Added squeezing functionality

Makefile

@@ -5,7 +5,7 @@ SOURCES = $(foreach x,$(MODS),$(x).ml $(x).mli) cpdfcommandrun.ml
 
 RESULT = cpdf
 ANNOTATE = true
-PACKS = camlpdf xml-light
+PACKS = camlpdf
 
 OCAMLNCFLAGS = -g
 OCAMLBCFLAGS = -g

cpdf.ml

@@ -2688,9 +2688,9 @@ let output_xml_info pdf =
   match get_metadata pdf with
     None -> ()
   | Some metadata ->
-      print_string (string_of_bytes metadata);
+      print_string (string_of_bytes metadata)
-      let parsed = Xml.parse_string (string_of_bytes metadata) in
+      (*let parsed = Xml.parse_string (string_of_bytes metadata) in
-        print_string (Xml.to_string parsed)
+        print_string (Xml.to_string parsed)*)
 
 let output_info encoding pdf =
   let getstring =

cpdfcommand.ml

@@ -257,7 +257,8 @@ type args =
    mutable uprightstamp : bool;
    mutable labelstyle : Pdfpagelabels.labelstyle option;
    mutable labelprefix : string option;
-   mutable labeloffset : int option}
+   mutable labeloffset : int option;
+   mutable squeeze : bool}
 
 (* List of all filenames in any AND stage - this is used to check that we don't
 overwrite any input file when -dont-overwrite-existing-files is used. *)
@@ -339,7 +340,8 @@ let args =
    uprightstamp = false;
    labelstyle = None;
    labelprefix = None;
-   labeloffset = None}
+   labeloffset = None;
+   squeeze = false}
 
 let reset_arguments () =
   args.op <- None;
@@ -412,7 +414,8 @@ let reset_arguments () =
   args.uprightstamp <- false;
   args.labelstyle <- None;
   args.labelprefix <- None;
-  args.labeloffset <- None
+  args.labeloffset <- None;
+  args.squeeze <- false
   (* We don't reset args.do_ask and args.verbose, because they operate on all
   parts of the AND-ed command line sent from cpdftk. *)
 
@@ -1010,6 +1013,9 @@ let setscalecontents f =
   args.op <- Some (ScaleContents f);
   args.position <- Cpdf.Diagonal (* Will be center *)
 
+let setsqueeze () =
+  args.squeeze <- true
+
 (* Parsing the control file *)
 let rec getuntilendquote prev = function
   | [] -> implode (rev prev), []
@@ -1374,6 +1380,9 @@ and specs =
    ("-remove-duplicate-streams",
        Arg.Unit setremoveduplicatestreams,
        "");
+   ("-squeeze",
+       Arg.Unit setsqueeze,
+       " Slow, lossless compression of a PDF file");
    ("-list-bookmarks",
       Arg.Unit (setop ListBookmarks),
       " List Bookmarks");
@@ -1756,6 +1765,42 @@ let rec writing_ok outname =
   else
     outname
 
+(* Equality on PDF streams *)
+let pdfobjeq pdf x y =
+  let x = Pdf.lookup_obj pdf x 
+  and y = Pdf.lookup_obj pdf y in
+    begin match x with Pdf.Stream _ -> Pdf.getstream x | _ -> () end;
+    begin match y with Pdf.Stream _ -> Pdf.getstream y | _ -> () end;
+    compare x y
+
+let squeeze pdf =
+  let objs = ref [] in
+    Pdf.objiter (fun objnum _ -> objs := objnum :: !objs) pdf;
+    let toprocess =
+      keep
+        (fun x -> length x > 1)
+        (collate (pdfobjeq pdf) (sort (pdfobjeq pdf) !objs))
+    in
+      Printf.printf "Found %i pools of duplicate objects to coalesce\n" (length toprocess);
+      (*List.iter
+        (fun x -> Printf.printf "\n\nPool: "; List.iter (Printf.printf "%i ") x)
+        toprocess;*)
+      let pdfr = ref pdf in
+      let changetable = Hashtbl.create 100 in
+        iter
+          (function [] -> assert false | h::t ->
+             iter (fun e -> Hashtbl.add changetable e h) t)
+          toprocess;
+        (* For a unknown reason, the output file is much smaller if
+           Pdf.renumber is run twice. This is bizarre, since Pdf.renumber is
+           an old, well-understood function in use for years -- what is
+           going on? *)
+        pdfr := Pdf.renumber changetable !pdfr;
+        pdfr := Pdf.renumber changetable !pdfr;
+        pdf.Pdf.root <- !pdfr.Pdf.root;
+        pdf.Pdf.objects <- !pdfr.Pdf.objects;
+        pdf.Pdf.trailerdict <- !pdfr.Pdf.trailerdict
+
 let write_pdf mk_id pdf =
   if args.create_objstm && not args.keepversion
     then pdf.Pdf.minor <- max pdf.Pdf.minor 5;
@@ -1766,6 +1811,7 @@ let write_pdf mk_id pdf =
     | File outname ->
         let outname = writing_ok outname in
           let pdf = Cpdf.recompress_pdf <| nobble pdf in
+            if args.squeeze then squeeze pdf;
             Pdf.remove_unreferenced pdf;
             Pdfwrite.pdf_to_file_options
               ~preserve_objstm:args.preserve_objstm
@@ -1773,6 +1819,7 @@ let write_pdf mk_id pdf =
               args.linearize None mk_id pdf outname
     | Stdout ->
         let pdf = Cpdf.recompress_pdf <| nobble pdf in
+          if args.squeeze then squeeze pdf;
           Pdf.remove_unreferenced pdf;
           Pdfwrite.pdf_to_channel
             ~preserve_objstm:args.preserve_objstm

cpdfmanual.tex

@@ -30,7 +30,7 @@ Command Line Toolkit}
 \vspace{12mm}
 
 {\Huge User Manual}\\
-Version 1.7 (August 2013)
+Version 1.8 (October 2014)
 
 \vspace{25mm}
 
@@ -911,8 +911,11 @@ metadata. Add \texttt{-no-encrypt-metadata} to the command line.
 
      \vspace{1.5mm}
      \noindent\verb!cpdf -compress in.pdf -o out.pdf!
-  \end{framed}
+     
-  \cpdf\ provides basic facilities for decompressing and compressing PDF streams.
+     \vspace{1.5mm}
+     \noindent\verb!cpdf -squeeze in.pdf -o out.pdf!  
+   \end{framed}
+  \cpdf\ provides basic facilities for decompressing and compressing PDF streams, and a more advanced PDF \textit{squeezer}.
   \section{Decompressing a Document}
 \index{decompressing}
   To decompress the streams in a PDF file, for instance to manually inspect the
@@ -931,6 +934,14 @@ PDF, use:
   \textbf{Flate\-Decode} method, with the exception of Metadata streams, which
   are left uncompressed.
   
+  \section{Squeezing a Document}
+\index{squeeze}
+  To \textit{squeeze} a PDF file, use:
+  \begin{framed}
+    \small\verb!cpdf -squeeze in.pdf -o out.pdf!
+  \end{framed}
+  \noindent Adding \texttt{-squeeze} to the command line will \textit{squeeze} the file upon output. The squeezing process involves several processes which losslessly attempt to reduce the file size. The squeezing process is slow. 
+  
 \chapter{Bookmarks}
   \begin{framed}
   \small\noindent\verb!cpdf -list-bookmarks [-utf8 | -raw] in.pdf!