Variable Features Investigation

This repository has a collection of test fonts and test documents using those fonts, to check how various applications apply OpenType Feature Variations attached to the features rvrn, rclt, and rlig.

Fonts

The test fonts are located in fonts/ and should be installed on your system before viewing most of the test documents.

Test documents

Test documents are in the folder test files/.

The HTML document, test.htm, is intended to check the behaviour of web browsers. It also serves as the reference of expected visual output, if checked in Chrome, which passes all the tests.

The other documents were created in the respective applications, and checked against that reference.

Scenarios

S1: Basic substitution based on axis value

1. The glyph for b switches to the glyph for 2 from wght=500 to wght=734.

Processing sequence	Input	Expected Output
(b → 2)	abc	a2c

Where (b → 2) is done by either the rvrn, rclt or rlig features.

S2: Basic substitution based on axis value + basic feature substitution

1. The glyph for b switches to the glyph for 2 from wght=500 to wght=734.
2. The glyph for b switches to the glyph b.sc when smcp is activated
3. The glyph for 2 switches to the glyph for ² when sups is activated

Processing sequence	Input	Expected Output
smcp + (b → 2)	abc 123	ABC 123
smcp + sups + (b → 2)	abc 123	ABC ¹²³
(b → 2) + smcp	abc 123	A2C 123
(b → 2) + smcp + sups	abc 123	A²C ¹²³

Where (b → 2) is done by either the rvrn, rclt or rlig features, and capital letters represent small-cap letters in the output.

S3: Contextual substitution based on axis value

1. The glyph for b, when followed by d, switches to the glyph for 2 from wght=500 to wght=734

Processing sequence	Input	Expected Output
(bd → 2d)	abc abd	abc a2d

Where (bd → 2d) is done by either the rvrn, rclt or rlig features.

S4: Contextual substitution based on axis value + basic feature substitution

1. The glyph for b, when followed by d, switches to the glyph for 2 from wght=500 to wght=734
2. The glyph for b switches to the glyph b.sc when smcp is activated
3. The glyph for 2 switches to the glyph for ² when sups is activated

Processing sequence	Input	Expected Output
smcp + (bd → 2d)	abc abd 123	ABC ABD 123
smcp + sups + (bd → 2d)	abc abd 123	ABC ABD ¹²³
(bd → 2d) + smcp	abc abd 123	ABC A2D 123
(bd → 2d) + smcp + sups	abc abd 123	ABC A²D ¹²³

Where (bd → 2d) is done by either the rvrn, rclt or rlig features, and capital letters represent small-cap letters in the output.

S5: Basic substitution based on multiple axes value

1. The glyph for b switches to the glyph for 2 from wght=500 to wght=734 and wdth=80 to wdth=85.

Processing sequence	Input	Expected Output
(b → 2)	abc	a2c

Where (b → 2) is done by either the rvrn, rclt or rlig features.

Results

	Scenario and Implementation		S1: rvrn	S1: rlig	S1: rclt	S2: rvrn + smcp/sups	S2: rlig + smcp/sups	S2: rclt + smcp/sups	S2: smcp/sups + rlig	S2: smcp/sups + rclt	S3: rvrn	S3: rlig	S3: rclt	S4: rvrn + smcp/sups	S4: rlig + smcp/sups	S4: rclt + smcp/sups	S4: smcp/sups + rlig	S4: smcp/sups + rclt	S5: rvrn	S5: rlig	S5: rclt
	Font file name		basic-substitution-rvrn.ttf	basic-substitution-rlig.ttf	basic-substitution-rclt.ttf	basic-substitution-plus-feature-rvrn.ttf	basic-substitution-plus-feature-rlig-feature-last.ttf	basic-substitution-plus-feature-rclt-feature-last.ttf	basic-substitution-plus-feature-rlig-feature-first.ttf	basic-substitution-plus-feature-rclt-feature-first.ttf	contextual-substitution-rvrn.ttf	contextual-substitution-rlig.ttf	contextual-substitution-rclt.ttf	contextual-substitution-plus-feature-rvrn.ttf	contextual-substitution-plus-feature-rlig-feature-first.ttf	contextual-substitution-plus-feature-rclt-feature-first.ttf	contextual-substitution-plus-feature-rlig-feature-last.ttf	contextual-substitution-plus-feature-rclt-feature-last.ttf	wgwd-rvrn.ttf	wgwd-rlig.ttf	wgwd-rclt.ttf
	Font family name		TEST Basic rvrn	TEST Basic rlig	TEST Basic rclt	TEST Basic rvrn plus feature	TEST Basic rlig plus feature last	TEST Basic rclt plus feature last	TEST Basic rlig plus feature first	TEST Basic rclt plus feature first	TEST Contextual rvrn	TEST Contextual rlig	TEST Contextual rclt	TEST Contextual rvrn plus feature	TEST Contextual rlig plus feature first	TEST Contextual rclt plus feature first	TEST Contextual rlig plus feature last	TEST Contextual rclt plus feature last	TEST WgWd rvrn	TEST WgWd rlig	TEST WgWd rclt
Mac	Chrome 145.0.7632.110		Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
	Safari26.2 (21623.1.14.11.9)		Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	No ②	Yes	Yes	No ②	Yes	Yes	Yes	Yes	Yes	Yes	Yes
	Figma 126.1.2		Yes	Yes	Yes	Partial ⑤	Partial ⑤	Partial ⑤	Partial ④	Partial ④	Yes	Yes	Yes	Partial ⑤	Partial ⑤	Partial ⑤	Partial ④	Partial ④	Yes	Yes	Yes
	Adobe InDesign 21.2	Adobe composer	Yes	Yes	No ②	Yes	Yes	No ②	Yes	Yes ⑥	Yes	Yes	No ②	Yes	Yes	No ②	Yes	Yes ⑥	Yes	Yes	No ②
		World-Ready	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
	Adobe Photoshop 27.4.0	Latin and East Asian Layout	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
		World-Ready Layout	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
	Adobe Illustrator 30.2.1	Adobe composer	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
		Middle Eastern & South Asian	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Windows	Chrome 145.0.7632.110		Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
	Figma 126.1.2		Yes	Yes	Yes	Partial ⑤	Partial ⑤	Partial ⑤	Partial ④	Partial ④	Yes	Yes	Yes	Partial ⑤	Partial ⑤	Partial ⑤	Partial ④	Partial ④	Yes	Yes	Yes
	Adobe InDesign 21.2	Adobe composer	Yes	Yes	No ②	Yes	Yes	No ②	Yes	Yes ⑥	Yes	Yes	No ②	Yes	Yes	No ②	Yes	Yes ⑥	Yes	Yes	No ②
		World-Ready	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
	Adobe Photoshop 27.4.0	Latin and East Asian Layout	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
		World-Ready Layout	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
	Adobe Illustrator 30.2.1	Adobe composer	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
		Middle Eastern & South Asian	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Linux	Chromium 145.0.7632.75		Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes

Issues

① Variable substitution is performed before other features when it should be performed after:

② Variable substitution is not performed:

③ Variable substitution is performed after other features, when it should be performed before:

④ Figma uses faux superscript instead of the OpenType feature substitution:

⑤ Superscript feature undoes the variable substitution (probably related to ④):

⑥ Because the axis substitution is performed at the end, the expected result is the same as not having the feature substitution: