includes/media/MediaHandler.php

   1 <?php
   2 /**
   3  * Media-handling base classes and generic functionality.
   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  * Base media handler class
  26  *
  27  * @ingroup Media
  28  */
  29 abstract class MediaHandler {
  30         const TRANSFORM_LATER = 1;
  31         const METADATA_GOOD = true;
  32         const METADATA_BAD = false;
  33         const METADATA_COMPATIBLE = 2; // for old but backwards compatible.
  34         /**
  35          * Max length of error logged by logErrorForExternalProcess()
  36          */
  37         const MAX_ERR_LOG_SIZE = 65535;
  38
  39         /** @var MediaHandler[] Instance cache with array of MediaHandler */
  40         protected static $handlers = array();
  41
  42         /**
  43          * Get a MediaHandler for a given MIME type from the instance cache
  44          *
  45          * @param string $type
  46          * @return MediaHandler
  47          */
  48         static function getHandler( $type ) {
  49                 global $wgMediaHandlers;
  50                 if ( !isset( $wgMediaHandlers[$type] ) ) {
  51                         wfDebug( __METHOD__ . ": no handler found for $type.\n" );
  52
  53                         return false;
  54                 }
  55                 $class = $wgMediaHandlers[$type];
  56                 if ( !isset( self::$handlers[$class] ) ) {
  57                         self::$handlers[$class] = new $class;
  58                         if ( !self::$handlers[$class]->isEnabled() ) {
  59                                 wfDebug( __METHOD__ . ": $class is not enabled\n" );
  60                                 self::$handlers[$class] = false;
  61                         }
  62                 }
  63
  64                 return self::$handlers[$class];
  65         }
  66
  67         /**
  68          * Resets all static caches
  69          */
  70         public static function resetCache() {
  71                 self::$handlers = array();
  72         }
  73
  74         /**
  75          * Get an associative array mapping magic word IDs to parameter names.
  76          * Will be used by the parser to identify parameters.
  77          */
  78         abstract function getParamMap();
  79
  80         /**
  81          * Validate a thumbnail parameter at parse time.
  82          * Return true to accept the parameter, and false to reject it.
  83          * If you return false, the parser will do something quiet and forgiving.
  84          *
  85          * @param string $name
  86          * @param mixed $value
  87          */
  88         abstract function validateParam( $name, $value );
  89
  90         /**
  91          * Merge a parameter array into a string appropriate for inclusion in filenames
  92          *
  93          * @param array $params Array of parameters that have been through normaliseParams.
  94          * @return string
  95          */
  96         abstract function makeParamString( $params );
  97
  98         /**
  99          * Parse a param string made with makeParamString back into an array
 100          *
 101          * @param string $str The parameter string without file name (e.g. 122px)
 102          * @return array|bool Array of parameters or false on failure.
 103          */
 104         abstract function parseParamString( $str );
 105
 106         /**
 107          * Changes the parameter array as necessary, ready for transformation.
 108          * Should be idempotent.
 109          * Returns false if the parameters are unacceptable and the transform should fail
 110          * @param File $image
 111          * @param array $params
 112          */
 113         abstract function normaliseParams( $image, &$params );
 114
 115         /**
 116          * Get an image size array like that returned by getimagesize(), or false if it
 117          * can't be determined.
 118          *
 119          * This function is used for determining the width, height and bitdepth directly
 120          * from an image. The results are stored in the database in the img_width,
 121          * img_height, img_bits fields.
 122          *
 123          * @note If this is a multipage file, return the width and height of the
 124          *  first page.
 125          *
 126          * @param File $image The image object, or false if there isn't one
 127          * @param string $path The filename
 128          * @return array Follow the format of PHP getimagesize() internal function.
 129          *   See http://www.php.net/getimagesize. MediaWiki will only ever use the
 130          *   first two array keys (the width and height), and the 'bits' associative
 131          *   key. All other array keys are ignored. Returning a 'bits' key is optional
 132          *   as not all formats have a notion of "bitdepth".
 133          */
 134         abstract function getImageSize( $image, $path );
 135
 136         /**
 137          * Get handler-specific metadata which will be saved in the img_metadata field.
