6805f39a30
In all these cases the property is unconditionally set in the constructor. The extra initialisation is effectively dead code and an extra source of errors and confusion. Change-Id: Icae13390d5ca5c14e2754f3be4eb956dd7f54ac4
383 lines
12 KiB
PHP
383 lines
12 KiB
PHP
<?php
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/**
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* Extraction of SVG image metadata.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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* http://www.gnu.org/copyleft/gpl.html
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*
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* @file
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* @ingroup Media
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* @author "Derk-Jan Hartman <hartman _at_ videolan d0t org>"
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* @author Brion Vibber
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* @copyright Copyright © 2010-2010 Brion Vibber, Derk-Jan Hartman
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* @license GPL-2.0-or-later
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*/
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/**
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* @ingroup Media
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*/
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class SVGReader {
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private const DEFAULT_WIDTH = 512;
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private const DEFAULT_HEIGHT = 512;
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private const NS_SVG = 'http://www.w3.org/2000/svg';
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public const LANG_PREFIX_MATCH = 1;
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public const LANG_FULL_MATCH = 2;
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/** @var XMLReader */
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private $reader;
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/** @var bool */
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private $mDebug = false;
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/** @var array */
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private $metadata = [];
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private $languages = [];
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private $languagePrefixes = [];
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/**
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* Creates an SVGReader drawing from the source provided
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* @param string $source URI from which to read
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* @throws MWException|Exception
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*/
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public function __construct( $source ) {
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global $wgSVGMetadataCutoff;
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$this->reader = new XMLReader();
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// Don't use $file->getSize() since file object passed to SVGHandler::getMetadata is bogus.
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$size = filesize( $source );
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if ( $size === false ) {
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throw new MWException( "Error getting filesize of SVG." );
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}
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if ( $size > $wgSVGMetadataCutoff ) {
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$this->debug( "SVG is $size bytes, which is bigger than $wgSVGMetadataCutoff. Truncating." );
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$contents = file_get_contents( $source, false, null, 0, $wgSVGMetadataCutoff );
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if ( $contents === false ) {
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throw new MWException( 'Error reading SVG file.' );
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}
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$this->reader->XML( $contents, null, LIBXML_NOERROR | LIBXML_NOWARNING );
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} else {
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$this->reader->open( $source, null, LIBXML_NOERROR | LIBXML_NOWARNING );
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}
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// Expand entities, since Adobe Illustrator uses them for xmlns
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// attributes (T33719). Note that libxml2 has some protection
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// against large recursive entity expansions so this is not as
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// insecure as it might appear to be. However, it is still extremely
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// insecure. It's necessary to wrap any read() calls with
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// libxml_disable_entity_loader() to avoid arbitrary local file
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// inclusion, or even arbitrary code execution if the expect
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// extension is installed (T48859).
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$oldDisable = libxml_disable_entity_loader( true );
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$this->reader->setParserProperty( XMLReader::SUBST_ENTITIES, true );
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$this->metadata['width'] = self::DEFAULT_WIDTH;
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$this->metadata['height'] = self::DEFAULT_HEIGHT;
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// The size in the units specified by the SVG file
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// (for the metadata box)
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// Per the SVG spec, if unspecified, default to '100%'
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$this->metadata['originalWidth'] = '100%';
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$this->metadata['originalHeight'] = '100%';
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// Because we cut off the end of the svg making an invalid one. Complicated
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// try catch thing to make sure warnings get restored. Seems like there should
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// be a better way.
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Wikimedia\suppressWarnings();
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try {
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$this->read();
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} catch ( Exception $e ) {
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// Note, if this happens, the width/height will be taken to be 0x0.
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// Should we consider it the default 512x512 instead?
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throw $e;
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} finally {
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Wikimedia\restoreWarnings();
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libxml_disable_entity_loader( $oldDisable );
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}
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}
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/**
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* @return array Array with the known metadata
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*/
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public function getMetadata() {
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return $this->metadata;
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}
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/**
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* Read the SVG
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* @throws MWException
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* @return bool
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*/
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protected function read() {
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$keepReading = $this->reader->read();
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/* Skip until first element */
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while ( $keepReading && $this->reader->nodeType != XMLReader::ELEMENT ) {
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$keepReading = $this->reader->read();
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}
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if ( $this->reader->localName != 'svg' || $this->reader->namespaceURI != self::NS_SVG ) {
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throw new MWException( "Expected <svg> tag, got " .
