exif.php

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/******************************************************************************
*
*         INTERNAL FUNCTIONS
*
******************************************************************************/











/******************************************************************************
*
* Internal Function:     get_TIFF_Packed_Data
*
* Description:  Packs TIFF IFD data from EXIF or Meta into a form ready for
*               either a JPEG EXIF/Meta segment or a TIFF file
*               This function attempts to protect the contents of an EXIF makernote,
*               by ensuring that it remains in the same position relative to the
*               TIFF header
*
* Parameters:   tiff_data - the EXIF array,as read from get_EXIF_JPEG or get_Meta_JPEG
*
* Returns:      packed_data - A string containing packed segment
*
******************************************************************************/

function get_TIFF_Packed_Data( $tiff_data )
{
        // Check that the segment is valid
        if ( $tiff_data === FALSE )
        {
                return FALSE;
        }

        // Get the byte alignment
        $Byte_Align = $tiff_data['Byte_Align'];

        // Add the Byte Alignment to the Packed data
        $packed_data = $Byte_Align;

        // Add the TIFF ID to the Packed Data
        $packed_data .= put_IFD_Data_Type( 42, 3, $Byte_Align );

        // Create a string for the makernote
        $makernote = "";

        // Check if the makernote exists
        if ( $tiff_data[ 'Makernote_Tag' ] !== FALSE )
        {
                // A makernote exists - We need to ensure that it stays in the same position as it was
                // Put the Makernote before any of the IFD's by padding zeros to the correct offset
                $makernote .= str_repeat("\x00",( $tiff_data[ 'Makernote_Tag' ][ 'Offset' ] - 8 ) );
                $makernote .= $tiff_data[ 'Makernote_Tag' ]['Data'];
        }

        // Calculage where the zeroth ifd will be
        $ifd_offset = strlen( $makernote ) + 8;

        // Add the Zeroth IFD pointer to the packed data
        $packed_data .= put_IFD_Data_Type( $ifd_offset, 4, $Byte_Align );

        // Add the makernote to the packed data (if there was one)
        $packed_data .= $makernote;

        //Add the IFD's to the packed data
        $packed_data .= get_IFD_Array_Packed_Data( $tiff_data, $ifd_offset, $Byte_Align );

        // Return the result
        return $packed_data;
}

/******************************************************************************
* End of Function:     get_TIFF_Packed_Data
******************************************************************************/




/******************************************************************************
*
* Internal Function:     get_IFD_Array_Packed_Data
*
* Description:  Packs a chain of IFD's from EXIF or Meta segments into a form
*               ready for either a JPEG EXIF/Meta segment or a TIFF file
*
* Parameters:   ifd_data - the IFD chain array, as read from get_EXIF_JPEG or get_Meta_JPEG
*               Zero_IFD_offset - The offset to the first IFD from the start of the TIFF header
*               Byte_Align - the Byte alignment to use - "MM" or "II"
*
* Returns:      packed_data - A string containing packed IFD's
*
******************************************************************************/

function get_IFD_Array_Packed_Data( $ifd_data, $Zero_IFD_offset, $Byte_Align )
{
        // Create a string to receive the packed output
        $packed_data = "";

        // Count the IFDs
        $ifd_count = 0;
        foreach( $ifd_data as $key => $IFD )
        {
                // Make sure we only count the IFD's, not other information keys
                if ( is_numeric( $key ) )
                {
                        $ifd_count++;
                }
        }


        // Cycle through each IFD,
        for ( $ifdno = 0; $ifdno < $ifd_count; $ifdno++ )
        {
                // Check if this IFD is the last one
                if ( $ifdno == $ifd_count - 1 )
                {
                        // This IFD is the last one, get it's packed data
                        $packed_data .= get_IFD_Packed_Data( $ifd_data[ $ifdno ], $Zero_IFD_offset +strlen($packed_data), $Byte_Align, FALSE );
                }
                else
                {
                        // This IFD is NOT the last one, get it's packed data
                        $packed_data .= get_IFD_Packed_Data( $ifd_data[ $ifdno ], $Zero_IFD_offset +strlen($packed_data), $Byte_Align, TRUE );
                }

        }

        // Return the packed output
        return $packed_data;
}

/******************************************************************************
* End of Function:     get_IFD_Array_Packed_Data
******************************************************************************/



/******************************************************************************
*
* Internal Function:     get_IFD_Packed_Data
*
* Description:  Packs an IFD from EXIF or Meta segments into a form
*               ready for either a JPEG EXIF/Meta segment or a TIFF file
*
* Parameters:   ifd_data - the IFD chain array, as read from get_EXIF_JPEG or get_Meta_JPEG
*               IFD_offset - The offset to the IFD from the start of the TIFF header
*               Byte_Align - the Byte alignment to use - "MM" or "II"
*               Another_IFD - boolean - false if this is the last IFD in the chain
*                                     - true if it is not the last
*
* Returns:      packed_data - A string containing packed IFD's
*
******************************************************************************/

function get_IFD_Packed_Data( $ifd_data, $IFD_offset, $Byte_Align, $Another_IFD )
{

        $ifd_body_str = "";
        $ifd_data_str = "";

        $Tag_Definitions_Name = $ifd_data[ 'Tags Name' ];


        // Count the Tags in this IFD
        $tag_count = 0;
        foreach( $ifd_data as $key => $tag )
        {
                // Make sure we only count the Tags, not other information keys
                if ( is_numeric( $key ) )
                {
                        $tag_count++;
                }
        }

