320 lines
11 KiB
OCaml
320 lines
11 KiB
OCaml
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open Pdfutil
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open Pdfio
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open Cpdferror
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(* \section{Blacken text} *)
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(*
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\begin{verbatim}
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Algorithm: Change
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BT
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<ops>
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ET
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...to...
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BT
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Op_g 0.
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<ops minus any color, shading or gs operators>
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ET
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<ops minus any text positioning or text rendering ones>
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\end{verbatim}
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*)
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let blacktext_ops colour pdf resources content =
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let not_text = function
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| Pdfops.Op_Tj _ | Pdfops.Op_TJ _
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| Pdfops.Op_' _ | Pdfops.Op_'' (_, _, _)
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| Pdfops.Op_Td (_, _) | Pdfops.Op_TD (_, _)
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| Pdfops.Op_Tm _ | Pdfops.Op_T'
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| Pdfops.Op_Tc _
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| Pdfops.Op_Tw _
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| Pdfops.Op_Tz _
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| Pdfops.Op_TL _
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| Pdfops.Op_Tf (_, _)
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| Pdfops.Op_Tr _
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| Pdfops.Op_Ts _ -> false
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| _ -> true
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in let textlevel = ref 0
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in let removed = ref []
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in let operators =
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Pdfops.parse_operators pdf resources content
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in
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let rec remove_colourops prev = function
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| [] -> rev prev
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| Pdfops.Op_BT::more ->
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incr textlevel;
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remove_colourops
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(Cpdfaddtext.colour_op colour::Pdfops.Op_BT::prev)
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more
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| Pdfops.Op_ET::more ->
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decr textlevel;
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let prev' = !removed @ Pdfops.Op_ET::prev in
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removed := [];
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remove_colourops prev' more
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| (Pdfops.Op_G _
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| Pdfops.Op_g _
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| Pdfops.Op_RG (_, _, _)
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| Pdfops.Op_rg (_, _, _)
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| Pdfops.Op_k (_, _, _, _)
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| Pdfops.Op_K (_, _, _, _)
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| Pdfops.Op_SCN _
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| Pdfops.Op_SC _
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| Pdfops.Op_scn _
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| Pdfops.Op_sc _
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| Pdfops.Op_SCNName (_, _)
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| Pdfops.Op_scnName (_, _)
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| Pdfops.Op_CS _
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| Pdfops.Op_cs _
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| Pdfops.Op_sh _
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| Pdfops.Op_gs _)
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as op::more ->
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if !textlevel > 0
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then
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begin
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removed =| op;
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remove_colourops prev more
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end
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else remove_colourops (op::prev) more
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| op::more ->
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if !textlevel > 0 && not_text op then removed =| op;
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remove_colourops (op::prev) more
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in
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let operators' = remove_colourops [] operators in
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[Pdfops.stream_of_ops operators']
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(* Blacken a form xobject, writing it to the same object. *)
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let blacktext c range pdf =
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let blacktext_page _ page =
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let content' =
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blacktext_ops c pdf page.Pdfpage.resources page.Pdfpage.content
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in
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Cpdfutil.process_xobjects pdf page (blacktext_ops c);
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{page with Pdfpage.content = content'}
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in
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Cpdfpage.process_pages (Cpdfutil.ppstub blacktext_page) pdf range
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(* \section{Blacken lines} *)
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let blacklines_ops c pdf resources content =
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let rec blacken_strokeops prev = function
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| [] -> rev prev
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| Pdfops.Op_CS _::t ->
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blacken_strokeops (Pdfops.Op_CS "/DeviceRGB"::prev) t
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| (Pdfops.Op_SC _ | Pdfops.Op_SCN _ | Pdfops.Op_SCNName _ | Pdfops.Op_G _
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| Pdfops.Op_RG _ | Pdfops.Op_K _)::t ->
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blacken_strokeops (Cpdfaddtext.colour_op_stroke c::prev) t
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| h::t -> blacken_strokeops (h::prev) t
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and operators =
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Pdfops.parse_operators pdf resources content
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in
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let operators' = blacken_strokeops [] operators in
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[Pdfops.stream_of_ops operators']
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let blacklines c range pdf =
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let blacklines_page _ page =
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let content' =
