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 use MediaWiki\MediaWikiServices;
  24
  25 /**
  26  * Base media handler class
  27  *
  28  * @ingroup Media
  29  */
  30 abstract class MediaHandler {
  31         const TRANSFORM_LATER = 1;
  32         const METADATA_GOOD = true;
  33         const METADATA_BAD = false;
  34         const METADATA_COMPATIBLE = 2; // for old but backwards compatible.
  35         /**
  36          * Max length of error logged by logErrorForExternalProcess()
  37          */
  38         const MAX_ERR_LOG_SIZE = 65535;
  39
  40         /**
  41          * Get a MediaHandler for a given MIME type from the instance cache
  42          *
  43          * @param string $type
  44          * @return MediaHandler|bool
  45          */
  46         static function getHandler( $type ) {
  47                 return MediaWikiServices::getInstance()
  48                         ->getMediaHandlerFactory()->getHandler( $type );
  49         }
  50
  51         /**
  52          * Get an associative array mapping magic word IDs to parameter names.
  53          * Will be used by the parser to identify parameters.
  54          */
  55         abstract public function getParamMap();
  56
  57         /**
  58          * Validate a thumbnail parameter at parse time.
  59          * Return true to accept the parameter, and false to reject it.
  60          * If you return false, the parser will do something quiet and forgiving.
  61          *
  62          * @param string $name
  63          * @param mixed $value
  64          */
  65         abstract public function validateParam( $name, $value );
  66
  67         /**
  68          * Merge a parameter array into a string appropriate for inclusion in filenames
  69          *
  70          * @param array $params Array of parameters that have been through normaliseParams.
  71          * @return string
  72          */
  73         abstract public function makeParamString( $params );
  74
  75         /**
  76          * Parse a param string made with makeParamString back into an array
  77          *
  78          * @param string $str The parameter string without file name (e.g. 122px)
  79          * @return array|bool Array of parameters or false on failure.
  80          */
  81         abstract public function parseParamString( $str );
  82
  83         /**
  84          * Changes the parameter array as necessary, ready for transformation.
  85          * Should be idempotent.
  86          * Returns false if the parameters are unacceptable and the transform should fail
  87          * @param File $image
  88          * @param array &$params
  89          */
  90         abstract public function normaliseParams( $image, &$params );
  91
  92         /**
  93          * Get an image size array like that returned by getimagesize(), or false if it
  94          * can't be determined.
  95          *
  96          * This function is used for determining the width, height and bitdepth directly
  97          * from an image. The results are stored in the database in the img_width,
  98          * img_height, img_bits fields.
  99          *
 100          * @note If this is a multipage file, return the width and height of the
 101          *  first page.
 102          *
 103          * @param File|FSFile $image The image object, or false if there isn't one.
 104          *   Warning, FSFile::getPropsFromPath might pass an FSFile instead of File (!)
 105          * @param string $path The filename
 106          * @return array|bool Follow the format of PHP getimagesize() internal function.
 107          *   See https://www.php.net/getimagesize. MediaWiki will only ever use the
 108          *   first two array keys (the width and height), and the 'bits' associative
 109          *   key. All other array keys are ignored. Returning a 'bits' key is optional
 110          *   as not all formats have a notion of "bitdepth". Returns false on failure.
 111          */
 112         abstract function getImageSize( $image, $path );
 113
 114         /**
 115          * Get handler-specific metadata which will be saved in the img_metadata field.
 116          *
 117          * @param File|FSFile $image The image object, or false if there isn't one.
 118          *   Warning, FSFile::getPropsFromPath might pass an FSFile instead of File (!)
 119          * @param string $path The filename
 120          * @return string A string of metadata in php serialized form (Run through serialize())
 121          */
 122         public function getMetadata( $image, $path ) {
 123                 return '';
 124         }
 125
 126         /**
 127          * Get metadata version.
