⚡️ Add support for mapping non-ligature glyphs

gsub.js

@@ -1,6 +1,4 @@
 const xpath = require('xpath');
-//const { XMLSerializer } = require('xmldom');
-//const format = require('xml-formatter');
 const NodeType = {};
 NodeType.TEXT_NODE = 3;
 
@@ -15,9 +13,23 @@ let chainIndex = 0;
 const substLookupMap = {};
 
 const buildGsubTables = (_dom, ligature) => {
-  const glyphs = ligature.name.replace(/\.liga$/, '').split('_');
-
   dom = _dom;
+
+  if (/_/.test(ligature.glyph) === false) {
+    // not a ligature, so see if glyph exists in font (as substitute)
+    const glyphNode = xpath.select(
+      `ttFont/GlyphOrder/GlyphID[@name="${ligature.name}"]`,
+      dom,
+      true
+    );
+    if (!glyphNode) {
+      return;
+    }
+  }
+
+  const glyphs = ligature.name.replace(/\.liga$/, '').split('_');
+  const isSingleGlyph = glyphs.length == 1;
+
   gsubDom = xpath.select('ttFont/GSUB', dom, true);
 
   // look for 'calt' feature
@@ -62,12 +74,10 @@ const buildGsubTables = (_dom, ligature) => {
   });
   appendChildren(
     lookupDom,
-    createElementWithAttributes('LookupType', { value: 6 }),
+    createElementWithAttributes('LookupType', { value: isSingleGlyph ? 1 : 6 }),
     createElementWithAttributes('LookupFlag', { value: 0 })
   );
 
-  lookupListDom.appendChild(lookupDom);
-
   // add contextual lookup to feature
   const featureLookupCount = xpath.select(
     'count(LookupListIndex)',
@@ -81,6 +91,11 @@ const buildGsubTables = (_dom, ligature) => {
     })
   );
 
+  if (isSingleGlyph) {
+    lookupDom.appendChild(
+      getSubstLookup(ligature.name, ligature.glyph, lookupDom)
+    );
+  } else {
     lookupDom.appendChild(buildBacktrackFirst(glyphs));
     lookupDom.appendChild(buildLookAheadLast(glyphs));
     lookupDom.appendChild(buildLigatureSubst(glyphs, ligature.glyph));
@@ -90,6 +105,8 @@ const buildGsubTables = (_dom, ligature) => {
         buildChainContext(getLIGs(n), [glyphs[n]], glyphs.slice(n + 1), 'LIG')
       );
     }
+  }
+  lookupListDom.appendChild(lookupDom);
 };
 
 const finalizeGsubTables = () => {
@@ -97,9 +114,8 @@ const finalizeGsubTables = () => {
   let newIndex = xpath.select('count(Lookup)', lookupListDom, true);
 
   // append added lookups
-  Object.entries(substLookupMap).forEach(lookupEntry => {
+  Object.entries(substLookupMap).forEach(([key, lookup]) => {
     // fixup existing lookups with new index
-    const lookup = lookupEntry[1];
     const oldIndex = lookup.getAttribute('index');
     const substLookups = xpath.select(
       `//ChainContextSubst/SubstLookupRecord/LookupListIndex[@value="${oldIndex}"]`,
@@ -212,8 +228,10 @@ const buildCoverage = (chainDom, tagName, coverage) => {
   }
 };
 
-const getSubstLookup = (input, output) => {
-  let lookupDom = substLookupMap[output];
+const getSubstLookup = (input, output, lookupDom) => {
+  if (!lookupDom) {
+    lookupDom = substLookupMap[output];
+  }
 
   if (!lookupDom) {
     lookupDom = createElementWithAttributes('Lookup', {
@@ -225,12 +243,18 @@ const getSubstLookup = (input, output) => {
     lookupDom.appendChild(
       createElementWithAttributes('LookupFlag', { value: 0 })
     );
-    lookupDom.appendChild(
-      createElementWithAttributes('SingleSubst', { index: 0, Format: 2 })
-    );
     substLookupMap[output] = lookupDom;
   }
-  const singleSubstDom = xpath.select('SingleSubst', lookupDom, true);
+
+  let singleSubstDom = xpath.select('SingleSubst', lookupDom, true);
+
+  if (!singleSubstDom) {
+    singleSubstDom = createElementWithAttributes('SingleSubst', {
+      index: 0,
+      Format: 2
+    });
+    lookupDom.appendChild(singleSubstDom);
+  }
 
   // look for input subst
   const substitionDom = xpath.select(

index.js

@@ -58,9 +58,9 @@ const buildFont = profile => {
   //[...ligatures, { name: 'LIG', glyph: 'LIG' }];
 
   processPatch('names', patchNames, dom, ligatures, profile);
-  processPatch('glyphs', patchGlyphs, dom, ligaturesWithLIG);
   processPatch('gsub', patchGsub, dom, ligatures);
   processPatch('charstrings', patchCharStrings, dom, ligaturesWithLIG);
+  processPatch('glyphs', patchGlyphs, dom, ligaturesWithLIG);
   processPatch('hmtx', patchHmtx, dom);
 
   console.log(`Writing ligature font file ${dstFileName}`);
@@ -103,7 +103,6 @@ const getProfiles = () => {
         profiles.push(profile);
       } else {
         if (!profile) {
-          console.log(`Found ${ch} instead of [`);
           throw new Error('You must profile a profile name in []');
         }
         profile.ligatures.push(line);
@@ -113,22 +112,24 @@ const getProfiles = () => {
   return profiles;
 };
 
-const filterLigatures = (name, ligatures) => {
-  // loop through ligatures and return if name applies or not
+const filterLigatures = (name, mappings) => {
+  // loop through mappings and return if name applies or not
   // skip if setting is !name
-  return ligatures.filter(ligature => ligature === '!' + name).length === 0;
+  return mappings.filter(entry => entry === '!' + name).length === 0;
 };
 
-const mapLigatures = (name, ligatures) => {
-  // return { ligature, glyph }
-  let entry = { name, glyph: name };
-  ligatures.forEach(ligature => {
-    const n = ligature.indexOf('=');
-    if (n > 0 && ligature.substr(0, n) === name) {
-      entry.glyph = ligature.substr(n + 1);
+const mapLigatures = (name, mappings) => {
+  let mapping = { name, glyph: name };
+  mappings.forEach(entry => {
+    const [val1, val2] = entry.split('=');
+    // handle lig=altliga
+    if (val1 === name) {
+      mapping.glyph = val2;
+    } else if (val2 === name) {
+      mapping.name = val1;
     }
   });
-  return entry;
+  return mapping;
 };
 
 const filterGlyphsExists = ({ glyph }) => {
@@ -266,7 +267,7 @@ const patchGsub = (dom, ligatures) => {
   if (ligatures.length <= 1) return;
 
   ligatures
-    .filter(ligature => /_/.test(ligature.glyph))
+    //.filter(ligature => /_/.test(ligature.glyph))
     .forEach(ligature => {
       // build gsub tables
       gsub.buildGsubTables(dom, ligature);