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PHP Cross Reference of MediaWiki-1.24.0 |
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1 <?php 2 /** 3 * PNG frame counter and metadata extractor. 4 * 5 * Slightly derived from GIFMetadataExtractor.php 6 * Deliberately not using MWExceptions to avoid external dependencies, encouraging 7 * redistribution. 8 * 9 * This program is free software; you can redistribute it and/or modify 10 * it under the terms of the GNU General Public License as published by 11 * the Free Software Foundation; either version 2 of the License, or 12 * (at your option) any later version. 13 * 14 * This program is distributed in the hope that it will be useful, 15 * but WITHOUT ANY WARRANTY; without even the implied warranty of 16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 17 * GNU General Public License for more details. 18 * 19 * You should have received a copy of the GNU General Public License along 20 * with this program; if not, write to the Free Software Foundation, Inc., 21 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. 22 * http://www.gnu.org/copyleft/gpl.html 23 * 24 * @file 25 * @ingroup Media 26 */ 27 28 /** 29 * PNG frame counter. 30 * 31 * @ingroup Media 32 */ 33 class PNGMetadataExtractor { 34 /** @var string */ 35 private static $pngSig; 36 37 /** @var int */ 38 private static $crcSize; 39 40 /** @var array */ 41 private static $textChunks; 42 43 const VERSION = 1; 44 const MAX_CHUNK_SIZE = 3145728; // 3 megabytes 45 46 static function getMetadata( $filename ) { 47 self::$pngSig = pack( "C8", 137, 80, 78, 71, 13, 10, 26, 10 ); 48 self::$crcSize = 4; 49 /* based on list at http://owl.phy.queensu.ca/~phil/exiftool/TagNames/PNG.html#TextualData 50 * and http://www.w3.org/TR/PNG/#11keywords 51 */ 52 self::$textChunks = array( 53 'xml:com.adobe.xmp' => 'xmp', 54 # Artist is unofficial. Author is the recommended 55 # keyword in the PNG spec. However some people output 56 # Artist so support both. 57 'artist' => 'Artist', 58 'model' => 'Model', 59 'make' => 'Make', 60 'author' => 'Artist', 61 'comment' => 'PNGFileComment', 62 'description' => 'ImageDescription', 63 'title' => 'ObjectName', 64 'copyright' => 'Copyright', 65 # Source as in original device used to make image 66 # not as in who gave you the image 67 'source' => 'Model', 68 'software' => 'Software', 69 'disclaimer' => 'Disclaimer', 70 'warning' => 'ContentWarning', 71 'url' => 'Identifier', # Not sure if this is best mapping. Maybe WebStatement. 72 'label' => 'Label', 73 'creation time' => 'DateTimeDigitized', 74 /* Other potentially useful things - Document */ 75 ); 76 77 $frameCount = 0; 78 $loopCount = 1; 79 $text = array(); 80 $duration = 0.0; 81 $bitDepth = 0; 82 $colorType = 'unknown'; 83 84 if ( !$filename ) { 85 throw new Exception( __METHOD__ . ": No file name specified" ); 86 } elseif ( !file_exists( $filename ) || is_dir( $filename ) ) { 87 throw new Exception( __METHOD__ . ": File $filename does not exist" ); 88 } 89 90 $fh = fopen( $filename, 'rb' ); 91 92 if ( !$fh ) { 93 throw new Exception( __METHOD__ . ": Unable to open file $filename" ); 94 } 95 96 // Check for the PNG header 97 $buf = fread( $fh, 8 ); 98 if ( $buf != self::$pngSig ) { 99 throw new Exception( __METHOD__ . ": Not a valid PNG file; header: $buf" ); 100 } 101 102 // Read chunks 103 while ( !feof( $fh ) ) { 104 $buf = fread( $fh, 4 ); 105 if ( !