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