includes/media/WebP.php

   1 <?php
   2 /**
   3  * Handler for Google's WebP format <https://developers.google.com/speed/webp/>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Media
  22  */
  23
  24 /**
  25  * Handler for Google's WebP format <https://developers.google.com/speed/webp/>
  26  *
  27  * @ingroup Media
  28  */
  29 class WebPHandler extends BitmapHandler {
  30         const BROKEN_FILE = '0'; // value to store in img_metadata if error extracting metadata.
  31         /**
  32          * @var int Minimum chunk header size to be able to read all header types
  33          */
  34         const MINIMUM_CHUNK_HEADER_LENGTH = 18;
  35         /**
  36          * @var int version of the metadata stored in db records
  37          */
  38         const _MW_WEBP_VERSION = 1;
  39
  40         const VP8X_ICC = 32;
  41         const VP8X_ALPHA = 16;
  42         const VP8X_EXIF = 8;
  43         const VP8X_XMP = 4;
  44         const VP8X_ANIM = 2;
  45
  46         public function getMetadata( $image, $filename ) {
  47                 $parsedWebPData = self::extractMetadata( $filename );
  48                 if ( !$parsedWebPData ) {
  49                         return self::BROKEN_FILE;
  50                 }
  51
  52                 $parsedWebPData['metadata']['_MW_WEBP_VERSION'] = self::_MW_WEBP_VERSION;
  53                 return serialize( $parsedWebPData );
  54         }
  55
  56         public function getMetadataType( $image ) {
  57                 return 'parsed-webp';
  58         }
  59
  60         public function isMetadataValid( $image, $metadata ) {
  61                 if ( $metadata === self::BROKEN_FILE ) {
  62                                 // Do not repetitivly regenerate metadata on broken file.
  63                                 return self::METADATA_GOOD;
  64                 }
  65
  66                 MediaWiki\suppressWarnings();
  67                 $data = unserialize( $metadata );
  68                 MediaWiki\restoreWarnings();
  69
  70                 if ( !$data || !is_array( $data ) ) {
  71                                 wfDebug( __METHOD__ . " invalid WebP metadata\n" );
  72
  73                                 return self::METADATA_BAD;
  74                 }
  75
  76                 if ( !isset( $data['metadata']['_MW_WEBP_VERSION'] )
  77                                 || $data['metadata']['_MW_WEBP_VERSION'] != self::_MW_WEBP_VERSION
  78                 ) {
  79                                 wfDebug( __METHOD__ . " old but compatible WebP metadata\n" );
  80
  81                                 return self::METADATA_COMPATIBLE;
  82                 }
  83                 return self::METADATA_GOOD;
  84         }
  85
  86         /**
  87          * Extracts the image size and WebP type from a file
  88          *
  89          * @param string $chunks Chunks as extracted by RiffExtractor
  90          * @return array|bool Header data array with entries 'compression', 'width' and 'height',
  91          * where 'compression' can be 'lossy', 'lossless', 'animated' or 'unknown'. False if
  92          * file is not a valid WebP file.
  93          */
  94         public static function extractMetadata( $filename ) {
  95                 wfDebugLog( 'WebP', __METHOD__ . ": Extracting metadata from $filename\n" );
  96
  97                 $info = RiffExtractor::findChunksFromFile( $filename, 100 );
  98                 if ( $info === false ) {
  99                         wfDebugLog( 'WebP', __METHOD__ . ": Not a valid RIFF file\n" );
 100                         return false;
 101                 }
 102
 103                 if ( $info['fourCC'] != 'WEBP' ) {
 104                         wfDebugLog( 'WebP', __METHOD__ . ': FourCC was not WEBP: ' .
