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OpenType Feature & Lookup Test Font

Posted: Mon Oct 09, 2017 8:29 pm
by Stephan B.
I am working on a text layout and rendering tool for a game engine. Currently, I am adding support for OpenType features and curious to know if anyone knows of a font file designed for testing each of the various lookup types and table formats?

Re: OpenType Feature & Lookup Test Font

Posted: Mon Oct 09, 2017 10:03 pm
by Bhikkhu Pesala
There are hundreds of OpenType features. Which do you need to use in your Application? You can test any font from FontCreator in a suitable browser using the Webfont test.

Re: OpenType Feature & Lookup Test Font

Posted: Tue Oct 10, 2017 7:48 am
by Stephan B.
I am looking for a font file that would include 1 example of each subtable type and related formats. Ie. (1) SingleSubstitution format 1 and format 2, (1) MultipleSubstitution, etc. Font would also include use of coverage table format 1 and format 2.

Although I can find font files that contains examples / use of some of these, I still have to hunt / go through several fonts to find ones that use the specific subtable and format that I seek to implement / test.

I am curious if someone might have created such a font file just for testing their own tools for reading these different subtable types and formats.

Re: OpenType Feature & Lookup Test Font

Posted: Tue Oct 10, 2017 12:54 pm
by Erwin Denissen
We are not aware of such fonts, but finding correct fonts is the easy part.

Over the years we've found numerous fonts with unique issues due to unique implementations of the specs. There is no way to create all variations of such fonts, as some issues depend on the order of data, or is corrupt, etc. Several widely used fonts still contain serious flaws, but such issues are ignored and undocumented.

Re: OpenType Feature & Lookup Test Font

Posted: Tue Oct 10, 2017 10:21 pm
by Stephan B.
Thanks for the reply.

A few more questions if I may.

I have noticed that many fonts use a Coverage table format 2 where the startGlyphID and endGlyphID for the range is the same. Why use format 2 in this case? Is this some legacy issue?

When I create Ligatures using FontCreator and check the coverage table, I always seem to get format 1. How can I go about creating lookup that end up using Coverage format 2 or does FontCreator only use / create Coverage table of format 1?