$buf || strlen( $buf ) < 4 ) { 106 throw new Exception( __METHOD__ . ": Read error" ); 107 } 108 $chunk_size = unpack( "N", $buf ); 109 $chunk_size = $chunk_size[1]; 110 111 if ( $chunk_size < 0 ) { 112 throw new Exception( __METHOD__ . ": Chunk size too big for unpack" ); 113 } 114 115 $chunk_type = fread( $fh, 4 ); 116 if ( !$chunk_type || strlen( $chunk_type ) < 4 ) { 117 throw new Exception( __METHOD__ . ": Read error" ); 118 } 119 120 if ( $chunk_type == "IHDR" ) { 121 $buf = self::read( $fh, $chunk_size ); 122 if ( !$buf || strlen( $buf ) < $chunk_size ) { 123 throw new Exception( __METHOD__ . ": Read error" ); 124 } 125 $bitDepth = ord( substr( $buf, 8, 1 ) ); 126 // Detect the color type in British English as per the spec 127 // http://www.w3.org/TR/PNG/#11IHDR 128 switch ( ord( substr( $buf, 9, 1 ) ) ) { 129 case 0: 130 $colorType = 'greyscale'; 131 break; 132 case 2: 133 $colorType = 'truecolour'; 134 break; 135 case 3: 136 $colorType = 'index-coloured'; 137 break; 138 case 4: 139 $colorType = 'greyscale-alpha'; 140 break; 141 case 6: 142 $colorType = 'truecolour-alpha'; 143 break; 144 default: 145 $colorType = 'unknown'; 146 break; 147 } 148 } elseif ( $chunk_type == "acTL" ) { 149 $buf = fread( $fh, $chunk_size ); 150 if ( !$buf || strlen( $buf ) < $chunk_size || $chunk_size < 4 ) { 151 throw new Exception( __METHOD__ . ": Read error" ); 152 } 153 154 $actl = unpack( "Nframes/Nplays", $buf ); 155 $frameCount = $actl['frames']; 156 $loopCount = $actl['plays']; 157 } elseif ( $chunk_type == "fcTL" ) { 158 $buf = self::read( $fh, $chunk_size ); 159 if ( !$buf || strlen( $buf ) < $chunk_size ) { 160 throw new Exception( __METHOD__ . ": Read error" ); 161 } 162 $buf = substr( $buf, 20 ); 163 if ( strlen( $buf ) < 4 ) { 164 throw new Exception( __METHOD__ . ": Read error" ); 165 } 166 167 $fctldur = unpack( "ndelay_num/ndelay_den", $buf ); 168 if ( $fctldur['delay_den'] == 0 ) { 169 $fctldur['delay_den'] = 100; 170 } 171 if ( $fctldur['delay_num'] ) { 172 $duration += $fctldur['delay_num'] / $fctldur['delay_den']; 173 } 174 } elseif ( $chunk_type == "iTXt" ) { 175 // Extracts iTXt chunks, uncompressing if necessary. 176 $buf = self::read( $fh, $chunk_size ); 177 $items = array(); 178 if ( preg_match( 179 '/^([^\x00]{1,79})\x00(\x00|\x01)\x00([^\x00]*)(.)[^\x00]*\x00(.*)$/Ds', 180 $buf, $items ) 181 ) { 182 /* $items[1] = text chunk name, $items[2] = compressed flag, 183 * $items[3] = lang code (or ""), $items[4]= compression type. 184 * $items[5] = content 185 */ 186 187 // Theoretically should be case-sensitive, but in practise... 188 $items[1] = strtolower( $items[1] ); 189 if ( !isset( self::$textChunks[$items[1]] ) ) { 190 // Only extract textual chunks on our list. 191 fseek( $fh, self::$crcSize, SEEK_CUR ); 192 continue; 193 } 194 195 $items[3] = strtolower( $items[3] ); 196 if ( $items[3] == '' ) { 197 // if no lang specified use x-default like in xmp. 198 $items[3] = 'x-default'; 199 } 200 201 // if compressed 202 if ( $items[2] == "\x01" ) { 203 if ( function_exists( 'gzuncompress' ) && $items[4] === "\x00" ) { 204 wfSuppressWarnings(); 205 $items[5] = gzuncompress( $items[5] ); 206 wfRestoreWarnings(); 207 208 if ( $items[5] === false ) { 209 // decompression failed 210 wfDebug( __METHOD__ . ' Error decompressing iTxt chunk - ' . $items[1] . "\n" ); 211 fseek( $fh, self::$crcSize, SEEK_CUR ); 212 continue; 213 } 214 } else { 215 wfDebug( __METHOD__ . ' Skipping compressed png iTXt chunk due to lack of zlib,' 216 . " or potentially invalid compression method\n" ); 217 fseek( $fh, self::$crcSize, SEEK_CUR ); 218 continue; 219 } 220 } 221 $finalKeyword = self::$textChunks[$items[1]]; 222 $text[$finalKeyword][$items[3]] = $items[5]; 223 $text[$finalKeyword]['_type'] = 'lang'; 224 } else { 225 // Error reading iTXt chunk 226 throw new Exception( __METHOD__ . ": Read error on iTXt chunk" ); 227 } 228 } elseif ( $chunk_type == 'tEXt' ) { 229 $buf = self::read( $fh, $chunk_size ); 230 231 // In case there is no \x00 which will make explode fail. 232 if ( strpos( $buf, "\x00" ) === false ) { 233 throw new Exception( __METHOD__ . ": Read error on tEXt chunk" ); 234 } 235 236 list( $keyword, $content ) = explode( "\x00", $buf, 2 ); 237 if ( $keyword === '' || $content === '' ) { 238 throw new Exception( __METHOD__ . ": Read error on tEXt chunk" ); 239 } 240 241 // Theoretically should be case-sensitive, but in practise... 242 $keyword = strtolower( $keyword ); 243 if ( !isset( self::$textChunks[$keyword] ) ) { 244 // Don't recognize chunk, so skip. 245 fseek( $fh, self::$crcSize, SEEK_CUR ); 246 continue; 247 } 248 wfSuppressWarnings(); 249 $content = iconv( 'ISO-8859-1', 'UTF-8', $content ); 250 wfRestoreWarnings(); 251 252 if ( $content === false ) { 253 throw new Exception( __METHOD__ . ": Read error (error with iconv)" ); 254 } 255 256 $finalKeyword = self::$textChunks[$keyword]; 257 $text[$finalKeyword]['x-default'] = $content; 258 $text[$finalKeyword]['_type'] = 'lang'; 259 } elseif ( $chunk_type == 'zTXt' ) { 260 if ( function_exists( 'gzuncompress' ) ) { 261 $buf = self::read( $fh, $chunk_size ); 262 263 // In case there is no \x00 which will make explode fail. 264 if ( strpos( $buf, "\x00" ) === false ) { 265 throw new Exception( __METHOD__ . ": Read error on zTXt chunk" ); 266 } 267 268 list( $keyword, $postKeyword ) = explode( "\x00", $buf, 2 ); 269 if ( $keyword === '' || $postKeyword === '' ) { 270 throw new Exception( __METHOD__ . ": Read error on zTXt chunk" ); 271 } 272 // Theoretically should be case-sensitive, but in practise... 273 $keyword = strtolower( $keyword ); 274 275 if ( !isset( self::$textChunks[$keyword] ) ) { 276 // Don't recognize chunk, so skip. 277 fseek( $fh, self::$crcSize, SEEK_CUR ); 278 continue; 279 } 280 $compression = substr( $postKeyword, 0, 1 ); 281 $content = substr( $postKeyword, 1 ); 282 if ( $compression !== "\x00" ) { 283 wfDebug( __METHOD__ . " Unrecognized compression method in zTXt ($keyword). Skipping.\n" ); 284 fseek( $fh, self::$crcSize, SEEK_CUR ); 285 continue; 286 } 287 288 wfSuppressWarnings(); 289 $content = gzuncompress( $content ); 290 wfRestoreWarnings(); 291 292 if ( $content === false ) { 293 // decompression failed 294 wfDebug( __METHOD__ . ' Error decompressing zTXt chunk - ' . $keyword . "\n" ); 295 fseek( $fh, self::$crcSize, SEEK_CUR ); 296 continue; 297 } 298 299 wfSuppressWarnings(); 300 $content = iconv( 'ISO-8859-1', 'UTF-8', $content ); 301 wfRestoreWarnings(); 302 303 if ( $content === false ) { 304 throw new Exception( __METHOD__ . ": Read error (error with iconv)" ); 305 } 306 307 $finalKeyword = self::$textChunks[$keyword]; 308 $text[$finalKeyword]['x-default'] = $content; 309 $text[$finalKeyword]['_type'] = 'lang'; 310 } else { 311 wfDebug( __METHOD__ . " Cannot decompress zTXt chunk due to lack of zlib. Skipping.