e6de99be92
Add a new config variable $wgSVGMetadataCutoff (currently set to 256kb, chosen rather arbitrarily) and only read that much of the svg file when finding metadata. In general: *Most (non-crazy huge map) svgs aren't that big, so there'd be no change in general *Almost all files have any relevent metadata (well except for when we look for animation tags) is at the begining of the file before actual image data. *At the end of the day, even if this does miss metadata in some files (which I really doubt it would), I'd consider that a better situation then the current situation where it can take 10 minutes or have OOM to parse the likes of [[:File:Puerto_Rico_ecosystems_map-fr.svg]] Also has parts of/parts are based on Hartman's patch from bugzilla in it. Also changes how it recurses into child elements looking for animation, to do so only when neccesary. Trims the results of reading values, because i was getting extra leading spaces when testing this. Last of all, add a comment to the MediaHandler class about how the first parameter of MediaHandler::getMetadata is kind of useless. (it confused me when I was doing this)
339 lines
10 KiB
PHP
339 lines
10 KiB
PHP
<?php
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/**
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* SVGMetadataExtractor.php
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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 http://www.gnu.org/copyleft/gpl.html GNU General Public License
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*/
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class SVGMetadataExtractor {
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static function getMetadata( $filename ) {
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$svg = new SVGReader( $filename );
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return $svg->getMetadata();
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}
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}
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class SVGReader {
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const DEFAULT_WIDTH = 512;
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const DEFAULT_HEIGHT = 512;
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private $reader = null;
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private $mDebug = false;
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private $metadata = Array();
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/**
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* Constructor
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*
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* Creates an SVGReader drawing from the source provided
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* @param $source String: URI from which to read
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*/
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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, -1, $wgSVGMetadataCutoff );
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if ($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( $source, null, LIBXML_NOERROR | LIBXML_NOWARNING );
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}
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$this->metadata['width'] = self::DEFAULT_WIDTH;
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$this->metadata['height'] = self::DEFAULT_HEIGHT;
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// Because we cut off the end of the svg making an invalid one. Complicated
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// try catch thing to make sure warnings get restored. Seems like there should
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// be a better way.
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wfSuppressWarnings();
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try {
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$this->read();
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} catch( Exception $e ) {
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wfRestoreWarnings();
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throw $e;
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}
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wfRestoreWarnings();
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}
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/*
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* @return Array with the known metadata
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*/
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public function getMetadata() {
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return $this->metadata;
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}
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/*
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* Read the SVG
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*/
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public function read() {
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$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->qualifiedNameEquals( $this->reader->name, 'svg', 'svg' ) ) {
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throw new MWException( "Expected <svg> tag, got ".
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$this->reader->name );
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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 = $this->reader->name;
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$type = $this->reader->nodeType;
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$this->debug( "$tag" );
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if ( $this->qualifiedNameEquals( $tag, 'svg', 'svg' ) && $type == XmlReader::END_ELEMENT && $this->reader->depth <= $exitDepth ) {
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break;
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} elseif ( $this->qualifiedNameEquals( $tag, 'svg', 'title' ) ) {
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$this->readField( $tag, 'title' );
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} elseif ( $this->qualifiedNameEquals( $tag, 'svg', 'desc' ) ) {
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$this->readField( $tag, 'description' );
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} elseif ( $this->qualifiedNameEquals( $tag, 'svg', 'metadata' ) && $type == XmlReader::ELEMENT ) {
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$this->readXml( $tag, 'metadata' );
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} elseif ( $tag !== '#text' ) {
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$this->debug( "Unhandled top-level XML tag $tag" );
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if ( !isset( $this->metadata['animated'] ) ) {
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// Recurse into children of current tag, looking for animation.
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$this->animateFilter( $tag );
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}
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}
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// Goto next element, which is sibling of current (Skip children).
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$keepReading = $this->reader->next();
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}
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$this->reader->close();
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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 of the element that we are reading from
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* @param String $metafield 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->name == $name && $this->reader->nodeType == XmlReader::END_ELEMENT ) {
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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 $metafield that we will fill with the result
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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] = $this->reader->readInnerXML();
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$this->reader->next();
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}
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/*
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* Filter all children, looking for animate elements
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*
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* @param String $name of the element that we are reading from
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*/
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private function animateFilter( $name ) {
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$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->name == $name && $this->reader->depth <= $exitDepth
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&& $this->reader->nodeType == XmlReader::END_ELEMENT ) {
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break;
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} elseif ( $this->reader->nodeType == XmlReader::ELEMENT ) {
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switch( $this->reader->name ) {
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case 'animate':
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case 'svg:animate':
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case 'set':
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case 'svg:set':
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case 'animateMotion':
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case 'svg:animateMotion':
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case 'animateColor':
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case 'svg:animateColor':
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case 'animateTransform':
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case 'svg:animateTransform':
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$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 throwXmlError( $err ) {
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$this->debug( "FAILURE: $err" );
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wfDebug( "SVGReader XML error: $err\n" );
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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\n" );
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}
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}
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private function warn( $data ) {
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wfDebug( "SVGReader: $data\n" );
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}
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private function notice( $data ) {
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wfDebug( "SVGReader WARN: $data\n" );
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}
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/*
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* Parse the attributes of an SVG element
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*
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* The parser has to be in the start element of <svg>
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*/
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private function handleSVGAttribs( ) {
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$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+/', 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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}
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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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}
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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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* http://www.w3.org/TR/SVG11/coords.html#UnitIdentifiers
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*
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* @param $length String: CSS/SVG length.
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* @param $viewportSize: Float optional scale for percentage units...
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* @return float: length in pixels
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*/
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static function scaleSVGUnit( $length, $viewportSize=512 ) {
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static $unitLength = array(
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'px' => 1.0,
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'pt' => 1.25,
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'pc' => 15.0,
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'mm' => 3.543307,
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'cm' => 35.43307,
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'in' => 90.0,
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'em' => 16.0, // fake it?
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'ex' => 12.0, // fake it?
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'' => 1.0, // "User units" pixels by default
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);
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$matches = array();
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if( preg_match( '/^\s*(\d+(?:\.\d+)?)(em|ex|px|pt|pc|cm|mm|in|%|)\s*$/', $length, $matches ) ) {
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$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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* XML namespace check
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*
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* Check if a read node name matches the expected nodeName
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* @param $qualifiedName as read by XMLReader
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* @param $prefix the namespace prefix that you expect for this element, defaults to svg namespace
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* @param $localName the localName part of the element that you want to match
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*
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* @return boolean
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*/
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private function qualifiedNameEquals( $qualifiedName, $prefix="svg", $localName ) {
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if( ($qualifiedName == $localName && $prefix == "svg" ) ||
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$qualifiedName == ($prefix . ":" . $localName) ) {
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return true;
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}
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return false;
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}
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}
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