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          * Instance cache
  36          */
  37         static $handlers = array();
  38
  39         /**
  40          * Get a MediaHandler for a given MIME type from the instance cache
  41          *
  42          * @param $type string
  43          *
  44          * @return MediaHandler
  45          */
  46         static function getHandler( $type ) {
  47                 global $wgMediaHandlers;
  48                 if ( !isset( $wgMediaHandlers[$type] ) ) {
  49                         wfDebug( __METHOD__ . ": no handler found for $type.\n" );
  50                         return false;
  51                 }
  52                 $class = $wgMediaHandlers[$type];
  53                 if ( !isset( self::$handlers[$class] ) ) {
  54                         self::$handlers[$class] = new $class;
  55                         if ( !self::$handlers[$class]->isEnabled() ) {
  56                                 self::$handlers[$class] = false;
  57                         }
  58                 }
  59                 return self::$handlers[$class];
  60         }
  61
  62         /**
  63          * Get an associative array mapping magic word IDs to parameter names.
  64          * Will be used by the parser to identify parameters.
  65          */
  66         abstract function getParamMap();
  67
  68         /**
  69          * Validate a thumbnail parameter at parse time.
  70          * Return true to accept the parameter, and false to reject it.
  71          * If you return false, the parser will do something quiet and forgiving.
  72          *
  73          * @param $name
  74          * @param $value
  75          */
  76         abstract function validateParam( $name, $value );
  77
  78         /**
  79          * Merge a parameter array into a string appropriate for inclusion in filenames
  80          *
  81          * @param $params array
  82          */
  83         abstract function makeParamString( $params );
  84
  85         /**
  86          * Parse a param string made with makeParamString back into an array
  87          *
  88          * @param $str string
  89          */
  90         abstract function parseParamString( $str );
  91
  92         /**
  93          * Changes the parameter array as necessary, ready for transformation.
  94          * Should be idempotent.
  95          * Returns false if the parameters are unacceptable and the transform should fail
  96          * @param $image
  97          * @param $params
  98          */
  99         abstract function normaliseParams( $image, &$params );
 100
 101         /**
 102          * Get an image size array like that returned by getimagesize(), or false if it
 103          * can't be determined.
 104          *
 105          * @param $image File: the image object, or false if there isn't one
 106          * @param string $path the filename
 107          * @return Array Follow the format of PHP getimagesize() internal function. See http://www.php.net/getimagesize
 108          */
 109         abstract function getImageSize( $image, $path );
 110
 111         /**
 112          * Get handler-specific metadata which will be saved in the img_metadata field.
 113          *
 114          * @param $image File: the image object, or false if there isn't one.
 115          *   Warning, FSFile::getPropsFromPath might pass an (object)array() instead (!)
 116          * @param string $path the filename
 117          * @return String
 118          */
 119         function getMetadata( $image, $path ) { return ''; }
 120
 121         /**
 122          * Get metadata version.
 123          *
 124          * This is not used for validating metadata, this is used for the api when returning
 125          * metadata, since api content formats should stay the same over time, and so things
 126          * using ForiegnApiRepo can keep backwards compatibility
 127          *
 128          * All core media handlers share a common version number, and extensions can
 129          * use the GetMetadataVersion hook to append to the array (they should append a unique
 130          * string so not to get confusing). If there was a media handler named 'foo' with metadata
 131          * version 3 it might add to the end of the array the element 'foo=3'. if the core metadata
 132          * version is 2, the end version string would look like '2;foo=3'.
 133          *
 134          * @return string version string
 135          */
 136         static function getMetadataVersion() {
 137                 $version = Array( '2' ); // core metadata version
 138                 wfRunHooks( 'GetMetadataVersion', Array( &$version ) );
 139                 return implode( ';', $version );
 140         }
 141
 142         /**
 143          * Convert metadata version.
 144          *
 145          * By default just returns $metadata, but can be used to allow
 146          * media handlers to convert between metadata versions.