 128          *
 129          * This is not used for validating metadata, this is used for the api when returning
 130          * metadata, since api content formats should stay the same over time, and so things
 131          * using ForeignApiRepo can keep backwards compatibility
 132          *
 133          * All core media handlers share a common version number, and extensions can
 134          * use the GetMetadataVersion hook to append to the array (they should append a unique
 135          * string so not to get confusing). If there was a media handler named 'foo' with metadata
 136          * version 3 it might add to the end of the array the element 'foo=3'. if the core metadata
 137          * version is 2, the end version string would look like '2;foo=3'.
 138          *
 139          * @return string Version string
 140          */
 141         static function getMetadataVersion() {
 142                 $version = [ '2' ]; // core metadata version
 143                 Hooks::run( 'GetMetadataVersion', [ &$version ] );
 144
 145                 return implode( ';', $version );
 146         }
 147
 148         /**
 149          * Convert metadata version.
 150          *
 151          * By default just returns $metadata, but can be used to allow
 152          * media handlers to convert between metadata versions.
 153          *
 154          * @param string|array $metadata Metadata array (serialized if string)
 155          * @param int $version Target version
 156          * @return array Serialized metadata in specified version, or $metadata on fail.
 157          */
 158         function convertMetadataVersion( $metadata, $version = 1 ) {
 159                 if ( !is_array( $metadata ) ) {
 160                         // unserialize to keep return parameter consistent.
 161                         Wikimedia\suppressWarnings();
 162                         $ret = unserialize( $metadata );
 163                         Wikimedia\restoreWarnings();
 164
 165                         return $ret;
 166                 }
 167
 168                 return $metadata;
 169         }
 170
 171         /**
 172          * Get a string describing the type of metadata, for display purposes.
 173          *
 174          * @note This method is currently unused.
 175          * @param File $image
 176          * @return string
 177          */
 178         function getMetadataType( $image ) {
 179                 return false;
 180         }
 181
 182         /**
 183          * Check if the metadata string is valid for this handler.
 184          * If it returns MediaHandler::METADATA_BAD (or false), Image
 185          * will reload the metadata from the file and update the database.
 186          * MediaHandler::METADATA_GOOD for if the metadata is a-ok,
 187          * MediaHandler::METADATA_COMPATIBLE if metadata is old but backwards
 188          * compatible (which may or may not trigger a metadata reload).
 189          *
 190          * @note Returning self::METADATA_BAD will trigger a metadata reload from
 191          *  file on page view. Always returning this from a broken file, or suddenly
 192          *  triggering as bad metadata for a large number of files can cause
 193          *  performance problems.
 194          * @param File $image
 195          * @param string $metadata The metadata in serialized form
 196          * @return bool
 197          */
 198         public function isMetadataValid( $image, $metadata ) {
 199                 return self::METADATA_GOOD;
 200         }
 201
 202         /**
 203          * Get an array of standard (FormatMetadata type) metadata values.
 204          *
 205          * The returned data is largely the same as that from getMetadata(),
 206          * but formatted in a standard, stable, handler-independent way.
 207          * The idea being that some values like ImageDescription or Artist
 208          * are universal and should be retrievable in a handler generic way.
 209          *
 210          * The specific properties are the type of properties that can be
 211          * handled by the FormatMetadata class. These values are exposed to the
 212          * user via the filemetadata parser function.
 213          *
 214          * Details of the response format of this function can be found at
 215          * https://www.mediawiki.org/wiki/Manual:File_metadata_handling
 216          * tl/dr: the response is an associative array of
 217          * properties keyed by name, but the value can be complex. You probably
 218          * want to call one of the FormatMetadata::flatten* functions on the
 219          * property values before using them, or call
 220          * FormatMetadata::getFormattedData() on the full response array, which
 221          * transforms all values into prettified, human-readable text.
 222          *
 223          * Subclasses overriding this function must return a value which is a
 224          * valid API response fragment (all associative array keys are valid
 225          * XML tagnames).
 226          *
 227          * Note, if the file simply has no metadata, but the handler supports
 228          * this interface, it should return an empty array, not false.