 138          *
 139          * @param File $image The image object, or false if there isn't one.
 140          *   Warning, FSFile::getPropsFromPath might pass an (object)array() instead (!)
 141          * @param string $path The filename
 142          * @return string A string of metadata in php serialized form (Run through serialize())
 143          */
 144         function getMetadata( $image, $path ) {
 145                 return '';
 146         }
 147
 148         /**
 149          * Get metadata version.
 150          *
 151          * This is not used for validating metadata, this is used for the api when returning
 152          * metadata, since api content formats should stay the same over time, and so things
 153          * using ForeignApiRepo can keep backwards compatibility
 154          *
 155          * All core media handlers share a common version number, and extensions can
 156          * use the GetMetadataVersion hook to append to the array (they should append a unique
 157          * string so not to get confusing). If there was a media handler named 'foo' with metadata
 158          * version 3 it might add to the end of the array the element 'foo=3'. if the core metadata
 159          * version is 2, the end version string would look like '2;foo=3'.
 160          *
 161          * @return string Version string
 162          */
 163         static function getMetadataVersion() {
 164                 $version = array( '2' ); // core metadata version
 165                 wfRunHooks( 'GetMetadataVersion', array( &$version ) );
 166
 167                 return implode( ';', $version );
 168         }
 169
 170         /**
 171          * Convert metadata version.
 172          *
 173          * By default just returns $metadata, but can be used to allow
 174          * media handlers to convert between metadata versions.
 175          *
 176          * @param string|array $metadata Metadata array (serialized if string)
 177          * @param int $version Target version
 178          * @return array Serialized metadata in specified version, or $metadata on fail.
 179          */
 180         function convertMetadataVersion( $metadata, $version = 1 ) {
 181                 if ( !is_array( $metadata ) ) {
 182
 183                         //unserialize to keep return parameter consistent.
 184                         wfSuppressWarnings();
 185                         $ret = unserialize( $metadata );
 186                         wfRestoreWarnings();
 187
 188                         return $ret;
 189                 }
 190
 191                 return $metadata;
 192         }
 193
 194         /**
 195          * Get a string describing the type of metadata, for display purposes.
 196          *
 197          * @note This method is currently unused.
 198          * @param File $image
 199          * @return string
 200          */
 201         function getMetadataType( $image ) {
 202                 return false;
 203         }
 204
 205         /**
 206          * Check if the metadata string is valid for this handler.
 207          * If it returns MediaHandler::METADATA_BAD (or false), Image
 208          * will reload the metadata from the file and update the database.
 209          * MediaHandler::METADATA_GOOD for if the metadata is a-ok,
 210          * MediaHandler::METADATA_COMPATIBLE if metadata is old but backwards
 211          * compatible (which may or may not trigger a metadata reload).
 212          *
 213          * @note Returning self::METADATA_BAD will trigger a metadata reload from
 214          *  file on page view. Always returning this from a broken file, or suddenly
 215          *  triggering as bad metadata for a large number of files can cause
 216          *  performance problems.
 217          * @param File $image
 218          * @param string $metadata The metadata in serialized form
 219          * @return bool
 220          */
 221         function isMetadataValid( $image, $metadata ) {
 222                 return self::METADATA_GOOD;
 223         }
 224
 225         /**
 226          * Get an array of standard (FormatMetadata type) metadata values.
 227          *
 228          * The returned data is largely the same as that from getMetadata(),
 229          * but formatted in a standard, stable, handler-independent way.
 230          * The idea being that some values like ImageDescription or Artist
 231          * are universal and should be retrievable in a handler generic way.
 232          *
 233          * The specific properties are the type of properties that can be
 234          * handled by the FormatMetadata class. These values are exposed to the
 235          * user via the filemetadata parser function.
 236          *
 237          * Details of the response format of this function can be found at
 238          * https://www.mediawiki.org/wiki/Manual:File_metadata_handling
 239          * tl/dr: the response is an associative array of
 240          * properties keyed by name, but the value can be complex. You probably
 241          * want to call one of the FormatMetadata::flatten* functions on the
 242          * property values before using them, or call
 243          * FormatMetadata::getFormattedData() on the full response array, which
 244          * transforms all values into prettified, human-readable text.
