327 lines
11 KiB
PHP
327 lines
11 KiB
PHP
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<?php
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/**
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* Zend Framework
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*
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* LICENSE
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*
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* This source file is subject to the new BSD license that is bundled
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* with this package in the file LICENSE.txt.
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* It is also available through the world-wide-web at this URL:
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* http://framework.zend.com/license/new-bsd
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* If you did not receive a copy of the license and are unable to
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* obtain it through the world-wide-web, please send an email
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* to license@zend.com so we can send you a copy immediately.
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*
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* @category Zend
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* @package Zend_Pdf
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* @subpackage FileParser
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* @copyright Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
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* @license http://framework.zend.com/license/new-bsd New BSD License
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* @version $Id: Png.php 16971 2009-07-22 18:05:45Z mikaelkael $
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*/
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/** Zend_Pdf_FileParser_Image */
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require_once 'Zend/Pdf/FileParser/Image.php';
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/**
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* Abstract base class for Image file parsers.
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*
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* @package Zend_Pdf
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* @subpackage FileParser
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* @copyright Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
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* @license http://framework.zend.com/license/new-bsd New BSD License
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*/
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class Zend_Pdf_FileParser_Image_Png extends Zend_Pdf_FileParser_Image
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{
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protected $_isPNG;
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protected $_width;
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protected $_height;
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protected $_bits;
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protected $_color;
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protected $_compression;
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protected $_preFilter;
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protected $_interlacing;
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protected $_imageData;
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protected $_paletteData;
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protected $_transparencyData;
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/**** Public Interface ****/
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public function getWidth() {
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if(!$this->_isParsed) {
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$this->parse();
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}
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return $this->_width;
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}
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public function getHeight() {
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if(!$this->_isParsed) {
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$this->parse();
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}
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return $this->_width;
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}
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public function getBitDepth() {
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if(!$this->_isParsed) {
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$this->parse();
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}
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return $this->_bits;
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}
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public function getColorSpace() {
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if(!$this->_isParsed) {
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$this->parse();
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}
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return $this->_color;
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}
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public function getCompressionStrategy() {
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if(!$this->_isParsed) {
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$this->parse();
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}
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return $this->_compression;
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}
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public function getPaethFilter() {
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if(!$this->_isParsed) {
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$this->parse();
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}
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return $this->_preFilter;
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}
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public function getInterlacingMode() {
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if(!$this->_isParsed) {
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$this->parse();
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}
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return $this->_interlacing;
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}
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public function getRawImageData() {
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if(!$this->_isParsed) {
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$this->parse();
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}
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return $this->_imageData;
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}
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public function getRawPaletteData() {
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if(!$this->_isParsed) {
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$this->parse();
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}
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return $this->_paletteData;
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}
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public function getRawTransparencyData() {
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if(!$this->_isParsed) {
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$this->parse();
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}
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return $this->_transparencyData;
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}
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/* Semi-Concrete Class Implementation */
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/**
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* Verifies that the image file is in the expected format.
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*
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* @throws Zend_Pdf_Exception
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*/
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public function screen()
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{
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if ($this->_isScreened) {
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return;
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}
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return $this->_checkSignature();
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}
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/**
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* Reads and parses the image data from the file on disk.
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*
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* @throws Zend_Pdf_Exception
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*/
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public function parse()
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{
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if ($this->_isParsed) {
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return;
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}
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/* Screen the font file first, if it hasn't been done yet.
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*/
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$this->screen();
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$this->_parseIHDRChunk();
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$this->_parseChunks();
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}
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protected function _parseSignature() {
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$this->moveToOffset(1); //Skip the first byte (%)
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if('PNG' != $this->readBytes(3)) {
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$this->_isPNG = false;
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} else {
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$this->_isPNG = true;
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}
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}
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protected function _checkSignature() {
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if(!isset($this->_isPNG)) {
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$this->_parseSignature();
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}
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return $this->_isPNG;
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}
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protected function _parseChunks() {
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$this->moveToOffset(33); //Variable chunks start at the end of IHDR
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//Start processing chunks. If there are no more bytes to read parsing is complete.
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$size = $this->getSize();
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while($size - $this->getOffset() >= 8) {
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$chunkLength = $this->readUInt(4);
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if($chunkLength < 0 || ($chunkLength + $this->getOffset() + 4) > $size) {
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throw new Zend_Pdf_Exception("PNG Corrupt: Invalid Chunk Size In File.");
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}
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$chunkType = $this->readBytes(4);
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$offset = $this->getOffset();
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//If we know how to process the chunk, do it here, else ignore the chunk and move on to the next
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switch($chunkType) {
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case 'IDAT': // This chunk may appear more than once. It contains the actual image data.
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$this->_parseIDATChunk($offset, $chunkLength);
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break;
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case 'PLTE': // This chunk contains the image palette.
