cpdf-source/cpdfaddtext.ml

616 lines
25 KiB
OCaml

(* Superimpose text, page numbers etc. *)
open Pdfutil
open Cpdferror
type color =
Grey of float
| RGB of float * float * float
| CYMK of float * float * float * float
(* Process UTF8 text to charcodes, given a font. *)
let charcodes_of_utf8 font s =
let extractor = Pdftext.charcode_extractor_of_font_real ~debug:false font in
let codepoints = Pdftext.codepoints_of_utf8 s in
let charcodes =
option_map
(fun codepoint ->
match extractor codepoint with
| Some cc -> Some cc
| None ->
Pdfe.log (Printf.sprintf "Warning: character not found in font for unicode codepoint 0x%X\n" codepoint);
None)
codepoints
in
implode (map char_of_int charcodes)
let unicode_codepoint_of_pdfcode encoding_table glyphlist_table p =
try
hd (Hashtbl.find glyphlist_table (Hashtbl.find encoding_table p))
with
Not_found -> 0
(* Get the width of some text in the given font *)
let width_of_text font text =
match font with
| Pdftext.SimpleFont {Pdftext.fontmetrics = Some fontmetrics} ->
begin try
fsum (map (fun c -> fontmetrics.(int_of_char c)) (explode text))
with
_ -> 0.
end
| _ -> 0.
let colour_op = function
| RGB (r, g, b) -> Pdfops.Op_rg (r, g, b)
| Grey g -> Pdfops.Op_g g
| CYMK (c, y, m, k) -> Pdfops.Op_k (c, y, m, k)
let colour_op_stroke = function
| RGB (r, g, b) -> Pdfops.Op_RG (r, g, b)
| Grey g -> Pdfops.Op_G g
| CYMK (c, y, m, k) -> Pdfops.Op_K (c, y, m, k)
let ops fontpack fontname longest_w x y rotate hoffset voffset outline linewidth unique_fontname unique_extgstatename colour fontsize text =
[Pdfops.Op_q;
Pdfops.Op_BMC "/CPDFSTAMP";
Pdfops.Op_cm
(Pdftransform.matrix_of_transform
[Pdftransform.Translate (x -. hoffset, y -. voffset);
Pdftransform.Rotate ((0., 0.), rotate)]);
Pdfops.Op_BT;
] @
(if outline then [Pdfops.Op_w linewidth; Pdfops.Op_Tr 1] else [Pdfops.Op_Tr 0]) @
[colour_op colour; colour_op_stroke colour]
@
(match unique_extgstatename with None -> [] | Some n -> [Pdfops.Op_gs n])
@
[Pdfops.Op_Tf (unique_fontname, fontsize);
Pdfops.Op_Tj text;
Pdfops.Op_ET;
Pdfops.Op_EMC;
Pdfops.Op_Q]
type justification = LeftJustify | CentreJustify | RightJustify
(* Find the h-offset for justification based on the longest width, the current
width, the justification and the position. *)
let find_justification_offsets longest_w w position j =
let open Cpdfposition in
match j with
| LeftJustify ->
begin match position with
| TopLeft _ | Left _ | PosLeft _ | BottomLeft _ -> 0.
| Top _ | PosCentre _ | Bottom _ | Centre -> (longest_w -. w) /. 2.
| TopRight _ | BottomRight _ | PosRight _ | Right _ -> longest_w -. w
| Diagonal -> 0.
| ReverseDiagonal -> 0.
end
| RightJustify ->
begin match position with
| TopLeft _ | Left _ | PosLeft _ | BottomLeft _ -> ~-.(longest_w -. w)
| Top _ | PosCentre _ | Bottom _ | Centre -> ~-.((longest_w -. w) /. 2.)
| TopRight _ | BottomRight _ | PosRight _ | Right _ -> 0.
| Diagonal -> 0.
| ReverseDiagonal -> 0.
end
| CentreJustify ->
begin match position with
| TopLeft _ | Left _ | PosLeft _ | BottomLeft _ -> ~-.((longest_w -. w) /. 2.)
| Top _ | PosCentre _ | Bottom _ | Centre -> 0.
| TopRight _ | BottomRight _ | PosRight _ | Right _ -> (longest_w -. w) /. 2.
