145 lines
4.8 KiB
OCaml
145 lines
4.8 KiB
OCaml
(* Truetype font embedding example *)
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open Pdfutil
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(* For the first stage of our embedder, we are only allowing standard encodings, and we don't actually subset.
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a) Get a list of Unicode codepoints;
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b) See which of them are in the glyph list;
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c) See which of those are in (StdEncoding|MacRomanEncoding|WinAnsiEncoding), and get their codes;
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d) Build a font to do just those;
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e) We put question marks for any character not in the encoding
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(* FUTURE *)
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1) Actually subset the font to save size
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2) Allow characters not in the standard encodings by builing one or more secondary subsets *)
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(* UTF8 Input text *)
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let text = "Noto Sans Black Àë"
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let encoding = Pdftext.MacRomanEncoding
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let unicodepoints = Pdftext.codepoints_of_utf8 text
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let glyphlist_table = Pdfglyphlist.reverse_glyph_hashes ()
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let encoding_table = Pdftext.reverse_table_of_encoding encoding
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let () =
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iter
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(fun u ->
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Printf.printf "unicode %i --> " u;
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let glyphname = Hashtbl.find glyphlist_table [u] in
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Printf.printf "glyph name %s --> " glyphname;
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let pdfcode = Hashtbl.find encoding_table glyphname in
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Printf.printf "pdf code %i\n" pdfcode)
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unicodepoints
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let pdfcode_of_unicode_codepoint u =
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try
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Some (Hashtbl.find encoding_table (Hashtbl.find glyphlist_table [u]))
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with
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Not_found -> None
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let tj_text =
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implode
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(map
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(fun x -> match pdfcode_of_unicode_codepoint x with Some c -> char_of_int c | None -> '?')
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unicodepoints)
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let calc_accepted_unicodepoints codepoints =
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setify
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(option_map
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(fun u -> match pdfcode_of_unicode_codepoint u with Some _ -> Some u | None -> None)
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codepoints)
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let accepted_unicodepoints =
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map
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(fun u -> (u, pdfcode_of_unicode_codepoint u))
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(calc_accepted_unicodepoints unicodepoints)
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let contents_of_file filename =
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let ch = open_in_bin filename in
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let s = really_input_string ch (in_channel_length ch) in
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close_in ch;
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s
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let fontname = "NotoSans-Black"
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let fontstr = contents_of_file (fontname ^ ".ttf")
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let f =
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Cpdftruetype.parse ~subset:accepted_unicodepoints (Pdfio.bytes_of_string fontstr)
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let contents =
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"1 0 0 1 50 770 cm BT/TT1 36 Tf(" ^ tj_text ^ ")Tj ET"
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let widths =
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Pdf.Array (map (fun x -> Pdf.Integer x) (Array.to_list f.Cpdftruetype.widths))
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let fontnum = ref 0
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let basename () =
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incr fontnum;
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"AAAAA" ^ string_of_char (char_of_int (!fontnum + 65))
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let name_1 = basename ()
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let string_of_encoding = function
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| Pdftext.WinAnsiEncoding -> "/WinAnsiEncoding"
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| Pdftext.MacRomanEncoding -> "/MacRomanEncoding"
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| Pdftext.StandardEncoding -> "/StandardEncoding"
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| _ -> failwith "unknown encoding"
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let font =
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Pdf.add_dict_entry
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(Pdfread.parse_single_object
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(Printf.sprintf "<</Type/Font/Subtype/TrueType/BaseFont/%s+%s/FontDescriptor 6 0 R/Encoding%s/FirstChar %i/LastChar %i>>" name_1 fontname (string_of_encoding encoding) f.Cpdftruetype.firstchar f.Cpdftruetype.lastchar))
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"/Widths"
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widths
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let fontdescriptor =
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Pdfread.parse_single_object
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(Printf.sprintf "<</Type/FontDescriptor/FontName/%s+%s/Flags %i/FontBBox[%i %i %i %i]/ItalicAngle %i/Ascent %i/Descent %i/CapHeight %i/StemV %i/XHeight %i/AvgWidth %i/MaxWidth %i/FontFile2 7 0 R>>"
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name_1 fontname f.Cpdftruetype.flags f.Cpdftruetype.minx f.Cpdftruetype.miny f.Cpdftruetype.maxx f.Cpdftruetype.maxy f.Cpdftruetype.italicangle
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f.Cpdftruetype.ascent f.Cpdftruetype.descent f.Cpdftruetype.capheight f.Cpdftruetype.stemv f.Cpdftruetype.xheight f.Cpdftruetype.avgwidth f.Cpdftruetype.maxwidth)
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let fontfile =
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let len = String.length fontstr in
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Pdf.Stream
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{contents =
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(Pdf.Dictionary [("/Length", Pdf.Integer len); ("/Length1", Pdf.Integer len)],
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Pdf.Got (Pdfio.bytes_of_string fontstr))}
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let objects =
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[(1, Pdfread.parse_single_object "<</Type/Catalog/Pages 2 0 R>>");
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(2, Pdfread.parse_single_object "<</Type/Pages/Kids[3 0 R]/Count 1>>");
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(3, Pdfread.parse_single_object "<</Type/Page/Resources<</Font <</TT1 5 0 R>>>>/Parent 2 0 R/MediaBox[0 0 595 842]/Rotate 0/Contents[4 0 R]>>");
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(4, Pdf.Stream
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{contents = (Pdf.Dictionary [("/Length", Pdf.Integer (String.length contents))],
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(Pdf.Got (Pdfio.bytes_of_string contents)))});
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(5, font);
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(6, fontdescriptor);
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(7, fontfile);
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]
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let root = 1
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let trailerdict =
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Pdfread.parse_single_object (Printf.sprintf "<</Root 1 0 R/Size %i>>" (length objects + 1))
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let pdf =
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let pdf =
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{Pdf.major = 2;
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Pdf.minor = 0;
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Pdf.root = root;
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Pdf.objects =
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{Pdf.maxobjnum = 0;
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Pdf.parse = None;
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Pdf.pdfobjects = Pdf.pdfobjmap_empty ();
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Pdf.object_stream_ids = null_hash ()};
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Pdf.trailerdict = trailerdict;
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Pdf.was_linearized = false;
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Pdf.saved_encryption = None}
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in
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iter (Pdf.addobj_given_num pdf) objects;
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pdf
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let () =
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Pdfwrite.pdf_to_file pdf "subset.pdf"
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