Add UI names for Stylistic Set / Character Variants features

src/opentype.js

@@ -345,6 +345,12 @@ function parseBuffer(buffer, opt) {
     if (gsubTableEntry) {
         const gsubTable = uncompressTable(data, gsubTableEntry);
         font.tables.gsub = gsub.parse(gsubTable.data, gsubTable.offset);
+        font.tables.gsub.features.forEach(f => {
+            if (f.tag.match(/ss(?:0[1-9]|1\d|20)/)) {
+                const { uiNameId } = f.feature.featureParamsTable;
+                f.feature.uiName = font.tables.name[uiNameId];
+            }
+        });
     }
 
     if (fvarTableEntry) {

src/parse.js

@@ -391,11 +391,16 @@ Parser.prototype.parseValueRecordList = function() {
     return values;
 };
 
-Parser.prototype.parsePointer = function(description) {
+Parser.prototype.parsePointer = function(description, storeOffset = false) {
     const structOffset = this.parseOffset16();
     if (structOffset > 0) {
         // NULL offset => return undefined
-        return new Parser(this.data, this.offset + structOffset).parseStruct(description);
+        const offset = this.offset + structOffset;
+        const struct = new Parser(this.data, offset).parseStruct(description);
+        if (storeOffset) {
+            struct.tableOffset = offset;
+        }
+        return struct;
     }
     return undefined;
 };
@@ -528,9 +533,9 @@ Parser.recordList32 = function(count, recordDescription) {
     };
 };
 
-Parser.pointer = function(description) {
+Parser.pointer = function(description, storeOffset = false) {
     return function() {
-        return this.parsePointer(description);
+        return this.parsePointer(description, storeOffset);
     };
 };
 
@@ -578,10 +583,17 @@ Parser.prototype.parseFeatureList = function() {
         feature: Parser.pointer({
             featureParams: Parser.offset16,
             lookupListIndexes: Parser.uShortList
-        })
+        }, true)
     })) || [];
 };
 
+Parser.prototype.parseFeatureParams = function() {
+    return this.parsePointer({
+        version: Parser.uShort,
+        uiNameId: Parser.uShort
+    }) || [];
+};
+
 Parser.prototype.parseLookupList = function(lookupTableParsers) {
     return this.parsePointer(Parser.list(Parser.pointer(function() {
         const lookupType = this.parseUShort();

src/tables/gsub.js

@@ -193,12 +193,20 @@ function parseGsubTable(data, start) {
     const tableVersion = p.parseVersion(1);
     check.argument(tableVersion === 1 || tableVersion === 1.1, 'Unsupported GSUB table version.');
     if (tableVersion === 1) {
-        return {
+        const table = {
             version: tableVersion,
             scripts: p.parseScriptList(),
             features: p.parseFeatureList(),
             lookups: p.parseLookupList(subtableParsers)
         };
+        table.features.forEach(f => {
+            if (f.tag.match(/ss(?:0[1-9]|1\d|20)/)) {
+                const p = new Parser(data, f.feature.tableOffset);
+                f.feature.featureParamsTable = p.parseFeatureParams();
+            }
+            delete f.feature.tableOffset;
+        });
+        return table;
     } else {
         return {
             version: tableVersion,

test/parse.js

@@ -208,9 +208,9 @@ describe('parse.js', function() {
                 '0000 0001 0000   0000 0002 0000 0001   0000 0003 0000 0001 0002';
             const p = new Parser(unhex(data), 0);
             assert.deepEqual(p.parseFeatureList(), [
-                { tag: 'liga', feature: { featureParams: 0, lookupListIndexes: [0] } },
-                { tag: 'liga', feature: { featureParams: 0, lookupListIndexes: [0, 1] } },
-                { tag: 'liga', feature: { featureParams: 0, lookupListIndexes: [0, 1, 2] } }
+                { tag: 'liga', feature: { featureParams: 0, lookupListIndexes: [0], tableOffset: 24 } },
+                { tag: 'liga', feature: { featureParams: 0, lookupListIndexes: [0, 1], tableOffset: 30 } },
+                { tag: 'liga', feature: { featureParams: 0, lookupListIndexes: [0, 1, 2], tableOffset: 38 } }
             ]);
             assert.equal(p.relativeOffset, 2);
         });