| Diagonal -> 0.
| ReverseDiagonal -> 0.
end
(* Lex an integer from the table *)
let extract_num header s =
match Pdfgenlex.lex_string (Hashtbl.find header s) with
[Pdfgenlex.LexInt i] -> Pdf.Integer i
| [Pdfgenlex.LexReal f] -> Pdf.Real f
| _ -> raise (Failure ("extract_num: " ^ s))
let extract_fontbbox header s =
let num = function
Pdfgenlex.LexInt i -> Pdf.Integer i
| Pdfgenlex.LexReal f -> Pdf.Real f
| _ -> raise (Failure "extract_fontbbox")
in
match Pdfgenlex.lex_string (Hashtbl.find header s) with
[a; b; c; d] -> [num a; num b; num c; num d]
| _ -> raise (Failure "extract_fontbbox")
let remove_slash s =
match explode s with
'/'::x -> implode x
| _ -> raise (Failure "remove_slash")
let extract_widths chars_and_widths =
let win_to_name = map (fun (x, y) -> (y, x)) Pdfglyphlist.name_to_win in
map
(fun x ->
try
let name = List.assoc x win_to_name in
let width = List.assoc (remove_slash name) chars_and_widths in
width
with
_ -> 0)
(ilist 0 255)
(* For finding the height for URL links, we try to find the Cap Height for the
font. We fall back to using the font size alone if we cannot get the cap
height. *)
let cap_height font fontname =
match font with
| Some (Pdftext.SimpleFont {fontdescriptor = Some {capheight}}) ->
Some capheight
| _ ->
try
let font = unopt (Pdftext.standard_font_of_name ("/" ^ fontname)) in
let header, _, _, _ = Pdfstandard14.afm_data font in
let capheight = try extract_num header "CapHeight" with _ -> Pdf.Integer 0 in
Some (match capheight with Pdf.Integer i -> float_of_int i | Pdf.Real r -> r | _ -> 0.)
with
_ -> None
let rec process_text time text m =
match m with
| [] -> Cpdfstrftime.strftime ~time text
| (s, r)::t -> process_text time (string_replace_all_lazy s r text) t
(* Find any %URL, sub in the text and return the new text together with a list
of ordered (line num, URL, startpos, endpos) data.
This will be used after any other %Specials have been processed, so that the
positions do not change. *)
(* text|url]abc -> text, url, abc *)
let extract_url line =
let text, rest = cleavewhile (neq '|') line in
if rest = [] then error "bad URL syntax in text" else
let url, rest = cleavewhile (neq ']') (tl rest) in
if rest = [] then error "bad URL syntax in text" else
(text, url, tl rest)
(* multiple %URL[a|b] *)
let get_urls_line line =
let line = explode line in
let urls = ref [] in
let pos = ref 0 in
let outline = ref [] in
let rec loop = function
| '%'::'U'::'R'::'L'::'['::t ->
let text, url, rest = extract_url t in
outline := rev text @ !outline;
urls := (implode url, !pos, !pos + length text)::!urls;
pos += length text;
loop rest
| h::t ->
outline := h::!outline;
pos += 1;
loop t
| [] -> ()
in
loop line;
(implode (rev !outline), rev !urls)
(* Return page label at pdf page num, or page number in arabic if no label *)
let pagelabel pdf num =
Pdfpagelabels.pagelabeltext_of_pagenumber
num
(Pdfpagelabels.complete (Pdfpagelabels.read pdf))
let replace_pairs pdf endpage extract_text_font_size filename bates batespad num page =
[
"%PageDiv2", (fun () -> string_of_int ((num + 1) / 2));
"%Page", (fun () -> string_of_int num);
"%Roman", (fun () -> roman_upper num);
"%roman", (fun () -> roman_lower num);
"%filename", (fun () -> filename);
"%Label", (fun () -> pagelabel pdf num);
