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cpdf-source
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Direct PNG output was misinformed

This commit is contained in:
John Whitington 2023-06-14 18:38:26 +01:00
parent 5f688481ea
commit 261f121040
1 changed files with 32 additions and 67 deletions
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39
cpdfimage.ml
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@ -22,42 +22,13 @@ let pnm_to_channel_24 channel w h s =
done
done
(* FIXME do this all at once *)
let write_stream name stream =
let fh = open_out_bin name in
for x = 0 to bytes_size stream - 1 do
output_byte fh (bget stream x)
done;
Pdfio.bytes_to_output_channel fh stream;
close_out fh
(* Detect images we can write directly as PNGs, to avoid going through pnm2png or imagemagick.
This is when BPC = 8, colourspace = DeviceRGB or CalRGB, compression is /FlateDecode. *)
let write_image_png pdf resources name dict =
(*Printf.printf "%s\n" (Pdfwrite.string_of_pdf (Pdf.direct pdf dict));*)
match
Pdfimage.colspace pdf dict resources,
Pdfimage.bpc pdf dict,
Pdf.lookup_direct pdf "/Filter" dict
with
| (Pdfspace.DeviceRGB | Pdfspace.CalRGB _),
Some (Pdf.Integer 8),
Some (Pdf.Name "/FlateDecode" | Pdf.Array [Pdf.Name "/FlateDecode"]) ->
(*Printf.printf "Direct to png...\n";*)
Pdf.getstream (Pdf.direct pdf dict);
let ch = open_out_bin (name ^ ".png") in
let o = Pdfio.output_of_channel ch in
let width = match Pdf.lookup_direct pdf "/Width" dict with Some (Pdf.Integer x) -> x | _ -> raise Exit in
let height = match Pdf.lookup_direct pdf "/Height" dict with Some (Pdf.Integer x) -> x | _ -> raise Exit in
let idat = match Pdf.direct pdf dict with Pdf.Stream {contents = (_, Got bytes)} -> bytes | _ -> raise Exit in
(*Printf.printf "all ok...\n";*)
Cpdfpng.write_png {width; height; idat} o;
close_out ch;
true
| _ -> false
let write_image path_to_p2p path_to_im pdf resources name image =
let main () =
begin match Pdfimage.get_image_24bpp pdf resources image with
match Pdfimage.get_image_24bpp pdf resources image with
| Pdfimage.JPEG (stream, _) -> write_stream (name ^ ".jpg") stream
| Pdfimage.JPEG2000 (stream, _) -> write_stream (name ^ ".jpx") stream
| Pdfimage.JBIG2 (stream, _) -> write_stream (name ^ ".jbig2") stream
@ -93,12 +64,6 @@ let write_image path_to_p2p path_to_im pdf resources name image =
end
| _ ->
Pdfe.log (Printf.sprintf "Unsupported image type when extracting image %s " name)
end
in
match write_image_png pdf resources name image with
| true -> ()
| exception x -> Pdfe.log (Printf.sprintf "Failed to write PNG directly (%s)\n" (Printexc.to_string x)); main ()
| _ -> main ()
let written = ref []