cpdf-source/cpdfchop.ml

61 lines
2.4 KiB
OCaml

open Pdfutil
open Cpdferror
(* Chop a single page into pieces. We prefer the cropbox when available. We set
mediabox only, and delete any other boxes. We delete /Annots, since
duplicate annotations are not allowed. *)
let get_box pdf page =
match Pdf.lookup_direct pdf "/CropBox" page.Pdfpage.rest with
| Some r -> Pdf.parse_rectangle pdf r
| None -> Pdf.parse_rectangle pdf page.Pdfpage.mediabox
let erase_boxes d =
let f = Pdf.remove_dict_entry in
f (f (f (f (f d "/CropBox") "/BleedBox") "/TrimBox") "/ArtBox") "/Annots"
let make_pages x y columns btt rtl w h ps move_page =
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
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;*)
let nminx, nminy, nmaxx, nmaxy = (mx +. dx, my +. dy, mx +. w +. dx, my +. h +. dy) in
(*Printf.printf "new box: %f, %f, %f, %f\n" nminx nminy nmaxx nmaxy;*)
{p with
Pdfpage.mediabox = Pdf.Array [Pdf.Real nminx; Pdf.Real nminy; Pdf.Real nmaxx; Pdf.Real nmaxy];
Pdfpage.rest = erase_boxes p.Pdfpage.rest}
in
let minx, miny, maxx, maxy = get_box pdf p in
(*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
make_pages x y columns btt rtl w h ps (move_page minx miny p w h);
rev !ps
(* Chop pages in the range into pieces *)
let chop ~x ~y ~columns ~btt ~rtl pdf range =
let pages = Pdfpage.pages_of_pagetree pdf in
let pages_out =
flatten
(map2
(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 =
let q = ref 0 in
flatten
(map2
(fun n p ->
if mem n range
then (q += 1; let r = combine (many n (x * y)) (ilist !q (!q + x * y - 1)) in q += (x * y - 1); r)
else (q += 1; [(n, !q)]))
(ilist 1 (Pdfpage.endpage pdf))
pages)
in
(*iter (fun (a, b) -> Printf.printf "%i -> %i\n" a b) changes;*)
Pdfpage.change_pages ~changes true pdf pages_out