<?php

/**

 * Zend Framework

 *

 * LICENSE

 *

 * This source file is subject to the new BSD license that is bundled

 * with this package in the file LICENSE.txt.

 * It is also available through the world-wide-web at this URL:

 * http://framework.zend.com/license/new-bsd

 * If you did not receive a copy of the license and are unable to

 * obtain it through the world-wide-web, please send an email

 * to license@zend.com so we can send you a copy immediately.

 *

 * @category   Zend

 * @package    Zend_Pdf

 * @copyright  Copyright (c) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)

 * @license    http://framework.zend.com/license/new-bsd     New BSD License

 * @version    $Id: Png.php 23395 2010-11-19 15:30:47Z alexander $

 */

/** Internally used classes */

require_once 'Zend/Pdf/Element/Array.php';

require_once 'Zend/Pdf/Element/Dictionary.php';

require_once 'Zend/Pdf/Element/Name.php';

require_once 'Zend/Pdf/Element/Numeric.php';

require_once 'Zend/Pdf/Element/String/Binary.php';

/** Zend_Pdf_Resource_Image */

require_once 'Zend/Pdf/Resource/Image.php';

/**

 * PNG image

 *

 * @package    Zend_Pdf

 * @copyright  Copyright (c) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)

 * @license    http://framework.zend.com/license/new-bsd     New BSD License

 */

class Zend_Pdf_Resource_Image_Png extends Zend_Pdf_Resource_Image

{

    const PNG_COMPRESSION_DEFAULT_STRATEGY = 0;

    const PNG_COMPRESSION_FILTERED = 1;

    const PNG_COMPRESSION_HUFFMAN_ONLY = 2;

    const PNG_COMPRESSION_RLE = 3;

    const PNG_FILTER_NONE = 0;

    const PNG_FILTER_SUB = 1;

    const PNG_FILTER_UP = 2;

    const PNG_FILTER_AVERAGE = 3;

    const PNG_FILTER_PAETH = 4;

    const PNG_INTERLACING_DISABLED = 0;

    const PNG_INTERLACING_ENABLED = 1;

    const PNG_CHANNEL_GRAY = 0;

    const PNG_CHANNEL_RGB = 2;

    const PNG_CHANNEL_INDEXED = 3;

    const PNG_CHANNEL_GRAY_ALPHA = 4;

    const PNG_CHANNEL_RGB_ALPHA = 6;

    protected $_width;

    protected $_height;

    protected $_imageProperties;

    /**

     * Object constructor

     *

     * @param string $imageFileName

     * @throws Zend_Pdf_Exception

     * @todo Add compression conversions to support compression strategys other than PNG_COMPRESSION_DEFAULT_STRATEGY.

     * @todo Add pre-compression filtering.

     * @todo Add interlaced image handling.

     * @todo Add support for 16-bit images. Requires PDF version bump to 1.5 at least.

     * @todo Add processing for all PNG chunks defined in the spec. gAMA etc.

     * @todo Fix tRNS chunk support for Indexed Images to a SMask.

     */

    public function __construct($imageFileName)

    {

        if (($imageFile = @fopen($imageFileName, 'rb')) === false ) {

            require_once 'Zend/Pdf/Exception.php';

            throw new Zend_Pdf_Exception( "Can not open '$imageFileName' file for reading." );

        }

        parent::__construct();

        //Check if the file is a PNG

        fseek($imageFile, 1, SEEK_CUR); //First signature byte (%)

        if ('PNG' != fread($imageFile, 3)) {

            require_once 'Zend/Pdf/Exception.php';

            throw new Zend_Pdf_Exception('Image is not a PNG');

        }

        fseek($imageFile, 12, SEEK_CUR); //Signature bytes (Includes the IHDR chunk) IHDR processed linerarly because it doesnt contain a variable chunk length

        $wtmp = unpack('Ni',fread($imageFile, 4)); //Unpack a 4-Byte Long

        $width = $wtmp['i'];

        $htmp = unpack('Ni',fread($imageFile, 4));

        $height = $htmp['i'];

        $bits = ord(fread($imageFile, 1)); //Higher than 8 bit depths are only supported in later versions of PDF.

