Support font-variant-ligatures values

The text style prop `fontVariant` in React Native is supposed to map
to the CSS `font-variant` property. The CSS property is a short-hand
for the following CSS properties:

- `[font-variant-alternates](https://developer.mozilla.org/en-US/docs/Web/CSS/font-variant-alternates)`
- `[font-variant-caps](https://developer.mozilla.org/en-US/docs/Web/CSS/font-variant-caps)`
- `[font-variant-east-asian](https://developer.mozilla.org/en-US/docs/Web/CSS/font-variant-east-asian)`
- `[font-variant-emoji](https://developer.mozilla.org/en-US/docs/Web/CSS/font-variant-emoji)`
- `[font-variant-ligatures](https://developer.mozilla.org/en-US/docs/Web/CSS/font-variant-ligatures)`
- `[font-variant-numeric](https://developer.mozilla.org/en-US/docs/Web/CSS/font-variant-numeric)`
- `[font-variant-position](https://developer.mozilla.org/en-US/docs/Web/CSS/font-variant-position)`

Currently React Native only supports a subset of the values from
`font-variant-numeric` and `font-variant-caps`.

This change increase the `font-variant` support by adding all values
from `font-variant-ligatures`.

- [Apple True Type Reference](https://developer.apple.com/fonts/TrueType-Reference-Manual/RM09/AppendixF.html)
- [Webkit Source Code](https://opensource.apple.com/source/WebCore/WebCore-7602.1.50.1.1/platform/graphics/cocoa/FontCacheCoreText.cpp)
- [MDN Documentation](https://developer.mozilla.org/en-US/docs/Web/CSS/font-variant-ligatures)
- [Android TextView Documentation](https://developer.android.com/reference/android/widget/TextView#setFontFeatureSettings(java.lang.String))

Author: finnp

packages/react-native/Libraries/StyleSheet/StyleSheetTypes.js

@@ -788,6 +788,14 @@ export type ____FontVariantArray_Internal = $ReadOnlyArray<
   | 'oldstyle-nums'
   | 'lining-nums'
   | 'tabular-nums'
+  | 'common-ligatures'
+  | 'no-common-ligatures'
+  | 'discretionary-ligatures'
+  | 'no-discretionary-ligatures'
+  | 'historical-ligatures'
+  | 'no-historical-ligatures'
+  | 'contextual'
+  | 'no-contextual'
   | 'proportional-nums'
   | 'stylistic-one'
   | 'stylistic-two'

packages/react-native/React/Views/RCTFont.mm

@@ -248,6 +248,38 @@ + (RCTFontVariantDescriptor *)RCTFontVariantDescriptor:(id)json
         UIFontFeatureTypeIdentifierKey : @(kNumberSpacingType),
         UIFontFeatureSelectorIdentifierKey : @(kProportionalNumbersSelector),
       },
+      @"common-ligatures" : @{
+        UIFontFeatureTypeIdentifierKey : @(kLigaturesType),
+        UIFontFeatureSelectorIdentifierKey : @(kCommonLigaturesOnSelector),
+      },
+      @"no-common-ligatures" : @{
+        UIFontFeatureTypeIdentifierKey : @(kLigaturesType),
+        UIFontFeatureSelectorIdentifierKey : @(kCommonLigaturesOffSelector),
+      },
+      @"discretionary-ligatures" : @{
+        UIFontFeatureTypeIdentifierKey : @(kLigaturesType),
+        UIFontFeatureSelectorIdentifierKey : @(kRareLigaturesOnSelector),
+      },
+      @"no-discretionary-ligatures" : @{
+        UIFontFeatureTypeIdentifierKey : @(kLigaturesType),
+        UIFontFeatureSelectorIdentifierKey : @(kRareLigaturesOffSelector),
+      },
+      @"historical-ligatures" : @{
+        UIFontFeatureTypeIdentifierKey : @(kLigaturesType),
+        UIFontFeatureSelectorIdentifierKey : @(kHistoricalLigaturesOnSelector),
+      },
+      @"no-historical-ligatures" : @{
+        UIFontFeatureTypeIdentifierKey : @(kLigaturesType),
+        UIFontFeatureSelectorIdentifierKey : @(kHistoricalLigaturesOffSelector),
+      },
+      @"contextual" : @{
+        UIFontFeatureTypeIdentifierKey : @(kContextualAlternatesType  ),
+        UIFontFeatureSelectorIdentifierKey : @(kContextualAlternatesOnSelector),
+      },
+      @"no-contextual" : @{
+        UIFontFeatureTypeIdentifierKey : @(kContextualAlternatesType),
+        UIFontFeatureSelectorIdentifierKey : @(kContextualAlternatesOffSelector),
+      },
       @"stylistic-one" : @{
         UIFontFeatureTypeIdentifierKey : @(kStylisticAlternativesType),
         UIFontFeatureSelectorIdentifierKey : @(kStylisticAltOneOnSelector),

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/views/text/ReactTypefaceUtils.java

@@ -85,6 +85,32 @@ public static int parseFontStyle(@Nullable String fontStyleString) {
           case "proportional-nums":
             features.add("'pnum'");
             break;
+          case "common-ligatures":
+            features.add("'liga'");
+            features.add("'clig'");
+            break;
+          case "no-common-ligatures":
+            features.add("'liga' off");
+            features.add("'clig' off");
+            break;
+          case "discretionary-ligatures":
+            features.add("'dlig'");
+            break;
+          case "no-discretionary-ligatures":
+            features.add("'dlig' off");
+            break;
+          case "historical-ligatures":
+            features.add("'hlig'");
+            break;
+          case "no-historical-ligatures":
+            features.add("'hlig' off");
+            break;
+          case "contextual":
+            features.add("'calt'");
+            break;
+          case "no-contextual":
+            features.add("'calt' off");
+            break;
           case "stylistic-one":
             features.add("'ss01'");
             break;