[XeTeX] Type0 fonts somehow not built correctly for Unicode text-extraction and Accessibility

[Ross Moore]

Hi all.

I think I’ve found a possible cause for this /ToUnicode  problem.
It’s with the way the  /CMapName  is constructed within the  CMap  resource itself,
at least when the font's name contains spaces.

See the attached image, where the window on the left is from a PDF constructed by XeLaTeX,
while the one on the right comes from the PDF/UA Association, and is properly valid.


[cid:26EE79DA-D1DD-4BDA-B30F-098631BE55E9 at telstra.com.au]


Because the space character is normally a delimiter, this is certainly invalid Postscript coding
to assign a value to  /CMapName .  So presumably it’s wrong in PDF too.
Surely the space needs to be encoded as #20 here?
The ‘.’ and ‘,’ are questionable. I think these are actually OK.


Changing the font to ‘Times’, the resulting PDF validates just fine.


Is it really a good idea to use the full path to the file, as the name here?
The PDF spec says it should be the name used in the file: viz.


CMapName


name


(Required) The name of the CMap. It shall be the same as the value of CMapName in the CMap file.




BTW, there was also an issue with Ghostscript, concerning the way  CMapName  is constructed.
see  https://bugs.ghostscript.com/show_bug.cgi?id=690114  .
There is was the  // at the start of the name that was questioned.
 dvipdfmx  seems to be encoding the directory delimiter as a `-` now.



On 6 Aug 2018, at 8:10 am, Ross Moore <ross.moore at mq.edu.au<mailto:ross.moore at mq.edu.au>> wrote:

There seems to be a subtle problem with the way subsetted Type0 fonts are built
by xdvipdfmx with XeLaTeX jobs, for the purposes of finding the /ToUnicode  resource.


So I cannot see why the /ToUnicode resource is not being found.

This error in naming is almost certainly the reason.


Cheers,

Ross


Dr Ross Moore

Mathematics Dept | 12 Wally’s Walk, 734
Macquarie University, NSW 2109, Australia

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