        $color = ord(fread($imageFile, 1));

        $compression = ord(fread($imageFile, 1));

        $prefilter = ord(fread($imageFile,1));

        if (($interlacing = ord(fread($imageFile,1))) != Zend_Pdf_Resource_Image_Png::PNG_INTERLACING_DISABLED) {

            require_once 'Zend/Pdf/Exception.php';

            throw new Zend_Pdf_Exception( "Only non-interlaced images are currently supported." );

        }

        $this->_width = $width;

        $this->_height = $height;

        $this->_imageProperties = array();

        $this->_imageProperties['bitDepth'] = $bits;

        $this->_imageProperties['pngColorType'] = $color;

        $this->_imageProperties['pngFilterType'] = $prefilter;

        $this->_imageProperties['pngCompressionType'] = $compression;

        $this->_imageProperties['pngInterlacingType'] = $interlacing;

        fseek($imageFile, 4, SEEK_CUR); //4 Byte Ending Sequence

        $imageData = '';

        /*

         * The following loop processes PNG chunks. 4 Byte Longs are packed first give the chunk length

         * followed by the chunk signature, a four byte code. IDAT and IEND are manditory in any PNG.

         */

        while (!feof($imageFile)) {

            $chunkLengthBytes = fread($imageFile, 4);

            if ($chunkLengthBytes === false) {

                require_once 'Zend/Pdf/Exception.php';

                throw new Zend_Pdf_Exception('Error ocuured while image file reading.');

            }

            $chunkLengthtmp = unpack('Ni', $chunkLengthBytes);

            $chunkLength    = $chunkLengthtmp['i'];

            $chunkType      = fread($imageFile, 4);

            switch($chunkType) {

                case 'IDAT': //Image Data

                    /*

                     * Reads the actual image data from the PNG file. Since we know at this point that the compression

                     * strategy is the default strategy, we also know that this data is Zip compressed. We will either copy

                     * the data directly to the PDF and provide the correct FlateDecode predictor, or decompress the data

                     * decode the filters and output the data as a raw pixel map.

                     */

                    $imageData .= fread($imageFile, $chunkLength);

                    fseek($imageFile, 4, SEEK_CUR);

                    break;

                case 'PLTE': //Palette

                    $paletteData = fread($imageFile, $chunkLength);

                    fseek($imageFile, 4, SEEK_CUR);

                    break;

                case 'tRNS': //Basic (non-alpha channel) transparency.

                    $trnsData = fread($imageFile, $chunkLength);

                    switch ($color) {

                        case Zend_Pdf_Resource_Image_Png::PNG_CHANNEL_GRAY:

                            $baseColor = ord(substr($trnsData, 1, 1));

                            $transparencyData = array(new Zend_Pdf_Element_Numeric($baseColor),

                                                      new Zend_Pdf_Element_Numeric($baseColor));

                            break;

                        case Zend_Pdf_Resource_Image_Png::PNG_CHANNEL_RGB:

                            $red = ord(substr($trnsData,1,1));

                            $green = ord(substr($trnsData,3,1));

                            $blue = ord(substr($trnsData,5,1));

                            $transparencyData = array(new Zend_Pdf_Element_Numeric($red),

                                                      new Zend_Pdf_Element_Numeric($red),

                                                      new Zend_Pdf_Element_Numeric($green),

                                                      new Zend_Pdf_Element_Numeric($green),

                                                      new Zend_Pdf_Element_Numeric($blue),

                                                      new Zend_Pdf_Element_Numeric($blue));

                            break;

                        case Zend_Pdf_Resource_Image_Png::PNG_CHANNEL_INDEXED:

                            //Find the first transparent color in the index, we will mask that. (This is a bit of a hack. This should be a SMask and mask all entries values).

                            if(($trnsIdx = strpos($trnsData, "\0")) !== false) {

                                $transparencyData = array(new Zend_Pdf_Element_Numeric($trnsIdx),

                                                          new Zend_Pdf_Element_Numeric($trnsIdx));

                            }

                            break;

                        case Zend_Pdf_Resource_Image_Png::PNG_CHANNEL_GRAY_ALPHA:

                            // Fall through to the next case

                        case Zend_Pdf_Resource_Image_Png::PNG_CHANNEL_RGB_ALPHA:

                            require_once 'Zend/Pdf/Exception.php';

                            throw new Zend_Pdf_Exception( "tRNS chunk illegal for Alpha Channel Images" );

                            break;

                    }

                    fseek($imageFile, 4, SEEK_CUR); //4 Byte Ending Sequence

                    break;

                case 'IEND';

                    break 2; //End the loop too

                default:

                    fseek($imageFile, $chunkLength + 4, SEEK_CUR); //Skip the section

                    break;

            }

        }

        fclose($imageFile);

        $compressed = true;

        $imageDataTmp = '';

        $smaskData = '';

        switch ($color) {

            case Zend_Pdf_Resource_Image_Png::PNG_CHANNEL_RGB:

                $colorSpace = new Zend_Pdf_Element_Name('DeviceRGB');

                break;

            case Zend_Pdf_Resource_Image_Png::PNG_CHANNEL_GRAY:

                $colorSpace = new Zend_Pdf_Element_Name('DeviceGray');

                break;

            case Zend_Pdf_Resource_Image_Png::PNG_CHANNEL_INDEXED:

                if(empty($paletteData)) {

                    require_once 'Zend/Pdf/Exception.php';

                    throw new Zend_Pdf_Exception( "PNG Corruption: No palette data read for indexed type PNG." );

                }

                $colorSpace = new Zend_Pdf_Element_Array();

                $colorSpace->items[] = new Zend_Pdf_Element_Name('Indexed');

                $colorSpace->items[] = new Zend_Pdf_Element_Name('DeviceRGB');

                $colorSpace->items[] = new Zend_Pdf_Element_Numeric((strlen($paletteData)/3-1));

                $paletteObject = $this->_objectFactory->newObject(new Zend_Pdf_Element_String_Binary($paletteData));

                $colorSpace->items[] = $paletteObject;

                break;

            case Zend_Pdf_Resource_Image_Png::PNG_CHANNEL_GRAY_ALPHA:

                /*

                 * To decode PNG's with alpha data we must create two images from one. One image will contain the Gray data

                 * the other will contain the Gray transparency overlay data. The former will become the object data and the latter

                 * will become the Shadow Mask (SMask).

                 */

                if($bits > 8) {

                    require_once 'Zend/Pdf/Exception.php';

                    throw new Zend_Pdf_Exception("Alpha PNGs with bit depth > 8 are not yet supported");

                }

                $colorSpace = new Zend_Pdf_Element_Name('DeviceGray');

                require_once 'Zend/Pdf/ElementFactory.php';

                $decodingObjFactory = Zend_Pdf_ElementFactory::createFactory(1);

                $decodingStream = $decodingObjFactory->newStreamObject($imageData);

                $decodingStream->dictionary->Filter      = new Zend_Pdf_Element_Name('FlateDecode');

                $decodingStream->dictionary->DecodeParms = new Zend_Pdf_Element_Dictionary();

                $decodingStream->dictionary->DecodeParms->Predictor        = new Zend_Pdf_Element_Numeric(15);

                $decodingStream->dictionary->DecodeParms->Columns          = new Zend_Pdf_Element_Numeric($width);

                $decodingStream->dictionary->DecodeParms->Colors           = new Zend_Pdf_Element_Numeric(2);   //GreyAlpha

                $decodingStream->dictionary->DecodeParms->BitsPerComponent = new Zend_Pdf_Element_Numeric($bits);

                $decodingStream->skipFilters();

                $pngDataRawDecoded = $decodingStream->value;

                //Iterate every pixel and copy out gray data and alpha channel (this will be slow)

                for($pixel = 0, $pixelcount = ($width * $height); $pixel < $pixelcount; $pixel++) {

                    $imageDataTmp .= $pngDataRawDecoded[($pixel*2)];

                    $smaskData .= $pngDataRawDecoded[($pixel*2)+1];

                }

                $compressed = false;

                $imageData  = $imageDataTmp; //Overwrite image data with the gray channel without alpha

                break;

            case Zend_Pdf_Resource_Image_Png::PNG_CHANNEL_RGB_ALPHA:

                /*

                 * To decode PNG's with alpha data we must create two images from one. One image will contain the RGB data

                 * the other will contain the Gray transparency overlay data. The former will become the object data and the latter

                 * will become the Shadow Mask (SMask).

                 */

                if($bits > 8) {

                    require_once 'Zend/Pdf/Exception.php';

                    throw new Zend_Pdf_Exception("Alpha PNGs with bit depth > 8 are not yet supported");

                }

                $colorSpace = new Zend_Pdf_Element_Name('DeviceRGB');

                require_once 'Zend/Pdf/ElementFactory.php';

                $decodingObjFactory = Zend_Pdf_ElementFactory::createFactory(1);

                $decodingStream = $decodingObjFactory->newStreamObject($imageData);

                $decodingStream->dictionary->Filter      = new Zend_Pdf_Element_Name('FlateDecode');

                $decodingStream->dictionary->DecodeParms = new Zend_Pdf_Element_Dictionary();

                $decodingStream->dictionary->DecodeParms->Predictor        = new Zend_Pdf_Element_Numeric(15);

                $decodingStream->dictionary->DecodeParms->Columns          = new Zend_Pdf_Element_Numeric($width);

                $decodingStream->dictionary->DecodeParms->Colors           = new Zend_Pdf_Element_Numeric(4);   //RGBA

                $decodingStream->dictionary->DecodeParms->BitsPerComponent = new Zend_Pdf_Element_Numeric($bits);