 147          *
 148          * @param $metadata Mixed String or Array metadata array (serialized if string)
 149          * @param $version Integer target version
 150          * @return Array serialized metadata in specified version, or $metadata on fail.
 151          */
 152         function convertMetadataVersion( $metadata, $version = 1 ) {
 153                 if ( !is_array( $metadata ) ) {
 154
 155                         //unserialize to keep return parameter consistent.
 156                         wfSuppressWarnings();
 157                         $ret = unserialize( $metadata );
 158                         wfRestoreWarnings();
 159                         return $ret;
 160                 }
 161                 return $metadata;
 162         }
 163
 164         /**
 165          * Get a string describing the type of metadata, for display purposes.
 166          *
 167          * @return string
 168          */
 169         function getMetadataType( $image ) { return false; }
 170
 171         /**
 172          * Check if the metadata string is valid for this handler.
 173          * If it returns MediaHandler::METADATA_BAD (or false), Image
 174          * will reload the metadata from the file and update the database.
 175          * MediaHandler::METADATA_GOOD for if the metadata is a-ok,
 176          * MediaHanlder::METADATA_COMPATIBLE if metadata is old but backwards
 177          * compatible (which may or may not trigger a metadata reload).
 178          * @return bool
 179          */
 180         function isMetadataValid( $image, $metadata ) {
 181                 return self::METADATA_GOOD;
 182         }
 183
 184         /**
 185          * Get a MediaTransformOutput object representing an alternate of the transformed
 186          * output which will call an intermediary thumbnail assist script.
 187          *
 188          * Used when the repository has a thumbnailScriptUrl option configured.
 189          *
 190          * Return false to fall back to the regular getTransform().
 191          * @return bool
 192          */
 193         function getScriptedTransform( $image, $script, $params ) {
 194                 return false;
 195         }
 196
 197         /**
 198          * Get a MediaTransformOutput object representing the transformed output. Does not
 199          * actually do the transform.
 200          *
 201          * @param $image File: the image object
 202          * @param string $dstPath filesystem destination path
 203          * @param string $dstUrl Destination URL to use in output HTML
 204          * @param array $params Arbitrary set of parameters validated by $this->validateParam()
 205          * @return MediaTransformOutput
 206          */
 207         final function getTransform( $image, $dstPath, $dstUrl, $params ) {
 208                 return $this->doTransform( $image, $dstPath, $dstUrl, $params, self::TRANSFORM_LATER );
 209         }
 210
 211         /**
 212          * Get a MediaTransformOutput object representing the transformed output. Does the
 213          * transform unless $flags contains self::TRANSFORM_LATER.
 214          *
 215          * @param $image File: the image object
 216          * @param string $dstPath filesystem destination path
 217          * @param string $dstUrl destination URL to use in output HTML
 218          * @param array $params arbitrary set of parameters validated by $this->validateParam()
 219          * @param $flags Integer: a bitfield, may contain self::TRANSFORM_LATER
 220          *
 221          * @return MediaTransformOutput
 222          */
 223         abstract function doTransform( $image, $dstPath, $dstUrl, $params, $flags = 0 );
 224
 225         /**
 226          * Get the thumbnail extension and MIME type for a given source MIME type
 227          * @return array thumbnail extension and MIME type
 228          */
 229         function getThumbType( $ext, $mime, $params = null ) {
 230                 $magic = MimeMagic::singleton();
 231                 if ( !$ext || $magic->isMatchingExtension( $ext, $mime ) === false ) {
 232                         // The extension is not valid for this mime type and we do
 233                         // recognize the mime type
 234                         $extensions = $magic->getExtensionsForType( $mime );
 235                         if ( $extensions ) {
 236                                 return array( strtok( $extensions, ' ' ), $mime );
 237                         }
 238                 }
 239
 240                 // The extension is correct (true) or the mime type is unknown to
 241                 // MediaWiki (null)
 242                 return array( $ext, $mime );
 243         }
 244
 245         /**
 246          * Get useful response headers for GET/HEAD requests for a file with the given metadata
