/**
* Clone page, extract it and dependent objects from the current document,
* so it can be used within other docs.
*/
public function __clone()
{
$factory = \ZendPdf\ObjectFactory::createFactory(1);
$processed = array();
// Clone dictionary object.
// Do it explicitly to prevent sharing page attributes between different
// results of clonePage() operation (other resources are still shared)
$dictionary = new InternalType\DictionaryObject();
foreach ($this->_pageDictionary->getKeys() as $key) {
$dictionary->{$key} = $this->_pageDictionary->{$key}->makeClone($factory, $processed, InternalType\AbstractTypeObject::CLONE_MODE_SKIP_PAGES);
}
$this->_pageDictionary = $factory->newObject($dictionary);
$this->_objFactory = $factory;
$this->_attached = false;
$this->_style = null;
$this->_font = null;
}
/**
* Object constructor
*
* @param string $imageFileName
* @throws \ZendPdf\Exception\ExceptionInterface
* @todo Add compression conversions to support compression strategys other than PNG_COMPRESSION_DEFAULT_STRATEGY.
* @todo Add pre-compression filtering.
* @todo Add interlaced image handling.
* @todo Add support for 16-bit images. Requires PDF version bump to 1.5 at least.
* @todo Add processing for all PNG chunks defined in the spec. gAMA etc.
* @todo Fix tRNS chunk support for Indexed Images to a SMask.
*/
public function __construct($imageFileName)
{
if (($imageFile = @fopen($imageFileName, 'rb')) === false) {
throw new Exception\IOException("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($imageFile, 3)) {
throw new Exception\DomainException('Image is not a PNG');
}
fseek($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))) != self::PNG_INTERLACING_DISABLED) {
throw new Exception\NotImplementedException('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
$imageData = '';
/*
* The following loop processes PNG chunks. 4 Byte Longs are packed first give the chunk length
* followed by the chunk signature, a four byte code. IDAT and IEND are manditory in any PNG.
*/
while (($chunkLengthBytes = fread($imageFile, 4)) !== false) {
$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 self::PNG_CHANNEL_GRAY:
$baseColor = ord(substr($trnsData, 1, 1));
$transparencyData = array(new InternalType\NumericObject($baseColor), new InternalType\NumericObject($baseColor));
break;
case self::PNG_CHANNEL_RGB:
$red = ord(substr($trnsData, 1, 1));
$green = ord(substr($trnsData, 3, 1));
$blue = ord(substr($trnsData, 5, 1));
$transparencyData = array(new InternalType\NumericObject($red), new InternalType\NumericObject($red), new InternalType\NumericObject($green), new InternalType\NumericObject($green), new InternalType\NumericObject($blue), new InternalType\NumericObject($blue));
break;
case self::PNG_CHANNEL_INDEXED:
//Find the first transparent color in the index, we will mask that. (This is a bit of a hack. This should be a SMask and mask all entries values).
if (($trnsIdx = strpos($trnsData, "")) !== false) {
$transparencyData = array(new InternalType\NumericObject($trnsIdx), new InternalType\NumericObject($trnsIdx));
}
break;
case self::PNG_CHANNEL_GRAY_ALPHA:
// Fall through to the next case
// Fall through to the next case
case self::PNG_CHANNEL_RGB_ALPHA:
throw new Exception\CorruptedImageException("tRNS chunk illegal for Alpha Channel Images");
break;
}
fseek($imageFile, 4, SEEK_CUR);
//4 Byte Ending Sequence
break;
case 'IEND':
break 2;
//End the loop too
//End the loop too
default:
fseek($imageFile, $chunkLength + 4, SEEK_CUR);
//Skip the section
break;
}
}
fclose($imageFile);
$compressed = true;
$imageDataTmp = '';
$smaskData = '';
switch ($color) {
case self::PNG_CHANNEL_RGB:
$colorSpace = new InternalType\NameObject('DeviceRGB');
break;
case self::PNG_CHANNEL_GRAY:
$colorSpace = new InternalType\NameObject('DeviceGray');
break;
case self::PNG_CHANNEL_INDEXED:
if (empty($paletteData)) {
throw new Exception\CorruptedImageException("PNG Corruption: No palette data read for indexed type PNG.");
}
$colorSpace = new InternalType\ArrayObject();
$colorSpace->items[] = new InternalType\NameObject('Indexed');
$colorSpace->items[] = new InternalType\NameObject('DeviceRGB');
$colorSpace->items[] = new InternalType\NumericObject(strlen($paletteData) / 3 - 1);
$paletteObject = $this->_objectFactory->newObject(new InternalType\BinaryStringObject($paletteData));
$colorSpace->items[] = $paletteObject;
break;
case self::PNG_CHANNEL_GRAY_ALPHA:
/*
* To decode PNG's with alpha data we must create two images from one. One image will contain the Gray data
* the other will contain the Gray transparency overlay data. The former will become the object data and the latter
* will become the Shadow Mask (SMask).
