Latest OTS warns on some LTSH tables

[Dave Crossland]

https://github.com/khaledhosny/ots reports the following non-fatal errors:

ufl/ubuntu/Ubuntu-BoldItalic.ttf
ERROR: LTSH: bad num_glyphs: 1268
ERROR: LTSH: Table discarded

ufl/ubuntu/Ubuntu-LightItalic.ttf
ERROR: LTSH: bad num_glyphs: 1268
ERROR: LTSH: Table discarded

ufl/ubuntu/Ubuntu-Medium.ttf
ERROR: LTSH: bad num_glyphs: 1263
ERROR: LTSH: Table discarded

ufl/ubuntu/Ubuntu-MediumItalic.ttf
ERROR: LTSH: bad num_glyphs: 1268
ERROR: LTSH: Table discarded

[Mark Shuttleworth (sabdfl)]

Thanks Dave, is it a regression in the latest beta?

Mark

[Dave Crossland (davelab6)]

No, this is Version 0.80 as served by Google Fonts today. Where can I get the latest beta? :)

[Mark Shuttleworth (sabdfl)]

On 06/01/16 17:50, Dave Crossland wrote:
> No, this is Version 0.80 as served by Google Fonts today. Where can I
> get the latest beta? :)

I know a guy :)

[Paul Sladen (sladen)]

To reproduce:

$ wget http://font.ubuntu.com/download/ubuntu-font-family-0.83.zip && unzip ubuntu-font-family-0.83.zip
$ git clone <email address hidden>:khaledhosny/ots.git && cd ots
$ sed -i -e 's/std=c++11/std=c++0x/' Makefile.am
$ ./autogen.sh && ./configure && make
$ echo ../ubuntu-font-family-0.83/*.ttf | xargs -tn1 ./ot-sanitise
gg/ots/ot-sanitise gg/0.83/ubuntu-font-family-0.83/Ubuntu-BI.ttf
ERROR: LTSH: bad num_glyphs: 1268
ERROR: LTSH: Table discarded
gg/ots/ot-sanitise gg/0.83/ubuntu-font-family-0.83/Ubuntu-B.ttf
gg/ots/ot-sanitise gg/0.83/ubuntu-font-family-0.83/Ubuntu-C.ttf
gg/ots/ot-sanitise gg/0.83/ubuntu-font-family-0.83/Ubuntu-LI.ttf
ERROR: LTSH: bad num_glyphs: 1268
ERROR: LTSH: Table discarded
gg/ots/ot-sanitise gg/0.83/ubuntu-font-family-0.83/Ubuntu-L.ttf
gg/ots/ot-sanitise gg/0.83/ubuntu-font-family-0.83/Ubuntu-MI.ttf
ERROR: LTSH: bad num_glyphs: 1268
ERROR: LTSH: Table discarded
gg/ots/ot-sanitise gg/0.83/ubuntu-font-family-0.83/UbuntuMono-BI.ttf
gg/ots/ot-sanitise gg/0.83/ubuntu-font-family-0.83/UbuntuMono-B.ttf
gg/ots/ot-sanitise gg/0.83/ubuntu-font-family-0.83/UbuntuMono-RI.ttf
gg/ots/ot-sanitise gg/0.83/ubuntu-font-family-0.83/UbuntuMono-R.ttf
gg/ots/ot-sanitise gg/0.83/ubuntu-font-family-0.83/Ubuntu-M.ttf
ERROR: LTSH: bad num_glyphs: 1263
ERROR: LTSH: Table discarded
gg/ots/ot-sanitise gg/0.83/ubuntu-font-family-0.83/Ubuntu-RI.ttf
gg/ots/ot-sanitise gg/0.83/ubuntu-font-family-0.83/Ubuntu-R.ttf

[Paul Sladen (sladen)]

On Monday a 'Ubuntu_0.831.zip' was handed to me (initially without any content/context…); these have been processed by DM with 'ttx' to change the name-table mapping, but exhibit the same warning, so it's something flagging up beyond a rebuild:

$ echo ../Ubuntu_0.831/Ubuntu-*.ttf | xargs -tn1 ./ot-sanitise
./ot-sanitise ../Ubuntu_0.831/Ubuntu-BI.ttf
ERROR: LTSH: bad num_glyphs: 1268
ERROR: LTSH: Table discarded
./ot-sanitise ../Ubuntu_0.831/Ubuntu-B.ttf
./ot-sanitise ../Ubuntu_0.831/Ubuntu-C.ttf
./ot-sanitise ../Ubuntu_0.831/Ubuntu-LI.ttf
ERROR: LTSH: bad num_glyphs: 1268
ERROR: LTSH: Table discarded
./ot-sanitise ../Ubuntu_0.831/Ubuntu-L.ttf
./ot-sanitise ../Ubuntu_0.831/Ubuntu-MI.ttf
ERROR: LTSH: bad num_glyphs: 1268
ERROR: LTSH: Table discarded
./ot-sanitise ../Ubuntu_0.831/Ubuntu-M.ttf
ERROR: LTSH: bad num_glyphs: 1263
ERROR: LTSH: Table discarded
./ot-sanitise ../Ubuntu_0.831/Ubuntu-RI.ttf
./ot-sanitise ../Ubuntu_0.831/Ubuntu-R.ttf

[Dave Crossland (davelab6)]

On 6 January 2016 at 13:49, Paul Sladen <email address hidden> wrote:

> $ sed -i -e 's/std=c++11/std=c++0x/' Makefile.am
>

Does that need to be a PR upstream?

