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Text::PDF::File(3)    User Contributed Perl Documentation   Text::PDF::File(3)

NAME
       Text::PDF::File - Holds the trailers and	cross-reference	tables for a
       PDF file

SYNOPSIS
	$p = Text::PDF::File->open("filename.pdf", 1);
	$p->new_obj($obj_ref);
	$p->free_obj($obj_ref);
	$p->append_file;
	$p->close_file;
	$p->release;	   # IMPORTANT!

DESCRIPTION
       This class keeps	track of the directory aspects of a PDF	file. There
       are two parts to	the directory: the main	directory object which is the
       parent to all other objects and a chain of cross-reference tables and
       corresponding trailer dictionaries starting with	the main directory
       object.

INSTANCE VARIABLES
       Within this class hierarchy, rather than	making everything visible via
       methods,	which would be a lot of	work, there are	various	instance
       variables which are accessible via associative array referencing. To
       distinguish instance variables from content variables (which may	come
       from the	PDF content itself), each such variable	will start with	a
       space.

       Variables which do not start with a space directly reflect elements in
       a PDF dictionary. In the	case of	a Text::PDF::File, the elements
       reflect those in	the trailer dictionary.

       Since some variables are	not designed for class users to	access,
       variables are marked in the documentation with (R) to indicate that
       such an entry should only be used as read-only information. (P)
       indicates that the information is private and not designed for user use
       at all, but is included in the documentation for	completeness and to
       ensure that nobody else tries to	use it.

       newroot
	   This	variable allows	the user to create a new root entry to occur
	   in the trailer dictionary which is output when the file is written
	   or appended.	If you wish to over-ride the root element in the
	   dictionary you have,	use this entry to indicate that	without	losing
	   the current Root entry. Notice that newroot should point to a PDF
	   level object	and not	just to	a dictionary which does	not have
	   object status.

       INFILE (R)
	   Contains the	filehandle used	to read	this information into this PDF
	   directory. Is an IO object.

       fname (R)
	   This	is the filename	which is reflected by INFILE, or the original
	   IO object passed in.

       update (R)
	   This	indicates that the read	file has been opened for update	and
	   that	at some	point, $p->appendfile()	can be called to update	the
	   file	with the changes that have been	made to	the memory
	   representation.

       maxobj (R)
	   Contains the	first useable object number above any that have
	   already appeared in the file	so far.

       outlist (P)
	   This	is a list of Objind which are to be output when	the next
	   appendfile or outfile occurs.

       firstfree (P)
	   Contains the	first free object in the free object list. Free
	   objects are removed from the	front of the list and added to the
	   end.

       lastfree	(P)
	   Contains the	last free object in the	free list. It may be the same
	   as the firstfree if there is	only one free object.

       objcache	(P)
	   All objects are held	in the cache to	ensure that a system only has
	   one occurrence of each object. In effect, the objind	class acts as
	   a container type class to hold the PDF object structure and it
	   would be unfortunate	if there were two identical place-holders
	   floating around a system.

       epos (P)
	   The end location of the read-file.

       Each trailer dictionary contains	a number of private instance variables
       which hold the chain together.

       loc (P)
	   Contains the	location of the	start of the cross-reference table
	   preceding the trailer.

       xref (P)
	   Contains an anonymous array of each cross-reference table entry.

       prev (P)
	   A reference to the previous table. Note this	differs	from the Prev
	   entry which is in PDF which contains	the location of	the previous
	   cross-reference table.

METHODS
   Text::PDF::File->new
       Creates a new, empty file object	which can act as the host to other PDF
       objects.	 Since there is	no file	associated with	this object, it	is
       assumed that the	object is created in readiness for creating a new PDF
       file.

   $p =	Text::PDF::File->open($filename, $update)
       Opens the file and reads	all the	trailers and cross reference tables to
       build a complete	directory of objects.

       $update specifies whether this file is being opened for updating	and
       editing,	or simply to be	read.

       $filename may be	an IO object

   $p->release()
       Releases	ALL of the memory used by the PDF document and all of its
       component objects.  After calling this method, do NOT expect to have
       anything	left in	the "Text::PDF::File" object (so if you	need to	save,
       be sure to do it	before calling this method).

       NOTE, that it is	important that you call	this method on any
       "Text::PDF::File" object	when you wish to destruct it and free up its
       memory.	Internally, PDF	files have an enormous number of cross-
       references and this causes circular references within the internal data
       structures.  Calling '"release()"' forces a brute-force cleanup of the
       data structures,	freeing	up all of the memory.  Once you've called this
       method, though, don't expect to be able to do anything else with	the
       "Text::PDF::File" object; it'll have no internal	state whatsoever.