 247          * @param $metadata mixed Result of the getMetadata() function of this handler for a file
 248          * @return Array
 249          */
 250         public function getStreamHeaders( $metadata ) {
 251                 return array();
 252         }
 253
 254         /**
 255          * True if the handled types can be transformed
 256          * @return bool
 257          */
 258         function canRender( $file ) { return true; }
 259         /**
 260          * True if handled types cannot be displayed directly in a browser
 261          * but can be rendered
 262          * @return bool
 263          */
 264         function mustRender( $file ) { return false; }
 265         /**
 266          * True if the type has multi-page capabilities
 267          * @return bool
 268          */
 269         function isMultiPage( $file ) { return false; }
 270         /**
 271          * Page count for a multi-page document, false if unsupported or unknown
 272          * @return bool
 273          */
 274         function pageCount( $file ) { return false; }
 275         /**
 276          * The material is vectorized and thus scaling is lossless
 277          * @return bool
 278          */
 279         function isVectorized( $file ) { return false; }
 280         /**
 281          * The material is an image, and is animated.
 282          * In particular, video material need not return true.
 283          * @note Before 1.20, this was a method of ImageHandler only
 284          * @return bool
 285          */
 286         function isAnimatedImage( $file ) { return false; }
 287         /**
 288          * If the material is animated, we can animate the thumbnail
 289          * @since 1.20
 290          * @return bool If material is not animated, handler may return any value.
 291          */
 292         function canAnimateThumbnail( $file ) { return true; }
 293         /**
 294          * False if the handler is disabled for all files
 295          * @return bool
 296          */
 297         function isEnabled() { return true; }
 298
 299         /**
 300          * Get an associative array of page dimensions
 301          * Currently "width" and "height" are understood, but this might be
 302          * expanded in the future.
 303          * Returns false if unknown or if the document is not multi-page.
 304          *
 305          * @param $image File
 306          * @param $page Unused, left for backcompatibility?
 307          * @return array
 308          */
 309         function getPageDimensions( $image, $page ) {
 310                 $gis = $this->getImageSize( $image, $image->getLocalRefPath() );
 311                 return array(
 312                         'width' => $gis[0],
 313                         'height' => $gis[1]
 314                 );
 315         }
 316
 317         /**
 318          * Generic getter for text layer.
 319          * Currently overloaded by PDF and DjVu handlers
 320          * @return bool
 321          */
 322         function getPageText( $image, $page ) {
 323                 return false;
 324         }
 325
 326         /**
 327          * Get an array structure that looks like this:
 328          *
 329          * array(
 330          *    'visible' => array(
 331          *       'Human-readable name' => 'Human readable value',
 332          *       ...
 333          *    ),
 334          *    'collapsed' => array(
 335          *       'Human-readable name' => 'Human readable value',
 336          *       ...
 337          *    )
 338          * )
 339          * The UI will format this into a table where the visible fields are always
 340          * visible, and the collapsed fields are optionally visible.
 341          *
 342          * The function should return false if there is no metadata to display.
 343          */
 344
 345         /**
 346          * @todo FIXME: I don't really like this interface, it's not very flexible
 347          * I think the media handler should generate HTML instead. It can do
 348          * all the formatting according to some standard. That makes it possible
 349          * to do things like visual indication of grouped and chained streams
 350          * in ogg container files.
 351          * @return bool
 352          */
 353         function formatMetadata( $image ) {
 354                 return false;
 355         }
 356
 357         /** sorts the visible/invisible field.
 358          * Split off from ImageHandler::formatMetadata, as used by more than
 359          * one type of handler.
 360          *
 361          * This is used by the media handlers that use the FormatMetadata class
 362          *
 363          * @param array $metadataArray metadata array
 364          * @return array for use displaying metadata.