"%EndPage", (fun () -> string_of_int endpage);
"%EndLabel", (fun () -> pagelabel pdf endpage);
"%ExtractedText", (fun () -> Cpdfextracttext.extract_page_text extract_text_font_size pdf num page);
"%Bates",
(fun () ->
(let numstring = string_of_int (bates + num - 1) in
match batespad with
None -> numstring
| Some w ->
if String.length numstring >= w
then numstring
else implode (many '0' (w - String.length numstring)) ^ numstring))]
let expand_lines text time pdf endpage extract_text_font_size filename bates batespad num page lines =
let expanded_lines =
map
(function text ->
process_text time text (replace_pairs pdf endpage extract_text_font_size filename bates batespad num page))
lines
in
(* process URLs for justification too *)
map (fun line -> fst (get_urls_line line)) expanded_lines
let addtext
time lines linewidth outline fast colour fontname encoding bates batespad
fontsize fontpack font fontpdfobj fontpackpdfobjs underneath position hoffset voffset text pages
cropbox opacity justification filename extract_text_font_size shift raw pdf
=
let endpage = Pdfpage.endpage pdf in
let shifts = Cpdfcoord.parse_coordinates pdf shift in
let addtext_page num page =
let shift_x, shift_y = List.nth shifts (num - 1) in
let resources', unique_extgstatename =
if opacity < 1.0 then
let dict =
match Pdf.lookup_direct pdf "/ExtGState" page.Pdfpage.resources with
| Some d -> d
| None -> Pdf.Dictionary []
in
let unique_extgstatename = Pdf.unique_key "gs" dict in
let dict' =
Pdf.add_dict_entry dict unique_extgstatename
(Pdf.Dictionary [("/ca", Pdf.Real opacity); ("/CA", Pdf.Real opacity)])
in
Pdf.add_dict_entry page.Pdfpage.resources "/ExtGState" dict', Some unique_extgstatename
else
page.Pdfpage.resources, None
in
let fontdict =
match Pdf.lookup_direct pdf "/Font" page.Pdfpage.resources with
| None -> Pdf.Dictionary []
| Some d -> d
in
let calc_textwidth text =
match fontpack with
| Some fontpack ->
let widthss = map (fun font -> Cpdftype.font_widths font fontsize) (fst fontpack) in
let triples = option_map (Cpdfembed.get_char fontpack) (Pdftext.codepoints_of_utf8 text) in
let widths = map (fun (charcode, fontnum, _) -> (List.nth widthss fontnum).(charcode)) triples in
fsum widths
| None ->
match font with
| Some (Pdftext.StandardFont (f, _)) ->
let rawwidth =
Pdfstandard14.textwidth false encoding f text
in
(float rawwidth *. fontsize) /. 1000.
| Some font ->
let rawwidth = width_of_text font text in
(rawwidth *. fontsize) /. 1000.
| None ->
let font =
match Pdf.lookup_direct pdf "/Font" page.Pdfpage.resources with
| Some fontdict ->
begin match Pdf.lookup_direct pdf fontname fontdict with
| Some font -> font
| None ->
(* For each item in the fontdict, follow its value and find the basename. If it matches, return that font *)
let font = ref None in
iter
(fun (k, v) ->
match Pdf.lookup_direct pdf "/BaseFont" v with
| Some (Pdf.Name n) when n = fontname -> font := Some v
| _ -> ())
(match fontdict with Pdf.Dictionary d -> d | _ -> []);
match !font with Some f -> f | None -> failwith (Printf.sprintf "addtext: font %s not found" fontname)
end
| _ -> failwith "addtext: font not found for width"
in
let rawwidth = width_of_text (Pdftext.read_font pdf font) text in
(rawwidth *. fontsize) /. 1000.