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$this->reader->localName . " in NS " . $this->reader->namespaceURI );
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}
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$this->debug( "<svg> tag is correct." );
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$this->handleSVGAttribs();
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$exitDepth = $this->reader->depth;
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$keepReading = $this->reader->read();
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while ( $keepReading ) {
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$tag = $this->reader->localName;
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$type = $this->reader->nodeType;
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$isSVG = ( $this->reader->namespaceURI == self::NS_SVG );
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$this->debug( "$tag" );
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if ( $isSVG && $tag == 'svg' && $type == XMLReader::END_ELEMENT
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&& $this->reader->depth <= $exitDepth
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) {
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break;
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} elseif ( $isSVG && $tag == 'title' ) {
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$this->readField( $tag, 'title' );
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} elseif ( $isSVG && $tag == 'desc' ) {
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$this->readField( $tag, 'description' );
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} elseif ( $isSVG && $tag == 'metadata' && $type == XMLReader::ELEMENT ) {
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$this->readXml( 'metadata' );
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} elseif ( $isSVG && $tag == 'script' ) {
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// We normally do not allow scripted svgs.
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// However its possible to configure MW to let them
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// in, and such files should be considered animated.
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$this->metadata['animated'] = true;
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} elseif ( $tag !== '#text' ) {
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$this->debug( "Unhandled top-level XML tag $tag" );
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// Recurse into children of current tag, looking for animation and languages.
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$this->animateFilterAndLang( $tag );
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}
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// Goto next element, which is sibling of current (Skip children).
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$keepReading = $this->reader->next();
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}
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$this->reader->close();
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$this->metadata['translations'] = $this->languages + $this->languagePrefixes;
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return true;
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}
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/**
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* Read a textelement from an element
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*
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* @param string $name Name of the element that we are reading from
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* @param string|null $metafield Field that we will fill with the result
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*/
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private function readField( $name, $metafield = null ) {
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$this->debug( "Read field $metafield" );
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if ( !$metafield || $this->reader->nodeType != XMLReader::ELEMENT ) {
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return;
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}
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$keepReading = $this->reader->read();
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while ( $keepReading ) {
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if ( $this->reader->localName == $name
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&& $this->reader->namespaceURI == self::NS_SVG
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&& $this->reader->nodeType == XMLReader::END_ELEMENT
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) {
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break;
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} elseif ( $this->reader->nodeType == XMLReader::TEXT ) {
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$this->metadata[$metafield] = trim( $this->reader->value );
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}
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$keepReading = $this->reader->read();
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}
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}
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/**
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* Read an XML snippet from an element
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*
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* @param string|null $metafield Field that we will fill with the result
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* @throws MWException
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*/
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private function readXml( $metafield = null ) {
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$this->debug( "Read top level metadata" );
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if ( !$metafield || $this->reader->nodeType != XMLReader::ELEMENT ) {
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return;
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}
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// @todo Find and store type of xml snippet. metadata['metadataType'] = "rdf"
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$this->metadata[$metafield] = trim( $this->reader->readInnerXml() );
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$this->reader->next();
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}
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/**
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* Filter all children, looking for animated elements.
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* Also get a list of languages that can be targeted.
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*
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* @param string $name Name of the element that we are reading from
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*/
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private function animateFilterAndLang( $name ) {
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$this->debug( "animate filter for tag $name" );
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if ( $this->reader->nodeType != XMLReader::ELEMENT ) {
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return;
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}
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if ( $this->reader->isEmptyElement ) {
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return;
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}
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$exitDepth = $this->reader->depth;
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$keepReading = $this->reader->read();
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while ( $keepReading ) {
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if ( $this->reader->localName == $name && $this->reader->depth <= $exitDepth
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&& $this->reader->nodeType == XMLReader::END_ELEMENT
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) {
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break;
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} elseif ( $this->reader->namespaceURI == self::NS_SVG
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&& $this->reader->nodeType == XMLReader::ELEMENT
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) {
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$sysLang = $this->reader->getAttribute( 'systemLanguage' );
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if ( $sysLang !== null && $sysLang !== '' ) {
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// See https://www.w3.org/TR/SVG/struct.html#SystemLanguageAttribute
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$langList = explode( ',', $sysLang );
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foreach ( $langList as $langItem ) {
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$langItem = trim( $langItem );
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if ( Language::isWellFormedLanguageTag( $langItem ) ) {
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$this->languages[$langItem] = self::LANG_FULL_MATCH;
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}
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// Note, the standard says that any prefix should work,
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// here we do only the initial prefix, since that will catch
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// 99% of cases, and we are going to compare against fallbacks.