 105                                 bin2hex( $info['fourCC'] ) . " \n" );
 106                         return false;
 107                 }
 108
 109                 $metadata = self::extractMetadataFromChunks( $info['chunks'], $filename );
 110                 if ( !$metadata ) {
 111                         wfDebugLog( 'WebP', __METHOD__ . ": No VP8 chunks found\n" );
 112                         return false;
 113                 }
 114
 115                 return $metadata;
 116         }
 117
 118         /**
 119          * Extracts the image size and WebP type from a file based on the chunk list
 120          * @param array $chunks Chunks as extracted by RiffExtractor
 121          * @return array Header data array with entries 'compression', 'width' and 'height', where
 122          * 'compression' can be 'lossy', 'lossless', 'animated' or 'unknown'
 123          */
 124         public static function extractMetadataFromChunks( $chunks, $filename ) {
 125                 $vp8Info = [];
 126
 127                 foreach ( $chunks as $chunk ) {
 128                         if ( !in_array( $chunk['fourCC'], [ 'VP8 ', 'VP8L', 'VP8X' ] ) ) {
 129                                 // Not a chunk containing interesting metadata
 130                                 continue;
 131                         }
 132
 133                         $chunkHeader = file_get_contents( $filename, false, null,
 134                                 $chunk['start'], self::MINIMUM_CHUNK_HEADER_LENGTH );
 135                         wfDebugLog( 'WebP', __METHOD__ . ": {$chunk['fourCC']}\n" );
 136
 137                         switch ( $chunk['fourCC'] ) {
 138                                 case 'VP8 ':
 139                                         return array_merge( $vp8Info,
 140                                                 self::decodeLossyChunkHeader( $chunkHeader ) );
 141                                 case 'VP8L':
 142                                         return array_merge( $vp8Info,
 143                                                 self::decodeLosslessChunkHeader( $chunkHeader ) );
 144                                 case 'VP8X':
 145                                         $vp8Info = array_merge( $vp8Info,
 146                                                 self::decodeExtendedChunkHeader( $chunkHeader ) );
 147                                         // Continue looking for other chunks to improve the metadata
 148                                         break;
 149                         }
 150                 }
 151                 return $vp8Info;
 152         }
 153
 154         /**
 155          * Decodes a lossy chunk header
 156          * @param string $header Header string
 157          * @return bool|array See WebPHandler::decodeHeader
 158          */
 159         protected static function decodeLossyChunkHeader( $header ) {
 160                 // Bytes 0-3 are 'VP8 '
 161                 // Bytes 4-7 are the VP8 stream size
 162                 // Bytes 8-10 are the frame tag
 163                 // Bytes 11-13 are 0x9D 0x01 0x2A called the sync code
 164                 $syncCode = substr( $header, 11, 3 );
 165                 if ( $syncCode != "\x9D\x01\x2A" ) {
 166                         wfDebugLog( 'WebP', __METHOD__ . ': Invalid sync code: ' .
 167                                 bin2hex( $syncCode ) . "\n" );
 168                         return [];
 169                 }
 170                 // Bytes 14-17 are image size
 171                 $imageSize = unpack( 'v2', substr( $header, 14, 4 ) );
 172                 // Image sizes are 14 bit, 2 MSB are scaling parameters which are ignored here
 173                 return [
 174                         'compression' => 'lossy',
 175                         'width' => $imageSize[1] & 0x3FFF,
 176                         'height' => $imageSize[2] & 0x3FFF
 177                 ];
 178         }
 179
 180         /**
 181          * Decodes a lossless chunk header
 182          * @param string $header Header string
 183          * @return bool|array See WebPHandler::decodeHeader
 184          */
 185         public static function decodeLosslessChunkHeader( $header ) {
 186                 // Bytes 0-3 are 'VP8L'
 187                 // Bytes 4-7 are chunk stream size
 188                 // Byte 8 is 0x2F called the signature
 189                 if ( $header{8} != "\x2F" ) {
 190                         wfDebugLog( 'WebP', __METHOD__ . ': Invalid signature: ' .