                $decodingStream->skipFilters();

                $pngDataRawDecoded = $decodingStream->value;

                //Iterate every pixel and copy out rgb data and alpha channel (this will be slow)

                for($pixel = 0, $pixelcount = ($width * $height); $pixel < $pixelcount; $pixel++) {

                    $imageDataTmp .= $pngDataRawDecoded[($pixel*4)+0] . $pngDataRawDecoded[($pixel*4)+1] . $pngDataRawDecoded[($pixel*4)+2];

                    $smaskData .= $pngDataRawDecoded[($pixel*4)+3];

                }

                $compressed = false;

                $imageData  = $imageDataTmp; //Overwrite image data with the RGB channel without alpha

                break;

            default:

                require_once 'Zend/Pdf/Exception.php';

                throw new Zend_Pdf_Exception( "PNG Corruption: Invalid color space." );

        }

        if(empty($imageData)) {

            require_once 'Zend/Pdf/Exception.php';

            throw new Zend_Pdf_Exception( "Corrupt PNG Image. Mandatory IDAT chunk not found." );

        }

        $imageDictionary = $this->_resource->dictionary;

        if(!empty($smaskData)) {

            /*

             * Includes the Alpha transparency data as a Gray Image, then assigns the image as the Shadow Mask for the main image data.

             */

            $smaskStream = $this->_objectFactory->newStreamObject($smaskData);

            $smaskStream->dictionary->Type             = new Zend_Pdf_Element_Name('XObject');

            $smaskStream->dictionary->Subtype          = new Zend_Pdf_Element_Name('Image');

            $smaskStream->dictionary->Width            = new Zend_Pdf_Element_Numeric($width);

            $smaskStream->dictionary->Height           = new Zend_Pdf_Element_Numeric($height);

            $smaskStream->dictionary->ColorSpace       = new Zend_Pdf_Element_Name('DeviceGray');

            $smaskStream->dictionary->BitsPerComponent = new Zend_Pdf_Element_Numeric($bits);

            $imageDictionary->SMask = $smaskStream;

            // Encode stream with FlateDecode filter

            $smaskStreamDecodeParms = array();

            $smaskStreamDecodeParms['Predictor']        = new Zend_Pdf_Element_Numeric(15);

            $smaskStreamDecodeParms['Columns']          = new Zend_Pdf_Element_Numeric($width);

            $smaskStreamDecodeParms['Colors']           = new Zend_Pdf_Element_Numeric(1);

            $smaskStreamDecodeParms['BitsPerComponent'] = new Zend_Pdf_Element_Numeric(8);

            $smaskStream->dictionary->DecodeParms  = new Zend_Pdf_Element_Dictionary($smaskStreamDecodeParms);

            $smaskStream->dictionary->Filter       = new Zend_Pdf_Element_Name('FlateDecode');

        }

        if(!empty($transparencyData)) {

            //This is experimental and not properly tested.

            $imageDictionary->Mask = new Zend_Pdf_Element_Array($transparencyData);

        }

        $imageDictionary->Width            = new Zend_Pdf_Element_Numeric($width);

        $imageDictionary->Height           = new Zend_Pdf_Element_Numeric($height);

        $imageDictionary->ColorSpace       = $colorSpace;

        $imageDictionary->BitsPerComponent = new Zend_Pdf_Element_Numeric($bits);

        $imageDictionary->Filter       = new Zend_Pdf_Element_Name('FlateDecode');

        $decodeParms = array();

        $decodeParms['Predictor']        = new Zend_Pdf_Element_Numeric(15); // Optimal prediction

        $decodeParms['Columns']          = new Zend_Pdf_Element_Numeric($width);

        $decodeParms['Colors']           = new Zend_Pdf_Element_Numeric((($color==Zend_Pdf_Resource_Image_Png::PNG_CHANNEL_RGB || $color==Zend_Pdf_Resource_Image_Png::PNG_CHANNEL_RGB_ALPHA)?(3):(1)));

        $decodeParms['BitsPerComponent'] = new Zend_Pdf_Element_Numeric($bits);

        $imageDictionary->DecodeParms  = new Zend_Pdf_Element_Dictionary($decodeParms);

        //Include only the image IDAT section data.

        $this->_resource->value = $imageData;

        //Skip double compression

        if ($compressed) {

            $this->_resource->skipFilters();

        }

    }

    /**

     * Image width

     */

    public function getPixelWidth() {

    return $this->_width;

    }

    /**

     * Image height

     */

    public function getPixelHeight() {

        return $this->_height;

    }

    /**

     * Image properties

     */

    public function getProperties() {

        return $this->_imageProperties;

    }

}