[NTG-pdftex] [PATCH v4] Allow .enc files for bitmap PK fonts

Hans Hagen pragma at wxs.nl
Fri Dec 15 20:47:30 CET 2017


On 12/15/2017 7:12 PM, Pali Rohár wrote:
> On Friday 15 December 2017 17:13:22 Karl Berry wrote:
>> (Sorry for the delayed reply.)
>>
>>      Date: Sat, 19 Aug 2017 16:02:17 +0200
>>      From: Pali Rohár <pali.rohar at gmail.com>
>>      Subject: [PATCH v4] Allow .enc files for bitmap PK fonts
>>
>> Thanks for splitting the patch into those separate pieces, Pali, and
>> doing the test and documentation updates. Very helpful. Reading through
>> the changes, they generally look fine.
>>
>> My only question at the moment is, why do duplicate glyph names have to
>> be removed in advance (in patch 3)? Otherwise we'll try to put two
>> glyphs by the same (PostScript/PDF) name in the output font? Or
>> something else? --thanks, karl.
> 
> Hi! Glyph names are put into /Differences PDF table and also glyphs
> itself are identified in PDF by its names. So we cannot have two
> different glyphs in PDF file with same name.

Where does the pdf standard mention that limitation? Why should glyph 
names be unique? If there is some nencoding issue it more looks like 
there is a shared Differences related dictionary / array that should not 
be shared

> Function remove_duplicate_glyph_names() just remove duplicate glyph
> names from enc file and later function writet3() for glyph index uses
> either glyph name or if is not available (e.g. because of duplicates),
> then it use name "a<glyph_index>" (like before). This ensures that every
> glyph has a unique name in PDF file.
> 
> If you comment that remove_duplicate_glyph_names() then you would see
> what happen. pdftex would not be able to create PDF file with two
> different glyphs with same name and would store just one glyph. That
> would result in damaged PDF font, one glyph would be used for all
> characters which had associated that one glyph name in enc file.
> Probably it would be the glyph with highest index.

> Test case for reproducing should be easy:
> 
> File my.enc:
> ============
> /my [
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef
> /mychar /mychar
> /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef
> ] def
> ============

Ok, but that is not related to pdf (as format) but to a bad vector 
and/or pdftex not taking the right one ... is messing around with names 
(thereby obscuring the problem) better than fixing the enc file? After 
all, now one of the glyphs will still have the wrong name.

> File test.tex:
> ============
> \pdfglyphtounicode{mychar}{269}
> \pdfgentounicode=1
> \pdfmapline{cmb10 <my.enc}
> \font\cmb=cmb10
> \cmb
> a b
> \bye
> ============
> 
> And result PDF file would not render glyph 'a' if function
> remove_duplicate_glyph_names() is disabled. There would be two glyphs 'b'.
> 


-- 

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