 245          *
 246          * Subclasses overriding this function must return a value which is a
 247          * valid API response fragment (all associative array keys are valid
 248          * XML tagnames).
 249          *
 250          * Note, if the file simply has no metadata, but the handler supports
 251          * this interface, it should return an empty array, not false.
 252          *
 253          * @param File $file
 254          * @return array|bool False if interface not supported
 255          * @since 1.23
 256          */
 257         public function getCommonMetaArray( File $file ) {
 258                 return false;
 259         }
 260
 261         /**
 262          * Get a MediaTransformOutput object representing an alternate of the transformed
 263          * output which will call an intermediary thumbnail assist script.
 264          *
 265          * Used when the repository has a thumbnailScriptUrl option configured.
 266          *
 267          * Return false to fall back to the regular getTransform().
 268          * @param File $image
 269          * @param string $script
 270          * @param array $params
 271          * @return bool|ThumbnailImage
 272          */
 273         function getScriptedTransform( $image, $script, $params ) {
 274                 return false;
 275         }
 276
 277         /**
 278          * Get a MediaTransformOutput object representing the transformed output. Does not
 279          * actually do the transform.
 280          *
 281          * @param File $image The image object
 282          * @param string $dstPath Filesystem destination path
 283          * @param string $dstUrl Destination URL to use in output HTML
 284          * @param array $params Arbitrary set of parameters validated by $this->validateParam()
 285          * @return MediaTransformOutput
 286          */
 287         final function getTransform( $image, $dstPath, $dstUrl, $params ) {
 288                 return $this->doTransform( $image, $dstPath, $dstUrl, $params, self::TRANSFORM_LATER );
 289         }
 290
 291         /**
 292          * Get a MediaTransformOutput object representing the transformed output. Does the
 293          * transform unless $flags contains self::TRANSFORM_LATER.
 294          *
 295          * @param File $image The image object
 296          * @param string $dstPath Filesystem destination path
 297          * @param string $dstUrl Destination URL to use in output HTML
 298          * @param array $params Arbitrary set of parameters validated by $this->validateParam()
 299          *   Note: These parameters have *not* gone through $this->normaliseParams()
 300          * @param int $flags A bitfield, may contain self::TRANSFORM_LATER
 301          * @return MediaTransformOutput
 302          */
 303         abstract function doTransform( $image, $dstPath, $dstUrl, $params, $flags = 0 );
 304
 305         /**
 306          * Get the thumbnail extension and MIME type for a given source MIME type
 307          *
 308          * @param string $ext Extension of original file
 309          * @param string $mime MIME type of original file
 310          * @param array $params Handler specific rendering parameters
 311          * @return array Thumbnail extension and MIME type
 312          */
 313         function getThumbType( $ext, $mime, $params = null ) {
 314                 $magic = MimeMagic::singleton();
 315                 if ( !$ext || $magic->isMatchingExtension( $ext, $mime ) === false ) {
 316                         // The extension is not valid for this MIME type and we do
 317                         // recognize the MIME type
 318                         $extensions = $magic->getExtensionsForType( $mime );
 319                         if ( $extensions ) {
 320                                 return array( strtok( $extensions, ' ' ), $mime );
 321                         }
 322                 }
 323
 324                 // The extension is correct (true) or the MIME type is unknown to
 325                 // MediaWiki (null)
 326                 return array( $ext, $mime );
 327         }
 328
 329         /**
 330          * Get useful response headers for GET/HEAD requests for a file with the given metadata
 331          *
 332          * @param mixed $metadata Result of the getMetadata() function of this handler for a file
 333          * @return array
 334          */
 335         public function getStreamHeaders( $metadata ) {
 336                 return array();
 337         }
 338
 339         /**
 340          * True if the handled types can be transformed
 341          *
 342          * @param File $file
 343          * @return bool
 344          */
 345         function canRender( $file ) {
 346                 return true;
 347         }
 348
 349         /**
 350          * True if handled types cannot be displayed directly in a browser
 351          * but can be rendered
 352          *
 353          * @param File $file
 354          * @return bool
 355          */
 356         function mustRender( $file ) {
 357                 return false;
 358         }
 359
 360         /**
 361          * True if the type has multi-page capabilities
 362          *
 363          * @param File $file
 364          * @return bool
 365          */
 366         function isMultiPage( $file ) {
 367                 return false;
 368         }
 369
 370         /**
 371          * Page count for a multi-page document, false if unsupported or unknown
 372          *
 373          * @param File $file
 374          * @return bool
 375          */
 376         function pageCount( $file ) {
 377                 return false;
 378         }
 379
 380         /**
 381          * The material is vectorized and thus scaling is lossless
 382          *
 383          * @param File $file
 384          * @return bool
 385          */
 386         function isVectorized( $file ) {
 387                 return false;
 388         }
 389
 390         /**
 391          * The material is an image, and is animated.