       Developer note: As part of the brute-force cleanup done here, this
       method will throw a warning message whenever unexpected key values are
       found within the	"Text::PDF::File" object.  This	is done	to help	ensure
       that any	unexpected and unfreed values are brought to your attention so
       that you	can bug	us to keep the module updated properly;	otherwise the
       potential for memory leaks due to dangling circular references will
       exist.

   $p->append_file()
       Appends the objects for output to the read file and then	appends	the
       appropriate tale.

   $p->out_file($fname)
       Writes a	PDF file to a file of the given	filename based on the current
       list of objects to be output. It	creates	the trailer dictionary based
       on information in $self.

       $fname may be an	IO object;

   $p->create_file($fname)
       Creates a new output file (no check is made of an existing open file)
       of the given filename or	IO object. Note, make sure that	$p->{'
       version'} is set	correctly before calling this function.

   $p->close_file
       Closes up the open file for output by outputting	the trailer etc.

   ($value, $str) = $p->readval($str, %opts)
       Reads a PDF value from the current position in the file.	If $str	is too
       short then read some more from the current location in the file until
       the whole object	is read. This is a recursive call which	may slurp in a
       whole big stream	(unprocessed).

       Returns the recursive data structure read and also the current $str
       that has	been read from the file.

   $ref	= $p->read_obj($objind,	%opts)
       Given an	indirect object	reference, locate it and read the object
       returning the read in object.

   $ref	= $p->read_objnum($num,	$gen, %opts)
       Returns a fully read object of given number and generation in this file

   $objind = $p->new_obj($obj)
       Creates a new, free object reference based on free space	in the cross
       reference chain.	 If nothing free then thinks up	a new number. If $obj
       then turns that object into this	new object rather than returning a new
       object.

   $p->out_obj($objind)
       Indicates that the given	object reference should	appear in the output
       xref table whether with data or freed.

   $p->free_obj($objind)
       Marks an	object reference for output as being freed.

   $p->remove_obj($objind)
       Removes the object from all places where	we might remember it

   $p->ship_out(@objects)
       Ships the given objects (or all objects for output if @objects is
       empty) to the currently open output file	(assuming there	is one). Freed
       objects are not shipped,	and once an object is shipped it is switched
       such that this file becomes its source and it will not be shipped again
       unless out_obj is called	again. Notice that a shipped out object	can be
       re-output or even freed,	but that it will not cause the data already
       output to be changed.

   $p->copy($outpdf, \&filter)
       Iterates	over every object in the file reading the object, calling
       filter with the object and outputting the result. if filter is not
       defined,	then just copies input to output.

PRIVATE	METHODS	& FUNCTIONS
       The following methods and functions are considered private to this
       class. This does	not mean you cannot use	them if	you have a need, just
       that they aren't	really designed	for users of this class.

   $offset = $p->locate_obj($num, $gen)
       Returns a file offset to	the object asked for by	following the chain of
       cross reference tables until it finds the one you want.

   update($fh, $str)
       Keeps reading $fh for more data to ensure that $str has at least	a line
       full for	"readval" to work on. At this point we also take the
       opportunity to ignore comments.

   $objind = $p->test_obj($num,	$gen)
       Tests the cache to see whether an object	reference (which may or	may
       not have	been getobj()ed) has been cached. Returns it if	it has.

   $p->add_obj($objind)
       Adds the	given object to	the internal object cache.

   $tdict = $p->readxrtr($xpos)
       Recursive function which	reads each of the cross-reference and trailer
       tables in turn until there are no more.

       Returns a dictionary corresponding to the trailer chain.	Each trailer
       also includes the corresponding cross-reference table.

       The structure of	the xref private element in a trailer dictionary is of
       an anonymous hash of cross reference elements by	object number. Each
       element consists	of an array of 3 elements corresponding	to the three
       elements	read in	[location, generation number, free or used]. See the
       PDF Specification for details.

   $p->out_trailer($tdict)
       Outputs the body	and trailer for	a PDF file by outputting all the
       objects in the '	outlist' and then outputting a xref table for those
       objects and any freed ones. It then outputs the trailing	dictionary and
       the trailer code.

   Text::PDF::File->_new
       Creates a very empty PDF	file object (used by new and open)

AUTHOR
       Martin Hosken Martin_Hosken@sil.org

       Copyright Martin	Hosken 1999 and	onwards

       No warranty or expression of effectiveness, least of all	regarding
       anyone's	safety,	is implied in this software or documentation.

   Licensing
       This Perl Text::PDF module is licensed under the	Perl Artistic License.

perl v5.24.1			  2006-03-17		    Text::PDF::File(3)

NAME | SYNOPSIS | DESCRIPTION | INSTANCE VARIABLES | METHODS | PRIVATE METHODS & FUNCTIONS | AUTHOR

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