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|
open Pdfutil
open Pdfio
type cmap =
{map : (int * string) list;
wmode : int option}
(* Parse a /ToUnicode CMap to extract font mapping. *)
type section =
| BfChar of char list
| BfRange of char list
let rec getuntilend prev = function
| [] -> rev prev, []
| 'e'::'n'::'d'::'b'::'f'::'c'::'h'::'a'::'r'::more -> rev prev, more
| h::t -> getuntilend (h::prev) t
let rec getuntilend_range prev = function
| [] -> rev prev, []
| 'e'::'n'::'d'::'b'::'f'::'r'::'a'::'n'::'g'::'e'::more -> rev prev, more
| h::t -> getuntilend_range (h::prev) t
let rec get_section = function
| [] -> None
| 'b'::'e'::'g'::'i'::'n'::'b'::'f'::'c'::'h'::'a'::'r'::more ->
let numbers, rest = getuntilend [] more in
Some (BfChar numbers, rest)
| 'b'::'e'::'g'::'i'::'n'::'b'::'f'::'r'::'a'::'n'::'g'::'e'::more ->
let numbers, rest = getuntilend_range [] more in
Some (BfRange numbers, rest)
| _::t -> get_section t
(* Read a character code. *)
let rec read_number = function
| x::more when Pdf.is_whitespace x -> read_number more
| '<'::a::'>'::more ->
int_of_string (implode ['0'; 'x'; a]), more
| '<'::a::b::'>'::more ->
int_of_string (implode ['0'; 'x'; a; b]), more
| '<'::a::b::c::'>'::more ->
int_of_string (implode ['0'; 'x'; a; b; c]), more
| '<'::a::b::c::d::'>'::more ->
int_of_string (implode ['0'; 'x'; a; b; c; d]), more
| [] -> raise Not_found
| _ -> raise (Pdf.PDFError "Unknown number in /ToUnicode")
(* Read the bytes of the UTF-16BE unicode sequence as a string. *)
let fail () =
raise (Pdf.PDFError "Bad unicode value")
let rec read_unicode = function
| x::rest when Pdf.is_whitespace x -> read_unicode rest
| '<'::rest ->
let chars, rest = cleavewhile (neq '>') rest in
let is_hex_digit = function
| x when (x >= '0' && x <= '9') || (x >= 'a' && x <= 'f') || (x >= 'A' && x <= 'F') -> true
| _ -> false
in
iter
(fun x -> if not (is_hex_digit x) then fail ())
chars;
if length chars > 0 && even (length chars) then
let bytes =
map
(function
| [x; y] -> char_of_int (int_of_string (implode ['0'; 'x'; x; y]))
| _ -> assert false)
(splitinto 2 chars)
in
let rest' =
match rest with
| [] -> []
| _ -> tl rest
in
implode bytes, rest'
else
fail ()
| _ -> fail ()
let rec get_sections chars =
match get_section chars with
| None -> []
| Some (sec, restchars) ->
sec::get_sections restchars
let pairs_of_section = function
| BfChar numbers ->
let results = ref []
in let numbers = ref numbers in
begin try
while true do
let number, rest = read_number !numbers in
let str, rest = read_unicode rest in
numbers := rest;
results =| (number, str)
done;
[]
with
Not_found -> rev !results
end
| BfRange numbers ->
let results = ref []
in let numbers = ref numbers in
begin try
while true do
let src1, rest = read_number !numbers in
let src2, rest = read_number rest in
if src1 > src2 then raise (Pdf.PDFError "Bad /ToUnicode") else
match rest with
| '<'::_ ->
(* It's a single unicode string *)
let increment_final code d =
match code with
| "" -> ""
| s ->
let chars = rev (explode s) in
implode ((rev (tl chars)) @
[char_of_int (int_of_char (hd chars) + d)])
in
let code, rest = read_unicode rest in
results =@
rev
(combine
(ilist src1 src2)
(map (increment_final code) (ilist 0 (src2 - src1))));
numbers := rest
| '['::rest ->
(* It's several. *)
let rest = ref rest in
results =@
combine
(ilist src1 src2)
(map
(fun _ ->
let num, rest' = read_unicode !rest in
rest := rest';
num)
(ilist 0 (src2 - src1)));
rest := (match !rest with [] -> [] | x -> tl x);
numbers := !rest
| _ -> raise (Pdf.PDFError "Bad BfRange")
done;
[]
with
Not_found -> rev !results
end
let extract_specifics data =
let wmode = ref None in
let read_number t =
let h, t = cleavewhile isdigit t in
int_of_string (implode h), t
in
let rec find = function
| [] -> ()
| '/'::'W'::'M'::'o'::'d'::'e'::' '::t ->
let n, t = read_number t in
wmode := Some n;
find t
| h::t -> find t
in
let chars = charlist_of_bytes data in
begin try find chars with _ -> () end;
!wmode
let rec parse_cmap pdf cmap =
match cmap with
| Pdf.Stream {contents = (dict, Pdf.Got data)} ->
Pdfcodec.decode_pdfstream pdf cmap;
begin match cmap with
| Pdf.Stream {contents = (dict, Pdf.Got data)} ->
let wmode = extract_specifics data in
begin try
{map =
flatten
(map pairs_of_section
(get_sections
(lose Pdf.is_whitespace (charlist_of_bytes data))));
wmode}
with
e ->
Pdfe.log (Printf.sprintf "/ToUnicode Parse Error : %s\n" (Printexc.to_string e));
raise e
end
| _ -> assert false
end
| Pdf.Stream {contents = (_, Pdf.ToGet _)} ->
Pdf.getstream cmap;
parse_cmap pdf cmap
| e -> raise (Pdf.PDFError (Printf.sprintf "Bad /ToUnicode %s" (Pdfwrite.string_of_pdf e)))
|
