"Generate and Update OpenType Features" missing rlig

[בן של מלך]

This feature is the most useful for me.

צילום מסך 2023-12-01 133514.png (74.29 KiB) Viewed 13050 times

[Erwin Denissen]

What ligatures do you have in mind?

[LisanAlGaib]

Tag: 'rlig'

Friendly name: Required Ligatures

Registered by: Microsoft

Function: Replaces a sequence of glyphs with a single glyph which is preferred for typographic purposes. This feature covers those ligatures, which the script determines as required to be used in normal conditions. This feature is important for some scripts to insure correct glyph formation.

Example: The Arabic character lam followed by alef will always form a ligated lamalef form. This ligated form is a requirement of the script’s shaping. The same happens with the Syriac script.

Recommended implementation: Glyph sequences are mapped to a single, ligature glyph (GSUB lookup type 4). Note that, if multiple sequences have the same initial sub-sequence, substitutions for longer sequences should be stored ahead of those for shorter sequences.

Application interface: In recommended usage, this feature triggers substitutions required for correct display of certain scripts. It should be applied in the appropriate contexts, as determined by script-specific processing requirements.

UI suggestion: Control of this feature should not generally be exposed to the user.

Script/language sensitivity: Used for Arabic and Syriac. May also be used for other scripts.

Feature interaction: This feature may be used in combination with other substitution (GSUB) features, whose results it may override. See also 'liga'.

[Erwin Denissen]

We do not have enough knowledge to come up with a list, so it might be awesome if people could add to this:

Code: Select all

sub alef-arab lam-arab.init lam-arab.medi heh-arab.fina by allah-arab.isol;
sub lam-arab.init alef-arab.fina by lamalef-arab.isol;
sub lam-arab.medi alef-arab.fina by lamalef-arab.fina;

We will consider adding support for it as soon as the list is large enough.

[בן של מלך]

For me, rlig is a replacement for liga, I put everything I want in it that people won't change.
It is used for me in every font.