cpdf-source/cpdfpagelabels.ml

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OCaml
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2021-12-20 10:02:39 +01:00
open Pdfutil
(* Split the given range (which is in order) into multiple contiguous ones. *)
let rec ranges_of_range curr prev = function
| [] -> begin match curr with [] -> rev prev | _ -> rev (rev curr::prev) end
| x::xs ->
match curr with
| [] -> ranges_of_range [x] prev xs
| c::cs when x = c + 1 -> ranges_of_range (x::curr) prev xs
| cs -> ranges_of_range [x] (rev cs::prev) xs
(* Predicate which is true if at least one page range starts at page 1 *)
let page1 labels =
mem true (map (function l -> l.Pdfpagelabels.startpage = 1) labels)
let add_page_labels pdf progress style prefix startval range =
let ranges = map extremes (ranges_of_range [] [] range)
and labels = Pdfpagelabels.read pdf in
assert (length ranges > 0);
let startval_additions =
let r = ref [] in
let sofar = ref 0 in
iter (fun (s, e) -> r := !sofar :: !r; sofar := e - s + 1 + !sofar) ranges;
rev !r
in
let labels =
if not (page1 labels) then
ref
({Pdfpagelabels.labelstyle = Pdfpagelabels.DecimalArabic;
Pdfpagelabels.labelprefix = None;
Pdfpagelabels.startpage = 1;
Pdfpagelabels.startvalue = 1}::labels)
else
ref labels
in
iter2
(fun (s, e) addition ->
let label =
{Pdfpagelabels.labelstyle = style;
Pdfpagelabels.labelprefix = prefix;
Pdfpagelabels.startpage = s;
Pdfpagelabels.startvalue = startval + if progress then addition else 0}
in
labels := Pdfpagelabels.add_label (Pdfpage.endpage pdf) !labels label e)
ranges
startval_additions;
Pdfpagelabels.write pdf !labels