\n" ); 312 fseek( $fh, $chunk_size, SEEK_CUR ); 313 } 314 } elseif ( $chunk_type == 'tIME' ) { 315 // last mod timestamp. 316 if ( $chunk_size !== 7 ) { 317 throw new Exception( __METHOD__ . ": tIME wrong size" ); 318 } 319 $buf = self::read( $fh, $chunk_size ); 320 if ( !$buf || strlen( $buf ) < $chunk_size ) { 321 throw new Exception( __METHOD__ . ": Read error" ); 322 } 323 324 // Note: spec says this should be UTC. 325 $t = unpack( "ny/Cm/Cd/Ch/Cmin/Cs", $buf ); 326 $strTime = sprintf( "%04d%02d%02d%02d%02d%02d", 327 $t['y'], $t['m'], $t['d'], $t['h'], 328 $t['min'], $t['s'] ); 329 330 $exifTime = wfTimestamp( TS_EXIF, $strTime ); 331 332 if ( $exifTime ) { 333 $text['DateTime'] = $exifTime; 334 } 335 } elseif ( $chunk_type == 'pHYs' ) { 336 // how big pixels are (dots per meter). 337 if ( $chunk_size !== 9 ) { 338 throw new Exception( __METHOD__ . ": pHYs wrong size" ); 339 } 340 341 $buf = self::read( $fh, $chunk_size ); 342 if ( !$buf || strlen( $buf ) < $chunk_size ) { 343 throw new Exception( __METHOD__ . ": Read error" ); 344 } 345 346 $dim = unpack( "Nwidth/Nheight/Cunit", $buf ); 347 if ( $dim['unit'] == 1 ) { 348 // Need to check for negative because php 349 // doesn't deal with super-large unsigned 32-bit ints well 350 if ( $dim['width'] > 0 && $dim['height'] > 0 ) { 351 // unit is meters 352 // (as opposed to 0 = undefined ) 353 $text['XResolution'] = $dim['width'] 354 . '/100'; 355 $text['YResolution'] = $dim['height'] 356 . '/100'; 357 $text['ResolutionUnit'] = 3; 358 // 3 = dots per cm (from Exif). 359 } 360 } 361 } elseif ( $chunk_type == "IEND" ) { 362 break; 363 } else { 364 fseek( $fh, $chunk_size, SEEK_CUR ); 365 } 366 fseek( $fh, self::$crcSize, SEEK_CUR ); 367 } 368 fclose( $fh ); 369 370 if ( $loopCount > 1 ) { 371 $duration *= $loopCount; 372 } 373 374 if ( isset( $text['DateTimeDigitized'] ) ) { 375 // Convert date format from rfc2822 to exif. 376 foreach ( $text['DateTimeDigitized'] as $name => &$value ) { 377 if ( $name === '_type' ) { 378 continue; 379 } 380 381 // @todo FIXME: Currently timezones are ignored. 382 // possibly should be wfTimestamp's 383 // responsibility. (at least for numeric TZ) 384 $formatted = wfTimestamp( TS_EXIF, $value ); 385 if ( $formatted ) { 386 // Only change if we could convert the 387 // date. 388 // The png standard says it should be 389 // in rfc2822 format, but not required. 390 // In general for the exif stuff we 391 // prettify the date if we can, but we 392 // display as-is if we cannot or if 393 // it is invalid. 394 // So do the same here. 395 396 $value = $formatted; 397 } 398 } 399 } 400 401 return array( 402 'frameCount' => $frameCount, 403 'loopCount' => $loopCount, 404 'duration' => $duration, 405 'text' => $text, 406 'bitDepth' => $bitDepth, 407 'colorType' => $colorType, 408 ); 409 } 410 411 /** 412 * Read a chunk, checking to make sure its not too big. 413 * 414 * @param resource $fh The file handle 415 * @param int $size Size in bytes. 416 * @throws Exception If too big 417 * @return string The chunk. 418 */ 419 private static function read( $fh, $size ) { 420 if ( $size > self::MAX_CHUNK_SIZE ) { 421 throw new Exception( __METHOD__ . ': Chunk size of ' . $size . 422 ' too big. Max size is: ' . self::MAX_CHUNK_SIZE ); 423 } 424 425 return fread( $fh, $size ); 426 } 427 }
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| Generated: Fri Nov 28 14:03:12 2014 | Cross-referenced by PHPXref 0.7.1 |