 191                                 bin2hex( $header{8} ) . "\n" );
 192                         return [];
 193                 }
 194                 // Bytes 9-12 contain the image size
 195                 // Bits 0-13 are width-1; bits 15-27 are height-1
 196                 $imageSize = unpack( 'C4', substr( $header, 9, 4 ) );
 197                 return [
 198                                 'compression' => 'lossless',
 199                                 'width' => ( $imageSize[1] | ( ( $imageSize[2] & 0x3F ) << 8 ) ) + 1,
 200                                 'height' => ( ( ( $imageSize[2] & 0xC0 ) >> 6 ) |
 201                                                 ( $imageSize[3] << 2 ) | ( ( $imageSize[4] & 0x03 ) << 10 ) ) + 1
 202                 ];
 203         }
 204
 205         /**
 206          * Decodes an extended chunk header
 207          * @param string $header Header string
 208          * @return bool|array See WebPHandler::decodeHeader
 209          */
 210         public static function decodeExtendedChunkHeader( $header ) {
 211                 // Bytes 0-3 are 'VP8X'
 212                 // Byte 4-7 are chunk length
 213                 // Byte 8-11 are a flag bytes
 214                 $flags = unpack( 'c', substr( $header, 8, 1 ) );
 215
 216                 // Byte 12-17 are image size (24 bits)
 217                 $width = unpack( 'V', substr( $header, 12, 3 ) . "\x00" );
 218                 $height = unpack( 'V', substr( $header, 15, 3 ) . "\x00" );
 219
 220                 return [
 221                         'compression' => 'unknown',
 222                         'animated' => ( $flags[1] & self::VP8X_ANIM ) == self::VP8X_ANIM,
 223                         'transparency' => ( $flags[1] & self::VP8X_ALPHA ) == self::VP8X_ALPHA,
 224                         'width' => ( $width[1] & 0xFFFFFF ) + 1,
 225                         'height' => ( $height[1] & 0xFFFFFF ) + 1
 226                 ];
 227         }
 228
 229         public function getImageSize( $file, $path, $metadata = false ) {
 230                 if ( $file === null ) {
 231                         $metadata = self::getMetadata( $file, $path );
 232                 }
 233                 if ( $metadata === false && $file instanceof File ) {
 234                         $metadata = $file->getMetadata();
 235                 }
 236
 237                 MediaWiki\suppressWarnings();
 238                 $metadata = unserialize( $metadata );
 239                 MediaWiki\restoreWarnings();
 240
 241                 if ( $metadata == false ) {
 242                         return false;
 243                 }
 244                 return [ $metadata['width'], $metadata['height'] ];
 245         }
 246
 247         /**
 248          * @param $file
 249          * @return bool True, not all browsers support WebP
 250          */
 251         public function mustRender( $file ) {
 252                 return true;
 253         }
 254
 255         /**
 256          * @param $file
 257          * @return bool False if we are unable to render this image
 258          */
 259         public function canRender( $file ) {
 260                 if ( self::isAnimatedImage( $file ) ) {
 261                         return false;
 262                 }
 263                 return true;
 264         }
 265
 266         /**
 267          * @param File $image
 268          * @return bool
 269          */
 270         public function isAnimatedImage( $image ) {
 271                 $ser = $image->getMetadata();
 272                 if ( $ser ) {
 273                         $metadata = unserialize( $ser );
 274                         if ( isset( $metadata['animated'] ) && $metadata['animated'] === true ) {
 275                                 return true;
 276                         }
 277                 }
 278
 279                 return false;
 280         }
 281
 282         public function canAnimateThumbnail( $file ) {
 283                 return false;
 284         }
 285
 286         /**
 287          * Render files as PNG
 288          *
 289          * @param $ext
 290          * @param $mime
 291          * @param $params
 292          * @return array
 293          */
 294         public function getThumbType( $ext, $mime, $params = null ) {
 295                 return [ 'png', 'image/png' ];
 296         }
 297
 298         /**
 299          * Must use "im" for XCF
 300          *
 301          * @return string
 302          */
 303         protected function getScalerType( $dstPath, $checkDstPath = true ) {
 304                 return 'im';
 305         }
 306 }