 392          * In particular, video material need not return true.
 393          * @note Before 1.20, this was a method of ImageHandler only
 394          *
 395          * @param File $file
 396          * @return bool
 397          */
 398         function isAnimatedImage( $file ) {
 399                 return false;
 400         }
 401
 402         /**
 403          * If the material is animated, we can animate the thumbnail
 404          * @since 1.20
 405          *
 406          * @param File $file
 407          * @return bool If material is not animated, handler may return any value.
 408          */
 409         function canAnimateThumbnail( $file ) {
 410                 return true;
 411         }
 412
 413         /**
 414          * False if the handler is disabled for all files
 415          * @return bool
 416          */
 417         function isEnabled() {
 418                 return true;
 419         }
 420
 421         /**
 422          * Get an associative array of page dimensions
 423          * Currently "width" and "height" are understood, but this might be
 424          * expanded in the future.
 425          * Returns false if unknown.
 426          *
 427          * It is expected that handlers for paged media (e.g. DjVuHandler)
 428          * will override this method so that it gives the correct results
 429          * for each specific page of the file, using the $page argument.
 430          *
 431          * @note For non-paged media, use getImageSize.
 432          *
 433          * @param File $image
 434          * @param int $page What page to get dimensions of
 435          * @return array|bool
 436          */
 437         function getPageDimensions( $image, $page ) {
 438                 $gis = $this->getImageSize( $image, $image->getLocalRefPath() );
 439                 if ( $gis ) {
 440                         return array(
 441                                 'width' => $gis[0],
 442                                 'height' => $gis[1]
 443                         );
 444                 } else {
 445                         return false;
 446                 }
 447         }
 448
 449         /**
 450          * Generic getter for text layer.
 451          * Currently overloaded by PDF and DjVu handlers
 452          * @param File $image
 453          * @param int $page Page number to get information for
 454          * @return bool|string Page text or false when no text found or if
 455          *   unsupported.
 456          */
 457         function getPageText( $image, $page ) {
 458                 return false;
 459         }
 460
 461         /**
 462          * Get the text of the entire document.
 463          * @param File $file
 464          * @return bool|string The text of the document or false if unsupported.
 465          */
 466         public function getEntireText( File $file ) {
 467                 $numPages = $file->pageCount();
 468                 if ( !$numPages ) {
 469                         // Not a multipage document
 470                         return $this->getPageText( $file, 1 );
 471                 }
 472                 $document = '';
 473                 for ( $i = 1; $i <= $numPages; $i++ ) {
 474                         $curPage = $this->getPageText( $file, $i );
 475                         if ( is_string( $curPage ) ) {
 476                                 $document .= $curPage . "\n";
 477                         }
 478                 }
 479                 if ( $document !== '' ) {
 480                         return $document;
 481                 }
 482                 return false;
 483         }
 484
 485         /**
 486          * Get an array structure that looks like this:
 487          *
 488          * array(
 489          *    'visible' => array(
 490          *       'Human-readable name' => 'Human readable value',
 491          *       ...
 492          *    ),
 493          *    'collapsed' => array(
 494          *       'Human-readable name' => 'Human readable value',
 495          *       ...
 496          *    )
 497          * )
 498          * The UI will format this into a table where the visible fields are always
 499          * visible, and the collapsed fields are optionally visible.
 500          *
 501          * The function should return false if there is no metadata to display.