 365          */
 366         function formatMetadataHelper( $metadataArray ) {
 367                 $result = array(
 368                         'visible' => array(),
 369                         'collapsed' => array()
 370                 );
 371
 372                 $formatted = FormatMetadata::getFormattedData( $metadataArray );
 373                 // Sort fields into visible and collapsed
 374                 $visibleFields = $this->visibleMetadataFields();
 375                 foreach ( $formatted as $name => $value ) {
 376                         $tag = strtolower( $name );
 377                         self::addMeta( $result,
 378                                 in_array( $tag, $visibleFields ) ? 'visible' : 'collapsed',
 379                                 'exif',
 380                                 $tag,
 381                                 $value
 382                         );
 383                 }
 384                 return $result;
 385         }
 386
 387         /**
 388          * Get a list of metadata items which should be displayed when
 389          * the metadata table is collapsed.
 390          *
 391          * @return array of strings
 392          * @access protected
 393          */
 394         function visibleMetadataFields() {
 395                 $fields = array();
 396                 $lines = explode( "\n", wfMessage( 'metadata-fields' )->inContentLanguage()->text() );
 397                 foreach( $lines as $line ) {
 398                         $matches = array();
 399                         if( preg_match( '/^\\*\s*(.*?)\s*$/', $line, $matches ) ) {
 400                                 $fields[] = $matches[1];
 401                         }
 402                 }
 403                 $fields = array_map( 'strtolower', $fields );
 404                 return $fields;
 405         }
 406
 407         /**
 408          * This is used to generate an array element for each metadata value
 409          * That array is then used to generate the table of metadata values
 410          * on the image page
 411          *
 412          * @param &$array Array An array containing elements for each type of visibility
 413          * and each of those elements being an array of metadata items. This function adds
 414          * a value to that array.
 415          * @param string $visibility ('visible' or 'collapsed') if this value is hidden
 416          * by default.
 417          * @param string $type type of metadata tag (currently always 'exif')
 418          * @param string $id the name of the metadata tag (like 'artist' for example).
 419          * its name in the table displayed is the message "$type-$id" (Ex exif-artist ).
 420          * @param string $value thingy goes into a wikitext table; it used to be escaped but
 421          * that was incompatible with previous practise of customized display
 422          * with wikitext formatting via messages such as 'exif-model-value'.
 423          * So the escaping is taken back out, but generally this seems a confusing
 424          * interface.
 425          * @param string $param value to pass to the message for the name of the field
 426          * as $1. Currently this parameter doesn't seem to ever be used.
 427          *
 428          * Note, everything here is passed through the parser later on (!)
 429          */
 430         protected static function addMeta( &$array, $visibility, $type, $id, $value, $param = false ) {
 431                 $msg = wfMessage( "$type-$id", $param );
 432                 if ( $msg->exists() ) {
 433                         $name = $msg->text();
 434                 } else {
 435                         // This is for future compatibility when using instant commons.
 436                         // So as to not display as ugly a name if a new metadata
 437                         // property is defined that we don't know about
 438                         // (not a major issue since such a property would be collapsed
 439                         // by default).