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blacklines_ops c pdf page.Pdfpage.resources page.Pdfpage.content
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in
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Cpdfutil.process_xobjects pdf page (blacklines_ops c);
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{page with Pdfpage.content = content'}
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in
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Cpdfpage.process_pages (Cpdfutil.ppstub blacklines_page) pdf range
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(* \section{Blacken Fills} *)
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let blackfills_ops c pdf resources content =
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let rec blacken_fillops prev = function
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| [] -> rev prev
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| Pdfops.Op_cs _::t ->
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blacken_fillops (Pdfops.Op_cs "/DeviceRGB"::prev) t
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| (Pdfops.Op_sc _ | Pdfops.Op_scn _ | Pdfops.Op_scnName _ | Pdfops.Op_g _
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| Pdfops.Op_rg _ | Pdfops.Op_k _)::t ->
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blacken_fillops (Cpdfaddtext.colour_op c::prev) t
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| h::t -> blacken_fillops (h::prev) t
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and operators =
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Pdfops.parse_operators pdf resources content
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in
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let operators' = blacken_fillops [] operators in
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[Pdfops.stream_of_ops operators']
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let blackfills c range pdf =
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let blackfills_page _ page =
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let content' =
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blackfills_ops c pdf page.Pdfpage.resources page.Pdfpage.content
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in
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Cpdfutil.process_xobjects pdf page (blackfills_ops c);
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{page with Pdfpage.content = content'}
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in
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Cpdfpage.process_pages (Cpdfutil.ppstub blackfills_page) pdf range
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(* \section{Set a minimum line width to avoid dropout} *)
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let thinlines range width pdf =
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let thinpage _ page =
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let operators =
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Pdfops.parse_operators pdf page.Pdfpage.resources page.Pdfpage.content
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in
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let ctmstack = ref [ref Pdftransform.i_matrix] in
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let scaleof_ctm () =
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try
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match Pdftransform.decompose (!(hd !ctmstack)) with
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(scale, _, _, _, _, _) ->
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scale
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with
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Failure _ (*"hd"*) -> 1.
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in
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let rec replace_operators prev = function
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| [] -> rev prev
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| (Pdfops.Op_w w)::more ->
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(* Alter width. *)
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let width' = width /. scaleof_ctm () in
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let w' =
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if w >= width' then Pdfops.Op_w w else Pdfops.Op_w width'
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in
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replace_operators (w'::prev) more
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| (Pdfops.Op_cm m)::more ->
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(* Update CTM *)
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begin try
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let top = hd !ctmstack in
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top := Pdftransform.matrix_compose !top m
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with
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Failure _ (*"hd"*) -> error "Malformed file."
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end;
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replace_operators ((Pdfops.Op_cm m)::prev) more
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| Pdfops.Op_q::more ->
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(* Push stack *)
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begin try
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ctmstack =| ref (!(hd !ctmstack))
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with
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Failure _ (*"hd"*) -> error "Malformed file"
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end;
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replace_operators (Pdfops.Op_q::prev) more
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| Pdfops.Op_Q::more ->
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(* Pop stack *)
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begin try
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ctmstack := tl !ctmstack
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with
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Failure _ (*"tl"*) -> error "Malformed file"
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end;
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replace_operators (Pdfops.Op_Q::prev) more
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| (Pdfops.Op_gs gsname)::more ->
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(* Perhaps insert [Op_w]. *)
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let opw =
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match Pdf.lookup_direct pdf "/ExtGState" page.Pdfpage.resources with
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| None -> []
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| Some ext_state_dict ->
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match Pdf.lookup_direct pdf gsname ext_state_dict with
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| None -> []
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| Some gdict ->
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match Pdf.lookup_direct pdf "/LW" gdict with
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| Some s -> (try [Pdfops.Op_w (Pdf.getnum s)] with _ -> [])
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| None -> []
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in
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replace_operators (opw @ ((Pdfops.Op_gs gsname)::prev)) more
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| x::more -> replace_operators (x::prev) more
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in
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let operators = replace_operators [] operators in
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(* 2. Add an initial 'w' if width more than default width *)
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let operators =
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if width > 1. then (Pdfops.Op_w width)::operators else operators
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in
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let content' = [Pdfops.stream_of_ops operators] in
