From 7824bd40f95eab39d3f332cf7611a49689c03632 Mon Sep 17 00:00:00 2001
From: John Whitington <john@coherentgraphics.co.uk>
Date: Thu, 27 Jun 2024 14:21:47 +0100
Subject: [PATCH] Adds -print-struct-tree

---
 cpdfcommand.ml |  9 ++++++++-
 cpdfua.ml      | 29 ++++++++++++++++++++++++++++-
 cpdfua.mli     |  2 ++
 3 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/cpdfcommand.ml b/cpdfcommand.ml
index 5a12448..f79622e 100644
--- a/cpdfcommand.ml
+++ b/cpdfcommand.ml
@@ -221,6 +221,7 @@ type op =
   | Verify of string
   | MarkAs of string
   | RemoveMark of string
+  | PrintStructTree
   | ExtractStructTree
   | ReplaceStructTree of string
   | SetLanguage of string
@@ -369,6 +370,7 @@ let string_of_op = function
   | Verify _ -> "Verify"
   | MarkAs _ -> "MarkAs"
   | RemoveMark _ -> "RemoveMark"
+  | PrintStructTree -> "PrintStructTree"
   | ExtractStructTree -> "ExtractStructTree"
   | ReplaceStructTree _ -> "ReplaceStructTree"
   | SetLanguage _ -> "SetLanguage"
@@ -895,7 +897,8 @@ let banned banlist = function
   | AddPageLabels | RemovePageLabels | OutputJSON | OCGCoalesce
   | OCGRename | OCGList | OCGOrderAll | PrintFontEncoding _ | TableOfContents | Typeset _ | Composition _
   | TextWidth _ | SetAnnotations _ | CopyAnnotations _ | ExtractStream _ | PrintObj _
-  | Verify _ | MarkAs _ | RemoveMark _ | ExtractStructTree | ReplaceStructTree _ | SetLanguage _ 
+  | Verify _ | MarkAs _ | RemoveMark _ | ExtractStructTree | ReplaceStructTree _ | SetLanguage _
+  | PrintStructTree
      -> false (* Always allowed *)
   (* Combine pages is not allowed because we would not know where to get the
   -recrypt from -- the first or second file? *)
@@ -2825,6 +2828,7 @@ and specs =
    ("-verify-single", Arg.String (fun s -> args.verify_single <- Some s), "Verify a single test");
    ("-mark-as", Arg.String (fun s -> setop (MarkAs s) ()), "Mark as conforming to a standard");
    ("-remove-mark", Arg.String (fun s -> setop (RemoveMark s) ()), "Remove conformance mark");
+   ("-print-struct-tree", Arg.Unit (fun () -> setop PrintStructTree ()), "Print structure tree");
    ("-extract-struct-tree", Arg.Unit (fun () -> setop ExtractStructTree ()), "Extract structure tree in JSON format");
    ("-replace-struct-tree", Arg.String (fun s -> setop (ReplaceStructTree s) ()), "Replace structure tree from JSON");
    (* These items are undocumented *)
@@ -4516,6 +4520,9 @@ let go () =
             write_pdf false pdf
       | _ -> error "Unknown standard"
       end
+  | Some PrintStructTree ->
+      let pdf = get_single_pdf args.op true in
+        Cpdfua.print_struct_tree pdf
   | Some ExtractStructTree ->
       let pdf = get_single_pdf args.op true in
       let json = Cpdfua.extract_struct_tree pdf in
diff --git a/cpdfua.ml b/cpdfua.ml
index 3f29627..d6515d3 100644
--- a/cpdfua.ml
+++ b/cpdfua.ml
@@ -54,7 +54,17 @@ let read_a pdf stnode =
     let at =
       match Pdf.lookup_direct pdf "/ActualText" stnode with | Some _ -> ["/ActualText"] | None -> []
     in
-      from_a @ id @ at @ alt
+    let pageref =
+      match Pdf.direct pdf stnode with
+      | Pdf.Dictionary d ->
+          begin match lookup "/Pg" d with
+          | Some (Pdf.Indirect i) ->
+              ["_" ^ string_of_int i]
+          | _ -> []
+          end
+      | _ -> []
+    in
+      from_a @ id @ at @ alt @ pageref
 
 let rec read_st_inner pdf stnode =
   let s =
@@ -1508,3 +1518,20 @@ let replace_struct_tree pdf json =
       | _ -> error "Top level JSON wrong. Must be list with 0 first."
   with
     e -> error (Printf.sprintf "replace_struct_tree: %s" (Printexc.to_string e))
+
+let print_struct_tree pdf =
+  let page_lookup =
+    hashtable_of_dictionary (combine (Pdf.page_reference_numbers pdf) (ilist 1 (Pdfpage.endpage pdf)))
+  in
+  let get_page attrs =
+    match option_map (fun x -> match explode x with '_'::more -> Some (implode more) | _ -> None) attrs with
+    | [i] -> string_of_int (try Hashtbl.find page_lookup (int_of_string i) with _ -> 0)
+    | _ -> "0"
+  in
+    let st = read_st2 pdf in
+      match st with E2 ("/StructTreeRoot", _, []) -> () | _ ->
+        flprint
+          (Cpdfprinttree.to_string
+            ~get_name:(fun (E2 (x, a, _)) -> if int_of_string (get_page a) > 0 then x ^ " (" ^ get_page a ^ ")" else x)
+            ~get_children:(fun (E2 (_, _, cs)) -> cs)
+            st)
diff --git a/cpdfua.mli b/cpdfua.mli
index a2c9876..e097a2d 100644
--- a/cpdfua.mli
+++ b/cpdfua.mli
@@ -9,6 +9,8 @@ val mark2 : int -> Pdf.t -> unit
 
 val remove_mark : Pdf.t -> unit
 
+val print_struct_tree : Pdf.t -> unit
+
 val extract_struct_tree : Pdf.t -> Cpdfyojson.Safe.t
 
 val replace_struct_tree : Pdf.t -> Cpdfyojson.Safe.t -> unit