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First rewrite of write_structure_tree

This commit is contained in:
John Whitington 2024-09-18 14:04:50 +01:00
parent d57575850c
commit cc01c8ddc1
1 changed files with 31 additions and 28 deletions
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59
cpdfdraw.ml
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@ -609,8 +609,7 @@ let make_structure_tree pdf items =
in
make_structure_tree pageobjnums pdf (ref 0) items
(* Write such a structure tree to a PDF. We have to make the objects and build
the root and its /K. *)
(* Write such a structure tree to a PDF. *)
let write_structure_tree pdf st =
let parentmap = ref [] in
let add_parentmap pon this_objnum =
@ -619,33 +618,37 @@ let write_structure_tree pdf st =
| Some objnums -> parentmap := add pon (this_objnum::objnums) !parentmap
in
let struct_tree_root = Pdf.addobj pdf Pdf.Null in
let items =
map
(function StItem {kind; pageobjnum; alt; children} ->
let this_objnum = Pdf.addobj pdf Pdf.Null in
let alt =
match alt with
| Some s -> [("/Alt", Pdf.String s)]
| None -> []
in
let page =
match pageobjnum with
| Some i -> [("/Pg", Pdf.Indirect i)]
| None -> []
in
let this_obj =
Pdf.Dictionary (alt @ page @
[("/S", Pdf.Name kind);
("/P", Pdf.Indirect struct_tree_root);
("/K", Pdf.Array (map (function StMCID x -> begin match pageobjnum with Some p -> add_parentmap p this_objnum | _ -> () end; Pdf.Integer x
| _ -> assert false) children))])
in
Pdf.addobj_given_num pdf (this_objnum, this_obj);
Pdf.Indirect this_objnum
| _ -> assert false
)
st
let rec mktree struct_tree_parent = function
| StItem {kind; pageobjnum; alt; children} ->
let this_objnum = Pdf.addobj pdf Pdf.Null in
begin match pageobjnum with
| Some p -> add_parentmap p this_objnum
| _ -> ()
end;
let alt =
match alt with
| Some s -> [("/Alt", Pdf.String s)]
| None -> []
in
let page =
match pageobjnum with
| Some i -> [("/Pg", Pdf.Indirect i)]
| None -> []
in
let this_obj =
Pdf.Dictionary
(alt
@ page
@ [("/S", Pdf.Name kind);
("/P", Pdf.Indirect struct_tree_parent);
("/K", Pdf.Array (map (mktree this_objnum) children))])
in
Pdf.addobj_given_num pdf (this_objnum, this_obj);
Pdf.Indirect this_objnum
| StMCID x ->
Pdf.Integer x
in
let items = map (mktree struct_tree_root) st in
iter
(fun (pon, _) ->
Pdf.addobj_given_num pdf (pon, Pdf.add_dict_entry (Pdf.lookup_obj pdf pon) "/StructParents" (Pdf.Integer pon)))