in
let unique_fontname = Pdf.unique_key "F" fontdict in
let ops, urls, x, y, hoffset, voffset, text, joffset =
let text = process_text time text (replace_pairs pdf endpage extract_text_font_size filename bates batespad num page) in
let text, urls = get_urls_line text in
let lines = map (fun text -> if raw || fontpack <> None then text else charcodes_of_utf8 (Pdftext.read_font pdf fontpdfobj) text) lines in
let expanded_lines = expand_lines text time pdf endpage extract_text_font_size filename bates batespad num page lines in
let textwidth = calc_textwidth text
and allwidths = map calc_textwidth expanded_lines in
let longest_w = last (sort compare allwidths) in
let joffset = find_justification_offsets longest_w textwidth position justification in
let mediabox =
if cropbox then
match Pdf.lookup_direct pdf "/CropBox" page.Pdfpage.rest with
| Some pdfobject -> Pdf.parse_rectangle pdf (Pdf.direct pdf pdfobject)
| None -> Pdf.parse_rectangle pdf page.Pdfpage.mediabox
else
Pdf.parse_rectangle pdf page.Pdfpage.mediabox
in
let x, y, rotate = Cpdfposition.calculate_position false textwidth mediabox position in
let hoffset, voffset =
if position = Diagonal || position = ReverseDiagonal
then -. (cos ((pi /. 2.) -. rotate) *. voffset), sin ((pi /. 2.) -. rotate) *. voffset
else hoffset, voffset
in
match font with
| Some f ->
ops fontpack fontname longest_w (x +. shift_x) (y +. shift_y) rotate (hoffset +. joffset) voffset outline linewidth
unique_fontname unique_extgstatename colour fontsize text,
urls, x, y, hoffset, voffset, text, joffset
| None ->
ops fontpack fontname longest_w (x +. shift_x) (y +. shift_y) rotate (hoffset +. joffset) voffset outline linewidth
fontname None colour fontsize text,
urls, x, y, hoffset, voffset, text, joffset
in
let newresources =
match fontpack with
| Some fontpack ->
let newfontdict =
let fd = ref fontdict in
iter
(fun i ->
(* FIXME make properly unique *)
fd := Pdf.add_dict_entry !fd ("/F" ^ fontname ^ string_of_int i) (Pdf.Indirect i))
fontpackpdfobjs;
!fd
in
Pdf.add_dict_entry resources' "/Font" newfontdict
| None ->
match font with
| Some (Pdftext.StandardFont _ as font) ->
let newfontdict =
Pdf.add_dict_entry fontdict unique_fontname (Pdf.Indirect (Pdftext.write_font pdf font))
in
Pdf.add_dict_entry resources' "/Font" newfontdict
| Some f ->
let newfontdict =
Pdf.add_dict_entry fontdict unique_fontname fontpdfobj
in
Pdf.add_dict_entry resources' "/Font" newfontdict
| None -> page.Pdfpage.resources
in
(* Build annotations from URL data (get_urls and some sense of metrics) *)
let annot (minx, miny, maxx, maxy) url =
Pdf.Dictionary
[("/Subtype", Pdf.Name "/Link");
("/Rect", Pdf.Array [Pdf.Real minx; Pdf.Real miny; Pdf.Real maxx; Pdf.Real maxy]);
("/BS", Pdf.Dictionary [("/W", Pdf.Integer 0)]);
("/A", Pdf.Dictionary [("/URI", Pdf.String url);
("/Type", Pdf.Name "/Action");
("/S", Pdf.Name "/URI")])]
in
let annots =
let annot_coord text pos =
let before = take (explode text) pos in
calc_textwidth (implode before)
in
map (fun (url, s, e) ->
let sx = annot_coord text s in
let ex = annot_coord text e in
let x, y = x -. hoffset -. joffset, y -. voffset in
let height =
match cap_height font fontname with
| Some c -> (c *. fontsize) /. 1000.
