Zend_Pdf_FileParser_Image_Png Class Reference

Inheritance diagram for Zend_Pdf_FileParser_Image_Png:

Public Member Functions
	getWidth ()
	getHeight ()
	getBitDepth ()
	getColorSpace ()
	getCompressionStrategy ()
	getPaethFilter ()
	getInterlacingMode ()
	getRawImageData ()
	getRawPaletteData ()
	getRawTransparencyData ()
	screen ()
	parse ()
Public Member Functions inherited from Zend_Pdf_FileParser_Image
	__construct (Zend_Pdf_FileParserDataSource $dataSource)
Public Member Functions inherited from Zend_Pdf_FileParser
	screen ()
	parse ()
	__construct (Zend_Pdf_FileParserDataSource $dataSource)
	__destruct ()
	isScreened ()
	isParsed ()
	getDataSource ()
	moveToOffset ($offset)
	getOffset ()
	getSize ()
	readBytes ($byteCount)
	skipBytes ($byteCount)
	readInt ($size, $byteOrder=Zend_Pdf_FileParser::BYTE_ORDER_BIG_ENDIAN)
	readUInt ($size, $byteOrder=Zend_Pdf_FileParser::BYTE_ORDER_BIG_ENDIAN)
	isBitSet ($bit, $bitField)
	readFixed ($mantissaBits, $fractionBits, $byteOrder=Zend_Pdf_FileParser::BYTE_ORDER_BIG_ENDIAN)
	readStringUTF16 ($byteCount, $byteOrder=Zend_Pdf_FileParser::BYTE_ORDER_BIG_ENDIAN, $characterSet='')
	readStringMacRoman ($byteCount, $characterSet='')
	readStringPascal ($characterSet='', $lengthBytes=1)

Protected Member Functions
	_parseSignature ()
	_checkSignature ()
	_parseChunks ()
	_parseIHDRChunk ()
	_parseIDATChunk ($chunkOffset, $chunkLength)
	_parsePLTEChunk ($chunkOffset, $chunkLength)
	_parseTRNSChunk ($chunkOffset, $chunkLength)

Protected Attributes
	$_isPNG
	$_width
	$_height
	$_bits
	$_color
	$_compression
	$_preFilter
	$_interlacing
	$_imageData
	$_paletteData
	$_transparencyData
Protected Attributes inherited from Zend_Pdf_FileParser_Image
	$imageType
Protected Attributes inherited from Zend_Pdf_FileParser
	$_isScreened = false
	$_isParsed = false
	$_dataSource = null

Additional Inherited Members
Data Fields inherited from Zend_Pdf_FileParser
const	BYTE_ORDER_LITTLE_ENDIAN = 0
const	BYTE_ORDER_BIG_ENDIAN = 1

Detailed Description

Definition at line 35 of file Png.php.

Member Function Documentation

_checkSignature()

_checkSignature ( )

protected

Definition at line 166 of file Png.php.

                                         {
         if(!isset($this->_isPNG)) {
              $this->_parseSignature();
         }
         return $this->_isPNG;
    }

_parseChunks()

_parseChunks ( )

protected

Definition at line 173 of file Png.php.

                                      {
         $this->moveToOffset(33); //Variable chunks start at the end of IHDR

         //Start processing chunks. If there are no more bytes to read parsing is complete.
         $size = $this->getSize();
         while($size - $this->getOffset() >= 8) {
              $chunkLength = $this->readUInt(4);
              if($chunkLength < 0 || ($chunkLength + $this->getOffset() + 4) > $size) {
                   #require_once 'Zend/Pdf/Exception.php';
                   throw new Zend_Pdf_Exception("PNG Corrupt: Invalid Chunk Size In File.");
              }

              $chunkType = $this->readBytes(4);
              $offset = $this->getOffset();

              //If we know how to process the chunk, do it here, else ignore the chunk and move on to the next
              switch($chunkType) {
                   case 'IDAT': // This chunk may appear more than once. It contains the actual image data.
                       $this->_parseIDATChunk($offset, $chunkLength);
                       break;

                   case 'PLTE': // This chunk contains the image palette.
                       $this->_parsePLTEChunk($offset, $chunkLength);
                       break;

                   case 'tRNS': // This chunk contains non-alpha channel transparency data
                       $this->_parseTRNSChunk($offset, $chunkLength);
                       break;

                   case 'IEND':
                       break 2; //End the loop too

                   //@TODO Implement the rest of the PNG chunks. (There are many not implemented here)
              }
              if($offset + $chunkLength + 4 < $size) {
                  $this->moveToOffset($offset + $chunkLength + 4); //Skip past the data finalizer. (Don't rely on the parse to leave the offsets correct)
              }
         }
         if(empty($this->_imageData)) {
              #require_once 'Zend/Pdf/Exception.php';
              throw new Zend_Pdf_Exception ( "This PNG is corrupt. All png must contain IDAT chunks." );
         }
    }

_parseIDATChunk()

_parseIDATChunk (   $chunkOffset,   $chunkLength  )

protected

Definition at line 236 of file Png.php.

