Mercurial > judyates
view e2gallerypro/e2upload/Backend/Assets/getid3/module.graphic.png.php @ 20:1038db2374ec judyates
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| author | Robert McIntyre <rlm@mit.edu> |
|---|---|
| date | Sun, 08 Sep 2013 00:47:09 -0400 |
| parents | 3f6b44aa6b35 |
| children |
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1 <?php2 // +----------------------------------------------------------------------+3 // | PHP version 5 |4 // +----------------------------------------------------------------------+5 // | Copyright (c) 2002-2006 James Heinrich, Allan Hansen |6 // +----------------------------------------------------------------------+7 // | This source file is subject to version 2 of the GPL license, |8 // | that is bundled with this package in the file license.txt and is |9 // | available through the world-wide-web at the following url: |10 // | http://www.gnu.org/copyleft/gpl.html |11 // +----------------------------------------------------------------------+12 // | getID3() - http://getid3.sourceforge.net or http://www.getid3.org |13 // +----------------------------------------------------------------------+14 // | Authors: James Heinrich <infoØgetid3*org> |15 // | Allan Hansen <ahØartemis*dk> |16 // +----------------------------------------------------------------------+17 // | module.graphic.png.php |18 // | Module for analyzing PNG graphic files. |19 // | dependencies: zlib support in PHP (optional) |20 // +----------------------------------------------------------------------+21 //22 // $Id: module.graphic.png.php,v 1.4 2006/11/02 10:48:02 ah Exp $26 class getid3_png extends getid3_handler27 {29 public function Analyze() {31 $getid3 = $this->getid3;33 $getid3->info['png'] = array ();34 $info_png = &$getid3->info['png'];36 $getid3->info['fileformat'] = 'png';37 $getid3->info['video']['dataformat'] = 'png';38 $getid3->info['video']['lossless'] = false;40 fseek($getid3->fp, $getid3->info['avdataoffset'], SEEK_SET);41 $png_filedata = fread($getid3->fp, getid3::FREAD_BUFFER_SIZE);43 // Magic bytes "\x89\x50\x4E\x47\x0D\x0A\x1A\x0A"45 $offset = 8;47 while (((ftell($getid3->fp) - (strlen($png_filedata) - $offset)) < $getid3->info['filesize'])) {49 $chunk['data_length'] = getid3_lib::BigEndian2Int(substr($png_filedata, $offset, 4));50 $offset += 4;51 while (((strlen($png_filedata) - $offset) < ($chunk['data_length'] + 4)) && (ftell($getid3->fp) < $getid3->info['filesize'])) {52 $png_filedata .= fread($getid3->fp, getid3::FREAD_BUFFER_SIZE);53 }55 $chunk['type_text'] = substr($png_filedata, $offset, 4);56 $chunk['type_raw'] = getid3_lib::BigEndian2Int($chunk['type_text']);57 $offset += 4;59 $chunk['data'] = substr($png_filedata, $offset, $chunk['data_length']);60 $offset += $chunk['data_length'];62 $chunk['crc'] = getid3_lib::BigEndian2Int(substr($png_filedata, $offset, 4));63 $offset += 4;65 $chunk['flags']['ancilliary'] = (bool)($chunk['type_raw'] & 0x20000000);66 $chunk['flags']['private'] = (bool)($chunk['type_raw'] & 0x00200000);67 $chunk['flags']['reserved'] = (bool)($chunk['type_raw'] & 0x00002000);68 $chunk['flags']['safe_to_copy'] = (bool)($chunk['type_raw'] & 0x00000020);70 // shortcut71 $info_png[$chunk['type_text']] = array ();72 $info_png_chunk_type_text = &$info_png[$chunk['type_text']];74 switch ($chunk['type_text']) {76 case 'IHDR': // Image Header77 $info_png_chunk_type_text['header'] = $chunk;78 $info_png_chunk_type_text['width'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 0, 4));79 $info_png_chunk_type_text['height'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 4, 4));81 getid3_lib::ReadSequence('BigEndian2Int', $info_png_chunk_type_text['raw'], $chunk['data'], 8,82 array (83 'bit_depth' => 1,84 'color_type' => 1,85 