 229          *
 230          * @param File $file
 231          * @return array|bool False if interface not supported
 232          * @since 1.23
 233          */
 234         public function getCommonMetaArray( File $file ) {
 235                 return false;
 236         }
 237
 238         /**
 239          * Get a MediaTransformOutput object representing an alternate of the transformed
 240          * output which will call an intermediary thumbnail assist script.
 241          *
 242          * Used when the repository has a thumbnailScriptUrl option configured.
 243          *
 244          * Return false to fall back to the regular getTransform().
 245          * @param File $image
 246          * @param string $script
 247          * @param array $params
 248          * @return bool|ThumbnailImage
 249          */
 250         function getScriptedTransform( $image, $script, $params ) {
 251                 return false;
 252         }
 253
 254         /**
 255          * Get a MediaTransformOutput object representing the transformed output. Does not
 256          * actually do the transform.
 257          *
 258          * @param File $image
 259          * @param string $dstPath Filesystem destination path
 260          * @param string $dstUrl Destination URL to use in output HTML
 261          * @param array $params Arbitrary set of parameters validated by $this->validateParam()
 262          * @return MediaTransformOutput
 263          */
 264         final function getTransform( $image, $dstPath, $dstUrl, $params ) {
 265                 return $this->doTransform( $image, $dstPath, $dstUrl, $params, self::TRANSFORM_LATER );
 266         }
 267
 268         /**
 269          * Get a MediaTransformOutput object representing the transformed output. Does the
 270          * transform unless $flags contains self::TRANSFORM_LATER.
 271          *
 272          * @param File $image
 273          * @param string $dstPath Filesystem destination path
 274          * @param string $dstUrl Destination URL to use in output HTML
 275          * @param array $params Arbitrary set of parameters validated by $this->validateParam()
 276          *   Note: These parameters have *not* gone through $this->normaliseParams()
 277          * @param int $flags A bitfield, may contain self::TRANSFORM_LATER
 278          * @return MediaTransformOutput
 279          */
 280         abstract function doTransform( $image, $dstPath, $dstUrl, $params, $flags = 0 );
 281
 282         /**
 283          * Get the thumbnail extension and MIME type for a given source MIME type
 284          *
 285          * @param string $ext Extension of original file
 286          * @param string $mime MIME type of original file
 287          * @param array|null $params Handler specific rendering parameters
 288          * @return array Thumbnail extension and MIME type
 289          */
 290         public function getThumbType( $ext, $mime, $params = null ) {
 291                 $magic = MediaWiki\MediaWikiServices::getInstance()->getMimeAnalyzer();
 292                 if ( !$ext || $magic->isMatchingExtension( $ext, $mime ) === false ) {
 293                         // The extension is not valid for this MIME type and we do
 294                         // recognize the MIME type
 295                         $extensions = $magic->getExtensionsForType( $mime );
 296                         if ( $extensions ) {
 297                                 return [ strtok( $extensions, ' ' ), $mime ];
 298                         }
 299                 }
 300
 301                 // The extension is correct (true) or the MIME type is unknown to
 302                 // MediaWiki (null)
 303                 return [ $ext, $mime ];
 304         }
 305
 306         /**
 307          * True if the handled types can be transformed
 308          *
 309          * @param File $file
 310          * @return bool
 311          */
 312         public function canRender( $file ) {
 313                 return true;
 314         }
 315
 316         /**
 317          * True if handled types cannot be displayed directly in a browser
 318          * but can be rendered
 319          *
 320          * @param File $file
 321          * @return bool
 322          */
 323         public function mustRender( $file ) {
 324                 return false;
 325         }
 326
 327         /**
 328          * True if the type has multi-page capabilities
 329          *
 330          * @param File $file
 331          * @return bool
 332          */
 333         public function isMultiPage( $file ) {
 334                 return false;
 335         }
 336
 337         /**
 338          * Page count for a multi-page document, false if unsupported or unknown
 339          *
 340          * @param File $file
 341          * @return bool
 342          */
 343         public function pageCount( File $file ) {
 344                 return false;
 345         }
 346
 347         /**
 348          * The material is vectorized and thus scaling is lossless
 349          *
 350          * @param File $file
 351          * @return bool
 352          */
 353         function isVectorized( $file ) {
 354                 return false;
 355         }
 356
 357         /**
 358          * The material is an image, and is animated.
