wiki.techinc.nl/includes/media/WebPHandler.php
Timo Tijhof 9bf3916322 media: Rename files to match the name of the class they define
This will make jumping from file to file much easier in text
editors when file name lookups will autocomplete naturally when
looking for a class by name.

Change-Id: I4b2e55a2e72674b619d5a592866c8a019a2b0224
2018-04-28 02:07:33 +01:00

309 lines
8.9 KiB
PHP

<?php
/**
* Handler for Google's WebP format <https://developers.google.com/speed/webp/>
*
* 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
*/
/**
* Handler for Google's WebP format <https://developers.google.com/speed/webp/>
*
* @ingroup Media
*/
class WebPHandler extends BitmapHandler {
const BROKEN_FILE = '0'; // value to store in img_metadata if error extracting metadata.
/**
* @var int Minimum chunk header size to be able to read all header types
*/
const MINIMUM_CHUNK_HEADER_LENGTH = 18;
/**
* @var int version of the metadata stored in db records
*/
const _MW_WEBP_VERSION = 1;
const VP8X_ICC = 32;
const VP8X_ALPHA = 16;
const VP8X_EXIF = 8;
const VP8X_XMP = 4;
const VP8X_ANIM = 2;
public function getMetadata( $image, $filename ) {
$parsedWebPData = self::extractMetadata( $filename );
if ( !$parsedWebPData ) {
return self::BROKEN_FILE;
}
$parsedWebPData['metadata']['_MW_WEBP_VERSION'] = self::_MW_WEBP_VERSION;
return serialize( $parsedWebPData );
}
public function getMetadataType( $image ) {
return 'parsed-webp';
}
public function isMetadataValid( $image, $metadata ) {
if ( $metadata === self::BROKEN_FILE ) {
// Do not repetitivly regenerate metadata on broken file.
return self::METADATA_GOOD;
}
Wikimedia\suppressWarnings();
$data = unserialize( $metadata );
Wikimedia\restoreWarnings();
if ( !$data || !is_array( $data ) ) {
wfDebug( __METHOD__ . " invalid WebP metadata\n" );
return self::METADATA_BAD;
}
if ( !isset( $data['metadata']['_MW_WEBP_VERSION'] )
|| $data['metadata']['_MW_WEBP_VERSION'] != self::_MW_WEBP_VERSION
) {
wfDebug( __METHOD__ . " old but compatible WebP metadata\n" );
return self::METADATA_COMPATIBLE;
}
return self::METADATA_GOOD;
}
/**
* Extracts the image size and WebP type from a file
*
* @param string $filename
* @return array|bool Header data array with entries 'compression', 'width' and 'height',
* where 'compression' can be 'lossy', 'lossless', 'animated' or 'unknown'. False if
* file is not a valid WebP file.
*/
public static function extractMetadata( $filename ) {
wfDebugLog( 'WebP', __METHOD__ . ": Extracting metadata from $filename\n" );
$info = RiffExtractor::findChunksFromFile( $filename, 100 );
if ( $info === false ) {
wfDebugLog( 'WebP', __METHOD__ . ": Not a valid RIFF file\n" );
return false;
}
if ( $info['fourCC'] != 'WEBP' ) {
wfDebugLog( 'WebP', __METHOD__ . ': FourCC was not WEBP: ' .
bin2hex( $info['fourCC'] ) . " \n" );
return false;
}
$metadata = self::extractMetadataFromChunks( $info['chunks'], $filename );
if ( !$metadata ) {
wfDebugLog( 'WebP', __METHOD__ . ": No VP8 chunks found\n" );
return false;
}
return $metadata;
}
/**
* Extracts the image size and WebP type from a file based on the chunk list
* @param array $chunks Chunks as extracted by RiffExtractor
* @param string $filename
* @return array Header data array with entries 'compression', 'width' and 'height', where
* 'compression' can be 'lossy', 'lossless', 'animated' or 'unknown'
*/
public static function extractMetadataFromChunks( $chunks, $filename ) {
$vp8Info = [];
foreach ( $chunks as $chunk ) {
if ( !in_array( $chunk['fourCC'], [ 'VP8 ', 'VP8L', 'VP8X' ] ) ) {
// Not a chunk containing interesting metadata
continue;
}
$chunkHeader = file_get_contents( $filename, false, null,
$chunk['start'], self::MINIMUM_CHUNK_HEADER_LENGTH );
wfDebugLog( 'WebP', __METHOD__ . ": {$chunk['fourCC']}\n" );
switch ( $chunk['fourCC'] ) {
case 'VP8 ':
return array_merge( $vp8Info,
self::decodeLossyChunkHeader( $chunkHeader ) );
case 'VP8L':
return array_merge( $vp8Info,
self::decodeLosslessChunkHeader( $chunkHeader ) );
case 'VP8X':
$vp8Info = array_merge( $vp8Info,
self::decodeExtendedChunkHeader( $chunkHeader ) );