*/
if ($bits > 8) {
throw new Exception\NotImplementedException('Alpha PNGs with bit depth > 8 are not yet supported');
}
$colorSpace = new InternalType\NameObject('DeviceGray');
$decodingObjFactory = ObjectFactory::createFactory(1);
$decodingStream = $decodingObjFactory->newStreamObject($imageData);
$decodingStream->dictionary->Filter = new InternalType\NameObject('FlateDecode');
$decodingStream->dictionary->DecodeParms = new InternalType\DictionaryObject();
$decodingStream->dictionary->DecodeParms->Predictor = new InternalType\NumericObject(15);
$decodingStream->dictionary->DecodeParms->Columns = new InternalType\NumericObject($width);
$decodingStream->dictionary->DecodeParms->Colors = new InternalType\NumericObject(2);
//GreyAlpha
$decodingStream->dictionary->DecodeParms->BitsPerComponent = new InternalType\NumericObject($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 = $imageDataTmp;
//Overwrite image data with the gray channel without alpha
break;
case self::PNG_CHANNEL_RGB_ALPHA:
/*
* To decode PNG's with alpha data we must create two images from one. One image will contain the RGB data
* the other will contain the Gray transparency overlay data. The former will become the object data and the latter
* will become the Shadow Mask (SMask).
*/
if ($bits > 8) {
throw new Exception\NotImplementedException('Alpha PNGs with bit depth > 8 are not yet supported');
}
$colorSpace = new InternalType\NameObject('DeviceRGB');
$decodingObjFactory = ObjectFactory::createFactory(1);
$decodingStream = $decodingObjFactory->newStreamObject($imageData);
$decodingStream->dictionary->Filter = new InternalType\NameObject('FlateDecode');
$decodingStream->dictionary->DecodeParms = new InternalType\DictionaryObject();
$decodingStream->dictionary->DecodeParms->Predictor = new InternalType\NumericObject(15);
$decodingStream->dictionary->DecodeParms->Columns = new InternalType\NumericObject($width);
$decodingStream->dictionary->DecodeParms->Colors = new InternalType\NumericObject(4);
//RGBA
$decodingStream->dictionary->DecodeParms->BitsPerComponent = new InternalType\NumericObject($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 = $imageDataTmp;
//Overwrite image data with the RGB channel without alpha
break;
default:
throw new Exception\CorruptedImageException('PNG Corruption: Invalid color space.');
}
if (empty($imageData)) {
throw new Exception\CorruptedImageException('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 InternalType\NameObject('XObject');
$smaskStream->dictionary->Subtype = new InternalType\NameObject('Image');
$smaskStream->dictionary->Width = new InternalType\NumericObject($width);
$smaskStream->dictionary->Height = new InternalType\NumericObject($height);
$smaskStream->dictionary->ColorSpace = new InternalType\NameObject('DeviceGray');
$smaskStream->dictionary->BitsPerComponent = new InternalType\NumericObject($bits);
$imageDictionary->SMask = $smaskStream;
// Encode stream with FlateDecode filter
$smaskStreamDecodeParms = array();
$smaskStreamDecodeParms['Predictor'] = new InternalType\NumericObject(15);
$smaskStreamDecodeParms['Columns'] = new InternalType\NumericObject($width);
$smaskStreamDecodeParms['Colors'] = new InternalType\NumericObject(1);
$smaskStreamDecodeParms['BitsPerComponent'] = new InternalType\NumericObject(8);
$smaskStream->dictionary->DecodeParms = new InternalType\DictionaryObject($smaskStreamDecodeParms);
$smaskStream->dictionary->Filter = new InternalType\NameObject('FlateDecode');
}
if (!empty($transparencyData)) {
//This is experimental and not properly tested.
$imageDictionary->Mask = new InternalType\ArrayObject($transparencyData);
}
$imageDictionary->Width = new InternalType\NumericObject($width);
$imageDictionary->Height = new InternalType\NumericObject($height);
$imageDictionary->ColorSpace = $colorSpace;
$imageDictionary->BitsPerComponent = new InternalType\NumericObject($bits);
$imageDictionary->Filter = new InternalType\NameObject('FlateDecode');
$decodeParms = array();
$decodeParms['Predictor'] = new InternalType\NumericObject(15);
// Optimal prediction
$decodeParms['Columns'] = new InternalType\NumericObject($width);
$decodeParms['Colors'] = new InternalType\NumericObject($color == self::PNG_CHANNEL_RGB || $color == self::PNG_CHANNEL_RGB_ALPHA ? 3 : 1);
$decodeParms['BitsPerComponent'] = new InternalType\NumericObject($bits);
$imageDictionary->DecodeParms = new InternalType\DictionaryObject($decodeParms);
//Include only the image IDAT section data.
$this->_resource->value = $imageData;
//Skip double compression
if ($compressed) {
$this->_resource->skipFilters();
}
}
private function decode($imageData, $width, $colors, $bits)
{
$decodingObjFactory = ObjectFactory::createFactory(1);
$decodingStream = $decodingObjFactory->newStreamObject($imageData);
$decodingStream->dictionary->Filter = new InternalType\NameObject('FlateDecode');
$decodingStream->dictionary->DecodeParms = new InternalType\DictionaryObject();
$decodingStream->dictionary->DecodeParms->Predictor = new InternalType\NumericObject(self::PREDICATOR);
$decodingStream->dictionary->DecodeParms->Columns = new InternalType\NumericObject($width);
$decodingStream->dictionary->DecodeParms->Colors = new InternalType\NumericObject($colors);
$decodingStream->dictionary->DecodeParms->BitsPerComponent = new InternalType\NumericObject($bits);
$decodingStream->skipFilters();
return $decodingStream->value;
}
/**
* Object constructor.
*/
public function __construct()
{
$this->_factory = Pdf\ObjectFactory::createFactory(1);
$this->_processed = array();
}