 359          * In particular, video material need not return true.
 360          * @note Before 1.20, this was a method of ImageHandler only
 361          *
 362          * @param File $file
 363          * @return bool
 364          */
 365         function isAnimatedImage( $file ) {
 366                 return false;
 367         }
 368
 369         /**
 370          * If the material is animated, we can animate the thumbnail
 371          * @since 1.20
 372          *
 373          * @param File $file
 374          * @return bool If material is not animated, handler may return any value.
 375          */
 376         function canAnimateThumbnail( $file ) {
 377                 return true;
 378         }
 379
 380         /**
 381          * False if the handler is disabled for all files
 382          * @return bool
 383          */
 384         public function isEnabled() {
 385                 return true;
 386         }
 387
 388         /**
 389          * Get an associative array of page dimensions
 390          * Currently "width" and "height" are understood, but this might be
 391          * expanded in the future.
 392          * Returns false if unknown.
 393          *
 394          * It is expected that handlers for paged media (e.g. DjVuHandler)
 395          * will override this method so that it gives the correct results
 396          * for each specific page of the file, using the $page argument.
 397          *
 398          * @note For non-paged media, use getImageSize.
 399          *
 400          * @param File $image
 401          * @param int $page What page to get dimensions of
 402          * @return array|bool
 403          */
 404         public function getPageDimensions( File $image, $page ) {
 405                 $gis = $this->getImageSize( $image, $image->getLocalRefPath() );
 406                 if ( $gis ) {
 407                         return [
 408                                 'width' => $gis[0],
 409                                 'height' => $gis[1]
 410                         ];
 411                 } else {
 412                         return false;
 413                 }
 414         }
 415
 416         /**
 417          * Generic getter for text layer.
 418          * Currently overloaded by PDF and DjVu handlers
 419          * @param File $image
 420          * @param int $page Page number to get information for
 421          * @return bool|string Page text or false when no text found or if
 422          *   unsupported.
 423          */
 424         function getPageText( File $image, $page ) {
 425                 return false;
 426         }
 427
 428         /**
 429          * Get the text of the entire document.
 430          * @param File $file
 431          * @return bool|string The text of the document or false if unsupported.
 432          */
 433         public function getEntireText( File $file ) {
 434                 $numPages = $file->pageCount();
 435                 if ( !$numPages ) {
 436                         // Not a multipage document
 437                         return $this->getPageText( $file, 1 );
 438                 }
 439                 $document = '';
 440                 for ( $i = 1; $i <= $numPages; $i++ ) {
 441                         $curPage = $this->getPageText( $file, $i );
 442                         if ( is_string( $curPage ) ) {
 443                                 $document .= $curPage . "\n";
 444                         }
 445                 }
 446                 if ( $document !== '' ) {
 447                         return $document;
 448                 }
 449                 return false;
 450         }
 451
 452         /**
 453          * Get an array structure that looks like this:
 454          *
 455          * [
 456          *    'visible' => [
 457          *       'Human-readable name' => 'Human readable value',
 458          *       ...
 459          *    ],
 460          *    'collapsed' => [
 461          *       'Human-readable name' => 'Human readable value',
 462          *       ...
 463          *    ]
 464          * ]
 465          * The UI will format this into a table where the visible fields are always
 466          * visible, and the collapsed fields are optionally visible.
 467          *
 468          * The function should return false if there is no metadata to display.
 469          */
 470
 471         /**
 472          * @todo FIXME: This interface is not very flexible. The media handler
 473          * should generate HTML instead. It can do all the formatting according
 474          * to some standard. That makes it possible to do things like visual
 475          * indication of grouped and chained streams in ogg container files.