// Continue looking for other chunks to improve the metadata
break;
}
}
return $vp8Info;
}
/**
* Decodes a lossy chunk header
* @param string $header First few bytes of the header, expected to be at least 18 bytes long
* @return bool|array See WebPHandler::decodeHeader
*/
protected static function decodeLossyChunkHeader( $header ) {
// Bytes 0-3 are 'VP8 '
// Bytes 4-7 are the VP8 stream size
// Bytes 8-10 are the frame tag
// Bytes 11-13 are 0x9D 0x01 0x2A called the sync code
$syncCode = substr( $header, 11, 3 );
if ( $syncCode != "\x9D\x01\x2A" ) {
wfDebugLog( 'WebP', __METHOD__ . ': Invalid sync code: ' .
bin2hex( $syncCode ) . "\n" );
return [];
}
// Bytes 14-17 are image size
$imageSize = unpack( 'v2', substr( $header, 14, 4 ) );
// Image sizes are 14 bit, 2 MSB are scaling parameters which are ignored here
return [
'compression' => 'lossy',
'width' => $imageSize[1] & 0x3FFF,
'height' => $imageSize[2] & 0x3FFF
];
}
/**
* Decodes a lossless chunk header
* @param string $header First few bytes of the header, expected to be at least 13 bytes long
* @return bool|array See WebPHandler::decodeHeader
*/
public static function decodeLosslessChunkHeader( $header ) {
// Bytes 0-3 are 'VP8L'
// Bytes 4-7 are chunk stream size
// Byte 8 is 0x2F called the signature
if ( $header{8} != "\x2F" ) {
wfDebugLog( 'WebP', __METHOD__ . ': Invalid signature: ' .
bin2hex( $header{8} ) . "\n" );
return [];
}
// Bytes 9-12 contain the image size
// Bits 0-13 are width-1; bits 15-27 are height-1
$imageSize = unpack( 'C4', substr( $header, 9, 4 ) );
return [
'compression' => 'lossless',
'width' => ( $imageSize[1] | ( ( $imageSize[2] & 0x3F ) << 8 ) ) + 1,
'height' => ( ( ( $imageSize[2] & 0xC0 ) >> 6 ) |
( $imageSize[3] << 2 ) | ( ( $imageSize[4] & 0x03 ) << 10 ) ) + 1
];
}
/**
* Decodes an extended chunk header
* @param string $header First few bytes of the header, expected to be at least 18 bytes long
* @return bool|array See WebPHandler::decodeHeader
*/
public static function decodeExtendedChunkHeader( $header ) {
// Bytes 0-3 are 'VP8X'
// Byte 4-7 are chunk length
// Byte 8-11 are a flag bytes
$flags = unpack( 'c', substr( $header, 8, 1 ) );
// Byte 12-17 are image size (24 bits)
$width = unpack( 'V', substr( $header, 12, 3 ) . "\x00" );
$height = unpack( 'V', substr( $header, 15, 3 ) . "\x00" );
return [
'compression' => 'unknown',
'animated' => ( $flags[1] & self::VP8X_ANIM ) == self::VP8X_ANIM,
'transparency' => ( $flags[1] & self::VP8X_ALPHA ) == self::VP8X_ALPHA,
'width' => ( $width[1] & 0xFFFFFF ) + 1,
'height' => ( $height[1] & 0xFFFFFF ) + 1
];
}
public function getImageSize( $file, $path, $metadata = false ) {
if ( $file === null ) {
$metadata = self::getMetadata( $file, $path );
}
if ( $metadata === false && $file instanceof File ) {
$metadata = $file->getMetadata();
}
Wikimedia\suppressWarnings();
$metadata = unserialize( $metadata );
Wikimedia\restoreWarnings();
if ( $metadata == false ) {
return false;
}
return [ $metadata['width'], $metadata['height'] ];
}
/**
* @param File $file
* @return bool True, not all browsers support WebP
*/
public function mustRender( $file ) {
return true;
}
/**
* @param File $file
* @return bool False if we are unable to render this image
*/
public function canRender( $file ) {
if ( self::isAnimatedImage( $file ) ) {
return false;
}
return true;
}
/**
* @param File $image
* @return bool
*/
public function isAnimatedImage( $image ) {
$ser = $image->getMetadata();
if ( $ser ) {
$metadata = unserialize( $ser );
if ( isset( $metadata['animated'] ) && $metadata['animated'] === true ) {
return true;
}
}
return false;
}
public function canAnimateThumbnail( $file ) {
return false;
}
/**
* Render files as PNG
*
* @param string $ext
* @param string $mime
* @param array|null $params
* @return array
*/
public function getThumbType( $ext, $mime, $params = null ) {
return [ 'png', 'image/png' ];
}
/**
* Must use "im" for XCF
*
* @param string $dstPath
* @param bool $checkDstPath
* @return string
*/
protected function getScalerType( $dstPath, $checkDstPath = true ) {
return 'im';
}
}