From b3951da415c64d0d95538e338c22b8c492920332 Mon Sep 17 00:00:00 2001
From: John Whitington <john@coherentgraphics.co.uk>
Date: Fri, 3 Mar 2023 16:02:16 +0000
Subject: [PATCH] Begin work on -composition

---
 Changes        |  1 +
 cpdfcommand.ml | 17 +++++++++++++++--
 cpdfmanual.tex |  1 +
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/Changes b/Changes
index 63e6a5b..1198c73 100644
--- a/Changes
+++ b/Changes
@@ -8,6 +8,7 @@ o Embed the 14 standard fonts if requested
 o Add links to parts of text with -add-text as %URL[|].
 o Convert JPEGs and PNGs to PDFs with -jpeg and -png
 o Export fully, import, and round-trip annotations via JSON
+o Show composition of PDF with -composition and -composition-json
 
 Extended features:
 
diff --git a/cpdfcommand.ml b/cpdfcommand.ml
index ad4bfa0..87a12cf 100644
--- a/cpdfcommand.ml
+++ b/cpdfcommand.ml
@@ -221,6 +221,7 @@ type op =
   | TableOfContents
   | Typeset of string
   | Draw
+  | Composition of bool
 
 let string_of_op = function
   | PrintFontEncoding _ -> "PrintFontEncoding"
@@ -352,6 +353,7 @@ let string_of_op = function
   | TableOfContents -> "TableOfContents"
   | Typeset _ -> "Typeset"
   | Draw -> "Draw"
+  | Composition _ -> "Composition"
 
 (* Inputs: filename, pagespec. *)
 type input_kind =
@@ -828,7 +830,7 @@ let banned banlist = function
   | SetModify _|SetCreator _|SetProducer _|RemoveDictEntry _ | ReplaceDictEntry _ | PrintDictEntry _ | SetMetadata _
   | ExtractText | ExtractImages | ExtractFontFile
   | AddPageLabels | RemovePageLabels | OutputJSON | OCGCoalesce
-  | OCGRename | OCGList | OCGOrderAll | PrintFontEncoding _ | TableOfContents | Typeset _
+  | OCGRename | OCGList | OCGOrderAll | PrintFontEncoding _ | TableOfContents | Typeset _ | Composition _
      -> false (* Always allowed *)
   (* Combine pages is not allowed because we would not know where to get the
   -recrypt from -- the first or second file? *)
@@ -866,7 +868,7 @@ let rec decrypt_if_necessary (_, _, user_pw, owner_pw, was_dec_with_owner, _) op
   if not (Pdfcrypt.is_encrypted pdf) then pdf else
     match op with Some (CombinePages _) ->
       (* This is a hack because we don't have support for recryption on combine
-       * pages. This is pervented by permissions above, but in the case that the
+       * pages. This is prevented by permissions above, but in the case that the
        * owner password is blank (e.g christmas_tree_lights.pdf), we would end
        * up here. *)
       soft_error "Combine pages: both files must be unencrypted for this operation, or add -decrypt-force"
@@ -2804,6 +2806,12 @@ and specs =
    ("-typeset",
      Arg.String settypeset,
      " Typeset a text file as a PDF");
+   ("-composition",
+     Arg.Unit (setop (Composition false)),
+     " Show composition of PDF");
+   ("-composition-json",
+     Arg.Unit (setop (Composition true)),
+     " Show composition of PDF in JSON format");
    (* Creating new PDF content *)
    ("-draw", Arg.Unit (setop Draw), " Begin drawing");
    ("-rect", Arg.String addrect, " Draw rectangle");
@@ -3368,6 +3376,8 @@ let warn_prerotate range pdf =
 let prerotate range pdf =
   Cpdfpage.upright ~fast:args.fast range pdf
 
+let show_composition json pdf = ()
+
 let embed_font () =
   match args.font with
   | StandardFont f ->
@@ -4348,6 +4358,9 @@ let go () =
       let pdf = get_single_pdf args.op false in
       let range = parse_pagespec_allow_empty pdf (get_pagespec ()) in
         write_pdf false (Cpdfdraw.draw args.fast range pdf (rev (Hashtbl.find drawops "_")))
+  | Some (Composition json) ->
+      let pdf = get_single_pdf args.op false in
+        show_composition json pdf
 
 (* Advise the user if a combination of command line flags makes little sense,
 or error out if it make no sense at all. *)
diff --git a/cpdfmanual.tex b/cpdfmanual.tex
index 46897fb..db18331 100644
--- a/cpdfmanual.tex
+++ b/cpdfmanual.tex
@@ -5,6 +5,7 @@
 %Document -list-annotations[-json] now obey page range
 %Document round-tripping of annotations, supersede -copy-annotations.
 %Document -utf for JSON and mark -clean-strings as deprecated since can fail to round-trip binary strings which begin with a BOM?
+%Document -composition[-json]
 \documentclass{book}
 % Edit here to produce cpdfmanual.pdf, cpdflibmanual.pdf, pycpdfmanual.pdf,
 % dotnetcpdflibmanual.pdf, jcpdflibmanual.pdf jscpdflibmanual.pdf etc.