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%% This is part of the OpTeX project, see http://petr.olsak.net/optex
\_codedecl \pdfunidef {PDFunicode strings for outlines <2020-03-12>} % preloaded in format
\_doc -----------------------------
The \`\_octalprint` is a Lua script that prints the character code in the
octal notation.
\_cod -----------------------------
\_edef\_octalprint#1#2{\_noexpand\_directlua{% #1=character-code #2=character
if ('#2'>='A' and '#2'<='Z') or ('#2'>='a' and '#2'<='z') then
tex.print(string.format('000\_pcent s',"#2"))
else
local num=#1\_pcent256
tex.print(string.format('\_pcent 03o\_nbb\_pcent03o',(#1-num)/256,num))
end
}}
\_doc -----------------------------
\`\pdfunidef``\macro{<text>}` does more things than only converting to octal notation.
The <text> can be scanned in verbatim mode (it is true becuase \^`\_Xtoc`
reads the <text> in verbatim mode). First `\edef` do
`\_scantextokens\unexpanded` and second `\edef` expands the parameter
according to current values on selected macros from `\_regoul`. Then
\`\_removeoutmath` converts `..$x^2$..` to `..x^2..`, i.e removes dollars.
Then \`\_removeoutbraces` converts `..{x}..` to `..x..`.
Finally, the <text> is detokenized, spaces are preprocessed using \^`\replstring`
and then the \`\_pdfunidefB` is repeated on each character. It calls the
`\directlua` chunk to print octal numbers in the macro \^`\_octalprint`.
\_cod -----------------------------
\_def\_pdfunidef#1#2{%
\_begingroup
\_the\_regoul \_relax % \_regmacro alternatives of logos etc.
\_ifx\_savedttchar\_undefined \_def#1{\_scantextokens{\_unexpanded{#2}}}%
\_else \_lccode`\;=\_savedttchar \_lowercase{\_prepinverb#1;}{#2}\fi
\_edef#1{#1}%
\_escapechar=-1
\_edef#1{#1\_empty}%
\_escapechar=`\\
\_ea\_edef \_ea#1\_ea{\_ea\_removeoutmath #1$\_end$}% $x$ -> x
\_ea\_edef \_ea#1\_ea{\_ea\_removeoutbraces #1{\_end}}% {x} -> x
\_edef#1{\_detokenize\_ea{#1}}%
\_replstring#1{ }{{ }}% text text -> text{ }text
\_catcode`\\=12 \_let\\=\_bslash
\_edef\_out{\\376\\377}%
\_ea\_pdfunidefB#1^% text -> \_out in octal
\_ea
\_endgroup
\_ea\_def\_ea#1\_ea{\_out}
}
\_def\_pdfunidefB#1{%
\_ifx^#1\_else
\_tmpnum=`#1
\_pdfunidefC{\_luaescapestring{#1}}%
\_ea\_pdfunidefB \_fi
}
\_def\_pdfunidefC #1{\_edef\_out{\_out \\\_ea\_octalprint\_ea{\_the\_tmpnum}{#1}}}
\_def\_removeoutbraces #1#{#1\_removeoutbracesA}
\_def\_removeoutbracesA #1{\_ifx\_end#1\_else #1\_ea\_removeoutbraces\_fi}
\_def\_removeoutmath #1$#2${#1\_ifx\_end#2\_else #2\_ea\_removeoutmath\_fi}
\_doc -----------------------------
The \`\_prepinverb``<macro><separator>{<text>}`,
e.g.\ `\_prepinverb\tmpb|{aaa |bbb| cccc |dd| ee}`
does `\def\tmpb{<su>{aaa }bbb<su>{ cccc }dd<su>{ ee}}` where
<su> is `\scantextokens\unexpanded`. It means that in-line verbatim
are not argument of `\scantextoken`. First `\edef\tmpb` tokenizes again
the <text> but not the parts which were in the the in-line verbatim.
\_cod -----------------------------
\_def\_prepinverb#1#2#3{\_def#1{}%
\_def\_dotmpb ##1#2##2{\_addto#1{\_scantextokens{\_unexpanded{##1}}}%
\_ifx\_end##2\_else\_ea\_dotmpbA\_ea##2\_fi}%
\_def\_dotmpbA ##1#2{\_addto#1{##1}\_dotmpb}%
\_dotmpb#3#2\_end
}
\_doc -----------------------------
The \^`\regmacro` is used in order to sed the values of macros
`\em`, `\rm`, `\bf`, `\it`, `\bi`, `\tt`, `\/` and `~` to values usable in
PDF outlines.
\_cod -----------------------------
\_regmacro {}{}{\_let\em=\_empty \_let\rm=\_empty \_let\bf=\_empty
\_let\it=\_empty \_let\bi=\_empty \_let\tt=\_empty \_let\/=\_empty
\_let~=\_space
}
\public \pdfunidef ;
\_endcode % --------------------------------
There are only two encodings for PDF strings (used in PDFoutlines, PDFinfo
, etc.). The first one is PDFDocEncoding which is one-byte encoding, but most
Czech or Slovak characters are missing here.
The second encoding is PDFunicode encoding which is implemented in this file.
This encoding is \TeX/-discomfortable because it looks like
\begtt
\376\377\000C\000v\000i\001\015\000e\000n\000\355\000\040\000j\000e\000\040
\000z\000\341\000t\001\033\001\176
\endtt
This example is the real encoding of the string "Cvičení je zátěž". You can see
that this is UTF-16 encoding (two bytes per character) with two starting
bytes FEFF. Moreover, each byte is encoded by three octal digits preceded by
a backslash. The only exception is the visible ASCII character encoding: such
a character is encoded by its real byte preceded by `\000`.
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