0bc583af2c
The Line continuation Coding conventions prefers the closing parenthesis on the same line than the beginning curly braces. This is done for ifs and functions. Also move some boolean operator from the end of a line to the beginning and changed some indentation to make the condition hopefully better readable. Change-Id: Id0437b06bde86eb5a75bc59eefa19e7edb624426
347 lines
9.2 KiB
PHP
347 lines
9.2 KiB
PHP
<?php
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/**
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* GIF frame counter.
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*
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* Originally written in Perl by Steve Sanbeg.
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* Ported to PHP by Andrew Garrett
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* Deliberately not using MWExceptions to avoid external dependencies, encouraging
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* redistribution.
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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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*/
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/**
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* GIF frame counter.
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*
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* @ingroup Media
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*/
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class GIFMetadataExtractor {
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static $gif_frame_sep;
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static $gif_extension_sep;
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static $gif_term;
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const VERSION = 1;
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// Each sub-block is less than or equal to 255 bytes.
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// Most of the time its 255 bytes, except for in XMP
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// blocks, where it's usually between 32-127 bytes each.
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const MAX_SUBBLOCKS = 262144; // 5mb divided by 20.
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/**
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* @throws Exception
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* @param $filename string
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* @return array
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*/
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static function getMetadata( $filename ) {
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self::$gif_frame_sep = pack( "C", ord( "," ) );
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self::$gif_extension_sep = pack( "C", ord( "!" ) );
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self::$gif_term = pack( "C", ord( ";" ) );
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$frameCount = 0;
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$duration = 0.0;
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$isLooped = false;
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$xmp = "";
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$comment = array();
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if ( !$filename ) {
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throw new Exception( "No file name specified" );
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} elseif ( !file_exists( $filename ) || is_dir( $filename ) ) {
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throw new Exception( "File $filename does not exist" );
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}
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$fh = fopen( $filename, 'rb' );
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if ( !$fh ) {
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throw new Exception( "Unable to open file $filename" );
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}
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// Check for the GIF header
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$buf = fread( $fh, 6 );
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if ( !( $buf == 'GIF87a' || $buf == 'GIF89a' ) ) {
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throw new Exception( "Not a valid GIF file; header: $buf" );
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}
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// Skip over width and height.
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fread( $fh, 4 );
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// Read BPP
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$buf = fread( $fh, 1 );
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$bpp = self::decodeBPP( $buf );
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// Skip over background and aspect ratio
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fread( $fh, 2 );
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// Skip over the GCT
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self::readGCT( $fh, $bpp );
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while ( !feof( $fh ) ) {
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$buf = fread( $fh, 1 );
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if ( $buf == self::$gif_frame_sep ) {
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// Found a frame
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$frameCount++;
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## Skip bounding box
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fread( $fh, 8 );
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## Read BPP
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$buf = fread( $fh, 1 );
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$bpp = self::decodeBPP( $buf );
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## Read GCT
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self::readGCT( $fh, $bpp );
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fread( $fh, 1 );
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self::skipBlock( $fh );
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} elseif ( $buf == self::$gif_extension_sep ) {
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$buf = fread( $fh, 1 );
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if ( strlen( $buf ) < 1 ) {
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throw new Exception( "Ran out of input" );
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}
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$extension_code = unpack( 'C', $buf );
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$extension_code = $extension_code[1];
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if ( $extension_code == 0xF9 ) {
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// Graphics Control Extension.
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fread( $fh, 1 ); // Block size
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fread( $fh, 1 ); // Transparency, disposal method, user input
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$buf = fread( $fh, 2 ); // Delay, in hundredths of seconds.
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if ( strlen( $buf ) < 2 ) {
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throw new Exception( "Ran out of input" );
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}
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$delay = unpack( 'v', $buf );
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$delay = $delay[1];
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$duration += $delay * 0.01;
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fread( $fh, 1 ); // Transparent colour index
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$term = fread( $fh, 1 ); // Should be a terminator
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if ( strlen( $term ) < 1 ) {
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throw new Exception( "Ran out of input" );
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}
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$term = unpack( 'C', $term );
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$term = $term[1];
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if ( $term != 0 ) {
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throw new Exception( "Malformed Graphics Control Extension block" );
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}
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} elseif ( $extension_code == 0xFE ) {
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// Comment block(s).
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$data = self::readBlock( $fh );
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if ( $data === "" ) {
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throw new Exception( 'Read error, zero-length comment block' );
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}
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// The standard says this should be ASCII, however its unclear if
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// thats true in practise. Check to see if its valid utf-8, if so
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// assume its that, otherwise assume its windows-1252 (iso-8859-1)
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$dataCopy = $data;
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// quickIsNFCVerify has the side effect of replacing any invalid characters
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UtfNormal::quickIsNFCVerify( $dataCopy );
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if ( $dataCopy !== $data ) {
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wfSuppressWarnings();
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$data = iconv( 'windows-1252', 'UTF-8', $data );
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wfRestoreWarnings();
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}
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$commentCount = count( $comment );
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if ( $commentCount === 0
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|| $comment[$commentCount - 1] !== $data
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) {
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// Some applications repeat the same comment on each
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// frame of an animated GIF image, so if this comment
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// is identical to the last, only extract once.