        // Add the Tag count to the packed data
        $packed_data = put_IFD_Data_Type( $tag_count, 3, $Byte_Align );

        // Calculate the total length of the IFD (without the offset data)
        $IFD_len = 2 + $tag_count * 12 + 4;


        // Cycle through each tag
        foreach( $ifd_data as $key => $tag )
        {
                // Make sure this is a tag, not another information key
                if ( is_numeric( $key ) )
                {

                        // Add the tag number to the packed data
                        $ifd_body_str .= put_IFD_Data_Type( $tag[ 'Tag Number' ], 3, $Byte_Align );

                        // Add the Data type to the packed data
                        $ifd_body_str .= put_IFD_Data_Type( $tag['Data Type'], 3, $Byte_Align );

                        // Check if this is a Print Image Matching entry
                        if ( $tag['Type'] == "PIM" )
                        {
                                // This is a Print Image Matching entry,
                                // encode it
                                $data = Encode_PIM( $tag, $Byte_Align );
                        }
                                // Check if this is a IPTC/NAA Record within the EXIF IFD
                        else if ( ( ( $Tag_Definitions_Name == "EXIF" ) || ( $Tag_Definitions_Name == "TIFF" ) ) &&
                                  ( $tag[ 'Tag Number' ] == 33723 ) )
                        {
                                // This is a IPTC/NAA Record, encode it
                                $data = put_IPTC( $tag['Data'] );
                        }
                                // Change: Check for embedded XMP as of version 1.11
                                // Check if this is a XMP Record within the EXIF IFD
                        else if ( ( ( $Tag_Definitions_Name == "EXIF" ) || ( $Tag_Definitions_Name == "TIFF" ) ) &&
                                  ( $tag[ 'Tag Number' ] == 700 ) )
                        {
                                // This is a XMP Record, encode it
                                $data = write_XMP_array_to_text( $tag['Data'] );
                        }
                                // Change: Check for embedded IRB as of version 1.11
                                // Check if this is a Photoshop IRB Record within the EXIF IFD
                        else if ( ( ( $Tag_Definitions_Name == "EXIF" ) || ( $Tag_Definitions_Name == "TIFF" ) ) &&
                                  ( $tag[ 'Tag Number' ] == 34377 ) )
                        {
                                // This is a Photoshop IRB Record, encode it
                                $data = pack_Photoshop_IRB_Data( $tag['Data'] );
                        }
                                // Exif Thumbnail Offset
                        else if ( ( $tag[ 'Tag Number' ] == 513 ) && ( $Tag_Definitions_Name == "TIFF" ) )
                        {
                                        // The Exif Thumbnail Offset is a pointer but of type Long, not Unknown
                                        // Hence we need to put the data into the packed string separately
                                        // Calculate the thumbnail offset
                                        $data_offset = $IFD_offset + $IFD_len + strlen($ifd_data_str);

                                        // Create the Offset for the IFD
                                        $data = put_IFD_Data_Type( $data_offset, 4, $Byte_Align );

                                        // Store the thumbnail
                                        $ifd_data_str .= $tag['Data'];
                        }
                                // Exif Thumbnail Length
                        else if ( ( $tag[ 'Tag Number' ] == 514 ) && ( $Tag_Definitions_Name == "TIFF" ) )
                        {
                                        // Encode the Thumbnail Length
                                        $data = put_IFD_Data_Type( strlen($ifd_data[513]['Data']), 4, $Byte_Align );
                        }
                                // Sub-IFD
                        else if ( $tag['Type'] == "SubIFD" )
                        {
                                        // This is a Sub-IFD
                                        // Calculate the offset to the start of the Sub-IFD
                                        $data_offset = $IFD_offset + $IFD_len + strlen($ifd_data_str);
                                        // Get the packed data for the IFD chain as the data for this tag
                                        $data = get_IFD_Array_Packed_Data( $tag['Data'], $data_offset, $Byte_Align );
                        }
                        else
                        {
                                // Not a special tag

                                // Create a string to receive the data
                                $data = "";

                                // Check if this is a type Unknown tag
                                if ( $tag['Data Type'] != 7 )
                                {
                                        // NOT type Unknown
                                        // Cycle through each data value and add it to the data string
                                        foreach( $tag[ 'Data' ] as $data_val )
                                        {
                                                $data .= put_IFD_Data_Type( $data_val, $tag['Data Type'], $Byte_Align );
                                        }
                                }
                                else
                                {
                                        // This is a type Unknown - just add the data as is to the data string
                                        $data .= $tag[ 'Data' ];
                                }
                        }

                        // Pad the data string out to at least 4 bytes
                        $data = str_pad ( $data, 4, "\x00" );


                        // Check if the data type is an ASCII String or type Unknown
                        if ( ( $tag['Data Type'] == 2 ) || ( $tag['Data Type'] == 7 ) )
                        {
                                // This is an ASCII String or type Unknown
                                // Add the Length of the string to the packed data as the Count
                                $ifd_body_str .= put_IFD_Data_Type( strlen($data), 4, $Byte_Align );
                        }
                        else
                        {
                                // Add the array count to the packed data as the Count
                                $ifd_body_str .= put_IFD_Data_Type( count($tag[ 'Data' ]), 4, $Byte_Align );
                        }