[luatex] strategy for margin kerning and pre_linebreak_filter?

[Patrick Gundlach]

Hello,

I have a question concerning margin kerning (\pdfprotrudechars) and  
pre_linebreak_filter.

When I define a font with right_protruding (\rpcode, see font table in  
manual p. 130) and using it as a TeX font, margin kerning is ok.

------------------------ example 1, works ok -------------------------
\directlua{
  local f = define_font("texgyreheros-regular.otf", "12pt")  -- sets  
right_protruding to a value > 0
  local num = font.define(f)
  tex.definefont("heros",num)
}
\heros
long paragraph with margin kerning (works fine)
----------------------------------------------------------------------



------------------------ example 2, does not work as expected --------
\directlua{
  local f = define_font("texgyreheros-regular.otf", "12pt")  -- same  
as above, sets rpcode > 0
  local num = font.define(f)

-- and now in pre_linebreak_filter I set for all glyphs the font code  
to the num above
}

\tenrm % some dummy font without rpcode
% no font switch to \heros!
long paragraph, the hyphen does not get into the margin! But all other  
glyphs I set the \rpcode for do.
----------------------------------------------------------------------

So the problem seems to be that when hyphenating the second paragraph,  
the hyphen will stick inside the paragraph. Am I missing something  
here? See also tracker item #274

Patrick