 476          * @param File $image
 477          * @param bool|IContextSource $context Context to use (optional)
 478          * @return array|bool
 479          */
 480         public function formatMetadata( $image, $context = false ) {
 481                 return false;
 482         }
 483
 484         /** sorts the visible/invisible field.
 485          * Split off from ImageHandler::formatMetadata, as used by more than
 486          * one type of handler.
 487          *
 488          * This is used by the media handlers that use the FormatMetadata class
 489          *
 490          * @param array $metadataArray
 491          * @param bool|IContextSource $context Context to use (optional)
 492          * @return array Array for use displaying metadata.
 493          */
 494         function formatMetadataHelper( $metadataArray, $context = false ) {
 495                 $result = [
 496                         'visible' => [],
 497                         'collapsed' => []
 498                 ];
 499
 500                 $formatted = FormatMetadata::getFormattedData( $metadataArray, $context );
 501                 // Sort fields into visible and collapsed
 502                 $visibleFields = $this->visibleMetadataFields();
 503                 foreach ( $formatted as $name => $value ) {
 504                         $tag = strtolower( $name );
 505                         self::addMeta( $result,
 506                                 in_array( $tag, $visibleFields ) ? 'visible' : 'collapsed',
 507                                 'exif',
 508                                 $tag,
 509                                 $value
 510                         );
 511                 }
 512
 513                 return $result;
 514         }
 515
 516         /**
 517          * Get a list of metadata items which should be displayed when
 518          * the metadata table is collapsed.
 519          *
 520          * @return array Array of strings
 521          */
 522         protected function visibleMetadataFields() {
 523                 return FormatMetadata::getVisibleFields();
 524         }
 525
 526         /**
 527          * This is used to generate an array element for each metadata value
 528          * That array is then used to generate the table of metadata values
 529          * on the image page
 530          *
 531          * @param array &$array An array containing elements for each type of visibility
 532          *   and each of those elements being an array of metadata items. This function adds
 533          *   a value to that array.
 534          * @param string $visibility ('visible' or 'collapsed') if this value is hidden
 535          *   by default.
 536          * @param string $type Type of metadata tag (currently always 'exif')
 537          * @param string $id The name of the metadata tag (like 'artist' for example).
 538          *   its name in the table displayed is the message "$type-$id" (Ex exif-artist ).
 539          * @param string $value Thingy goes into a wikitext table; it used to be escaped but
 540          *   that was incompatible with previous practise of customized display
 541          *   with wikitext formatting via messages such as 'exif-model-value'.
 542          *   So the escaping is taken back out, but generally this seems a confusing
 543          *   interface.
 544          * @param bool|string $param Value to pass to the message for the name of the field
 545          *   as $1. Currently this parameter doesn't seem to ever be used.
 546          *
 547          * Note, everything here is passed through the parser later on (!)
 548          */
 549         protected static function addMeta( &$array, $visibility, $type, $id, $value, $param = false ) {
 550                 $msg = wfMessage( "$type-$id", $param );
 551                 if ( $msg->exists() ) {
 552                         $name = $msg->text();
 553                 } else {
 554                         // This is for future compatibility when using instant commons.
 555                         // So as to not display as ugly a name if a new metadata
 556                         // property is defined that we don't know about
 557                         // (not a major issue since such a property would be collapsed
 558                         // by default).
 559                         wfDebug( __METHOD__ . ' Unknown metadata name: ' . $id . "\n" );
 560                         $name = wfEscapeWikiText( $id );
 561                 }
 562                 $array[$visibility][] = [
 563                         'id' => "$type-$id",
 564                         'name' => $name,
 565                         'value' => $value
 566                 ];
 567         }
 568
 569         /**
 570          * Short description. Shown on Special:Search results.
 571          *
 572          * @param File $file
 573          * @return string
 574          */
 575         function getShortDesc( $file ) {
 576                 return self::getGeneralShortDesc( $file );
 577         }
 578
 579         /**
 580          * Long description. Shown under image on image description page surounded by ().
