JS文件压缩成png图片，canvas解析
<div id="cnblogs_post_body">为了压缩js文件，把js文件转化成PNG图像，然后用 canvas 控件中的 getImageData() 函数将图像再重新读成js文件，这样可以做到很高的压缩比。PHP写的压缩方法
<div class="cnblogs_code">1 <?2 header('Content-type: text/plain');3 4 $GLOBALS = 'phpgd_images/';5 $GLOBALS = 'phpgd_filtered_images/';6 7 define('OUTPUT_FILTERED', 0);8 define('OUTPUT_8BIT', 1);9 define('OUTPUT_8BIT_GRAY', 1); 10 define('OUTPUT_24BIT', 1); 11 define('OUTPUT_32BIT', 1); 12 13 14 encode_file('lipsum.txt', 'lipsum'); 15 encode_file('jquery-1.4.2.min.js', 'jquery'); 16 17 18 #################################################################################################### 19 20 function encode_file($path, $prefix){ 21 22 $data = file_get_contents($path); 23 $size = strlen($data); 24 25 echo "$path is $size bytes\n"; 26 27 28 # 29 # the simplest method is to store the bytes as they are in ascii. 30 # this is the least space-efficient. 31 # 32 33 $bytes = array(); 34 for ($i=0; $i<strlen($data); $i++){ 35 $bytes[] = ord(substr($data, $i, 1)); 36 } 37 38 store_bytes($bytes, $prefix.'_ascii'); 39 40 41 # 42 # next simplest is to store values using 7 bits, so we store 8 43 # characters in every 7 bytes 44 # 45 # 11111112 22222233 33333444 44445555 55566666 66777777 78888888 46 # 47 48 $bytes = array(); 49 $seqs = ceil(strlen($data) / 8); 50 for ($i=0; $i<$seqs; $i++){ 51 52 $c1 = ord(substr($data, ($i*8)+0, 1)); 53 $c2 = ord(substr($data, ($i*8)+1, 1)); 54 $c3 = ord(substr($data, ($i*8)+2, 1)); 55 $c4 = ord(substr($data, ($i*8)+3, 1)); 56 $c5 = ord(substr($data, ($i*8)+4, 1)); 57 $c6 = ord(substr($data, ($i*8)+5, 1)); 58 $c7 = ord(substr($data, ($i*8)+6, 1)); 59 $c8 = ord(substr($data, ($i*8)+7, 1)); 60 61 $b1 = (($c1 << 1) | ($c2 >> 6)) & 0xff; 62 $b2 = (($c2 << 2) | ($c3 >> 5)) & 0xff; 63 $b3 = (($c3 << 3) | ($c4 >> 4)) & 0xff; 64 $b4 = (($c4 << 4) | ($c5 >> 3)) & 0xff; 65 $b5 = (($c5 << 5) | ($c6 >> 2)) & 0xff; 66 $b6 = (($c6 << 6) | ($c7 >> 1)) & 0xff; 67 $b7 = ((($c7 << 7) & 0x80) | ($c8 & 0x7f)) & 0xff; 68 69 $bytes[] = $b1; 70 $bytes[] = $b2; 71 $bytes[] = $b3; 72 $bytes[] = $b4; 73 $bytes[] = $b5; 74 $bytes[] = $b6; 75 $bytes[] = $b7; 76 } 77 78 store_bytes($bytes, $prefix.'_seq8'); 79 } 80 81 #################################################################################################### 82 83 function store_bytes($bytes, $mode){ 84 85 $size = count($bytes); 86 87 88 # 89 # 8b 90 # 91 92 $w = floor(sqrt($size)); 93 $h = ceil($size / $w); 94 95 if (OUTPUT_8BIT){ 96 create_8b($mode, 'wide', $bytes, $size, 1); 97 create_8b($mode, 'tall', $bytes, 1, $size); 98 create_8b($mode, 'square', $bytes, $w, $h); 99 }100 if (OUTPUT_8BIT_GRAY){101 create_8b_gray($mode, 'wide', $bytes, $size, 1);102 create_8b_gray($mode, 'tall', $bytes, 1, $size);103 create_8b_gray($mode, 'square', $bytes, $w, $h);104 }105 106 107 #108 # 24b109 #110 111 $px = ceil($size / 3);112 113 $w = floor(sqrt($px));114 $h = ceil($px / $w);115 116 if (OUTPUT_24BIT){117 create_24b($mode, 'wide', $bytes, $px, 1);118 create_24b($mode, 'tall', $bytes, 1, $px);119 create_24b($mode, 'square', $bytes, $w, $h);120 }121 122 123 #124 # 32b125 #126 127 $px = ceil($size / 4);128 129 $w = floor(sqrt($px));130 $h = ceil($px / $w);131 132 if (OUTPUT_32BIT){133 create_32b($mode, 'wide', $bytes, $px, 1);134 create_32b($mode, 'tall', $bytes, 1, $px);135 