Add cmap table format 6

docs/glyph-inspector.html

@@ -387,8 +387,12 @@ <h1>Free Software</h1>
     hline('yMin', font.tables.head.yMin);
     hline('Ascender', font.tables.hhea.ascender);
     hline('Descender', font.tables.hhea.descender);
-    hline('Typo Ascender', font.tables.os2.sTypoAscender);
-    hline('Typo Descender', font.tables.os2.sTypoDescender);
+
+    // Some PDF-embedded fonts might not have the OS/2 table
+    if (font.tables.os2) {
+        hline('Typo Ascender', font.tables.os2.sTypoAscender);
+        hline('Typo Descender', font.tables.os2.sTypoDescender);
+    }
 }
 
 window.redraw = function(options = { withColors: true, withVariations: true }) {

src/encoding.mjs

@@ -324,7 +324,7 @@ function addGlyphNamesAll(font) {
         glyph = font.glyphs.get(i);
         if (font.cffEncoding) {
             glyph.name = font.cffEncoding.charset[i];
-        } else if (font.glyphNames.names) {
+        } else if (font.glyphNames && font.glyphNames.names) {
             glyph.name = font.glyphNames.glyphIndexToName(i);
         }
     }

src/tables/cmap.mjs

@@ -99,6 +99,19 @@ function parseCmapTableFormat4(cmap, p, data, start, offset) {
     }
 }
 
+function parseCmapTableFormat6(cmap, p) {   
+    cmap.length = p.parseUShort();
+    cmap.language = p.parseUShort();
+
+    cmap.firstCode = p.parseUShort();
+    cmap.entryCount = p.parseUShort();
+    cmap.glyphIndexMap = {};
+
+    for (let i = 0; i < cmap.entryCount; i += 1) {
+        cmap.glyphIndexMap[cmap.firstCode + i] = p.parseUShort();
+    }
+}
+
 function parseCmapTableFormat14(cmap, p) {
     const varSelectorList = {};
 
@@ -216,6 +229,8 @@ function parseCmapTable(data, start) {
         parseCmapTableFormat12or13(cmap, p, cmap.format);
     } else if (cmap.format === 4) {
         parseCmapTableFormat4(cmap, p, data, start, offset);
+    } else if (cmap.format === 6) {
+        parseCmapTableFormat6(cmap, p);
     } else {
         throw new Error(
             'Only format 0 (platformId 1, encodingId 0), 4, 12 and 14 cmap tables are supported ' +
@@ -410,4 +425,4 @@ function makeCmapTable(glyphs) {
 
 export default { parse: parseCmapTable, make: makeCmapTable };
 
-export { parseCmapTableFormat0, parseCmapTableFormat14 };
+export { parseCmapTableFormat0, parseCmapTableFormat6, parseCmapTableFormat14 };

test/tables/cmap.spec.mjs

@@ -1,7 +1,7 @@
 import assert from 'assert';
 import { unhex } from '../testutil.mjs';
 import { Parser } from '../../src/parse.mjs';
-import { parseCmapTableFormat14, parseCmapTableFormat0 } from '../../src/tables/cmap.mjs';
+import { parseCmapTableFormat14, parseCmapTableFormat6, parseCmapTableFormat0 } from '../../src/tables/cmap.mjs';
 import { parse } from '../../src/opentype.mjs';
 import { readFileSync } from 'fs';
 const loadSync = (url, opt) => parse(readFileSync(url), opt);
@@ -82,4 +82,18 @@ describe('tables/cmap.mjs', function() {
         const expectedGlyphIds = [1,2,3,4];
         assert.deepEqual(glyphIds, expectedGlyphIds);
     });
+
+    it('can parse CMAP table format 6', function() {
+        let font;
+        assert.doesNotThrow(function() {
+            font = loadSync('./test/fonts/PDF-Embedded-Calibri-Subset.ttf');
+        });
+
+        // The embedded char IDs for the string "Living Room" in the PDF embedded font
+        const testString = '!"#"$%&\'(()';
+        const glyphIds = font.stringToGlyphIndexes(testString);
+
+        const expectedGlyphIds = [3, 13, 21, 13, 16, 11, 1, 5, 17, 17, 15];
+        assert.deepEqual(glyphIds, expectedGlyphIds);
+    });
 });