[NTG-pdftex] [ pdftex-Feature Requests-715 ] highlight ligatures

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Tue Nov 13 11:37:51 CET 2007


Feature Requests item #715, was opened at 2006-12-22 09:48
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Category: Fonts
Group: v1.50
Status: Open
Resolution: None
Priority: 3
Submitted By: Uli Laube (ulilaube)
Assigned to: Hartmut Henkel (hhenkel)
Summary: highlight ligatures

Initial Comment:
Hello!

>From time to time people in de.comp.text.tex ask for a
solution to remove ligatures from german words
automatically. As this requires quite some knowledge of
the morphology of the german language, packages like 
rmligs  or  ligatex  use lists of words to remove
unwanted ligatures. As this depends on the ligatures
available in the font used, it is quite troublesome to
the compile the lists.

I'am proposing the following addtion to be incorporated
into pdftex: highlighting of the ligatures.

If enabled pdftex uses a bold version of the font when
it inserts ligatures in normal text and vice versa.
Like /em and /emph work for italic text. This would
allow the user of pdftex to prepare a draft copy of the
document were all ligatures are highlighted and can be
easily spotted. The user can then insert "| manually to
remove the unwanted ligatures.

Kind Regards and Happy Holidays

Uli Laube

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>Comment By: Hans Hagen (hagen)
Date: 2007-11-13 10:37

Message:
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this feature does not belong in pdftex (one can implement it
in luatex if needed); proper implementation of such features
involves additional font definitions i.e. a bold (or
whatever variant) for each (!) defined font



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Comment By: Uli Laube (ulilaube)
Date: 2006-12-22 13:12

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Highlighting the ligatures would only be necessary in a
draft copy. Then one would insert the "| in the appropriate
places and disable the highlighting. A change in paragraph
breaking is acceptable in my opinion as I would not want to
distribute the version with highlighted ligatures.

Changing the font color is a nice idea. But it would require
an extra virtual font for every font used in the document as
they might have different ligatures. Seems to me, that I
have to learn how to write .vlp files :)

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Comment By: Hartmut Henkel (hhenkel)
Date: 2006-12-22 13:08

Message:
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...an example .vpl file with colorchange command:

(CHARACTER O 2
   (CHARWD R 0.777781)
   (CHARHT R 0.683332)
   (MAP
      (SPECIAL pdf:direct: 0.486 0.104 0.291 rg)
      (SETCHAR O 2)
      (SPECIAL pdf:direct: 0 0 0 rg)
      )
   )

Regards, Hartmut

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Comment By: Hartmut Henkel (hhenkel)
Date: 2006-12-22 12:55

Message:
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For highlighting a boldface font is needed that has the same
metrics as the non-highlighted one, to keep paragraph
breaking unchanged.

What you can do right now is to generate a virtual font that
contains colored ligatures! It is in fact possible to add
PDF color change command specials into the .vpl virtual
property list files of the virtual font, These commands will
then be inserted into the PDF page stream in front of the
glyphs.

But also some solution on engine level should be doable.

Regards, Hartmut

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Comment By: Uli Laube (ulilaube)
Date: 2006-12-22 10:22

Message:
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If a document uses different fonts, they might have
different ligatures available. The special font and the
macro packages might not be aware of this. As far as I know,
the insertion of ligatures happens late when the .dvi oder
.pdf is created. My hope is that switching to the bold
version of the font when a ligature is inserted might be a
way to have this feature work for all fonts. 

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Comment By: Frank Küster (frank)
Date: 2006-12-22 10:08

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Since ligatures are inserted according to information in the
fonts, I think this should be implemented as a combination
of a special font (which uses noticeably different glyphs
for ligatures), and a macro package that switches fonts.

----------------------------------------------------------------------

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