 440                         wfDebug( __METHOD__ . ' Unknown metadata name: ' . $id . "\n" );
 441                         $name = wfEscapeWikiText( $id );
 442                 }
 443                 $array[$visibility][] = array(
 444                         'id' => "$type-$id",
 445                         'name' => $name,
 446                         'value' => $value
 447                 );
 448         }
 449
 450         /**
 451          * @param $file File
 452          * @return string
 453          */
 454         function getShortDesc( $file ) {
 455                 global $wgLang;
 456                 return htmlspecialchars( $wgLang->formatSize( $file->getSize() ) );
 457         }
 458
 459         /**
 460          * @param $file File
 461          * @return string
 462          */
 463         function getLongDesc( $file ) {
 464                 global $wgLang;
 465                 return wfMessage( 'file-info', htmlspecialchars( $wgLang->formatSize( $file->getSize() ) ),
 466                         $file->getMimeType() )->parse();
 467         }
 468
 469         /**
 470          * @param $file File
 471          * @return string
 472          */
 473         static function getGeneralShortDesc( $file ) {
 474                 global $wgLang;
 475                 return $wgLang->formatSize( $file->getSize() );
 476         }
 477
 478         /**
 479          * @param $file File
 480          * @return string
 481          */
 482         static function getGeneralLongDesc( $file ) {
 483                 global $wgLang;
 484                 return wfMessage( 'file-info', $wgLang->formatSize( $file->getSize() ),
 485                         $file->getMimeType() )->parse();
 486         }
 487
 488         /**
 489          * Calculate the largest thumbnail width for a given original file size
 490          * such that the thumbnail's height is at most $maxHeight.
 491          * @param $boxWidth Integer Width of the thumbnail box.
 492          * @param $boxHeight Integer Height of the thumbnail box.
 493          * @param $maxHeight Integer Maximum height expected for the thumbnail.
 494          * @return Integer.
 495          */
 496         public static function fitBoxWidth( $boxWidth, $boxHeight, $maxHeight ) {
 497                 $idealWidth = $boxWidth * $maxHeight / $boxHeight;
 498                 $roundedUp = ceil( $idealWidth );
 499                 if( round( $roundedUp * $boxHeight / $boxWidth ) > $maxHeight ) {
 500                         return floor( $idealWidth );
 501                 } else {
 502                         return $roundedUp;
 503                 }
 504         }
 505
 506         function getDimensionsString( $file ) {
 507                 return '';
 508         }
 509
 510         /**
 511          * Modify the parser object post-transform
 512          */
 513         function parserTransformHook( $parser, $file ) {}
 514
 515         /**
 516          * File validation hook called on upload.
 517          *
 518          * If the file at the given local path is not valid, or its MIME type does not
 519          * match the handler class, a Status object should be returned containing
 520          * relevant errors.
 521          *
 522          * @param string $fileName The local path to the file.
 523          * @return Status object
 524          */
 525         function verifyUpload( $fileName ) {
 526                 return Status::newGood();
 527         }
 528
 529         /**
 530          * Check for zero-sized thumbnails. These can be generated when
 531          * no disk space is available or some other error occurs
 532          *
 533          * @param string $dstPath The location of the suspect file
 534          * @param int $retval Return value of some shell process, file will be deleted if this is non-zero
 535          * @return bool True if removed, false otherwise
 536          */
 537         function removeBadFile( $dstPath, $retval = 0 ) {
 538                 if( file_exists( $dstPath ) ) {
 539                         $thumbstat = stat( $dstPath );
 540                         if( $thumbstat['size'] == 0 || $retval != 0 ) {
 541                                 $result = unlink( $dstPath );
 542
 543                                 if ( $result ) {
 544                                         wfDebugLog( 'thumbnail',
 545                                                 sprintf( 'Removing bad %d-byte thumbnail "%s". unlink() succeeded',
 546                                                         $thumbstat['size'], $dstPath ) );
 547                                 } else {
 548                                         wfDebugLog( 'thumbnail',
 549                                                 sprintf( 'Removing bad %d-byte thumbnail "%s". unlink() failed',
 550                                                         $thumbstat['size'], $dstPath ) );
 551                                 }
 552                                 return true;
 553                         }
 554                 }
 555                 return false;
 556         }
 557
 558         /**
 559          * Remove files from the purge list
 560          *
 561          * @param array $files
 562          * @param array $options
 563          */
 564         public function filterThumbnailPurgeList( &$files, $options ) {
 565                 // Do nothing
 566         }
 567
 568         /*
 569          * True if the handler can rotate the media
 570          * @since 1.21
 571          * @return bool
 572          */
 573         public static function canRotate() {
 574                 return false;
 575         }
 576 }