cpdf-source/cpdfremovetext.ml

66 lines
2.1 KiB
OCaml
Raw Normal View History

2022-09-27 20:58:27 +02:00
open Pdfutil
let removetext range pdf =
(* Could fail on nesting, or other marked content inside our marked content.*)
let rec remove_until_last_EMC level = function
| [] -> []
| Pdfops.Op_BMC "/CPDFSTAMP"::more ->
remove_until_last_EMC (level + 1) more
| Pdfops.Op_EMC::more ->
if level = 1
then more
else remove_until_last_EMC (level - 1) more
| _::more ->
remove_until_last_EMC level more
in
let rec remove_stamps prev = function
| [] -> rev prev
| Pdfops.Op_BMC "/CPDFSTAMP"::more ->
let rest = remove_until_last_EMC 1 more in
remove_stamps prev rest
| h::t -> remove_stamps (h::prev) t
in
let removetext_page _ page =
{page with
Pdfpage.content =
let ops = Pdfops.parse_operators pdf page.Pdfpage.resources page.Pdfpage.content in
[Pdfops.stream_of_ops (remove_stamps [] ops)]}
in
Cpdfpage.process_pages (Cpdfutil.ppstub removetext_page) pdf range
let rec remove_all_text_ops pdf resources content =
let is_textop = function
Pdfops.Op_Tj _ | Pdfops.Op_' _ | Pdfops.Op_'' _ | Pdfops.Op_TJ _ -> true
| _ -> false
in
let content' =
let ops = Pdfops.parse_operators pdf resources content in
Pdfops.stream_of_ops
(option_map (function x -> if is_textop x then None else Some x) ops)
in
[content']
let remove_all_text_page pdf p =
let resources = p.Pdfpage.resources in
let content = p.Pdfpage.content in
Cpdfutil.process_xobjects pdf p remove_all_text_ops;
{p with Pdfpage.content = remove_all_text_ops pdf resources content}, pdf
let remove_all_text range pdf =
let pages = Pdfpage.pages_of_pagetree pdf in
let pagenums = indx pages in
let pdf = ref pdf in
let pages' = ref [] in
iter2
(fun p pagenum ->
let p', pdf' =
if mem pagenum range
then remove_all_text_page !pdf p
else p, !pdf
in
pdf := pdf';
pages' =| p')
pages
pagenums;
Pdfpage.change_pages true !pdf (rev !pages')