From 5793a24e2894a4a2c00f1f9bfae563f1903e3a90 Mon Sep 17 00:00:00 2001
From: John Whitington <john@coherentgraphics.co.uk>
Date: Wed, 1 Oct 2014 12:05:13 +0100
Subject: [PATCH] -squeeze now deals with form xobjects

---
 cpdf.ml | 49 +++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 43 insertions(+), 6 deletions(-)

diff --git a/cpdf.ml b/cpdf.ml
index 1ddea61..fb5841d 100644
--- a/cpdf.ml
+++ b/cpdf.ml
@@ -74,10 +74,35 @@ let really_squeeze pdf =
           pdf.Pdf.objects <- !pdfr.Pdf.objects;
           pdf.Pdf.trailerdict <- !pdfr.Pdf.trailerdict
 
-(* Squeeze the form xobject at objnum. Any resources from the page (or its
-ancestors in the page tree!) are also needed - we must merge them with the
-ones from the xobject itself. *)
-let squeeze_form_xobjects page_resources pdf objnum = ()
+(* Squeeze the form xobject at objnum. FIXME: For old PDFs (< v1.2) any
+resources from the page (or its ancestors in the page tree!) are also needed -
+we must merge them with the ones from the xobject itself. *)
+let squeeze_form_xobject pdf objnum =
+  let obj = Pdf.lookup_obj pdf objnum in
+    match Pdf.lookup_direct pdf "/Subtype" obj with
+      Some (Pdf.Name "/Form") ->
+        Printf.printf "squeeze_form_xobject at object %i\n%!" objnum;
+        let resources =
+          match Pdf.lookup_direct pdf "/Resources" obj with
+            Some d -> d
+          | None -> Pdf.Dictionary []
+        in
+          begin match
+            Pdfops.stream_of_ops
+              (Pdfops.parse_operators pdf resources [Pdf.Indirect objnum])
+          with
+            Pdf.Stream {contents = (_, Pdf.Got data)} ->
+              (* Put replacement data in original stream, and overwrite /Length *)
+              begin match obj with
+                Pdf.Stream ({contents = (d, _)} as str) ->
+                  str :=
+                    (Pdf.add_dict_entry d "/Length" (Pdf.Integer (bytes_size data)),
+                     Pdf.Got data)
+              | _ -> failwith "squeeze_form_xobject"
+              end
+          | _ -> failwith "squeeze_form_xobject"
+          end
+    | _ -> ()
 
 (* For each object in the PDF marked with /Type /Page, for each /Contents
 indirect reference or array of such, decode and recode that content stream. *)
@@ -113,9 +138,21 @@ let squeeze_all_content_streams pdf =
                     Pdf.add_dict_entry
                       d "/Contents" (Pdf.Indirect (Pdf.addobj pdf newstream))
                   in
-                    Pdf.addobj_given_num pdf (objnum, newdict)
+                    Pdf.addobj_given_num pdf (objnum, newdict);
+                    (* Now process all xobjects related to this page *)
+                    begin match Pdf.lookup_direct pdf "/XObject" resources with
+                      Some (Pdf.Dictionary xobjs) ->
+                        iter
+                          (function
+                             (_, Pdf.Indirect i) -> squeeze_form_xobject pdf i
+                            | _ -> failwith "squeeze_xobject")
+                          xobjs
+                    | _ -> ()
+                    end
               with
-                (* No /Contents, which is ok. *)
+                (* No /Contents, which is ok. Or a parsing failure due to
+                 uninherited resources. FIXME: Add support for inherited
+                 resources. *)
                 Not_found -> ()
               end
         | _ -> ())