Previous  Up  Next

Module Pdf

module Pdf: sig .. end
Representing PDF Files in Memory

PDF Objects


type toget 
type stream =
| Got of Pdfio.bytes
| ToGet of toget
A stream is either in memory, or at a position and of a length in an Pdfio.input.
type pdfobject =
| Null
| Boolean of bool
| Integer of int
| Real of float
| String of string
| Name of string
| Array of pdfobject list
| Dictionary of (string * pdfobject) list
| Stream of (pdfobject * stream) Pervasives.ref
| Indirect of int
PDF objects. An object is a tree-like structure containing various things. A PDF file is basically a directed graph of objects.

The Object map



You should not expect to manipulate these types and functions directly.
type objectdata =
| Parsed of pdfobject
| ParsedAlreadyDecrypted of pdfobject
| ToParse
| ToParseFromObjectStream of (int, int list) Hashtbl.t * int * int
* (int -> int list -> (int * (objectdata Pervasives.ref * int)) list)
This type represents a possibly-parsed, possibly-decrypted, possibly-read-from-an-object-stream object.
type pdfobjmap_key = int 
type pdfobjmap = (pdfobjmap_key, objectdata Pervasives.ref * int) Hashtbl.t
The object map maps object numbers pdfobjmap_key to a reference to the object data and the generation number
val pdfobjmap_empty : unit -> pdfobjmap
Make an empty object map
val pdfobjmap_find : pdfobjmap_key -> pdfobjmap -> objectdata Pervasives.ref * int
Find an object in the object map
type pdfobjects = {
   mutable maxobjnum : int;
   mutable parse : (pdfobjmap_key -> pdfobject) option;
   mutable pdfobjects : pdfobjmap;
   mutable object_stream_ids : (int, int) Hashtbl.t;
}
The objects. Again, you won't normally manipulate this directly. maxobjnum is the biggest object number seen yet. parse is a function to parse a non-object stream object given its object number, pdfobjects is the object map itself. object_stream_ids is a hash table of (object number, was-stored-in-obect-stream-number) pairs, which is used to reconstruct stream objects when preserving them upon write.

The PDF document


type saved_encryption = {
   from_get_encryption_values : Pdfcryptprimitives.encryption * string * string * int32 * string *
string option * string option;
   encrypt_metadata : bool;
   perms : string;
} 
type deferred_encryption = {
   crypt_type : Pdfcryptprimitives.encryption;
   file_encryption_key : string option;
   obj : int;
   gen : int;
   key : int array;
   keylength : int;
   r : int;
} 
type t = {
   mutable major : int;
   mutable minor : int;
   mutable root : int;
   mutable objects : pdfobjects;
   mutable trailerdict : pdfobject;
   mutable was_linearized : bool;
   mutable saved_encryption : saved_encryption option;
}
A Pdf document. Major and minor version numbers, object number of root, the objects objects and the trailer dictionary as a Dictionary pdfobject.
val empty : unit -> t
The empty document (PDF 1.0, no objects, no root, empty trailer dictionary). Note this is not a well-formed PDF.

Exceptions and errors


exception PDFError of string
This exception is raised when some malformity in a PDF is found -- quite a wide range of circumstances, and may be raised from many functions.
val input_pdferror : Pdfio.input -> string -> string
This function, given a Pdfio.input and an ancilliary string, builds an error string which includes the source of the Pdfio.input (filename, string, bytes etc) so we can trace what it was originally built from

Useful utilities


val getstream : pdfobject -> unit
Get a stream from disc if it hasn't already been got. The input is a Stream pdfobject.
val getnum : pdfobject -> float
Return a float from either a Real or an Int
val lookup_obj : t -> int -> pdfobject
Lookup an object in a document, parsing it if required. Raises Not_found if the object does not exist.
val lookup_fail : string -> t -> string -> pdfobject -> pdfobject
lookup_fail errtext doc key dict looks up a key in a PDF dictionary or the dictionary of a PDF stream. Fails with PDFError errtext if the key is not found. Follows indirect object links.
val lookup_exception : exn -> t -> string -> pdfobject -> pdfobject
Same, but with customised exception.
val lookup_direct : t -> string -> pdfobject -> pdfobject option
lookup_direct doc key dict looks up the key returning an option type.
val indirect_number : t -> string -> pdfobject -> int option
Return the object number of an indirect dictionary object, if it is indirect.
val lookup_direct_orelse : t -> string -> string -> pdfobject -> pdfobject option
Same as lookup_direct, but allow a second, alternative key.
val remove_dict_entry : pdfobject -> string -> pdfobject
Remove a dictionary entry, if it exists.
val replace_dict_entry : pdfobject -> string -> pdfobject -> pdfobject
replace_dict_entry dict key value replaces a dictionary entry, raising Not_found if it's not there.
val add_dict_entry : pdfobject -> string -> pdfobject -> pdfobject
add_dict_entry dict key value adds a dictionary entry, replacing if already there.
val direct : t -> pdfobject -> pdfobject
Make a PDF object direct -- that is, follow any indirect links.
val objcard : t -> int
Return the size of the object map.
val removeobj : t -> int -> unit
Remove the given object
val addobj : t -> pdfobject -> int
Add an object. Returns the number chosen.
val addobj_given_num : t -> int * pdfobject -> unit
Same as addobj, but pick a number ourselves.

Compound structures


val parse_rectangle : pdfobject -> float * float * float * float
Parse a PDF rectangle structure into min x, min y, max x, max y.
val parse_matrix : t -> string -> pdfobject -> Pdftransform.transform_matrix
Calling parse_matrix pdf name dict parses a PDF matrix found under key name in dictionary dict into a Transform.transform_matrix. If there is no matrix, the identity matrix is returned.
val make_matrix : Pdftransform.transform_matrix -> pdfobject
Build a matrix pdfobject.
val renumber_pdfs : t list -> t list
Make a number of PDF documents contain no mutual object numbers. They can then be merged etc. without clashes.
val unique_key : string -> pdfobject -> string
Given a dictionary and a prefix (e.g gs), return a name, starting with the prefix, which is not already in the dictionary (e.g /gs0).

Iteration


val objiter : (int -> pdfobject -> unit) -> t -> unit
Iterate over the objects in a document. The iterating functions recieves both object number and object from the object map.
val objiter_inorder : (int -> pdfobject -> unit) -> t -> unit
The same, but in object number order.
val objiter_gen : (int -> int -> pdfobject -> unit) -> t -> unit
Iterate over the objects in a document. The iterating functions recieves object number, generation number and object from the object map.
val objselfmap : (pdfobject -> pdfobject) -> t -> unit
Map over all pdf objects in a document. Does not include trailer dictionary.
val iter_stream : (pdfobject -> unit) -> t -> unit
Iterate over just the stream objects in a document.

Garbage collection


val remove_unreferenced : t -> unit
Garbage-collect a pdf document.