Handle ligatures when guessing placeholder string

googlefonts · Feb 8, 2025 · 5b939de · 5b939de
1 parent 26eac62
commit 5b939de
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Showing 3 changed files with 27 additions and 10 deletions.
diff --git a/src/fontra/client/core/glyph-data.js b/src/fontra/client/core/glyph-data.js
@@ -124,23 +124,32 @@ export function guessGlyphPlaceholderString(codePoints, glyphName) {
 
   if (!glyphString && glyphName) {
     const [baseGlyphName, extension] = splitGlyphNameExtension(glyphName);
-    if (extension) {
-      const codePoint = getCodePointFromGlyphName(baseGlyphName);
-      if (codePoint) {
-        const baseChar = getCharFromCodePoint(codePoint);
+
+    let baseGlyphNames = [baseGlyphName];
+    if (baseGlyphName.indexOf("_") != -1) {
+      const [base, suffix] = splitGlyphNameExtension(baseGlyphName, "-");
+      baseGlyphNames = base.split("_").map((name) => name + suffix);
+    }
+
+    const codePoints = baseGlyphNames.map((name) => getCodePointFromGlyphName(name));
+    if (codePoints.length == baseGlyphNames.length) {
+      glyphString = codePoints
+        .map((codePoint) => getCharFromCodePoint(codePoint))
+        .join("");
+
+      if (extension) {
         const ZWJ = "\u200D";
         switch (extension) {
           case ".isol":
-            glyphString = baseChar;
             break;
           case ".init":
-            glyphString = baseChar + ZWJ;
+            glyphString = glyphString + ZWJ;
             break;
           case ".medi":
-            glyphString = ZWJ + baseChar + ZWJ;
+            glyphString = ZWJ + glyphString + ZWJ;
             break;
           case ".fina":
-            glyphString = ZWJ + baseChar;
+            glyphString = ZWJ + glyphString;
             break;
           default:
             break;

diff --git a/src/fontra/client/core/utils.js b/src/fontra/client/core/utils.js
@@ -487,8 +487,8 @@ export function* iter(iterable) {
   }
 }
 
-export function splitGlyphNameExtension(glyphName) {
-  const periodIndex = glyphName.indexOf(".");
+export function splitGlyphNameExtension(glyphName, separator = ".") {
+  const periodIndex = glyphName.indexOf(separator);
   const baseGlyphName = periodIndex >= 1 ? glyphName.slice(0, periodIndex) : glyphName;
   const extension = periodIndex >= 1 ? glyphName.slice(periodIndex) : "";
   return [baseGlyphName, extension];

diff --git a/test-js/test-glyph-data.js b/test-js/test-glyph-data.js
@@ -70,6 +70,14 @@ describe("glyph-data Tests", () => {
     { glyphName: "beh-ar.init", codePoints: [], glyphString: "\u0628\u200D" },
     { glyphName: "beh-ar.medi", codePoints: [], glyphString: "\u200D\u0628\u200D" },
     { glyphName: "uni0628.medi", codePoints: [], glyphString: "\u200D\u0628\u200D" },
+    { glyphName: "f_i", codePoints: [], glyphString: "fi" },
+    { glyphName: "lam_alef-ar", codePoints: [], glyphString: "\u0644\u0627" },
+    {
+      glyphName: "lam_alef-ar.fina",
+      codePoints: [],
+      glyphString: "\u200D\u0644\u0627",
+    },
+    { glyphName: "lam_lam_alef-ar", codePoints: [], glyphString: "\u0644\u0644\u0627" },
   ];
 
   parametrize(