 581          *
 582          * @param File $file
 583          * @return string
 584          */
 585         public function getLongDesc( $file ) {
 586                 return self::getGeneralLongDesc( $file );
 587         }
 588
 589         /**
 590          * Used instead of getShortDesc if there is no handler registered for file.
 591          *
 592          * @param File $file
 593          * @return string
 594          */
 595         static function getGeneralShortDesc( $file ) {
 596                 global $wgLang;
 597
 598                 return htmlspecialchars( $wgLang->formatSize( $file->getSize() ) );
 599         }
 600
 601         /**
 602          * Used instead of getLongDesc if there is no handler registered for file.
 603          *
 604          * @param File $file
 605          * @return string
 606          */
 607         static function getGeneralLongDesc( $file ) {
 608                 return wfMessage( 'file-info' )->sizeParams( $file->getSize() )
 609                         ->params( '<span class="mime-type">' . $file->getMimeType() . '</span>' )->parse();
 610         }
 611
 612         /**
 613          * Calculate the largest thumbnail width for a given original file size
 614          * such that the thumbnail's height is at most $maxHeight.
 615          * @param int $boxWidth Width of the thumbnail box.
 616          * @param int $boxHeight Height of the thumbnail box.
 617          * @param int $maxHeight Maximum height expected for the thumbnail.
 618          * @return int
 619          */
 620         public static function fitBoxWidth( $boxWidth, $boxHeight, $maxHeight ) {
 621                 $idealWidth = $boxWidth * $maxHeight / $boxHeight;
 622                 $roundedUp = ceil( $idealWidth );
 623                 if ( round( $roundedUp * $boxHeight / $boxWidth ) > $maxHeight ) {
 624                         return floor( $idealWidth );
 625                 } else {
 626                         return $roundedUp;
 627                 }
 628         }
 629
 630         /**
 631          * Shown in file history box on image description page.
 632          *
 633          * @param File $file
 634          * @return string Dimensions
 635          */
 636         function getDimensionsString( $file ) {
 637                 return '';
 638         }
 639
 640         /**
 641          * Modify the parser object post-transform.
 642          *
 643          * This is often used to do $parser->addOutputHook(),
 644          * in order to add some javascript to render a viewer.
 645          * See TimedMediaHandler or OggHandler for an example.
 646          *
 647          * @param Parser $parser
 648          * @param File $file
 649          */
 650         function parserTransformHook( $parser, $file ) {
 651         }
 652
 653         /**
 654          * File validation hook called on upload.
 655          *
 656          * If the file at the given local path is not valid, or its MIME type does not
 657          * match the handler class, a Status object should be returned containing
 658          * relevant errors.
 659          *
 660          * @param string $fileName The local path to the file.
 661          * @return Status
 662          */
 663         public function verifyUpload( $fileName ) {
 664                 return Status::newGood();
 665         }
 666
 667         /**
 668          * Check for zero-sized thumbnails. These can be generated when
 669          * no disk space is available or some other error occurs
 670          *
 671          * @param string $dstPath The location of the suspect file
 672          * @param int $retval Return value of some shell process, file will be deleted if this is non-zero
 673          * @return bool True if removed, false otherwise
 674          */
 675         function removeBadFile( $dstPath, $retval = 0 ) {
 676                 if ( file_exists( $dstPath ) ) {
 677                         $thumbstat = stat( $dstPath );
 678                         if ( $thumbstat['size'] == 0 || $retval != 0 ) {
 679                                 $result = unlink( $dstPath );
 680
 681                                 if ( $result ) {
 682                                         wfDebugLog( 'thumbnail',
 683                                                 sprintf( 'Removing bad %d-byte thumbnail "%s". unlink() succeeded',
 684                                                         $thumbstat['size'], $dstPath ) );
 685                                 } else {
 686                                         wfDebugLog( 'thumbnail',
 687                                                 sprintf( 'Removing bad %d-byte thumbnail "%s". unlink() failed',
 688                                                         $thumbstat['size'], $dstPath ) );
 689                                 }
 690
 691                                 return true;
 692                         }
 693                 }
 694
 695                 return false;
 696         }
 697
 698         /**
 699          * Remove files from the purge list.