| None -> fontsize
in
Pdf.Indirect (Pdf.addobj pdf (annot (x +. sx, y, x +. ex, y +. height) url))) urls
in
let newrest =
if annots = [] then page.Pdfpage.rest else
let existing =
match Pdf.lookup_direct pdf "/Annots" page.Pdfpage.rest with
| Some (Pdf.Array a) -> a
| _ -> []
in
Pdf.add_dict_entry page.Pdfpage.rest "/Annots" (Pdf.Array (annots @ existing))
in
let page =
{page with
Pdfpage.resources = newresources;
Pdfpage.rest = newrest}
in
if underneath
then Pdfpage.prepend_operators pdf ops ~fast:fast page
else Pdfpage.postpend_operators pdf ops ~fast:fast page
in
Cpdfpage.process_pages (Pdfpage.ppstub addtext_page) pdf pages
(* Prev is a list of lists of characters *)
let split_at_newline t =
let rec split_at_newline_inner prev = function
| [] -> rev (map implode (map rev prev))
| '\\'::'\\'::'n'::t -> split_at_newline_inner (('n'::'\\'::'\\'::hd prev)::tl prev) t
| '\\'::'n'::t -> split_at_newline_inner ([]::prev) t
| h::t -> split_at_newline_inner ((h::hd prev)::tl prev) t
in
split_at_newline_inner [[]] (explode t)
let rec unescape_chars prev = function
| [] -> rev prev
| '\\'::('0'..'7' as a)::('0'..'7' as b)::('0'..'7' as c)::t ->
let chr = char_of_int (int_of_string ("0o" ^ implode [a;b;c])) in
unescape_chars (chr::prev) t
| '\\'::'\\'::t -> unescape_chars ('\\'::prev) t
| '\\'::c::t when c <> 'n' -> unescape_chars (c::prev) t
| h::t -> unescape_chars (h::prev) t
let unescape_string s =
implode (unescape_chars [] (explode s))
let
addtexts linewidth outline fast fontname (cpdffont : Cpdfembed.cpdffont) bates batespad
colour position linespacing fontsize underneath text pages cropbox opacity
justification midline topline filename extract_text_font_size shift
?(raw=false) pdf
=
if pages = [] then error "addtexts: empty page range" else
let time = Cpdfstrftime.current_time () in
let endpage = Pdfpage.endpage pdf in
let ps = Pdfpage.pages_of_pagetree pdf in
let used = null_hash () in
let lines = map unescape_string (split_at_newline text) in
iter2
(fun num page ->
let expanded_lines = expand_lines text time pdf endpage extract_text_font_size filename bates batespad num page lines in
let codepoints = map Pdftext.codepoints_of_utf8 expanded_lines in
iter (iter (fun x -> Hashtbl.replace used x ())) codepoints)
pages
(map (fun x -> List.nth ps (x - 1)) pages);
let realfontname = ref fontname in
let font, fontpack =
match cpdffont with
| Cpdfembed.PreMadeFontPack f ->
Some (hd (fst f)), Some f
| Cpdfembed.EmbedInfo {fontfile; fontname; encoding} ->
let embedded = Cpdfembed.embed_truetype pdf ~fontfile ~fontname ~codepoints:(map fst (list_of_hashtbl used)) ~encoding in
Some (hd (fst embedded)), Some embedded
| Cpdfembed.ExistingNamedFont -> None, None
in
let fontpdfobj =
match font with
| Some (Pdftext.StandardFont _ as font) ->
Pdf.Indirect (Pdftext.write_font pdf font)
| Some f ->
Pdf.Indirect (Pdftext.write_font pdf f)
| None ->
let firstpage =
List.nth (Pdfpage.pages_of_pagetree pdf) (hd pages - 1)
in
match Pdf.lookup_direct pdf "/Font" firstpage.Pdfpage.resources with
| Some fontdict ->
begin match Pdf.lookup_direct pdf fontname fontdict with
| Some font -> font
| _ ->
(* For each item in the fontdict, follow its value and find the basename. If it matches, return that font *)
let font = ref None in
iter
(fun (k, v) ->
match Pdf.lookup_direct pdf "/BaseFont" v with
| Some (Pdf.Name n) when n = fontname ->
font := Some v; realfontname := k
| _ -> ())
(match fontdict with Pdf.Dictionary d -> d | _ -> []);
match !font with Some f -> f | None -> failwith (Printf.sprintf "addtext: font %s not found" fontname)
end
| _ -> failwith "addtext: font dictionary not present"
in
let lines = map unescape_string (split_at_newline text) in
let pdf = ref pdf in
let voffset =
let open Cpdfposition in
match position with
| Bottom _ | BottomLeft _ | BottomRight _ ->
ref (0. -. (linespacing *. fontsize *. (float (length lines) -. 1.)))
| Left _ | Right _ ->
(* Vertically align *)
ref (0. -. (linespacing *. ((fontsize *. (float (length lines) -. 1.)) /. 2.)))
| Diagonal | ReverseDiagonal ->
(* Change so that the whole paragraph sits on the centre... *)
ref (0. -. ((linespacing *. fontsize *. (float (length lines) -. 1.)) /. 2.))
| _ -> ref 0.
in
if midline then
begin match font with
| Some (Pdftext.StandardFont (font, _)) ->
let baseline_adjustment =
(fontsize *. float (Pdfstandard14.baseline_adjustment font)) /. 1000.