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$this->_parsePLTEChunk($offset, $chunkLength);
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break;
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case 'tRNS': // This chunk contains non-alpha channel transparency data
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$this->_parseTRNSChunk($offset, $chunkLength);
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break;
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case 'IEND':
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break 2; //End the loop too
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//@TODO Implement the rest of the PNG chunks. (There are many not implemented here)
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}
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if($offset + $chunkLength + 4 < $size) {
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$this->moveToOffset($offset + $chunkLength + 4); //Skip past the data finalizer. (Don't rely on the parse to leave the offsets correct)
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}
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}
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if(empty($this->_imageData)) {
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throw new Zend_Pdf_Exception ( "This PNG is corrupt. All png must contain IDAT chunks." );
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}
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}
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protected function _parseIHDRChunk() {
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$this->moveToOffset(12); //IHDR must always start at offset 12 and run for 17 bytes
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if(!$this->readBytes(4) == 'IHDR') {
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throw new Zend_Pdf_Exception( "This PNG is corrupt. The first chunk in a PNG file must be IHDR." );
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}
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$this->_width = $this->readUInt(4);
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$this->_height = $this->readUInt(4);
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$this->_bits = $this->readInt(1);
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$this->_color = $this->readInt(1);
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$this->_compression = $this->readInt(1);
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$this->_preFilter = $this->readInt(1);
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$this->_interlacing = $this->readInt(1);
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if($this->_interlacing != Zend_Pdf_Image::PNG_INTERLACING_DISABLED) {
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throw new Zend_Pdf_Exception( "Only non-interlaced images are currently supported." );
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}
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}
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protected function _parseIDATChunk($chunkOffset, $chunkLength) {
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$this->moveToOffset($chunkOffset);
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if(!isset($this->_imageData)) {
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$this->_imageData = $this->readBytes($chunkLength);
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} else {
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$this->_imageData .= $this->readBytes($chunkLength);
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}
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}
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protected function _parsePLTEChunk($chunkOffset, $chunkLength) {
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$this->moveToOffset($chunkOffset);
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$this->_paletteData = $this->readBytes($chunkLength);
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}
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protected function _parseTRNSChunk($chunkOffset, $chunkLength) {
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$this->moveToOffset($chunkOffset);
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//Processing of tRNS data varies dependending on the color depth
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switch($this->_color) {
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case Zend_Pdf_Image::PNG_CHANNEL_GRAY:
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$baseColor = $this->readInt(1);
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$this->_transparencyData = array($baseColor, $baseColor);
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break;
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case Zend_Pdf_Image::PNG_CHANNEL_RGB:
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//@TODO Fix this hack.
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//This parser cheats and only uses the lsb's (and only works with < 16 bit depth images)
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/*
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From the standard:
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For color type 2 (truecolor), the tRNS chunk contains a single RGB color value, stored in the format:
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Red: 2 bytes, range 0 .. (2^bitdepth)-1
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Green: 2 bytes, range 0 .. (2^bitdepth)-1
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Blue: 2 bytes, range 0 .. (2^bitdepth)-1
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(If the image bit depth is less than 16, the least significant bits are used and the others are 0.)
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Pixels of the specified color value are to be treated as transparent (equivalent to alpha value 0);
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all other pixels are to be treated as fully opaque (alpha value 2bitdepth-1).
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*/
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$red = $this->readInt(1);
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$this->skipBytes(1);
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$green = $this->readInt(1);
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$this->skipBytes(1);
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$blue = $this->readInt(1);
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$this->_transparencyData = array($red, $red, $green, $green, $blue, $blue);
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break;
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case Zend_Pdf_Image::PNG_CHANNEL_INDEXED:
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//@TODO Fix this hack.
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//This parser cheats too. It only masks the first color in the palette.
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/*
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From the standard:
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For color type 3 (indexed color), the tRNS chunk contains a series of one-byte alpha values, corresponding to entries in the PLTE chunk:
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Alpha for palette index 0: 1 byte
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Alpha for palette index 1: 1 byte
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...etc...
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Each entry indicates that pixels of the corresponding palette index must be treated as having the specified alpha value.
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Alpha values have the same interpretation as in an 8-bit full alpha channel: 0 is fully transparent, 255 is fully opaque,
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regardless of image bit depth. The tRNS chunk must not contain more alpha values than there are palette entries,
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but tRNS can contain fewer values than there are palette entries. In this case, the alpha value for all remaining palette
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entries is assumed to be 255. In the common case in which only palette index 0 need be made transparent, only a one-byte
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tRNS chunk is needed.
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*/
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$tmpData = $this->readBytes($chunkLength);
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if(($trnsIdx = strpos($tmpData, chr(0))) !== false) {
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$this->_transparencyData = array($trnsIdx, $trnsIdx);
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}
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break;
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case Zend_Pdf_Image::PNG_CHANNEL_GRAY_ALPHA:
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//Fall through to the next case
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case Zend_Pdf_Image::PING_CHANNEL_RGB_ALPHA:
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throw new Zend_Pdf_Exception( "tRNS chunk illegal for Alpha Channel Images" );
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break;
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}
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}
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}
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