 700          *
 701          * This is used by some video handlers to prevent ?action=purge
 702          * from removing a transcoded video, which is expensive to
 703          * regenerate.
 704          *
 705          * @see LocalFile::purgeThumbnails
 706          *
 707          * @param array &$files
 708          * @param array $options Purge options. Currently will always be
 709          *  an array with a single key 'forThumbRefresh' set to true.
 710          */
 711         public function filterThumbnailPurgeList( &$files, $options ) {
 712                 // Do nothing
 713         }
 714
 715         /**
 716          * True if the handler can rotate the media
 717          * @since 1.24 non-static. From 1.21-1.23 was static
 718          * @return bool
 719          */
 720         public function canRotate() {
 721                 return false;
 722         }
 723
 724         /**
 725          * On supporting image formats, try to read out the low-level orientation
 726          * of the file and return the angle that the file needs to be rotated to
 727          * be viewed.
 728          *
 729          * This information is only useful when manipulating the original file;
 730          * the width and height we normally work with is logical, and will match
 731          * any produced output views.
 732          *
 733          * For files we don't know, we return 0.
 734          *
 735          * @param File $file
 736          * @return int 0, 90, 180 or 270
 737          */
 738         public function getRotation( $file ) {
 739                 return 0;
 740         }
 741
 742         /**
 743          * Log an error that occurred in an external process
 744          *
 745          * Moved from BitmapHandler to MediaHandler with MediaWiki 1.23
 746          *
 747          * @since 1.23
 748          * @param int $retval
 749          * @param string $err Error reported by command. Anything longer than
 750          * MediaHandler::MAX_ERR_LOG_SIZE is stripped off.
 751          * @param string $cmd
 752          */
 753         protected function logErrorForExternalProcess( $retval, $err, $cmd ) {
 754                 # Keep error output limited (T59985)
 755                 $errMessage = trim( substr( $err, 0, self::MAX_ERR_LOG_SIZE ) );
 756
 757                 wfDebugLog( 'thumbnail',
 758                         sprintf( 'thumbnail failed on %s: error %d "%s" from "%s"',
 759                                         wfHostname(), $retval, $errMessage, $cmd ) );
 760         }
 761
 762         /**
 763          * Get list of languages file can be viewed in.
 764          *
 765          * @param File $file
 766          * @return string[] Array of language codes, or empty array if unsupported.
 767          * @since 1.23
 768          */
 769         public function getAvailableLanguages( File $file ) {
 770                 return [];
 771         }
 772
 773         /**
 774          * When overridden in a descendant class, returns a language code most suiting
 775          *
 776          * @since 1.32
 777          *
 778          * @param string $userPreferredLanguage Language code requesed
 779          * @param string[] $availableLanguages Languages present in the file
 780          * @return string|null Language code picked or null if not supported/available
 781          */
 782         public function getMatchedLanguage( $userPreferredLanguage, array $availableLanguages ) {
 783                 return null;
 784         }
 785
 786         /**
 787          * On file types that support renderings in multiple languages,
 788          * which language is used by default if unspecified.
 789          *
 790          * If getAvailableLanguages returns a non-empty array, this must return
 791          * a valid language code. Otherwise can return null if files of this
 792          * type do not support alternative language renderings.
 793          *
 794          * @param File $file
 795          * @return string|null Language code or null if multi-language not supported for filetype.
 796          * @since 1.23
 797          */
 798         public function getDefaultRenderLanguage( File $file ) {
 799                 return null;
 800         }
 801
 802         /**
 803          * If its an audio file, return the length of the file. Otherwise 0.
 804          *
 805          * File::getLength() existed for a long time, but was calling a method
 806          * that only existed in some subclasses of this class (The TMH ones).