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{page with Pdfpage.content = content'}
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in
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Cpdfpage.process_pages (Cpdfutil.ppstub thinpage) pdf range
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(* Parse the new content to make sure syntactically ok, append
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* as required. Rewrite the content *)
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let append_page_content_page fast s before pdf n page =
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let ops =
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Pdfops.parse_stream pdf page.Pdfpage.resources [bytes_of_string s]
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in
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(if before then Pdfpage.prepend_operators else Pdfpage.postpend_operators)
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pdf ops ~fast page
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let append_page_content s before fast range pdf =
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Cpdfpage.process_pages (Cpdfutil.ppstub (append_page_content_page fast s before pdf)) pdf range
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(* 1. Extend remove_dict_entry with search term
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2. Implement replace_dict_entry by analogy to remove_dict_entry *)
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let rec dict_entry_single_object f pdf = function
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| (Pdf.Dictionary d) -> f (Pdf.recurse_dict (dict_entry_single_object f pdf) d)
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| (Pdf.Stream {contents = (Pdf.Dictionary dict, data)}) ->
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f (Pdf.Stream {contents = (Pdf.recurse_dict (dict_entry_single_object f pdf) dict, data)})
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| Pdf.Array a -> Pdf.recurse_array (dict_entry_single_object f pdf) a
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| x -> x
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(* FIXME are we sure that functional values can never appear in the equality here? *)
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let remove_dict_entry pdf key search =
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let f d =
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match search with
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| None -> Pdf.remove_dict_entry d key
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| Some s ->
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match Pdf.lookup_direct pdf key d with
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| Some v when v = s -> Pdf.remove_dict_entry d key
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| _ -> d
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in
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Pdf.objselfmap (dict_entry_single_object f pdf) pdf;
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pdf.Pdf.trailerdict <- dict_entry_single_object f pdf pdf.Pdf.trailerdict
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let replace_dict_entry pdf key value search =
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let f d =
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match search with
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| None -> Pdf.replace_dict_entry d key value
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| Some s ->
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match Pdf.lookup_direct pdf key d with
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| Some v when v = s -> Pdf.replace_dict_entry d key value
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| _ -> d
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in
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Pdf.objselfmap (dict_entry_single_object f pdf) pdf;
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pdf.Pdf.trailerdict <- dict_entry_single_object f pdf pdf.Pdf.trailerdict
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(* FIXME no need to self map here, since nothing changes *)
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let print_dict_entry pdf key =
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let f d =
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match Pdf.lookup_direct pdf key d with
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| Some v ->
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(* We use a double newline as a separator. *)
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Printf.printf "%s\n\n" (Cpdfyojson.Safe.to_string (Cpdfjson.json_of_object pdf (fun _ -> ()) false false v));
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d
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| None -> d
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in
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Pdf.objselfmap (dict_entry_single_object f pdf) pdf;
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pdf.Pdf.trailerdict <- dict_entry_single_object f pdf pdf.Pdf.trailerdict
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let remove_clipping_ops pdf resources content =
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let ops = Pdfops.parse_operators pdf resources content in
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let rec process a = function
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Pdfops.Op_W::Pdfops.Op_n::t -> process (Pdfops.Op_n::a) t
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| h::t -> process (h::a) t
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| [] -> rev a
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in
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[Pdfops.stream_of_ops (process [] ops)]
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let remove_clipping pdf range =
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let remove_clipping_page _ page =
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let content' =
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remove_clipping_ops pdf page.Pdfpage.resources page.Pdfpage.content
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in
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Cpdfutil.process_xobjects pdf page remove_clipping_ops;
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{page with Pdfpage.content = content'}
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in
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Cpdfpage.process_pages (Cpdfutil.ppstub remove_clipping_page) pdf range
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let remove_unused_resources_page pdf n page =
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let xobjects, all_names =
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match Pdf.lookup_direct pdf "/XObject" page.Pdfpage.resources with
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| Some (Pdf.Dictionary d) -> Pdf.Dictionary d, map fst d
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| _ -> Pdf.Dictionary [], []
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in
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let names_to_keep =
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option_map
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(function Pdfops.Op_Do n -> Some n | _ -> None)
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(Pdfops.parse_operators pdf page.Pdfpage.resources page.Pdfpage.content)
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in
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let names_to_remove = lose (mem' names_to_keep) all_names in
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let xobjdict = fold_left (Pdf.remove_dict_entry) xobjects names_to_remove in
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{page with Pdfpage.resources = Pdf.add_dict_entry page.Pdfpage.resources "/XObject" xobjdict}
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let remove_unused_resources pdf =
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Cpdfpage.process_pages (Cpdfutil.ppstub (remove_unused_resources_page pdf)) pdf (ilist 1 (Pdfpage.endpage pdf))
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