'compression_method' => 1,86 'filter_method' => 1,87 'interlace_method' => 188 )89 );91 $info_png_chunk_type_text['compression_method_text'] = getid3_png::PNGcompressionMethodLookup($info_png_chunk_type_text['raw']['compression_method']);92 $info_png_chunk_type_text['color_type']['palette'] = (bool)($info_png_chunk_type_text['raw']['color_type'] & 0x01);93 $info_png_chunk_type_text['color_type']['true_color'] = (bool)($info_png_chunk_type_text['raw']['color_type'] & 0x02);94 $info_png_chunk_type_text['color_type']['alpha'] = (bool)($info_png_chunk_type_text['raw']['color_type'] & 0x04);96 $getid3->info['video']['resolution_x'] = $info_png_chunk_type_text['width'];97 $getid3->info['video']['resolution_y'] = $info_png_chunk_type_text['height'];99 $getid3->info['video']['bits_per_sample'] = getid3_png::IHDRcalculateBitsPerSample($info_png_chunk_type_text['raw']['color_type'], $info_png_chunk_type_text['raw']['bit_depth']);100 break;103 case 'PLTE': // Palette104 $info_png_chunk_type_text['header'] = $chunk;105 $palette_offset = 0;106 for ($i = 0; $i <= 255; $i++) {107 $red = @getid3_lib::BigEndian2Int($chunk['data']{$palette_offset++});108 $green = @getid3_lib::BigEndian2Int($chunk['data']{$palette_offset++});109 $blue = @getid3_lib::BigEndian2Int($chunk['data']{$palette_offset++});110 $info_png_chunk_type_text[$i] = (($red << 16) | ($green << 8) | ($blue));111 }112 break;115 case 'tRNS': // Transparency116 $info_png_chunk_type_text['header'] = $chunk;117 switch ($info_png['IHDR']['raw']['color_type']) {118 case 0:119 $info_png_chunk_type_text['transparent_color_gray'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 0, 2));120 break;122 case 2:123 $info_png_chunk_type_text['transparent_color_red'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 0, 2));124 $info_png_chunk_type_text['transparent_color_green'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 2, 2));125 $info_png_chunk_type_text['transparent_color_blue'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 4, 2));126 break;128 case 3:129 for ($i = 0; $i < strlen($chunk['data']); $i++) {130 $info_png_chunk_type_text['palette_opacity'][$i] = getid3_lib::BigEndian2Int($chunk['data'][$i]);131 }132 break;134 case 4:135 case 6:136 throw new getid3_exception('Invalid color_type in tRNS chunk: '.$info_png['IHDR']['raw']['color_type']);138 default:139 $getid3->warning('Unhandled color_type in tRNS chunk: '.$info_png['IHDR']['raw']['color_type']);140 break;141 }142 break;145 case 'gAMA': // Image Gamma146 $info_png_chunk_type_text['header'] = $chunk;147 $info_png_chunk_type_text['gamma'] = getid3_lib::BigEndian2Int($chunk['data']) / 100000;148 break;151 case 'cHRM': // Primary Chromaticities152 $info_png_chunk_type_text['header'] = $chunk;153 $info_png_chunk_type_text['white_x'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 0, 4)) / 100000;154 $info_png_chunk_type_text['white_y'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 4, 4)) / 100000;155 $info_png_chunk_type_text['red_y'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 8, 4)) / 100000;156 $info_png_chunk_type_text['red_y'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 12, 4)) / 100000;157 $info_png_chunk_type_text['green_y'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 16, 4)) / 100000;158 $info_png_chunk_type_text['green_y'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 20, 4)) / 100000;159 $info_png_chunk_type_text['blue_y'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 24, 4)) / 100000;160 $info_png_chunk_type_text['blue_y'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 28, 4)) / 100000;161 break;164 case 'sRGB': // Standard RGB Color Space165 $info_png_chunk_type_text['header'] = $chunk;166 $info_png_chunk_type_text['reindering_intent'] = getid3_lib::BigEndian2Int($chunk['data']);167 $info_png_chunk_type_text['reindering_intent_text'] = getid3_png::PNGsRGBintentLookup($info_png_chunk_type_text['reindering_intent']);168 break;171 case 'iCCP': // Embedded ICC Profile172 $info_png_chunk_type_text['header'] = $chunk;173 list($profilename, $compressiondata) = explode("\x00", $chunk['data'], 2);174 $info_png_chunk_type_text['profile_name'] = $profilename;175 $info_png_chunk_type_text['compression_method'] = getid3_lib::BigEndian2Int($compressiondata[0]);176 $info_png_chunk_type_text['compression_profile'] = substr($compressiondata, 1);177 $info_png_chunk_type_text['compression_method_text'] = getid3_png::PNGcompressionMethodLookup($info_png_chunk_type_text['compression_method']);178 break;181 case 'tEXt': // Textual Data182 $info_png_chunk_type_text['header'] = $chunk;183 list($keyword, $text) = explode("\x00", $chunk['data'], 2);184 $info_png_chunk_type_text['keyword'] = $keyword;185 $info_png_chunk_type_text['text'] = $text;187 $info_png['comments'][$info_png_chunk_type_text['keyword']][] = $info_png_chunk_type_text['text'];188 break;191 case 'zTXt': // Compressed Textual Data192 $info_png_chunk_type_text['header'] = $chunk;193 list($keyword, $otherdata) = explode("\x00", $chunk['data'], 2);194 $info_png_chunk_type_text['keyword'] = $keyword;195 $info_png_chunk_type_text['compression_method'] = getid3_lib::BigEndian2Int(substr($otherdata, 0, 1));196 $info_png_chunk_type_text['compressed_text'] = substr($otherdata, 1);197 $info_png_chunk_type_text['compression_method_text'] = getid3_png::PNGcompressionMethodLookup($info_png_chunk_type_text['compression_method']);199 if ($info_png_chunk_type_text['compression_method'] != 0) {200 // unknown compression method201 break;202 }204 if (function_exists('gzuncompress')) {205 $info_png_chunk_type_text['text'] = gzuncompress($info_png_chunk_type_text['compressed_text']);206 }207 else {208 if (!@$this->zlib_warning) {209 $getid3->warning('PHP does not have --with-zlib support - cannot gzuncompress()');210 }211 $this->zlib_warning = true;212 }215 if (isset($info_png_chunk_type_text['text'])) {216 $info_png['comments'][$info_png_chunk_type_text['keyword']][] = $info_png_chunk_type_text['text'];217 }218 break;221 case 'iTXt': // International Textual Data222 $info_png_chunk_type_text['header'] = $chunk;223 list($keyword, $otherdata) = explode("\x00", $chunk['data'], 2);224 $info_png_chunk_type_text['keyword'] = $keyword;225 $info_png_chunk_type_text['compression'] = (bool)getid3_lib::BigEndian2Int(substr($otherdata, 0, 1));226 $info_png_chunk_type_text['compression_method'] = getid3_lib::BigEndian2Int($otherdata[1]);227 $info_png_chunk_type_text['compression_method_text'] = getid3_png::PNGcompressionMethodLookup($info_png_chunk_type_text['compression_method']);228 list($languagetag, $translatedkeyword, $text) = explode("\x00", substr($otherdata, 2), 3);229 $info_png_chunk_type_text['language_tag'] = $languagetag;230 $info_png_chunk_type_text['translated_keyword'] = $translatedkeyword;232 if ($info_png_chunk_type_text['compression']) {234 switch ($info_png_chunk_type_text['compression_method']) {235 case 0:236 if (function_exists('gzuncompress')) {237 $info_png_chunk_type_text['text'] = gzuncompress($text);238 }239 else {240 if (!