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Working (but not yet efficient) MaxSplit

This commit is contained in:
John Whitington 2023-10-26 15:55:55 +01:00
parent 6b640a128d
commit 889874fd37
1 changed files with 23 additions and 19 deletions
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42
cpdfcommand.ml
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@ -3154,7 +3154,8 @@ let split_pdf
(splitinto chunksize (indx pdf_pages)) pdf_pages (splitinto chunksize (indx pdf_pages)) pdf_pages
(* Given a PDF, write the split as if we had selected pages, and return its filesize. Delete it. *) (* Given a PDF, write the split as if we had selected pages, and return its filesize. Delete it. *)
let split_max_fits pdf p q = let split_max_fits pdf s p q =
Printf.printf "split_max_fits: %i, %i\n%!" p q;
assert (q >= p); assert (q >= p);
let filename = Filename.temp_file "cpdf" "sm" in let filename = Filename.temp_file "cpdf" "sm" in
let range = ilist p q in let range = ilist p q in
@ -3167,30 +3168,33 @@ let split_max_fits pdf p q =
let size = in_channel_length fh in let size = in_channel_length fh in
close_in fh; close_in fh;
Sys.remove filename; Sys.remove filename;
size size <= s
(* Binary search on q from current value down to p to find max which fits. Returns q. Upon failure, returns -1 *)
let rec split_max_search_down pdf s p q =
Printf.printf "split_max_search_down p q %i %i\n%!" p q;
(* If down to one page, we can split no more *)
if p = q then
if split_max_fits pdf s p q then q else -1
else
if split_max_fits pdf s p q then q else split_max_search_down pdf s p (q - 1)
(* FIXME: Show that it terminates and fails if (p, q) do not change *)
let rec split_max enc original_filename ~squeeze output_spec s pdf = let rec split_max enc original_filename ~squeeze output_spec s pdf =
let outs = ref [] in let outs = ref [] in
let p = ref 1 in let p = ref 1 in
let endpage = Pdfpage.endpage pdf in let endpage = Pdfpage.endpage pdf in
let q = ref endpage in let q = ref endpage in
Printf.printf "Target %i: %i->%i has filesize %i\n" s !p !q (split_max_fits pdf !p !q); while !p < !q do
if split_max_fits pdf !p !q <= s then let newq = split_max_search_down pdf s !p !q in
begin if newq = -1 then (Printf.eprintf "Failed to make small enough split at page %i\n" !p; exit 2) else
Printf.printf "Fits\n"; begin
outs := ilist !p !q::!outs; Printf.printf "Found a suitable interval (%i, %i)\n%!" !p newq;
if !q = endpage outs := ilist !p newq::!outs;
then p := newq + 1;
begin q := endpage
Printf.printf "All splits found, and all fit, so writing results\n"; end
assert (!outs <> []); done;
fast_write_split_pdfs enc 0 original_filename squeeze output_spec pdf (rev !outs) (Pdfpage.pages_of_pagetree pdf) fast_write_split_pdfs enc 0 original_filename squeeze output_spec pdf (rev !outs) (Pdfpage.pages_of_pagetree pdf)
end
else Printf.printf "more to do\n"
end
else
Printf.printf "did not fit, chopping in half.\n"
let getencryption pdf = let getencryption pdf =
match Pdfread.what_encryption pdf with match Pdfread.what_encryption pdf with