[Paul Sladen (sladen)]

And the test release/0.84 beta presently testing in X (but not in Google Fonts) :

$ COLUMNS=120 dpkg -l ttf-ubuntu-font-family | awk '{print $2,$3}' | tail -n1
ttf-ubuntu-font-family 0.84~mono0.83+arabicfont

$ dpkg -L ttf-ubuntu-font-family | grep '.ttf$' | xargs -tn1 ./ot-sanitise 2>&1 | sed -e 'sX/u.*/XX'
./ot-sanitise Ubuntu-RI.ttf
./ot-sanitise UbuntuMono-RI.ttf
./ot-sanitise Ubuntu-C.ttf
WARNING: glyf: 2-bytes indexing is not possible (due to the padding above)
./ot-sanitise Ubuntu-Arabic_B.ttf
ERROR: Layout: DFLT script doesn't satisfy the spec. LangSysCount is not zero: 15
ERROR: Layout: Failed to parse script table 0
ERROR: GPOS: Failed to parse script list table
Failed to sanitise file!
./ot-sanitise Ubuntu-BI.ttf
./ot-sanitise Ubuntu-MI.ttf
./ot-sanitise UbuntuMono-R.ttf
./ot-sanitise Ubuntu-Th.ttf
./ot-sanitise Ubuntu-B.ttf
./ot-sanitise Ubuntu-LI.ttf
./ot-sanitise Ubuntu-L.ttf
./ot-sanitise Ubuntu-Arabic_R.ttf
ERROR: Layout: DFLT script doesn't satisfy the spec. LangSysCount is not zero: 15
ERROR: Layout: Failed to parse script table 0
ERROR: GPOS: Failed to parse script list table
Failed to sanitise file!
./ot-sanitise Ubuntu-R.ttf
./ot-sanitise UbuntuMono-BI.ttf
./ot-sanitise UbuntuMono-B.ttf
./ot-sanitise Ubuntu-M.ttf

First is gone, but different warnings!

[Dave Crossland (davelab6)]

On 6 January 2016 at 14:03, Paul Sladen <email address hidden> wrote:

> First is gone, but different warnings!
>

These are much worse :(

[Dave Crossland (davelab6)]

If you "ttx -s font.ttf" then font.G_S_U_B_.ttx you'll see something like,

<?xml version="1.0" encoding="UTF-8"?>
<ttFont ttLibVersion="3.0">

  <GSUB>
    <Version value="1.0"/>
    <ScriptList>
      <!-- ScriptCount=1 -->
      <ScriptRecord index="0">
        <ScriptTag value="DFLT"/>
        <Script>
          <DefaultLangSys>
            <ReqFeatureIndex value="65535"/>
            <!-- FeatureCount=4 -->
            <FeatureIndex index="0" value="0"/>
            <FeatureIndex index="1" value="1"/>
            <FeatureIndex index="2" value="2"/>
            <FeatureIndex index="3" value="4"/>
          </DefaultLangSys>
          <!-- LangSysCount=1 -->
          <LangSysRecord index="0">
            <LangSysTag value="TRK "/>
            <LangSys>
              <ReqFeatureIndex value="65535"/>
              <!-- FeatureCount=1 -->
              <FeatureIndex index="0" value="3"/>
            </LangSys>
          </LangSysRecord>
        </Script>

This is wrong, in that it contains actual LangSysRecords in the DFLT script. According to the spec at https://www.microsoft.com/typography/otspec/chapter2.htm:

"If a Script table with the script tag 'DFLT' (default) is present in the ScriptList table, it must have a non-NULL DefaultLangSys and LangSysCount must be equal to 0."

Therefore you can removed those lines, making the top of the file as follows

<?xml version="1.0" encoding="UTF-8"?>
<ttFont ttLibVersion="3.0">

  <GSUB>
    <Version value="1.0"/>
    <ScriptList>
      <!-- ScriptCount=1 -->
      <ScriptRecord index="0">
        <ScriptTag value="DFLT"/>
        <Script>
          <DefaultLangSys>
            <ReqFeatureIndex value="65535"/>
            <!-- FeatureCount=4 -->
            <FeatureIndex index="0" value="0"/>
            <FeatureIndex index="1" value="1"/>
            <FeatureIndex index="2" value="2"/>
            <FeatureIndex index="3" value="4"/>
          </DefaultLangSys>
          <!-- LangSysCount=0 -->
        </Script>

And that will hot-fix it.

[Paul Sladen (sladen)]

@Dave, Re #6 above; I was for a few minutes pondering doing an Automake macro to detect the gcc version and use 'std=c++0x' for gcc versions < 4.7 from before the C++ standard was ratified and to use 'std=c++11' on more recent gcc, but I fear that's going to be time-consuming—although perhaps I could do a PR to the documentation to at least mention it.

[Paul Sladen (sladen)]

@Dave, Re: #9; that has come out of DM's latest workflow/build-path, so (hopefully) DM might have an interest in deploying a fix upstream; if not, then the before/after above is enough to write a fixer/patcher; and as it is the 'Ubuntu-Arabic' split could work better and one possibility is sticking two sets o numerals in along with OT locale overrides for Arabic.