Re: [NTG-context] post_linebreak_filter in context

25 Feb 2011


      On 25-2-2011 12:28, Patrick Gundlach wrote:
...
Hi,
how do I install a custom post_linebreak_filter in ConTeXt? I have this LaTeX file:
------------------------------------------------------------------------------------
\documentclass[12pt,a4paper]{scrartcl}
\usepackage[english]{babel}
\usepackage{blindtext}
\usepackage{fontspec}
\directlua{
show_hyph = function(head)
   while head do
     if head.id == 0 or head.id == 1 then % hlist, vlist
       show_hyph(head.list) % should be head.head in a newer luatex than 0.64
     elseif head.id == 7 then             % disc
       local n = node.new("whatsit","pdf_literal")
       n.mode = 0
       n.data = "q 0.3 w 0 2 m 0 7 l S Q"
       n.next = head.next
       n.prev = head
       head.next = n
       head = n
     end
   head = head.next
   end
   return true
end
luatexbase.add_to_callback("post_linebreak_filter",show_hyph,"show_hyph")
}
\begin{document}
\begin{minipage}{5cm}
\blindtext
\end{minipage}
\end{document}
------------------------------------------------------------------------------------
which registers a function "show_hyph" as the post_linebreak_filter (the rest is not really interesting). How would I do this in ConTeXt?
first put the function in some namespace, like:

moduledata.mystuff = { }
moduledata.mystuff.show_hyph = show_hyph

then register it in the finalizer group (which is the post_linebreak stuff)

nodes.tasks.appendaction("finalizers","after","moduledata.mystuff.show_hyph")

(before and after are subgroups that can be used by users if needed; of 
course one never know to what extent it will influence other processes, 
so "shipouts","after" might be a better choice)

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