create_32b($mode, 'square', $bytes, $w, $h);136 }137 }138 139 ####################################################################################################140 141 function create_8b($mode, $shape, $bytes, $w, $h){142 143 $im = imagecreate($w, $h);144 145 $cols = array();146 for ($i=0; $i<256; $i++){147 $cols[$i] = imagecolorallocate($im, $i, 0, 0);148 }149 150 $i=0;151 for ($y=0; $y<$h; $y++){152 for ($x=0; $x<$w; $x++){153 154 $b1 = intval($bytes[$i]);155 156 $col = $cols[$b1];157 158 imagesetpixel($im, $x, $y, $col);159 160 $i++;161 }162 }163 164 save_png($im, "{$mode}_8b_{$shape}");165 imagedestroy($im);166 }167 168 ####################################################################################################169 170 function create_8b_gray($mode, $shape, $bytes, $w, $h){171 172 $im = imagecreate($w, $h);173 174 $cols = array();175 for ($i=0; $i<256; $i++){176 $cols[$i] = imagecolorallocate($im, $i, $i, $i);177 }178 179 $i=0;180 for ($y=0; $y<$h; $y++){181 for ($x=0; $x<$w; $x++){182 183 $b1 = intval($bytes[$i]);184 185 $col = $cols[$b1];186 187 imagesetpixel($im, $x, $y, $col);188 189 $i++;190 }191 }192 193 save_png($im, "{$mode}_8b_gray_{$shape}");194 imagedestroy($im);195 }196 197 ####################################################################################################198 function create_24b($mode, $shape, $bytes, $w, $h){199 200 $im = imagecreatetruecolor($w, $h);201 imageAlphaBlending($im, false);202 imageSaveAlpha($im, false);203 204 $i=0;205 for ($y=0; $y<$h; $y++){206 for ($x=0; $x<$w; $x++){207 208 $b1 = $bytes[($i*3)+0];209 $b2 = $bytes[($i*3)+1];210 $b3 = $bytes[($i*3)+2];211 212 $col = imagecolorallocate($im, $b1, $b2, $b3);213 214 imagesetpixel($im, $x, $y, $col);215 216 $i++;217 }218 }219 220 save_png($im, "{$mode}_24b_{$shape}");221 imagedestroy($im);222 }223 224 ####################################################################################################225 226 function create_32b($mode, $shape, $bytes, $w, $h){227 228 $im = imagecreatetruecolor($w, $h);229 imageAlphaBlending($im, false);230 imageSaveAlpha($im, true);231 232 $i=0;233 for ($y=0; $y<$h; $y++){234 for ($x=0; $x<$w; $x++){235 236 $b1 = $bytes[($i*4)+0];237 $b2 = $bytes[($i*4)+1];238 $b3 = $bytes[($i*4)+2];239 $b4 = $bytes[($i*4)+3];240 241 $col = imagecolorallocatealpha($im, $b1, $b2, $b3, $b4);242 243 #echo "$b1, $b2, $b3, $b4 ..";244 245 imagesetpixel($im, $x, $y, $col);246 247 $i++;248 }249 }250 251 save_png($im, "{$mode}_32b_{$shape}");252 imagedestroy($im); 253 }254 255 ####################################################################################################256 257 function save_png($im, $name){258 259 for ($a=0; $a<2; $a++){260 for ($b=0; $b<2; $b++){261 for ($c=0; $c<2; $c++){262 for ($d=0; $d<2; $d++){263 264 $filter = 0;265 $bits = '';266 if ($a){ $filter |= PNG_FILTER_SUB; $bits .= '_sub'; }267 if ($b){ $filter |= PNG_FILTER_UP; $bits .= '_up'; }268 if ($c){ $filter |= PNG_FILTER_AVG; $bits .= '_avg'; }269 if ($d){ $filter |= PNG_FILTER_PAETH; $bits .= '_paeth'; }270 271 if ($filter){272 if (OUTPUT_FILTERED){273 imagepng($im, $GLOBALS."{$name}{$bits}.png", 9, $filter);274 }275 }else{276 imagepng($im, $GLOBALS."{$name}.png", 9, $filter);277 }278 }279 }280 }281 }282 }283 284 ?>
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