From bd7cba7730cb13c54280d26ee3d15da039536f3c Mon Sep 17 00:00:00 2001
From: John Whitington <john@coherentgraphics.co.uk>
Date: Tue, 18 Apr 2023 16:39:51 +0100
Subject: [PATCH] more

---
 cpdfannot.ml  | 18 ++++++++++++++++--
 cpdfannot.mli | 20 ++++++++------------
 2 files changed, 24 insertions(+), 14 deletions(-)

diff --git a/cpdfannot.ml b/cpdfannot.ml
index 50e2701..c9f17c3 100644
--- a/cpdfannot.ml
+++ b/cpdfannot.ml
@@ -1,4 +1,5 @@
 open Pdfutil
+open Cpdferror
 
 (* List annotations *)
 let get_annotation_string encoding pdf annot =
@@ -200,8 +201,21 @@ let get_annotations_json pdf =
   let json = `List (flatten (map2 (annotations_json_page pdf) pages pagenums)) in
     Pdfio.bytes_of_string (J.to_string json)
 
-(** Set annotations from JSON. Existing annotations? *)
-let set_annotations_json pdf json = ()
+(** Set annotations from JSON, keeping any existing ones. *)
+let set_annotations_json pdf i =
+  let module J = Cpdfyojson.Safe in
+  let content = Pdfio.string_of_bytes (Pdfio.bytes_of_input i 0 i.Pdfio.in_channel_length) in
+  let json = J.from_string content in
+  (* Find largest negative objnumber. Then add number of annot objects. *)
+  match json with
+  | `List entries ->
+      let maxobjnum =
+        fold_left max min_int (map (fun e -> match e with `List (`Int i::_) -> abs i | _ -> error "Bad annots JSON entry") entries)
+      in
+        (* Renumber the PDF so everything has bigger object numbers than that. *)
+        Printf.printf "maxobjnum = %i\n" maxobjnum;
+        ()
+  | _ -> error "Bad Annotations JSON file"
 
 (* Equalise the page lengths of two PDFs by chopping or extending the first one.
 *)
diff --git a/cpdfannot.mli b/cpdfannot.mli
index 3e95d6a..235e152 100644
--- a/cpdfannot.mli
+++ b/cpdfannot.mli
@@ -1,6 +1,13 @@
 (** Annotations *)
 
-(** Old fashioned functions first, still in use for backward-compatibilty *)
+(** Remove the annotations on given pages. *)
+val remove_annotations : int list -> Pdf.t -> Pdf.t
+
+(** Get annotations as JSON *)
+val get_annotations_json : Pdf.t -> Pdfio.bytes
+
+(** Set annotations from JSON. *)
+val set_annotations_json : Pdf.t -> Pdfio.input -> unit
 
 (** Return the annotations as a (pagenumber, content) list. *)
 val get_annotations : Cpdfmetadata.encoding -> Pdf.t -> (int * string) list
@@ -10,14 +17,3 @@ val copy_annotations : int list -> Pdf.t -> Pdf.t -> Pdf.t
 
 (** List the annotations to standard output in a given encoding. See cpdfmanual.pdf for the format details. *)
 val list_annotations : json:bool -> int list -> Cpdfmetadata.encoding -> Pdf.t -> unit
-
-(** Remove the annotations on given pages. *)
-val remove_annotations : int list -> Pdf.t -> Pdf.t
-
-(** Modern functions *)
-
-(** Get annotations as JSON *)
-val get_annotations_json : Pdf.t -> Pdfio.bytes
-
-(** Set annotations from JSON. Existing annotations will be removed. *)
-val set_annotations_json : Pdf.t -> Pdfio.input -> unit