Testing OpenType for Hebrew

[cunliffethompson]

I have developed a Hebrew font in OpenType  (called Hebrew Font Shuneet).

One way to gain insight into testing is to deliberately break it. The results are disturbing.
I removed all the lookups from my .VTP file and built the .OTF again.   The font displayed
Hebrew text very nicely including nikud!  ('nikud' = vowel points.)

I'm running VISTA and OOwriter and after installing my OpenType font with all the lookups removed, find
that it displays text with nikud much in the way a TrueType font does, for instance, nikud are placed under the
midline of the associated letter.

Why is this disturbing? Say my OpenType code has missed a letter-nikud combination then
on displaying the text on VISTA, the operating system might provide the TrueType default behavior
instead. I WOULD NEVER SEE THE OMISSION.

Now say we use this font on some unix or mac... will the same default behavior be there?

What is the best approach to dealing with this?  I don't have a mac or a unix machine for testing.
Mike

[tiro_hudson]

I believe the situation here is that if a Hebrew font does not contain OpenType layout features, then Microsoft uses an older layout engine which mechanically positions nikudot. So the potential problem you've identified shouldn't occur, because the older layout engine is only used if there is no OTL data in the font.

That, at least, is how I remember it working.

[cunliffethompson]

Thanks John,
I think you are right. What was happening was that I deleted all the lookups from the features. Then I put in one lookup with
deliberate and very obvious mistakes. On building an OTF file and displaying it, these mistakes did not appear. However
when the compilation took place an error message was displayed saying something like "Feature XXX has no lookup.  I took this
to be a warning but it seems it was a fatal message and the font file may have contained no OTF data or insufficient for
VISTA to recognize the file as an OTF.  The result was that it was treated as a TT file.

I have now successfully compiled the font with a conspicuous mistake which did appear in a word processor. Also the TT
positioning of nikud did NOT appear so I now know what the default looks like.  Nikud are simply placed on the border between Hebrew
characters.
Mike

[cunliffethompson]

My strategy up to now has been to add any conceivably useful lookup and if I come across any errors in
displayed text I just correct them which may involve adding another lookup. My current version of the
Hebrew Font Shuneet looks good with no obvious errors.

This reminds me of how once I worked in Artificial Intelligence programming. Such systems tended to be 'brittle'
as the real world always came up with situations that the programmer had not anticipated.

In OpenType programming I would like to be a bit systematic. Some lookups can mask the effect of others for instance
A          The composition rule:        shin  followed by dagesh    =  composite shinwithdagesh
means that the following rule will never be executed:
B          Mark positioning rule:      shin followed by dagesh

Currently I'm putting both into the code 'just in case'. The only problem is that there are a LOT of such cases.
In order to test rule B, I have to be sure that rule A is disabled.
Any suggestions?
Mike

[Typograph]

Mike, Did i not build for you a working prohect?

[cunliffethompson]

Dear "typograph",
Yes you did and if a search on the Web for "Michael Cunliffe Thompson Eliyahu Fried" will reveal
my acknowledgement of your help. Thanks Eli.  I offer seven Open Type fonts.

The topic of testing still concerns me and I will get back to it before I put out the next release.
I must accept that I couldn't have time or energy to test every possible Hebrew document to see if it
displays and prints without error and with good aesthetics. However there could be a set of tests
that should be applied to test a VOLT file to see it covers all possible valid keystroke input
and produces good output. 

Here is just one topic for testing:
shin shindot sheva dagesh.
shin shindot dagesh sheva
shin dagesh shindot sheva
shin dagesh sheva shindot 
shin sheva dagesh shindot
(and 13 more...)

When I last did testing I found that not all of the 18 sequences worked.
Some produced one or more dotted circles (U+25CC).
Should the software accept all 18 input sequences?  If my test software
fails then where does the fault lie, with vista, with VOLT, with Word or
with my VTX file?  I have control only over the contents of my VTX file.

Mike

[Typograph]

25CC = a dotted round circel.
You should delete the glyph and make sure the width is 0,
The foult lies with Win7/Vista

thats what i did with my fonts and they work great under Win7/Vista also on TAG 64Bit

[cunliffethompson]

Bizarre!   Thanks Eli

[Tags:]

Jump to: Please select a destination: ----------------------------- News and announcements ----------------------------- => Announcements from the forum’s moderators => News from the font industry ----------------------------- Type design and font technology ----------------------------- => Principles of type design => OpenType Layout feature development => Hinting => Font Formats and OpenType => Web font embedding => Font licensing ===> Electronic EULA Abstract (EEULAA) ----------------------------- Education and collaboration ----------------------------- => Work: Offers => Work: Looking for => Education: Offers => Education: Looking for => Typographic Events and Conferences ----------------------------- FontLab products ----------------------------- => News from FontLab => FontLab Studio ===> FontLab Studio Problems ===> FontLab Studio Tips and Tricks ===> FontLab Studio Wish List ===> FontLab Studio Public Preview => Fontographer ===> Fontographer Problems ===> Fontographer Wish List => TypeTool => AsiaFont Studio => TransType => ScanFont => SigMaker => Other Products ----------------------------- Photofont products ----------------------------- => BitFonter => Photofont WebReady => Photofont Start => Photofont ID => Photofont QX => The Photofont technology ----------------------------- Adobe Type products ----------------------------- => Adobe FDK for OpenType (AFDKO) ----------------------------- Apple Font products ----------------------------- => Apple Font Tools ----------------------------- Microsoft Typography products ----------------------------- => Microsoft Font Validator => Microsoft Visual OpenType Layout Tool (VOLT) => Microsoft Web Embedding Fonts Tool (WEFT) => Microsoft Visual TrueType (VTT) ----------------------------- Other products and Python scripting ----------------------------- => Python scripting => FontTools/TTX => Other font-related tools ----------------------------- Special interest groups ----------------------------- => SBL Fonts ===> SBL Hebrew ===> SBL Greek ===> SBL BibLit ----------------------------- FAQ and TechNotes ----------------------------- => OpenType Layout feature development FAQ and TechNotes => Hinting FAQ and TechNotes => Font Formats and OpenType FAQ and TechNotes => Web font embedding FAQ and TechNotes => Font licensing FAQ and TechNotes => FontLab Studio FAQ and TechNotes => Fontographer FAQ and TechNotes => TypeTool FAQ and TechNotes => AsiaFont Studio FAQ and TechNotes => TransType FAQ and TechNotes => ScanFont FAQ and TechNotes => SigMaker FAQ and TechNotes => BitFonter FAQ and TechNotes => Photofont WebReady FAQ and TechNotes => Photofont Start FAQ and TechNotes => Photofont ID FAQ and TechNotes => Photofont QX FAQ and TechNotes ----------------------------- Archive (MSN Groups) ----------------------------- => Archive: Old FontLab forum ===> Archive: FontLab Tips and Tricks ===> Archive: FontLab Bugs and Problems ===> Archive: FontLab Wish List ===> Archive: FontLab Announcements => Archive: Old Microsoft Font Validator group => Archive: Old Microsoft VOLT group => Archive: Old Microsoft VTT group ===> Archive: VTT Downloads ===> Archive: VTT Support ===> Archive: VTT Suggestions => Archive: Old Microsoft WEFT group ===> Archive: WEFT III ===> Archive: EOT for Email => Archive: Old SBL Fonts group ===> Archive: SBL Hebrew ===> Archive: SBL Greek ----------------------------- Various ----------------------------- => fontlab.com — the FontLab website => forum.fontlab.com — this forum => Other Topics