[Bug 1824260] Re: wrong kerning in SS-5 PDF form fields

Tue Oct 27 11:21:23 UTC 2020

The following config would be better than the one I proposed earlier:

    <alias binding="same">
      <family>CourierStd</family>
      <accept>
      <family>Courier</family>
      </accept>
    </alias>

    <alias>
      <family>CourierStd</family>
      <default><family>monospace</family></default>
    </alias>

I submitted a request to fontconfig:

    https://gitlab.freedesktop.org/fontconfig/fontconfig/-/issues/262

-----

What one person considers sane isn't necessarily so.
*Assuming* sane defaults isn't really sensible.

Here are some examples, not directly related to the issue at hand:

  * In a "sane" configuration, we'd expect a list of monospace fonts 
    when requesting the generic monospace font family.  Similarly for 
    the generic serif and sans-serif families.  However, the following 
    commands show that fonts of all three types are included in all of 
    the generic families.

       fc-match -s monospace
       fc-match -s sans-serif
       fc-match -s serif

    Normally, it doesn't cause problems because fonts of the right 
    type are at the beginning of the list.  However, if a specific font 
    is requested, an obviously incorrect substitution can be made 
    (eg, sans-serif font shown when serif was requested) because fonts 
    of all types are in all of the lists.

	 Maybe developers in the past thought it was fine because some 
	 config further along could be assumed to have sane defaults?  
	 Or maybe they thought it was just a theoretical problem that 
	 wouldn't ever occur?  But it's not just theoretical. I have 
	 encountered real issues, which is why I know of it at all.

  * Many people believe that if they request a font that isn't 
    installed, Ubuntu will substitute a font it "thinks" looks 
    similar.  They don't realize that it has to be defined in the 
    config files.

    So if they request a font that's not defined, like CourierStd, 
    Ubuntu will fallback to sans-serif, even though every human 
    immediately knows the Courier substitutions should be used – 
    and that would be the sane default.  But here, we're explicitly 
    deciding *not* to, even knowing there is a theoretical risk of 
    problematic substitutions in the future.

** Bug watch added: gitlab.freedesktop.org/fontconfig/fontconfig/-/issues #262
   https://gitlab.freedesktop.org/fontconfig/fontconfig/-/issues/262

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https://bugs.launchpad.net/bugs/1824260

Title:
  wrong kerning in SS-5 PDF form fields

Status in Poppler:
  New
Status in fontconfig package in Ubuntu:
  In Progress

Bug description:
  What I expected to happen:

  I am filling out the SS-5 Social Security Administration form (see
  attached). I entered "John Jacob Smith" into the "First", "Full Middle
  Name", and "Last" fields on page 5.

  What happened instead:

  I can enter the text without issue, but some of the letters are
  wrongly positioned, i.e. the kerning is wrong. For example, the letter
  "i" overlaps with the letter "m" in "Smith" (see attached image). It
  looks like the font in the fields might be displaying a variable width
  font when it is supposed to be a fixed-wdith font.

  Discussion:

  Since this bug is also present in xpdf and Okular (but not mupdf), I'm
  guessing this isn't a bug in Evince itself. However, I am reporting it
  here as a courtesy to other users (since Evince is the default PDF
  reader) and because I'm not sure which dependency is responsible. (I'm
  also not sure if it's a direct dependency problem or if it's something
  else like a font configuration issue.)

  Here is the output for pdffonts ss-5.pdf:

  name                                 type              encoding         emb sub uni object ID
  ------------------------------------ ----------------- ---------------- --- --- --- ---------
  IHPIKC+ArialMT                       CID TrueType      Identity-H       yes yes yes    824  0
  ArialMT                              TrueType          WinAnsi          no  no  no     826  0
  Arial-BoldMT                         TrueType          WinAnsi          no  no  no     828  0
  CourierStd                           Type 1            WinAnsi          no  no  no     145  0
  Helvetica                            Type 1            WinAnsi          no  no  no     197  0
  MyriadPro-Regular                    Type 1            WinAnsi          no  no  no     198  0
  ZapfDingbats                         Type 1            ZapfDingbats     no  no  no     199  0

  I asked about this in an Ask Ubuntu question nearly a year ago, but
  received no response, so I am reporting a bug now instead:

  https://askubuntu.com/questions/1031235/wrong-letter-positioning-and-
  font-in-pdf-form

  Ubuntu version:

  Description:	Ubuntu 18.04.2 LTS
  Release:	18.04

  evince version:

  $ apt-cache policy evince
  evince:
    Installed: 3.28.4-0ubuntu1
    Candidate: 3.28.4-0ubuntu1
    Version table:
   *** 3.28.4-0ubuntu1 500
          500 http://us.archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages
          100 /var/lib/dpkg/status
       3.28.2-1 500
          500 http://us.archive.ubuntu.com/ubuntu bionic/main amd64 Packages

  ProblemType: Bug
  DistroRelease: Ubuntu 18.04
  Package: evince 3.28.4-0ubuntu1
  ProcVersionSignature: Ubuntu 4.15.0-47.50-generic 4.15.18
  Uname: Linux 4.15.0-47-generic x86_64
  ApportVersion: 2.20.9-0ubuntu7.6
  Architecture: amd64
  CurrentDesktop: KDE
  Date: Wed Apr 10 21:27:11 2019
  InstallationDate: Installed on 2018-12-12 (119 days ago)
  InstallationMedia: Kubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
  SourcePackage: evince
  UpgradeStatus: No upgrade log present (probably fresh install)

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