in
voffset := !voffset +. baseline_adjustment
| Some (Pdftext.SimpleFont {fontdescriptor = Some {capheight}}) ->
voffset := !voffset +. capheight /. 2.
| _ ->
Pdfe.log "Unable to find midline adjustment in this font\n"
end
else
if topline then
begin match font with
| Some (Pdftext.StandardFont (font, _)) ->
let baseline_adjustment =
(fontsize *. float (Pdfstandard14.baseline_adjustment font) *. 2.0) /. 1000.
in
voffset := !voffset +. baseline_adjustment
| Some (Pdftext.SimpleFont {fontdescriptor = Some {capheight}}) ->
voffset := !voffset +. capheight
| _ ->
Pdfe.log "Unable to find midline adjustment in this font\n"
end;
let encoding =
match font with
| Some (Pdftext.StandardFont (_, e)) -> e
| Some (Pdftext.SimpleFont {encoding}) -> encoding
| _ -> Pdftext.WinAnsiEncoding
in
let fontpackpdfobjs =
match cpdffont with
| Cpdfembed.EmbedInfo {fontfile; fontname; encoding} ->
let codepoints = map fst (list_of_hashtbl used) in
let fonts = fst (Cpdfembed.embed_truetype !pdf ~fontfile ~fontname ~codepoints ~encoding) in
map (Pdftext.write_font !pdf) fonts
| _ -> []
in
iter
(fun line ->
let voff, hoff = !voffset, 0. in
pdf :=
addtext time lines linewidth outline fast colour !realfontname encoding
bates batespad fontsize fontpack font fontpdfobj fontpackpdfobjs underneath
position hoff voff line pages cropbox opacity justification filename
extract_text_font_size shift raw !pdf;
voffset := !voffset +. (linespacing *. fontsize))
lines;
!pdf
let addrectangle
fast (w, h) colour outline linewidth opacity position relative_to_cropbox
underneath range pdf
=
let addrectangle_page _ page =
let resources', unique_extgstatename =
if opacity < 1.0 then
let dict =
match Pdf.lookup_direct pdf "/ExtGState" page.Pdfpage.resources with
| Some d -> d
| None -> Pdf.Dictionary []
in
let unique_extgstatename = Pdf.unique_key "gs" dict in
let dict' =
Pdf.add_dict_entry dict unique_extgstatename
(Pdf.Dictionary [("/ca", Pdf.Real opacity); ("/CA", Pdf.Real opacity)])
in
Pdf.add_dict_entry page.Pdfpage.resources "/ExtGState" dict', Some unique_extgstatename
else
page.Pdfpage.resources, None
in
let mediabox =
if relative_to_cropbox then
match Pdf.lookup_direct pdf "/CropBox" page.Pdfpage.rest with
| Some pdfobject -> Pdf.parse_rectangle pdf (Pdf.direct pdf pdfobject)
| None -> Pdf.parse_rectangle pdf page.Pdfpage.mediabox
else
Pdf.parse_rectangle pdf page.Pdfpage.mediabox
in
let x, y, _ =
Cpdfposition.calculate_position false w mediabox position
in
let x, y =
match position with
Cpdfposition.Top _ | Cpdfposition.TopLeft _ | Cpdfposition.TopRight _ -> (x, y -. h)
| Cpdfposition.Centre | Cpdfposition.PosCentre _ -> (x, y -. (h /. 2.))
| _ -> (x, y)
in
let ops =
[
Pdfops.Op_q;
Pdfops.Op_BMC "/CPDFSTAMP";
colour_op colour;
colour_op_stroke colour;
]
@
(if outline then [Pdfops.Op_w linewidth] else [])
@
(match unique_extgstatename with None -> [] | Some n -> [Pdfops.Op_gs n])
@
[
Pdfops.Op_re (x, y, w, h);
(if outline then Pdfops.Op_s else Pdfops.Op_f);
Pdfops.Op_EMC;
Pdfops.Op_Q
]
in
let page = {page with Pdfpage.resources = resources'} in
if underneath
then Pdfpage.prepend_operators pdf ops ~fast:fast page
else Pdfpage.postpend_operators pdf ops ~fast:fast page
in
Cpdfpage.process_pages (Pdfpage.ppstub addrectangle_page) pdf range