 807          *
 808          * @param File $file
 809          * @return float Length in seconds
 810          * @since 1.23
 811          */
 812         public function getLength( $file ) {
 813                 return 0.0;
 814         }
 815
 816         /**
 817          * True if creating thumbnails from the file is large or otherwise resource-intensive.
 818          * @param File $file
 819          * @return bool
 820          */
 821         public function isExpensiveToThumbnail( $file ) {
 822                 return false;
 823         }
 824
 825         /**
 826          * Returns whether or not this handler supports the chained generation of thumbnails according
 827          * to buckets
 828          * @return bool
 829          * @since 1.24
 830          */
 831         public function supportsBucketing() {
 832                 return false;
 833         }
 834
 835         /**
 836          * Returns a normalised params array for which parameters have been cleaned up for bucketing
 837          * purposes
 838          * @param array $params
 839          * @return array
 840          */
 841         public function sanitizeParamsForBucketing( $params ) {
 842                 return $params;
 843         }
 844
 845         /**
 846          * Gets configuration for the file warning message. Return value of
 847          * the following structure:
 848          *   [
 849          *     // Required, module with messages loaded for the client
 850          *     'module' => 'example.filewarning.messages',
 851          *     // Required, array of names of messages
 852          *     'messages' => [
 853          *       // Required, main warning message
 854          *       'main' => 'example-filewarning-main',
 855          *       // Optional, header for warning dialog
 856          *       'header' => 'example-filewarning-header',
 857          *       // Optional, footer for warning dialog
 858          *       'footer' => 'example-filewarning-footer',
 859          *       // Optional, text for more-information link (see below)
 860          *       'info' => 'example-filewarning-info',
 861          *     ],
 862          *     // Optional, link for more information
 863          *     'link' => 'http://example.com',
 864          *   ]
 865          *
 866          * Returns null if no warning is necessary.
 867          * @param File $file
 868          * @return array|null
 869          */
 870         public function getWarningConfig( $file ) {
 871                 return null;
 872         }
 873
 874         /**
 875          * Converts a dimensions array about a potentially multipage document from an
 876          * exhaustive list of ordered page numbers to a list of page ranges
 877          * @param array $pagesByDimensions
 878          * @return string
 879          * @since 1.30
 880          */
 881         public static function getPageRangesByDimensions( $pagesByDimensions ) {
 882                 $pageRangesByDimensions = [];
 883
 884                 foreach ( $pagesByDimensions as $dimensions => $pageList ) {
 885                         $ranges = [];
 886                         $firstPage = $pageList[0];
 887                         $lastPage = $firstPage - 1;
 888
 889                         foreach ( $pageList as $page ) {
 890                                 if ( $page > $lastPage + 1 ) {
 891                                         if ( $firstPage != $lastPage ) {
 892                                                 $ranges[] = "$firstPage-$lastPage";
 893                                         } else {
 894                                                 $ranges[] = "$firstPage";
 895                                         }
 896
 897                                         $firstPage = $page;
 898                                 }
 899
 900                                 $lastPage = $page;
 901                         }
 902
 903                         if ( $firstPage != $lastPage ) {
 904                                 $ranges[] = "$firstPage-$lastPage";
 905                         } else {
 906                                 $ranges[] = "$firstPage";
 907                         }
 908
 909                         $pageRangesByDimensions[ $dimensions ] = $ranges;
 910                 }
 911
 912                 $dimensionsString = [];
 913                 foreach ( $pageRangesByDimensions as $dimensions => $pageRanges ) {
 914                         $dimensionsString[] = "$dimensions:" . implode( ',', $pageRanges );
 915                 }
 916
 917                 return implode( '/', $dimensionsString );
 918         }
 919
 920         /**
 921          * Get useful response headers for GET/HEAD requests for a file with the given metadata
 922          * @param array $metadata Contains this handler's unserialized getMetadata() for a file
 923          * @return array
 924          * @since 1.30
 925          */
 926         public function getContentHeaders( $metadata ) {
 927                 return [ 'X-Content-Dimensions' => '' ]; // T175689
 928         }
 929 }