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// This differs mildly from how the spec says languages should be
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// handled, however it matches better how the MediaWiki language
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// preference is generally handled.
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$dash = strpos( $langItem, '-' );
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// Intentionally checking both !false and > 0 at the same time.
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if ( $dash ) {
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$itemPrefix = substr( $langItem, 0, $dash );
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if ( Language::isWellFormedLanguageTag( $itemPrefix ) ) {
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$this->languagePrefixes[$itemPrefix] = self::LANG_PREFIX_MATCH;
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}
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}
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}
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}
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switch ( $this->reader->localName ) {
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case 'script':
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// Normally we disallow files with
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// <script>, but its possible
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// to configure MW to disable
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// such checks.
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case 'animate':
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case 'set':
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case 'animateMotion':
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case 'animateColor':
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case 'animateTransform':
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$this->debug( "HOUSTON WE HAVE ANIMATION" );
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$this->metadata['animated'] = true;
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break;
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}
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}
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$keepReading = $this->reader->read();
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}
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}
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private function debug( $data ) {
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if ( $this->mDebug ) {
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wfDebug( "SVGReader: $data" );
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}
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}
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/**
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* Parse the attributes of an SVG element
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*
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* The parser has to be in the start element of "<svg>"
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*/
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private function handleSVGAttribs() {
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$defaultWidth = self::DEFAULT_WIDTH;
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$defaultHeight = self::DEFAULT_HEIGHT;
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$aspect = 1.0;
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$width = null;
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$height = null;
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if ( $this->reader->getAttribute( 'viewBox' ) ) {
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// min-x min-y width height
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$viewBox = preg_split( '/\s*[\s,]\s*/', trim( $this->reader->getAttribute( 'viewBox' ) ) );
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if ( count( $viewBox ) == 4 ) {
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$viewWidth = $this->scaleSVGUnit( $viewBox[2] );
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$viewHeight = $this->scaleSVGUnit( $viewBox[3] );
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if ( $viewWidth > 0 && $viewHeight > 0 ) {
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$aspect = $viewWidth / $viewHeight;
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$defaultHeight = $defaultWidth / $aspect;
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}
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}
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}
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if ( $this->reader->getAttribute( 'width' ) ) {
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$width = $this->scaleSVGUnit( $this->reader->getAttribute( 'width' ), $defaultWidth );
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$this->metadata['originalWidth'] = $this->reader->getAttribute( 'width' );
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}
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if ( $this->reader->getAttribute( 'height' ) ) {
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$height = $this->scaleSVGUnit( $this->reader->getAttribute( 'height' ), $defaultHeight );
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$this->metadata['originalHeight'] = $this->reader->getAttribute( 'height' );
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}
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if ( !isset( $width ) && !isset( $height ) ) {
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$width = $defaultWidth;
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$height = $width / $aspect;
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} elseif ( isset( $width ) && !isset( $height ) ) {
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$height = $width / $aspect;
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} elseif ( isset( $height ) && !isset( $width ) ) {
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$width = $height * $aspect;
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}
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if ( $width > 0 && $height > 0 ) {
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$this->metadata['width'] = intval( round( $width ) );
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$this->metadata['height'] = intval( round( $height ) );
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}
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}
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/**
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* Return a rounded pixel equivalent for a labeled CSS/SVG length.
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* https://www.w3.org/TR/SVG11/coords.html#Units
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*
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* @param string $length CSS/SVG length.
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* @param float|int $viewportSize Optional scale for percentage units...
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* @return float Length in pixels
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*/
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public static function scaleSVGUnit( $length, $viewportSize = 512 ) {
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static $unitLength = [
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'px' => 1.0,
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'pt' => 1.25,
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'pc' => 15.0,
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'mm' => 3.543307,
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'cm' => 35.43307,
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'in' => 90.0,
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'em' => 16.0, // fake it?
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'ex' => 12.0, // fake it?
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'' => 1.0, // "User units" pixels by default
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];
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$matches = [];
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if ( preg_match(
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'/^\s*([-+]?\d*(?:\.\d+|\d+)(?:[Ee][-+]?\d+)?)\s*(em|ex|px|pt|pc|cm|mm|in|%|)\s*$/',
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$length,
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$matches
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) ) {
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$length = floatval( $matches[1] );
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$unit = $matches[2];
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if ( $unit == '%' ) {
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return $length * 0.01 * $viewportSize;
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} else {
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return $length * $unitLength[$unit];
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}
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} else {
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// Assume pixels
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return floatval( $length );
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}
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}
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}
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