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1 <HTML |
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2 ><HEAD |
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3 ><TITLE |
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4 >SDL_DisplayFormatAlpha</TITLE |
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40 >SDL Library Documentation</TH |
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70 WIDTH="100%"></DIV |
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71 ><H1 |
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72 ><A |
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73 NAME="SDLDISPLAYFORMATALPHA" |
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74 ></A |
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75 >SDL_DisplayFormatAlpha</H1 |
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76 ><DIV |
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77 CLASS="REFNAMEDIV" |
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78 ><A |
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79 NAME="AEN2432" |
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80 ></A |
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81 ><H2 |
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82 >Name</H2 |
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83 >SDL_DisplayFormatAlpha -- Convert a surface to the display format</DIV |
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84 ><DIV |
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85 CLASS="REFSYNOPSISDIV" |
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86 ><A |
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87 NAME="AEN2435" |
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88 ></A |
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89 ><H2 |
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90 >Synopsis</H2 |
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91 ><DIV |
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92 CLASS="FUNCSYNOPSIS" |
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94 NAME="AEN2436" |
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95 ></A |
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96 ><P |
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97 ></P |
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98 ><PRE |
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99 CLASS="FUNCSYNOPSISINFO" |
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100 >#include "SDL.h"</PRE |
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101 ><P |
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102 ><CODE |
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103 ><CODE |
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104 CLASS="FUNCDEF" |
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105 >SDL_Surface *<B |
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106 CLASS="FSFUNC" |
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107 >SDL_DisplayFormatAlpha</B |
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108 ></CODE |
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109 >(SDL_Surface *surface);</CODE |
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110 ></P |
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111 ><P |
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112 ></P |
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116 CLASS="REFSECT1" |
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118 NAME="AEN2442" |
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119 ></A |
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120 ><H2 |
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121 >Description</H2 |
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122 ><P |
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123 >This function takes a surface and copies it to a new surface of the |
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124 pixel format and colors of the video framebuffer plus an alpha channel, |
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125 suitable for fast blitting onto the display surface. It calls |
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126 <A |
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127 HREF="sdlconvertsurface.html" |
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128 >SDL_ConvertSurface</A |
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129 ></P |
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130 ><P |
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131 >If you want to take advantage of hardware colorkey or alpha blit |
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132 acceleration, you should set the colorkey and alpha value before |
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133 calling this function.</P |
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134 ><P |
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135 >This function can be used to convert a colourkey to an alpha channel, |
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136 if the <TT |
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137 CLASS="LITERAL" |
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138 >SDL_SRCCOLORKEY</TT |
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139 > flag is set on the surface. |
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140 The generated surface will then be transparent (alpha=0) where the |
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141 pixels match the colourkey, and opaque (alpha=255) elsewhere.</P |
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142 ></DIV |
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143 ><DIV |
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144 CLASS="REFSECT1" |
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145 ><A |
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146 NAME="AEN2449" |
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147 ></A |
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148 ><H2 |
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149 >Return Value</H2 |
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150 ><P |
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151 >If the conversion fails or runs out of memory, it returns |
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152 <SPAN |
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153 CLASS="RETURNVALUE" |
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154 >NULL</SPAN |
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155 ></P |
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156 ></DIV |
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157 ><DIV |
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158 CLASS="REFSECT1" |
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159 ><A |
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160 NAME="AEN2453" |
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161 ></A |
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162 ><H2 |
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163 >See Also</H2 |
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164 ><P |
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165 ><A |
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166 HREF="sdlconvertsurface.html" |
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167 >SDL_ConvertSurface</A |
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168 >, |
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169 <A |
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170 HREF="sdlsetalpha.html" |
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171 >SDL_SetAlpha</A |
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172 >, |
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173 <A |
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174 HREF="sdlsetcolorkey.html" |
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175 >SDL_SetColorKey</A |
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176 >, |
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177 <A |
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178 HREF="sdldisplayformat.html" |
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179 >SDL_DisplayFormat</A |
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180 >, |
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181 <A |
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182 HREF="sdlsurface.html" |
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183 >SDL_Surface</A |
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184 ></P |
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