cpdf-source/cpdfocg.ml

open Pdfutil

(* 1. Get list of indirects of all OCGs from the /OCProperties, and their textual names
 * 2. Calculate a change list to coalesce them
 * 3. Remove any changed ones from the /OCGs and /Order and /ON and /OFF in /OCProperties
 * 4. Do the changes to all indirect references in the whole pdf  *)
(*FIXME Pre-existing nulls - what to do? *)
let ocg_coalesce pdf =
  match Pdf.lookup_direct pdf "/OCProperties" (Pdf.catalog_of_pdf pdf) with
    None -> ()
  | Some ocpdict ->
      let number_name_pairs =
        match Pdf.lookup_direct pdf "/OCGs" ocpdict with
          Some (Pdf.Array ocgs) ->
            begin let numbers =
              map (function Pdf.Indirect i -> i | _ -> failwith "Malformed /OCG entry") ocgs
            in
              let names =
                map
                  (fun i ->
                     try
                       begin match Pdf.lookup_obj pdf i with
                         Pdf.Dictionary d ->
                           begin match Pdf.lookup_direct pdf "/Name" (Pdf.Dictionary d) with
                             Some (Pdf.String s) -> s
                           | _ -> failwith "ocg: missing name"
                           end
                       | _ -> 
                           failwith "ocg: not a dictionary"
                       end
                      with _ -> failwith "OCG object missing")
                  numbers
              in
                combine numbers names
            end
        | _ -> failwith "Malformed or missing /OCGs"
      in
        (*iter (fun (num, name) -> Printf.printf "%i = %s\n" num name) number_name_pairs;*)
        let changes =
          let cf (_, name) (_, name') = compare name name' in
          let sets = collate cf (List.stable_sort cf number_name_pairs) in
          flatten (option_map (function [] -> None | (hnum, _)::t -> Some (map (function (tnum, _) -> (tnum, hnum)) t)) sets)
        in
        (*Printf.printf "\nChanges are:\n";
        List.iter (fun (f, t) -> Printf.printf "%i -> %i\n" f t) changes;*)
        let new_ocproperties =
          let remove_from_array key nums dict =
            match Pdf.lookup_direct pdf key dict with
            | Some (Pdf.Array elts) ->
                let elts' = option_map (function Pdf.Indirect i -> if mem i nums then None else Some (Pdf.Indirect i) | _ -> None) elts in
                  Pdf.add_dict_entry dict key (Pdf.Array elts')
            | _ -> dict
          in
          let remove_from_array_inside_d key nums dict =
            match Pdf.lookup_direct pdf "/D" dict with
            | Some (Pdf.Dictionary ddict) ->
                begin match Pdf.lookup_direct pdf key (Pdf.Dictionary ddict) with
                | Some (Pdf.Array elts) ->
                    let elts' = option_map (function Pdf.Indirect i -> if mem i nums then None else Some (Pdf.Indirect i) | _ -> None) elts in
                    Pdf.add_dict_entry dict "/D" (Pdf.add_dict_entry (Pdf.Dictionary ddict) key (Pdf.Array elts'))
                | _ -> dict
                end
            | _ -> failwith "No /D dict in OCGProperties"
          in
          let nums = map fst changes in
            (*Printf.printf "\nto remove:\n";
            List.iter (Printf.printf "%i ") nums;*)
            remove_from_array "/OCGs" nums
              (remove_from_array_inside_d "/ON" nums
                (remove_from_array_inside_d "/OFF" nums
                  (remove_from_array_inside_d "/Order" nums ocpdict)))
        in
        (*flprint (Pdfwrite.string_of_pdf new_ocproperties);*)
        let ocp_objnum = Pdf.addobj pdf new_ocproperties in
        let new_catalog = Pdf.addobj pdf (Pdf.add_dict_entry (Pdf.catalog_of_pdf pdf) "/OCProperties" (Pdf.Indirect ocp_objnum)) in
        pdf.Pdf.trailerdict <- Pdf.add_dict_entry pdf.Pdf.trailerdict "/Root" (Pdf.Indirect new_catalog);
        pdf.Pdf.root <- new_catalog;
        Pdf.objselfmap (Pdf.renumber_object_parsed pdf (hashtable_of_dictionary changes)) pdf

let ocg_get_list pdf =
  let l = ref [] in
  begin match Pdf.lookup_direct pdf "/OCProperties" (Pdf.catalog_of_pdf pdf) with
    None -> ()
  | Some ocpdict ->
      match Pdf.lookup_direct pdf "/OCGs" ocpdict with
        Some (Pdf.Array elts) ->
          iter
            (function
               Pdf.Indirect i ->
                 (match Pdf.lookup_direct pdf "/Name" (Pdf.lookup_obj pdf i) with
                    Some (Pdf.String s) -> l := s::!l | _ -> ())
             | _ -> ())
            elts
      | _ -> ()
  end;
  rev !l

let ocg_list pdf =
  List.iter (Printf.printf "%s\n") (ocg_get_list pdf)

let ocg_rename f t pdf =
  Pdf.objselfmap
    (function
      Pdf.Dictionary d ->
        begin match Pdf.lookup_direct pdf "/Type" (Pdf.Dictionary d) with
          Some (Pdf.Name "/OCG") ->
            begin match Pdf.lookup_direct pdf "/Name" (Pdf.Dictionary d) with
              Some (Pdf.String s) when s = f ->
                Pdf.add_dict_entry (Pdf.Dictionary d) "/Name" (Pdf.String t)
            | _ -> Pdf.Dictionary d
            end
        | _ -> Pdf.Dictionary d
        end
     | x -> x
    )
    pdf

let ocg_order_all pdf =
  match Pdf.lookup_direct pdf "/OCProperties" (Pdf.catalog_of_pdf pdf) with
    None -> ()
  | Some ocpdict ->
      match Pdf.lookup_direct pdf "/OCGs" ocpdict with
        Some (Pdf.Array elts) ->
          begin match Pdf.lookup_direct pdf "/D" ocpdict with
            Some (Pdf.Dictionary d) ->
              let newd = Pdf.add_dict_entry (Pdf.Dictionary d) "/Order" (Pdf.Array elts) in
              let new_ocproperties = Pdf.add_dict_entry ocpdict "/D" newd in
              let ocp_objnum = Pdf.addobj pdf new_ocproperties in
              let new_catalog = Pdf.addobj pdf (Pdf.add_dict_entry (Pdf.catalog_of_pdf pdf) "/OCProperties" (Pdf.Indirect ocp_objnum)) in
                pdf.Pdf.trailerdict <- Pdf.add_dict_entry pdf.Pdf.trailerdict "/Root" (Pdf.Indirect new_catalog);
                pdf.Pdf.root <- new_catalog
          | _ -> ()
          end
      | _ -> ()