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$comment[] = $data;
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}
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} elseif ( $extension_code == 0xFF ) {
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// Application extension (Netscape info about the animated gif)
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// or XMP (or theoretically any other type of extension block)
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$blockLength = fread( $fh, 1 );
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if ( strlen( $blockLength ) < 1 ) {
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throw new Exception( "Ran out of input" );
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}
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$blockLength = unpack( 'C', $blockLength );
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$blockLength = $blockLength[1];
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$data = fread( $fh, $blockLength );
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if ( $blockLength != 11 ) {
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wfDebug( __METHOD__ . " GIF application block with wrong length\n" );
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fseek( $fh, -( $blockLength + 1 ), SEEK_CUR );
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self::skipBlock( $fh );
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continue;
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}
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// NETSCAPE2.0 (application name for animated gif)
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if ( $data == 'NETSCAPE2.0' ) {
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$data = fread( $fh, 2 ); // Block length and introduction, should be 03 01
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if ( $data != "\x03\x01" ) {
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throw new Exception( "Expected \x03\x01, got $data" );
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}
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// Unsigned little-endian integer, loop count or zero for "forever"
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$loopData = fread( $fh, 2 );
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if ( strlen( $loopData ) < 2 ) {
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throw new Exception( "Ran out of input" );
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}
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$loopData = unpack( 'v', $loopData );
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$loopCount = $loopData[1];
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if ( $loopCount != 1 ) {
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$isLooped = true;
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}
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// Read out terminator byte
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fread( $fh, 1 );
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} elseif ( $data == 'XMP DataXMP' ) {
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// application name for XMP data.
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// see pg 18 of XMP spec part 3.
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$xmp = self::readBlock( $fh, true );
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if ( substr( $xmp, -257, 3 ) !== "\x01\xFF\xFE"
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|| substr( $xmp, -4 ) !== "\x03\x02\x01\x00"
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) {
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// this is just a sanity check.
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throw new Exception( "XMP does not have magic trailer!" );
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}
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// strip out trailer.
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$xmp = substr( $xmp, 0, -257 );
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} else {
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// unrecognized extension block
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fseek( $fh, -( $blockLength + 1 ), SEEK_CUR );
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self::skipBlock( $fh );
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continue;
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}
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} else {
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self::skipBlock( $fh );
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}
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} elseif ( $buf == self::$gif_term ) {
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break;
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} else {
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if ( strlen( $buf ) < 1 ) {
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throw new Exception( "Ran out of input" );
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}
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$byte = unpack( 'C', $buf );
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$byte = $byte[1];
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throw new Exception( "At position: " . ftell( $fh ) . ", Unknown byte " . $byte );
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}
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}
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return array(
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'frameCount' => $frameCount,
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'looped' => $isLooped,
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'duration' => $duration,
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'xmp' => $xmp,
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'comment' => $comment,
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);
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}
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/**
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* @param $fh
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* @param $bpp
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* @return void
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*/
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static function readGCT( $fh, $bpp ) {
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if ( $bpp > 0 ) {
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for ( $i = 1; $i <= pow( 2, $bpp ); ++$i ) {
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fread( $fh, 3 );
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}
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}
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}
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/**
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* @param $data
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* @throws Exception
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* @return int
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*/
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static function decodeBPP( $data ) {
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if ( strlen( $data ) < 1 ) {
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throw new Exception( "Ran out of input" );
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}
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$buf = unpack( 'C', $data );
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$buf = $buf[1];
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$bpp = ( $buf & 7 ) + 1;
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$buf >>= 7;
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$have_map = $buf & 1;
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return $have_map ? $bpp : 0;
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}
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/**
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* @param $fh
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* @throws Exception
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*/
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static function skipBlock( $fh ) {
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while ( !feof( $fh ) ) {
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$buf = fread( $fh, 1 );
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if ( strlen( $buf ) < 1 ) {
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throw new Exception( "Ran out of input" );
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}
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$block_len = unpack( 'C', $buf );
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$block_len = $block_len[1];
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if ( $block_len == 0 ) {
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return;
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}
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fread( $fh, $block_len );
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}
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}
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/**
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* Read a block. In the GIF format, a block is made up of
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* several sub-blocks. Each sub block starts with one byte
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* saying how long the sub-block is, followed by the sub-block.
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* The entire block is terminated by a sub-block of length
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* 0.
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* @param $fh FileHandle
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* @param $includeLengths Boolean Include the length bytes of the
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* sub-blocks in the returned value. Normally this is false,
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* except XMP is weird and does a hack where you need to keep
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* these length bytes.
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* @throws Exception
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* @return string The data.
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*/
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static function readBlock( $fh, $includeLengths = false ) {
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$data = '';
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$subLength = fread( $fh, 1 );
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$blocks = 0;
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while ( $subLength !== "\0" ) {
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$blocks++;
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if ( $blocks > self::MAX_SUBBLOCKS ) {
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throw new Exception( "MAX_SUBBLOCKS exceeded (over $blocks sub-blocks)" );
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}
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if ( feof( $fh ) ) {
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throw new Exception( "Read error: Unexpected EOF." );
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}
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if ( $includeLengths ) {
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$data .= $subLength;
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}
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$data .= fread( $fh, ord( $subLength ) );
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$subLength = fread( $fh, 1 );
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}
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return $data;
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}
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}
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