@$this->zlib_warning) {241 $getid3->warning('PHP does not have --with-zlib support - cannot gzuncompress()');242 }243 $this->zlib_warning = true;244 }245 break;247 default:248 // unknown compression method249 break;250 }252 } else {254 $info_png_chunk_type_text['text'] = $text;256 }258 if (isset($info_png_chunk_type_text['text'])) {259 $info_png['comments'][$info_png_chunk_type_text['keyword']][] = $info_png_chunk_type_text['text'];260 }261 break;264 case 'bKGD': // Background Color265 $info_png_chunk_type_text['header'] = $chunk;266 switch ($info_png['IHDR']['raw']['color_type']) {267 case 0:268 case 4:269 $info_png_chunk_type_text['background_gray'] = getid3_lib::BigEndian2Int($chunk['data']);270 break;272 case 2:273 case 6:274 $info_png_chunk_type_text['background_red'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 0 * $info_png['IHDR']['raw']['bit_depth'], $info_png['IHDR']['raw']['bit_depth']));275 $info_png_chunk_type_text['background_green'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 1 * $info_png['IHDR']['raw']['bit_depth'], $info_png['IHDR']['raw']['bit_depth']));276 $info_png_chunk_type_text['background_blue'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 2 * $info_png['IHDR']['raw']['bit_depth'], $info_png['IHDR']['raw']['bit_depth']));277 break;279 case 3:280 $info_png_chunk_type_text['background_index'] = getid3_lib::BigEndian2Int($chunk['data']);281 break;283 default:284 break;285 }286 break;289 case 'pHYs': // Physical Pixel Dimensions290 $info_png_chunk_type_text['header'] = $chunk;291 $info_png_chunk_type_text['pixels_per_unit_x'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 0, 4));292 $info_png_chunk_type_text['pixels_per_unit_y'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 4, 4));293 $info_png_chunk_type_text['unit_specifier'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 8, 1));294 $info_png_chunk_type_text['unit'] = getid3_png::PNGpHYsUnitLookup($info_png_chunk_type_text['unit_specifier']);295 break;298 case 'sBIT': // Significant Bits299 $info_png_chunk_type_text['header'] = $chunk;300 switch ($info_png['IHDR']['raw']['color_type']) {301 case 0:302 $info_png_chunk_type_text['significant_bits_gray'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 0, 1));303 break;305 case 2:306 case 3:307 $info_png_chunk_type_text['significant_bits_red'] = getid3_lib::BigEndian2Int($chunk['data'][0]);308 $info_png_chunk_type_text['significant_bits_green'] = getid3_lib::BigEndian2Int($chunk['data'][1]);309 $info_png_chunk_type_text['significant_bits_blue'] = getid3_lib::BigEndian2Int($chunk['data'][2]);310 break;312 case 4:313 $info_png_chunk_type_text['significant_bits_gray'] = getid3_lib::BigEndian2Int($chunk['data'][0]);314 $info_png_chunk_type_text['significant_bits_alpha'] = getid3_lib::BigEndian2Int($chunk['data'][1]);315 break;317 case 6:318 $info_png_chunk_type_text['significant_bits_red'] = getid3_lib::BigEndian2Int($chunk['data'][0]);319 $info_png_chunk_type_text['significant_bits_green'] = getid3_lib::BigEndian2Int($chunk['data'][1]);320 $info_png_chunk_type_text['significant_bits_blue'] = getid3_lib::BigEndian2Int($chunk['data'][2]);321 $info_png_chunk_type_text['significant_bits_alpha'] = getid3_lib::BigEndian2Int($chunk['data'][3]);322 break;324 default:325 break;326 }327 break;330 case 'sPLT': // Suggested Palette331 $info_png_chunk_type_text['header'] = $chunk;333 list($palettename, $otherdata) = explode("\x00", $chunk['data'], 2);334 $info_png_chunk_type_text['palette_name'] = $palettename;336 $info_png_chunk_type_text['sample_depth_bits'] = getid3_lib::BigEndian2Int($otherdata[0]);337 $info_png_chunk_type_text['sample_depth_bytes'] = $info_png_chunk_type_text['sample_depth_bits'] / 8;339 $s_plt_offset = 1;340 $paletteCounter = 0;341 while ($s_plt_offset < strlen($otherdata)) {343 $info_png_chunk_type_text['red'][$paletteCounter] = getid3_lib::BigEndian2Int(substr($otherdata, $s_plt_offset, $info_png_chunk_type_text['sample_depth_bytes']));344 $s_plt_offset += $info_png_chunk_type_text['sample_depth_bytes'];346 $info_png_chunk_type_text['green'][$paletteCounter] = getid3_lib::BigEndian2Int(substr($otherdata, $s_plt_offset, $info_png_chunk_type_text['sample_depth_bytes']));347 $s_plt_offset += $info_png_chunk_type_text['sample_depth_bytes'];349 $info_png_chunk_type_text['blue'][$paletteCounter] = getid3_lib::BigEndian2Int(substr($otherdata, $s_plt_offset, $info_png_chunk_type_text['sample_depth_bytes']));350 $s_plt_offset += $info_png_chunk_type_text['sample_depth_bytes'];352 $info_png_chunk_type_text['alpha'][$paletteCounter] = getid3_lib::BigEndian2Int(substr($otherdata, $s_plt_offset, $info_png_chunk_type_text['sample_depth_bytes']));353 $s_plt_offset += $info_png_chunk_type_text['sample_depth_bytes'];355 $info_png_chunk_type_text['frequency'][$paletteCounter] = getid3_lib::BigEndian2Int(substr($otherdata, $s_plt_offset, 2));356 $s_plt_offset += 2;358 $paletteCounter++;359 }360 break;363 case 'hIST': // Palette Histogram364 $info_png_chunk_type_text['header'] = $chunk;365 $h_ist_counter = 0;366 while ($h_ist_counter < strlen($chunk['data'])) {367 $info_png_chunk_type_text[$h_ist_counter] = getid3_lib::BigEndian2Int(substr($chunk['data'], $h_ist_counter / 2, 2));368 $h_ist_counter += 2;369 }370 break;373 case 'tIME': // Image Last-Modification Time374 $info_png_chunk_type_text['header'] = $chunk;375 $info_png_chunk_type_text['year'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 0, 2));376 $info_png_chunk_type_text['month'] = getid3_lib::BigEndian2Int($chunk['data']{2});377 $info_png_chunk_type_text['day'] = getid3_lib::BigEndian2Int($chunk['data']{3});378 $info_png_chunk_type_text['hour'] = getid3_lib::BigEndian2Int($chunk['data']{4});379 $info_png_chunk_type_text['minute'] = getid3_lib::BigEndian2Int($chunk['data']{5});380 $info_png_chunk_type_text['second'] = getid3_lib::BigEndian2Int($chunk['data']{6});381 $info_png_chunk_type_text['unix'] = gmmktime($info_png_chunk_type_text['hour'], $info_png_chunk_type_text['minute'], $info_png_chunk_type_text['second'], $info_png_chunk_type_text['month'], $info_png_chunk_type_text['day'], $info_png_chunk_type_text['year']);382 break;385 case 'oFFs': // Image Offset386 $info_png_chunk_type_text['header'] = $chunk;387 $info_png_chunk_type_text['position_x'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 0, 4), false, true);388 $info_png_chunk_type_text['position_y'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 4, 4), false, true);389 $info_png_chunk_type_text['unit_specifier'] = getid3_lib::BigEndian2Int($chunk['data'][8]);390 $info_png_chunk_type_text['unit'] = getid3_png::PNGoFFsUnitLookup($info_png_chunk_type_text['unit_specifier']);391 break;394 case 'pCAL': // Calibration Of Pixel Values395 $info_png_chunk_type_text['header'] = $chunk;396 list($calibrationname, $otherdata) = explode("\x00", $chunk['data'], 2);397 $info_png_chunk_type_text['calibration_name'] = $calibrationname;398 $info_png_chunk_type_text['original_zero'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 0, 4), false, true);399 $info_png_chunk_type_text['original_max'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 4, 4), false, true);400 $info_png_chunk_type_text['equation_type'] = getid3_lib::BigEndian2Int($chunk['data'][8]);401 $info_png_chunk_type_text['equation_type_text'] = getid3_png::PNGpCALequationTypeLookup($info_png_chunk_type_text['equation_type']);402 $info_png_chunk_type_text['parameter_count'] = getid3_lib::BigEndian2Int($chunk['data'][9]);403 $info_png_chunk_type_text['parameters'] = explode("\x00", substr($chunk['data'], 10));404 break;407 case 'sCAL': // Physical Scale Of Image Subject408 $info_png_chunk_type_text['header'] = $chunk;409 $info_png_chunk_type_text['unit_specifier'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 0, 1));410 $info_png_chunk_type_text['unit'] = getid3_png::PNGsCALUnitLookup($info_png_chunk_type_text['unit_specifier']);411 list($info_png_chunk_type_text['pixel_width'], $info_png_chunk_type_text['pixel_height']) = explode("\x00", substr($chunk['data'], 