                                                                   {
         $this->moveToOffset($chunkOffset);
         if(!isset($this->_imageData)) {
              $this->_imageData = $this->readBytes($chunkLength);
         } else {
              $this->_imageData .= $this->readBytes($chunkLength);
         }
    }

_parseIHDRChunk()

_parseIHDRChunk ( )

protected

Definition at line 217 of file Png.php.

                                         {
         $this->moveToOffset(12); //IHDR must always start at offset 12 and run for 17 bytes
         if(!$this->readBytes(4) == 'IHDR') {
              #require_once 'Zend/Pdf/Exception.php';
              throw new Zend_Pdf_Exception( "This PNG is corrupt. The first chunk in a PNG file must be IHDR." );
         }
         $this->_width = $this->readUInt(4);
         $this->_height = $this->readUInt(4);
         $this->_bits = $this->readInt(1);
         $this->_color = $this->readInt(1);
         $this->_compression = $this->readInt(1);
         $this->_preFilter = $this->readInt(1);
         $this->_interlacing = $this->readInt(1);
         if($this->_interlacing != Zend_Pdf_Image::PNG_INTERLACING_DISABLED) {
              #require_once 'Zend/Pdf/Exception.php';
              throw new Zend_Pdf_Exception( "Only non-interlaced images are currently supported." );
         }
    }

_parsePLTEChunk()

_parsePLTEChunk (   $chunkOffset,   $chunkLength  )

protected

Definition at line 245 of file Png.php.

                                                                   {
         $this->moveToOffset($chunkOffset);
         $this->_paletteData = $this->readBytes($chunkLength);
    }

_parseSignature()

_parseSignature ( )

protected

Definition at line 157 of file Png.php.

                                         {
         $this->moveToOffset(1); //Skip the first byte (%)
         if('PNG' != $this->readBytes(3)) {
               $this->_isPNG = false;
         } else {
               $this->_isPNG = true;
         }
    }

_parseTRNSChunk()

_parseTRNSChunk (   $chunkOffset,   $chunkLength  )

protected

Definition at line 250 of file Png.php.

                                                                   {
         $this->moveToOffset($chunkOffset);

         //Processing of tRNS data varies dependending on the color depth

         switch($this->_color) {
             case Zend_Pdf_Image::PNG_CHANNEL_GRAY:
                  $baseColor = $this->readInt(1);
                  $this->_transparencyData = array($baseColor, $baseColor);
                  break;

             case Zend_Pdf_Image::PNG_CHANNEL_RGB:

                  //@TODO Fix this hack.
                  //This parser cheats and only uses the lsb's (and only works with < 16 bit depth images)

                  /*
                       From the standard:

                       For color type 2 (truecolor), the tRNS chunk contains a single RGB color value, stored in the format:

                       Red:   2 bytes, range 0 .. (2^bitdepth)-1
                       Green: 2 bytes, range 0 .. (2^bitdepth)-1
                       Blue:  2 bytes, range 0 .. (2^bitdepth)-1

                       (If the image bit depth is less than 16, the least significant bits are used and the others are 0.)
                       Pixels of the specified color value are to be treated as transparent (equivalent to alpha value 0);
                       all other pixels are to be treated as fully opaque (alpha value 2bitdepth-1).

                  */

                  $red = $this->readInt(1);
                  $this->skipBytes(1);
                  $green = $this->readInt(1);
                  $this->skipBytes(1);
                  $blue = $this->readInt(1);

                  $this->_transparencyData = array($red, $red, $green, $green, $blue, $blue);

                  break;

             case Zend_Pdf_Image::PNG_CHANNEL_INDEXED:

                  //@TODO Fix this hack.
                  //This parser cheats too. It only masks the first color in the palette.

                  /*
                       From the standard:

                       For color type 3 (indexed color), the tRNS chunk contains a series of one-byte alpha values, corresponding to entries in the PLTE chunk:

                          Alpha for palette index 0:  1 byte
                          Alpha for palette index 1:  1 byte
                          ...etc...

