[luatex] PDF strings.

[Heiko Oberdiek]

On Sun, Nov 28, 2010 at 04:51:55PM +0100, Paul Isambert wrote:

> As you may know, PDF reads strings encoded in either its own scheme,
> or in UTF-16.
> My problem is I want accented characters in bookmarks, e.g:
> 
> \pdfoutline goto name {there}{Héhé}
> 
> I can't feed PDF-encoded strings directly (LuaTeX would complain),
> but PDF also understands \nnn-encoded characters, where \nnn is a
> number in base-8, so I actually do
> 
> \pdfoutline goto name {there}{\octal{Héhé}}
> 
> where \octal calls Lua to convert each character into \nnn, so that
> LuaTeX actually reads (the backslash has catcode 12):
> 
> \pdfoutline goto name {there}{\110\351\150\351}
> 
> which works fine, except the number are Unicode, which the PDF
> encoding doesn't follow exactly, so that I also need a mapping from
> Unicode to PDF encoding, and then octal.

If hyperref is loaded, you can use \pdfstringdef.
Otherwise package `stringenc' might help, PDFDocEncoding
and UTF-16 are supported. But I think I haven't
implemented big char support (chars with character code > 255
for LuaTeX and XeTeX) yet (it's done in hyperref). If this is
true, then the package might still help you at some conversion
steps.

> The other solution is UTF-16BE, which can't be fed directly to
> LuaTeX (you can't use \nnn to represent bytes). I.e you can't have:
> 
> \pdfoutline goto name {there}{\sixteen{Héhé}}
> 
> where \sixteen would return a string encoded in UTF-16BE, because
> LuaTeX will complain about non-utf-8 characters. You can do that
> directly in Lua, though, but there's no pdf.outline primitive:
> 
> pdf.outline(to_utf16("Héhé"))

You can still use \nnn, because this notation is restricted
to plain ASCII ('\', '0', ... '9'). Of course the \nnn are
used for bytes only.

Yours sincerely
  Heiko Oberdiek