uint16)pixel;
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248 break;
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249 case 3: { /* Format/endian independent */
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250 Uint8 r, g, b;
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251
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252 r = (pixel>>screen->format->Rshift)&0xFF;
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253 g = (pixel>>screen->format->Gshift)&0xFF;
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254 b = (pixel>>screen->format->Bshift)&0xFF;
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255 *((bits)+screen->format->Rshift/8) = r;
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256 *((bits)+screen->format->Gshift/8) = g;
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257 *((bits)+screen->format->Bshift/8) = b;
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258 }
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259 break;
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260 case 4:
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261 *((Uint32 *)(bits)) = (Uint32)pixel;
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262 break;
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263 }
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264
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265 /* Update the display */
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266 if ( SDL_MUSTLOCK(screen) ) {
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267 SDL_UnlockSurface(screen);
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268 }
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269 SDL_UpdateRect(screen, X, Y, 1, 1);
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270
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271 return;</PRE
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272 ></P
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273 ></DIV
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274 ><DIV
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275 CLASS="SECT2"
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276 ><H2
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277 CLASS="SECT2"
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278 ><A
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279 NAME="AEN319"
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280 >Fastest possible surface blit</A
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281 ></H2
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282 ><P
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283 >There are three different ways you can draw an image to the screen:
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284 <P
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285 ></P
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286 ><TABLE
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287 BORDER="0"
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288 ><TBODY
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289 ><TR
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290 ><TD
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291 >1.Create a surface and use <A
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292 HREF="sdlblitsurface.html"
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293 ><TT
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294 CLASS="FUNCTION"
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295 >SDL_BlitSurface</TT
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296 ></A
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297 > to blit it to the screen</TD
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298 ></TR
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299 ><TR
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300 ><TD
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301 >2.Create the video surface in system memory and call <A
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302 HREF="sdlupdaterect.html"
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303 ><TT
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304 CLASS="FUNCTION"
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305 >SDL_UpdateRect</TT
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306 ></A
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307 ></TD
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308 ></TR
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309 ><TR
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310 ><TD
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311 >3.Create the video surface in video memory and call <A
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312 HREF="sdllocksurface.html"
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313 ><TT
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314 CLASS="FUNCTION"
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315 >SDL_LockSurface</TT
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316 ></A
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317 ></TD
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318 ></TR
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319 ></TBODY
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320 ></TABLE
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321 ><P
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322 ></P
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323 >
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324 The best way to do this is to combine methods:
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325 <PRE
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326 CLASS="PROGRAMLISTING"
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327 >#include <stdio.h>
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328 #include <stdlib.h>
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329 #include "SDL.h"
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330 #include "SDL_timer.h"
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331
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332 void ComplainAndExit(void)
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333 {
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334 fprintf(stderr, "Problem: %s\n", SDL_GetError());
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335 exit(1);
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336 }
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337
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338 int main(int argc, char *argv[])
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339 {
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340 SDL_PixelFormat fmt;
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341 SDL_Surface *screen, *locked;
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342 SDL_Surface *imagebmp, *image;
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343 SDL_Rect dstrect;
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344 int i;
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345 Uint8 *buffer;
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346
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347 /* Initialize SDL */
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348 if ( SDL_Init(SDL_INIT_VIDEO) < 0 ) {
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349 ComplainAndExit();
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350 }
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351 atexit(SDL_Quit);
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352
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353 /* Load a BMP image into a surface */
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354 imagebmp = SDL_LoadBMP("image.bmp");
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355 if ( imagebmp == NULL ) {
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356 ComplainAndExit();
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357 }
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358
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359 /* Set the video mode (640x480 at native depth) */
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360 screen = SDL_SetVideoMode(640, 480, 0, SDL_HWSURFACE|SDL_FULLSCREEN);
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361 if ( screen == NULL ) {
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362 ComplainAndExit();
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363 }
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364
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365 /* Set the video colormap */
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366 if ( imagebmp->format->palette != NULL ) {
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367 SDL_SetColors(screen,
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368 imagebmp->format->palette->colors, 0,
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369 imagebmp->format->palette->ncolors);
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370 }
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371
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372 /* Convert the image to the video format (maps colors) */
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373 image = SDL_DisplayFormat(imagebmp);
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374 SDL_FreeSurface(imagebmp);
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375 if ( image == NULL ) {
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376 ComplainAndExit();
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377 }
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378
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379 /* Draw bands of color on the raw surface */
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380 if ( SDL_MUSTLOCK(screen) ) {
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381 if ( SDL_LockSurface(screen) < 0 )
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382 ComplainAndExit();
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383 }
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384 buffer=(Uint8 *)screen->pixels;
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385 for ( i=0; i<screen->h; ++i ) {
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386 memset(buffer,(i*255)/screen->h,
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387 screen->w*screen->format->BytesPerPixel);
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388 buffer += screen->pitch;
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389 }
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390 if ( SDL_MUSTLOCK(screen) ) {
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391 SDL_UnlockSurface(screen);
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392 }
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393
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394 /* Blit the image to the center of the screen */
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395 dstrect.x = (screen->w-image->w)/2;
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396 dstrect.y = (screen->h-image->h)/2;
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397 dstrect.w = image->w;
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398 dstrect.h = image->h;
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399 if ( SDL_BlitSurface(image, NULL, screen, &dstrect) < 0 ) {
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400 SDL_FreeSurface(image);
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401 ComplainAndExit();
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402 }
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403 SDL_FreeSurface(image);
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404
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405 /* Update the screen */
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406 SDL_UpdateRects(screen, 1, &dstrect);
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407
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408 SDL_Delay(5000); /* Wait 5 seconds */
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409 exit(0);
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410 }</PRE
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411 ></P
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412 ></DIV
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413 ></DIV
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414 ><DIV
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415 CLASS="NAVFOOTER"
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416 ><HR
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417 ALIGN="LEFT"
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418 WIDTH="100%"><TABLE
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419 WIDTH="100%"
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420 BORDER="0"
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421 CELLPADDING="0"
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422 CELLSPACING="0"
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423 ><TR
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424 ><TD
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425 WIDTH="33%"
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426 ALIGN="left"
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427 VALIGN="top"
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428 ><A
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429 HREF="guideexamples.html"
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430 >Prev</A
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431 ></TD
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432 ><TD
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433 WIDTH="34%"
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434 ALIGN="center"
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435 VALIGN="top"
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436 ><A
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437 HREF="index.html"
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438 >Home</A
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439 ></TD
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440 ><TD
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441 WIDTH="33%"
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442 ALIGN="right"
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443 VALIGN="top"
|
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444 ><A
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445 HREF="guideeventexamples.html"
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446 >Next</A
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447 ></TD
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448 ></TR
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449 ><TR
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450 ><TD
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451 WIDTH="33%"
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452 ALIGN="left"
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453 VALIGN="top"
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454 >Examples</TD
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455 ><TD
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456 WIDTH="34%"
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457 ALIGN="center"
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458 VALIGN="top"
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459 ><A
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460 HREF="guideexamples.html"
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461 >Up</A
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462 ></TD
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463 ><TD
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464 WIDTH="33%"
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465 ALIGN="right"
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466 VALIGN="top"
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467 >Event Examples</TD
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468 ></TR
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469 ></TABLE
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470 ></DIV
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471 ></BODY
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472 ></HTML
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473 > |
