From 70961eb692cef26f28505b809594960f0abfe973 Mon Sep 17 00:00:00 2001
From: John Whitington <john@coherentgraphics.co.uk>
Date: Mon, 20 Nov 2023 16:42:00 +0200
Subject: [PATCH] first resonable working chop

---
 cpdfchop.ml    | 22 ++++++++++++----------
 cpdfchop.mli   |  4 ++--
 cpdfcommand.ml |  2 +-
 3 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/cpdfchop.ml b/cpdfchop.ml
index 0611d0f..bfa74cf 100644
--- a/cpdfchop.ml
+++ b/cpdfchop.ml
@@ -2,11 +2,13 @@ open Pdfutil
 open Cpdferror
 
 (* FIXME Resources - what to do with each. Bookmarks? Annotations - must be duplicated... *)
+(* FIXME How to link annotations within the document work? *)
+(* FIXME Are 'changes' for change_pages important? *)
 (* FIXME Test how the sharing affects other cpdf operations - especially with -fast! *)
 
 (* Chop a single page into pieces. We prefer the cropbox when available. We set
    mediabox only, and delete any other boxes. *)
-(* FIXME btt / rtl *)
+(* FIXME btt / rtl / columns *)
 let get_box pdf page =
   match Pdf.lookup_direct pdf "/CropBox" page.Pdfpage.rest with
   | Some r -> Pdf.parse_rectangle pdf r
@@ -16,7 +18,7 @@ let erase_boxes d =
   let f = Pdf.remove_dict_entry in
     f (f (f (f d "/CropBox") "/BleedBox") "/TrimBox") "/ArtBox"
 
-let chop_boxes pdf x y p =
+let chop_boxes pdf x y columns btt rtl p =
   if x < 1 || y < 1 then Cpdferror.error "chop_boxes bad specification" else
     let move_page mx my p w h dx dy =
       (*Printf.printf "move_page by %f %f\n" dx dy;*)
@@ -30,22 +32,22 @@ let chop_boxes pdf x y p =
     (*Printf.printf "minx, miny, maxx, maxy = %f, %f, %f, %f\n" minx miny maxx maxy;*)
     let w, h = (maxx -. minx) /. float_of_int x, (maxy -. miny) /. float_of_int y in
     let ps = ref [] in
-      for ty = y - 1 downto 0 do
-        for tx = 0 to x - 1 do
-          ps =| move_page minx miny p w h (w *. float_of_int tx) (h *. float_of_int ty)
-        done
-      done;
+    let move_page = move_page minx miny p w h in
+      (* columns, btt, rtl *)
+      for ty = y - 1 downto 0 do for tx = 0 to x - 1 do
+        ps =| move_page (w *. float_of_int tx) (h *. float_of_int ty)
+      done done;
       rev !ps
 
 (* Chop pages in the range into pieces *)
-let chop ~x ~y pdf range =
+let chop ~x ~y ~columns ~btt ~rtl pdf range =
   let pages = Pdfpage.pages_of_pagetree pdf in
   let pages =
     flatten
       (map2
-        (fun n p -> if mem n range then (chop_boxes pdf x y p) else [p])
+        (fun n p -> if mem n range then chop_boxes pdf x y columns btt rtl p else [p])
         (ilist 1 (Pdfpage.endpage pdf))
         pages)
   in
-  let changes = [] in (* FIXME *)
+  let changes = [] in
     Pdfpage.change_pages ~changes true pdf pages
diff --git a/cpdfchop.mli b/cpdfchop.mli
index df6a08f..3bf8803 100644
--- a/cpdfchop.mli
+++ b/cpdfchop.mli
@@ -1,4 +1,4 @@
 (** Chop *)
 
-(** Chop *)
-val chop : x:int -> y:int -> Pdf.t -> int list -> Pdf.t
+(** Chop a page into pieces. *)
+val chop : x:int -> y:int -> columns:bool -> btt:bool -> rtl:bool -> Pdf.t -> int list -> Pdf.t
diff --git a/cpdfcommand.ml b/cpdfcommand.ml
index e78692f..114ceca 100644
--- a/cpdfcommand.ml
+++ b/cpdfcommand.ml
@@ -4381,7 +4381,7 @@ let go () =
   | Some (Chop (x, y)) ->
       let pdf = get_single_pdf args.op false in
       let range = parse_pagespec_allow_empty pdf (get_pagespec ()) in
-        write_pdf false (Cpdfchop.chop ~x ~y pdf range)
+        write_pdf false (Cpdfchop.chop ~x ~y ~columns:args.impose_columns ~btt:args.impose_btt ~rtl:args.impose_rtl pdf range)
 
 (* Advise the user if a combination of command line flags makes little sense,
 or error out if it make no sense at all. *)