Contextual substitution bug

[Dan]

If a font save as '.otf', then all features with contextual substitution have in addition unnecessary glyph .notdef

And if I insert, for example, feature ORDN (with context. subst.) with the glyph group [zero.slashed zero one two three four five six seven eight nine zero.tab one.tab two.tab three.tab four.tab five.tab six.tab seven.tab eight.tab nine.tab], then in font (.otf file) we have unnecessary glyph .notdef and only this glyphs: nine zero.tab one.tab two.tab three.tab four.tab five.tab six.tab seven.tab eight.tab nine.tab

[Allan Murray]

Can you please post your full ORDN script so I can test. Thanks.

[Dan]

languagesystem DFLT dflt;
languagesystem latn dflt;

@numbrs = [zero.slashed zero one two three four five six seven eight nine zero.tab one.tab two.tab three.tab four.tab five.tab six.tab seven.tab eight.tab nine.tab];

feature ordn {

sub @numbrs a' by ordfeminine;
sub @numbrs A' by ordfeminine;
sub @numbrs o' by ordmasculine;
sub @numbrs O' by ordmasculine;

} ordn;

feature ordn {

sub @numbrs s' t' by ST.ord;
sub @numbrs n' d' by ND.ord;
sub @numbrs S' T' by ST.ord;
sub @numbrs N' D' by ND.ord;
sub @numbrs S' t' by ST.ord;
sub @numbrs N' d' by ND.ord;
sub @numbrs s' T' by ST.ord;
sub @numbrs n' D' by ND.ord;

} ordn;


And this we have after 'save as .otf' :

[Allan Murray]

What application are you using there to examine the feature tables?

I used your ORDN .feax script in a test font (with all the required glyphs present) and the output font seems to be fine.

I am using DTL OTMaster Light to examine the output tables (which is a very useful free application for doing this, by the way) fontmaster.nl/


Couple of thoughts:
- Are you also including other .feax features? As a test, try outputting with just the ORDN to eliminate the possibility of interference/overflow from the other features.
- Have you tried the output font in InDesign or other application to see if the features are actually working?


P.S. Another really good application for testing OpenType features is TrueTypeViewer ( home.kabelfoon.nl/~slam/fonts/truetypeviewer.html ).
Only works with TrueType (.ttf) fonts though.

[Allan Murray]

OK I figured out that you are using FontForge to check the tables.

I compared the glyphs shown in the coverage table between FontForge and OTMMaster Light, and it appears that FontForge is not displaying all of the glyphs:




I will do some further checks with Type 3.2 (specifically the output structure of the coverage table), but I think this appears to be a FontForge issue?

UPDATE: I have identified a small error in the output of the coverage table for contextual lookups. This was not apparent in DTL OTMaster Light, TrueTypeViewer and does not even appear to affect the operation of the font (in InDesign etc). But has shown up in FontForge (note that the glyphs are actually in the coverage table, but some index values are incorrect). I will issue an update asap.

[Allan Murray]

This has been resolved in version 3.2.043 update today (20 June 2017).

[Dan]

I did not respond quickly, sorry.
Yes, I used FontForge to test Lookups Tables. Yes, I included only one ORDN features in the OTF file. In InDesign this feature working correctly.
I used DTL OTMaster Light (an excellent program for testing; thanks for the recommendation!) to test this my OTF file and I got exactly the same results as you did.

[Dan]

Thanks, updated today version 3.2.043 works fine. All contextual tables in FontForge are displayed correctly.