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open Pdfutil
open Pdfio
(* Return the width and height of a JPEG image, per Michael Petrov's C version.
Altered to accept Exif too. *)
exception Answer of int * int
let jpeg_dimensions bs =
try
let get = bget bs in
let i = ref 0 in
if get !i = 0xFF && get (!i + 1) = 0xD8 && get (!i + 2) = 0xFF && (get (!i + 3) = 0xE0 || get (!i + 3) = 0xE1) then
begin
i += 4;
if
get (!i + 2) = int_of_char 'J' && get (!i + 3) = int_of_char 'F'
&& get (!i + 4) = int_of_char 'I' && get (!i + 5) = int_of_char 'F'
&& get (!i + 6) = 0
||
get (!i + 2) = int_of_char 'E' && get (!i + 3) = int_of_char 'x'
&& get (!i + 4) = int_of_char 'i' && get (!i + 5) = int_of_char 'f'
&& get (!i + 6) = 0
then
let block_length = ref (get !i * 256 + get (!i + 1)) in
while !i < bytes_size bs do
i := !i + !block_length;
if !i > bytes_size bs then raise (Pdf.PDFError "jpeg_dimensions: too short") else
if get !i <> 0xFF then raise (Pdf.PDFError "jpeg_dimensions: not a valid block") else
if get (!i + 1) = 0xC0 then
raise (Answer (get (!i + 7) * 256 + get (!i + 8), (get (!i + 5) * 256 + get (!i + 6))))
else
begin
i += 2;
block_length := get !i * 256 + get (!i + 1)
end
done
else
raise (Pdf.PDFError "jpeg_dimensions: Not a valid JFIF string")
end
else
raise (Pdf.PDFError "jpeg_dimensions: Not a valid SOI header");
assert false
with
Answer (w, h) -> (w, h)
let backup_jpeg_dimensions ~path_to_im filename =
Cpdfutil.check_injectible filename;
let tmp = Filename.temp_file "cpdf" "info" in
let command = Filename.quote_command path_to_im ["-format"; "%[width] %[height]"; filename; "info:"] ^ " >" ^ tmp in
let out = Sys.command command in
if out > 0 then (Pdfe.log "unable to find JPEG dimensions"; (0, 0)) else
let w, h =
let w, rest = cleavewhile (neq ' ') (explode (contents_of_file tmp)) in
let h = tl rest in
int_of_string (implode w), int_of_string (implode h)
in
begin try Sys.remove tmp with _ -> () end;
(w, h)
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