 502          */
 503
 504         /**
 505          * @todo FIXME: This interface is not very flexible. The media handler
 506          * should generate HTML instead. It can do all the formatting according
 507          * to some standard. That makes it possible to do things like visual
 508          * indication of grouped and chained streams in ogg container files.
 509          * @param File $image
 510          * @return array|bool
 511          */
 512         function formatMetadata( $image ) {
 513                 return false;
 514         }
 515
 516         /** sorts the visible/invisible field.
 517          * Split off from ImageHandler::formatMetadata, as used by more than
 518          * one type of handler.
 519          *
 520          * This is used by the media handlers that use the FormatMetadata class
 521          *
 522          * @param array $metadataArray Metadata array
 523          * @return array Array for use displaying metadata.
 524          */
 525         function formatMetadataHelper( $metadataArray ) {
 526                 $result = array(
 527                         'visible' => array(),
 528                         'collapsed' => array()
 529                 );
 530
 531                 $formatted = FormatMetadata::getFormattedData( $metadataArray );
 532                 // Sort fields into visible and collapsed
 533                 $visibleFields = $this->visibleMetadataFields();
 534                 foreach ( $formatted as $name => $value ) {
 535                         $tag = strtolower( $name );
 536                         self::addMeta( $result,
 537                                 in_array( $tag, $visibleFields ) ? 'visible' : 'collapsed',
 538                                 'exif',
 539                                 $tag,
 540                                 $value
 541                         );
 542                 }
 543
 544                 return $result;
 545         }
 546
 547         /**
 548          * Get a list of metadata items which should be displayed when
 549          * the metadata table is collapsed.
 550          *
 551          * @return array Array of strings
 552          */
 553         protected function visibleMetadataFields() {
 554                 return FormatMetadata::getVisibleFields();
 555         }
 556
 557         /**
 558          * This is used to generate an array element for each metadata value
 559          * That array is then used to generate the table of metadata values
 560          * on the image page
 561          *
 562          * @param array &$array An array containing elements for each type of visibility
 563          *   and each of those elements being an array of metadata items. This function adds
 564          *   a value to that array.
 565          * @param string $visibility ('visible' or 'collapsed') if this value is hidden
 566          *   by default.
 567          * @param string $type Type of metadata tag (currently always 'exif')
 568          * @param string $id The name of the metadata tag (like 'artist' for example).
 569          *   its name in the table displayed is the message "$type-$id" (Ex exif-artist ).
 570          * @param string $value Thingy goes into a wikitext table; it used to be escaped but
 571          *   that was incompatible with previous practise of customized display
 572          *   with wikitext formatting via messages such as 'exif-model-value'.
 573          *   So the escaping is taken back out, but generally this seems a confusing
 574          *   interface.
 575          * @param bool|string $param Value to pass to the message for the name of the field
 576          *   as $1. Currently this parameter doesn't seem to ever be used.
 577          *
 578          * Note, everything here is passed through the parser later on (!)
 579          */
 580         protected static function addMeta( &$array, $visibility, $type, $id, $value, $param = false ) {
 581                 $msg = wfMessage( "$type-$id", $param );
 582                 if ( $msg->exists() ) {
 583                         $name = $msg->text();
 584                 } else {
 585                         // This is for future compatibility when using instant commons.
 586                         // So as to not display as ugly a name if a new metadata
 587                         // property is defined that we don't know about
 588                         // (not a major issue since such a property would be collapsed
 589                         // by default).
 590                         wfDebug( __METHOD__ . ' Unknown metadata name: ' . $id . "\n" );
 591                         $name = wfEscapeWikiText( $id );
 592                 }
 593                 $array[$visibility][] = array(
 594                         'id' => "$type-$id",
 595                         'name' => $name,
 596                         'value' => $value
 597                 );
 598         }
 599
 600         /**
 601          * Short description. Shown on Special:Search results.
 602          *
 603          * @param File $file
 604          * @return string
 605          */
 606         function getShortDesc( $file ) {
 607                 return self::getGeneralShortDesc( $file );
 608         }
 609
 610         /**
 611          * Long description. Shown under image on image description page surounded by ().