                       Each entry indicates that pixels of the corresponding palette index must be treated as having the specified alpha value.
                       Alpha values have the same interpretation as in an 8-bit full alpha channel: 0 is fully transparent, 255 is fully opaque,
                       regardless of image bit depth. The tRNS chunk must not contain more alpha values than there are palette entries,
                       but tRNS can contain fewer values than there are palette entries. In this case, the alpha value for all remaining palette
                       entries is assumed to be 255. In the common case in which only palette index 0 need be made transparent, only a one-byte
                       tRNS chunk is needed.

                  */

                  $tmpData = $this->readBytes($chunkLength);
                  if(($trnsIdx = strpos($tmpData, "\0")) !== false) {
                       $this->_transparencyData = array($trnsIdx, $trnsIdx);
                  }

                  break;

             case Zend_Pdf_Image::PNG_CHANNEL_GRAY_ALPHA:
                  //Fall through to the next case
             case Zend_Pdf_Image::PNG_CHANNEL_RGB_ALPHA:
                  #require_once 'Zend/Pdf/Exception.php';
                  throw new Zend_Pdf_Exception( "tRNS chunk illegal for Alpha Channel Images" );
                  break;
         }
    }

getBitDepth()

getBitDepth

(

)

Definition at line 66 of file Png.php.

                                   {
          if(!$this->_isParsed) {
               $this->parse();
          }
          return $this->_bits;
     }

getColorSpace()

getColorSpace

(

)

Definition at line 73 of file Png.php.

                                     {
          if(!$this->_isParsed) {
               $this->parse();
          }
          return $this->_color;
     }

getCompressionStrategy()

getCompressionStrategy

(

)

Definition at line 80 of file Png.php.

                                              {
          if(!$this->_isParsed) {
               $this->parse();
          }
          return $this->_compression;
     }

getHeight()

getHeight

(

)

Definition at line 59 of file Png.php.

                                 {
          if(!$this->_isParsed) {
               $this->parse();
          }
          return $this->_width;
     }

getInterlacingMode()

getInterlacingMode

(

)

Definition at line 94 of file Png.php.

                                          {
          if(!$this->_isParsed) {
               $this->parse();
          }
          return $this->_interlacing;
     }

getPaethFilter()

getPaethFilter

(

)

Definition at line 87 of file Png.php.

                                      {
          if(!$this->_isParsed) {
               $this->parse();
          }
          return $this->_preFilter;
     }

getRawImageData()

getRawImageData

(

)

Definition at line 101 of file Png.php.

                                       {
          if(!$this->_isParsed) {
               $this->parse();
          }
          return $this->_imageData;
     }

getRawPaletteData()

getRawPaletteData

(

)

Definition at line 108 of file Png.php.

                                         {
          if(!$this->_isParsed) {
               $this->parse();
          }
          return $this->_paletteData;
     }

getRawTransparencyData()

getRawTransparencyData

(

)

Definition at line 115 of file Png.php.

                                              {
          if(!$this->_isParsed) {
               $this->parse();
          }
          return $this->_transparencyData;
     }

getWidth()

getWidth

(

)

Definition at line 52 of file Png.php.

                                {
          if(!$this->_isParsed) {
               $this->parse();
          }
          return $this->_width;
     }

parse()

parse

(

)

Reads and parses the image data from the file on disk.

Exceptions

Zend_Pdf_Exception

Definition at line 142 of file Png.php.

    {
        if ($this->_isParsed) {
            return;
        }

        /* Screen the font file first, if it hasn't been done yet.
        */
        $this->screen();

        $this->_parseIHDRChunk();
        $this->_parseChunks();
    }

screen()

screen

(

)

Verifies that the image file is in the expected format.

Exceptions

Zend_Pdf_Exception

Definition at line 129 of file Png.php.

    {
         if ($this->_isScreened) {
             return;
         }
         return $this->_checkSignature();
    }

Field Documentation

$_bits

$_bits

protected

Definition at line 40 of file Png.php.

$_color

$_color

protected

Definition at line 41 of file Png.php.

$_compression

$_compression

protected

Definition at line 42 of file Png.php.

$_height

$_height

protected

Definition at line 39 of file Png.php.

$_imageData

$_imageData

protected

Definition at line 46 of file Png.php.

$_interlacing

$_interlacing

protected

Definition at line 44 of file Png.php.

$_isPNG

$_isPNG

protected

Definition at line 37 of file Png.php.

$_paletteData

$_paletteData

protected

Definition at line 47 of file Png.php.

$_preFilter

$_preFilter

protected

Definition at line 43 of file Png.php.

$_transparencyData

$_transparencyData

protected

Definition at line 48 of file Png.php.

$_width

$_width

protected

Definition at line 38 of file Png.php.

---

The documentation for this class was generated from the following file:

• vendor/magento/zendframework1/library/Zend/Pdf/FileParser/Image/Png.php