1));412 break;415 case 'gIFg': // GIF Graphic Control Extension416 $gIFg_counter = 0;417 if (isset($info_png_chunk_type_text) && is_array($info_png_chunk_type_text)) {418 $gIFg_counter = count($info_png_chunk_type_text);419 }420 $info_png_chunk_type_text[$gIFg_counter]['header'] = $chunk;421 $info_png_chunk_type_text[$gIFg_counter]['disposal_method'] = getid3_lib::BigEndian2Int($chunk['data'][0]);422 $info_png_chunk_type_text[$gIFg_counter]['user_input_flag'] = getid3_lib::BigEndian2Int($chunk['data'][1]);423 $info_png_chunk_type_text[$gIFg_counter]['delay_time'] = getid3_lib::BigEndian2Int($chunk['data'][2]);424 break;427 case 'gIFx': // GIF Application Extension428 $gIFx_counter = 0;429 if (isset($info_png_chunk_type_text) && is_array($info_png_chunk_type_text)) {430 $gIFx_counter = count($info_png_chunk_type_text);431 }432 $info_png_chunk_type_text[$gIFx_counter]['header'] = $chunk;433 $info_png_chunk_type_text[$gIFx_counter]['application_identifier'] = substr($chunk['data'], 0, 8);434 $info_png_chunk_type_text[$gIFx_counter]['authentication_code'] = substr($chunk['data'], 8, 3);435 $info_png_chunk_type_text[$gIFx_counter]['application_data'] = substr($chunk['data'], 11);436 break;439 case 'IDAT': // Image Data440 $idat_information_field_index = 0;441 if (isset($info_png['IDAT']) && is_array($info_png['IDAT'])) {442 $idat_information_field_index = count($info_png['IDAT']);443 }444 unset($chunk['data']);445 $info_png_chunk_type_text[$idat_information_field_index]['header'] = $chunk;446 break;449 case 'IEND': // Image Trailer450 $info_png_chunk_type_text['header'] = $chunk;451 break;454 default:455 $info_png_chunk_type_text['header'] = $chunk;456 $getid3->warning('Unhandled chunk type: '.$chunk['type_text']);457 break;458 }459 }461 return true;462 }466 public static function PNGsRGBintentLookup($sRGB) {468 static $lookup = array (469 0 => 'Perceptual',470 1 => 'Relative colorimetric',471 2 => 'Saturation',472 3 => 'Absolute colorimetric'473 );474 return (isset($lookup[$sRGB]) ? $lookup[$sRGB] : 'invalid');475 }479 public static function PNGcompressionMethodLookup($compression_method) {481 return ($compression_method == 0 ? 'deflate/inflate' : 'invalid');482 }486 public static function PNGpHYsUnitLookup($unit_id) {488 static $lookup = array (489 0 => 'unknown',490 1 => 'meter'491 );492 return (isset($lookup[$unit_id]) ? $lookup[$unit_id] : 'invalid');493 }497 public static function PNGoFFsUnitLookup($unit_id) {499 static $lookup = array (500 0 => 'pixel',501 1 => 'micrometer'502 );503 return (isset($lookup[$unit_id]) ? $lookup[$unit_id] : 'invalid');504 }508 public static function PNGpCALequationTypeLookup($equation_type) {510 static $lookup = array (511 0 => 'Linear mapping',512 1 => 'Base-e exponential mapping',513 2 => 'Arbitrary-base exponential mapping',514 3 => 'Hyperbolic mapping'515 );516 return (isset($lookup[$equation_type]) ? $lookup[$equation_type] : 'invalid');517 }521 public static function PNGsCALUnitLookup($unit_id) {523 static $lookup = array (524 0 => 'meter',525 1 => 'radian'526 );527 return (isset($lookup[$unit_id]) ? $lookup[$unit_id] : 'invalid');528 }532 public static function IHDRcalculateBitsPerSample($color_type, $bit_depth) {534 switch ($color_type) {535 case 0: // Each pixel is a grayscale sample.536 return $bit_depth;538 case 2: // Each pixel is an R,G,B triple539 return 3 * $bit_depth;541 case 3: // Each pixel is a palette index; a PLTE chunk must appear.542 return $bit_depth;544 case 4: // Each pixel is a grayscale sample, followed by an alpha sample.545 return 2 * $bit_depth;547 case 6: // Each pixel is an R,G,B triple, followed by an alpha sample.548 return 4 * $bit_depth;549 }550 return false;551 }553 }556 ?>