 612          *
 613          * @param File $file
 614          * @return string
 615          */
 616         function getLongDesc( $file ) {
 617                 return self::getGeneralLongDesc( $file );
 618         }
 619
 620         /**
 621          * Used instead of getShortDesc if there is no handler registered for file.
 622          *
 623          * @param File $file
 624          * @return string
 625          */
 626         static function getGeneralShortDesc( $file ) {
 627                 global $wgLang;
 628
 629                 return htmlspecialchars( $wgLang->formatSize( $file->getSize() ) );
 630         }
 631
 632         /**
 633          * Used instead of getLongDesc if there is no handler registered for file.
 634          *
 635          * @param File $file
 636          * @return string
 637          */
 638         static function getGeneralLongDesc( $file ) {
 639                 return wfMessage( 'file-info' )->sizeParams( $file->getSize() )
 640                         ->params( $file->getMimeType() )->parse();
 641         }
 642
 643         /**
 644          * Calculate the largest thumbnail width for a given original file size
 645          * such that the thumbnail's height is at most $maxHeight.
 646          * @param int $boxWidth Width of the thumbnail box.
 647          * @param int $boxHeight Height of the thumbnail box.
 648          * @param int $maxHeight Maximum height expected for the thumbnail.
 649          * @return int
 650          */
 651         public static function fitBoxWidth( $boxWidth, $boxHeight, $maxHeight ) {
 652                 $idealWidth = $boxWidth * $maxHeight / $boxHeight;
 653                 $roundedUp = ceil( $idealWidth );
 654                 if ( round( $roundedUp * $boxHeight / $boxWidth ) > $maxHeight ) {
 655                         return floor( $idealWidth );
 656                 } else {
 657                         return $roundedUp;
 658                 }
 659         }
 660
 661         /**
 662          * Shown in file history box on image description page.
 663          *
 664          * @param File $file
 665          * @return string Dimensions
 666          */
 667         function getDimensionsString( $file ) {
 668                 return '';
 669         }
 670
 671         /**
 672          * Modify the parser object post-transform.
 673          *
 674          * This is often used to do $parser->addOutputHook(),
 675          * in order to add some javascript to render a viewer.
 676          * See TimedMediaHandler or OggHandler for an example.
 677          *
 678          * @param Parser $parser
 679          * @param File $file
 680          */
 681         function parserTransformHook( $parser, $file ) {
 682         }
 683
 684         /**
 685          * File validation hook called on upload.
 686          *
 687          * If the file at the given local path is not valid, or its MIME type does not
 688          * match the handler class, a Status object should be returned containing
 689          * relevant errors.
 690          *
 691          * @param string $fileName The local path to the file.
 692          * @return Status
 693          */
 694         function verifyUpload( $fileName ) {
 695                 return Status::newGood();
 696         }
 697
 698         /**
 699          * Check for zero-sized thumbnails. These can be generated when
 700          * no disk space is available or some other error occurs
 701          *
 702          * @param string $dstPath The location of the suspect file
 703          * @param int $retval Return value of some shell process, file will be deleted if this is non-zero
 704          * @return bool True if removed, false otherwise
 705          */
 706         function removeBadFile( $dstPath, $retval = 0 ) {
 707                 if ( file_exists( $dstPath ) ) {
 708                         $thumbstat = stat( $dstPath );
 709                         if ( $thumbstat['size'] == 0 || $retval != 0 ) {
 710                                 $result = unlink( $dstPath );
 711
 712                                 if ( $result ) {
 713                                         wfDebugLog( 'thumbnail',
 714                                                 sprintf( 'Removing bad %d-byte thumbnail "%s". unlink() succeeded',
 715                                                         $thumbstat['size'], $dstPath ) );
 716                                 } else {
 717                                         wfDebugLog( 'thumbnail',
 718                                                 sprintf( 'Removing bad %d-byte thumbnail "%s". unlink() failed',
 719                                                         $thumbstat['size'], $dstPath ) );
 720                                 }
 721
 722                                 return true;
 723                         }
 724                 }
 725
 726                 return false;
 727         }
 728
 729         /**
 730          * Remove files from the purge list.
 731          *
 732          * This is used by some video handlers to prevent ?action=purge
 733          * from removing a transcoded video, which is expensive to
 734          * regenerate.
 735          *
 736          * @see LocalFile::purgeThumbnails
 737          *
 738          * @param array $files
 739          * @param array $options Purge options. Currently will always be
 740          *  an array with a single key 'forThumbRefresh' set to true.
 741          */
 742         public function filterThumbnailPurgeList( &$files, $options ) {
 743                 // Do nothing
 744         }
 745
 746         /**
 747          * True if the handler can rotate the media
 748          * @since 1.24 non-static. From 1.21-1.23 was static
 749          * @return bool
 750          */
 751         public function canRotate() {
 752                 return false;
 753         }
 754
 755         /**
 756          * On supporting image formats, try to read out the low-level orientation
 757          * of the file and return the angle that the file needs to be rotated to
 758          * be viewed.
 759          *
 760          * This information is only useful when manipulating the original file;
 761          * the width and height we normally work with is logical, and will match
 762          * any produced output views.
 763          *
 764          * For files we don't know, we return 0.
 765          *
 766          * @param File $file
 767          * @return int 0, 90, 180 or 270
 768          */
 769         public function getRotation( $file ) {
 770                 return 0;
 771         }
 772
 773         /**
 774          * Log an error that occurred in an external process
 775          *
 776          * Moved from BitmapHandler to MediaHandler with MediaWiki 1.23
 777          *
 778          * @since 1.23
 779          * @param int $retval
 780          * @param string $err Error reported by command. Anything longer than
 781          * MediaHandler::MAX_ERR_LOG_SIZE is stripped off.
 782          * @param string $cmd
 783          */
 784         protected function logErrorForExternalProcess( $retval, $err, $cmd ) {
 785                 # Keep error output limited (bug 57985)
 786                 $errMessage = trim( substr( $err, 0, self::MAX_ERR_LOG_SIZE ) );
 787
 788                 wfDebugLog( 'thumbnail',
 789                         sprintf( 'thumbnail failed on %s: error %d "%s" from "%s"',
 790                                         wfHostname(), $retval, $errMessage, $cmd ) );
 791         }
 792
 793         /**
 794          * Get list of languages file can be viewed in.
 795          *
 796          * @param File $file
 797          * @return string[] Array of language codes, or empty array if unsupported.
 798          * @since 1.23
 799          */
 800         public function getAvailableLanguages( File $file ) {
 801                 return array();
 802         }
 803
 804         /**
 805          * On file types that support renderings in multiple languages,
 806          * which language is used by default if unspecified.
 807          *
 808          * If getAvailableLanguages returns a non-empty array, this must return
 809          * a valid language code. Otherwise can return null if files of this
 810          * type do not support alternative language renderings.
 811          *
 812          * @param File $file
 813          * @return string|null Language code or null if multi-language not supported for filetype.
 814          * @since 1.23
 815          */
 816         public function getDefaultRenderLanguage( File $file ) {
 817                 return null;
 818         }
 819
 820         /**
 821          * If its an audio file, return the length of the file. Otherwise 0.
 822          *
 823          * File::getLength() existed for a long time, but was calling a method
 824          * that only existed in some subclasses of this class (The TMH ones).
 825          *
 826          * @param File $file
 827          * @return float Length in seconds
 828          * @since 1.23
 829          */
 830         public function getLength( $file ) {
 831                 return 0.0;
 832         }
 833
 834         /**
 835          * True if creating thumbnails from the file is large or otherwise resource-intensive.
 836          * @param File $file
 837          * @return bool
 838          */
 839         public function isExpensiveToThumbnail( $file ) {
 840                 return false;
 841         }
 842
 843         /**
 844          * Returns whether or not this handler supports the chained generation of thumbnails according
 845          * to buckets
 846          * @return bool
 847          * @since 1.24
 848          */
 849         public function supportsBucketing() {
 850                 return false;
 851         }
 852
 853         /**
 854          * Returns a normalised params array for which parameters have been cleaned up for bucketing
 855          * purposes
 856          * @param array $params
 857          * @return array
 858          */
 859         public function sanitizeParamsForBucketing( $params ) {
 860                 return $params;
 861         }
 862 }