Merge pull request #595 from moontypespace/gasp_table

gasp table

src/opentype.js

@@ -33,6 +33,7 @@ import _name from './tables/name.js';
 import os2 from './tables/os2.js';
 import post from './tables/post.js';
 import meta from './tables/meta.js';
+import gasp from './tables/gasp.js';
 /**
  * The opentype library.
  * @namespace opentype
@@ -338,6 +339,10 @@ function parseBuffer(buffer, opt={}) {
             case 'meta':
                 metaTableEntry = tableEntry;
                 break;
+            case 'gasp':
+                table = uncompressTable(data, tableEntry);
+                font.tables.gasp = gasp.parse(table.data, table.offset);
+                break;
         }
     }
 

src/tables/gasp.js

@@ -0,0 +1,46 @@
+// The `gasp` table contains global information about the font.
+// https://learn.microsoft.com/de-de/typography/opentype/spec/gasp
+
+import check from '../check.js';
+import parse from '../parse.js';
+import table from '../table.js';
+
+//const GASP_SYMMETRIC_GRIDFIT = 0x0004
+//const GASP_SYMMETRIC_SMOOTHING = 0x0008
+//const GASP_DOGRAY = 0x0002
+//const GASP_GRIDFIT = 0x0001
+
+// Parse the `gasp` table
+function parseGaspTable(data, start) {
+    const gasp = {};
+    const p = new parse.Parser(data, start);
+    gasp.version = p.parseUShort();
+    check.argument(gasp.version <= 0x0001, 'Unsupported gasp table version.');
+    gasp.numRanges = p.parseUShort();
+    gasp.gaspRanges = [];
+    for (let i = 0; i < gasp.numRanges; i++) {
+        gasp.gaspRanges[i] = {
+            rangeMaxPPEM: p.parseUShort(),
+            rangeGaspBehavior: p.parseUShort(),
+        };
+    }
+    return gasp;
+}
+
+
+function makeGaspTable(gasp) {
+    const result = new table.Table('gasp', [
+        {name: 'version', type: 'USHORT', value: 0x0001},
+        {name: 'numRanges', type: 'USHORT', value: gasp.numRanges},
+    ]);
+
+    for (let i in gasp.numRanges) {
+        result.fields.push({name: 'rangeMaxPPEM', type: 'USHORT', value: gasp.numRanges[i].rangeMaxPPEM});
+        result.fields.push({name: 'rangeGaspBehavior', type: 'USHORT', value: gasp.numRanges[i].rangeGaspBehavior});
+    }
+
+    return result;
+}
+
+export default { parse: parseGaspTable, make: makeGaspTable };
+

src/tables/sfnt.js

@@ -24,6 +24,7 @@ import cpal from './cpal.js';
 import fvar from './fvar.js';
 import stat from './stat.js';
 import avar from './avar.js';
+import gasp from './gasp.js';
 
 function log2(v) {
     return Math.log(v) / Math.log(2) | 0;
@@ -318,6 +319,7 @@ function fontToSfntTable(font) {
 
     // we have to handle fvar before name, because it may modify name IDs
     const fvarTable = font.tables.fvar ? fvar.make(font.tables.fvar, font.names) : undefined;
+    const gaspTable = font.tables.gasp ? gasp.make(font.tables.gasp) : undefined;
 
     const languageTags = [];
     const nameTable = _name.make(names, languageTags);
@@ -371,6 +373,10 @@ function fontToSfntTable(font) {
         tables.push(metaTable);
     }
 
+    if (gaspTable) {
+        tables.push(gaspTable);
+    }
+
     const sfntTable = makeSfntTable(tables);
 
     // Compute the font's checkSum and store it in head.checkSumAdjustment.

test/tables/gasp.js

@@ -0,0 +1,32 @@
+import assert from 'assert';
+import { Font, Path, Glyph, parse, load} from '../../src/opentype.js';
+import { readFileSync } from 'fs';
+const loadSync = (url, opt) => parse(readFileSync(url), opt);
+
+describe('tables/gasp.js', function () {
+    const font = loadSync('./test/fonts/Roboto-Black.ttf');
+
+    it('can parse gasp table version', function() {
+        assert.equal(font.tables.gasp.version, 1);
+    });
+    it('can parse gasp table numRanges', function() {
+        assert.equal(font.tables.gasp.numRanges, 2);
+    });
+
+    it('can parse gasp table numRanges 0 rangeMaxPPEM', function() {
+        assert.equal(font.tables.gasp.gaspRanges[0].rangeMaxPPEM, 8); // default value
+    });
+
+    it('can parse gasp table numRanges 0 rangeGaspBehavior', function() {
+        assert.equal(font.tables.gasp.gaspRanges[0].rangeGaspBehavior, 0x0002); //GASP_DOGRAY = 0x0002
+    });
+
+    it('can parse gasp table numRanges 1 rangeMaxPPEM', function() {
+        assert.equal(font.tables.gasp.gaspRanges[1].rangeMaxPPEM, 0xFFFF); // default value
+    });
+
+    it('can parse gasp table numRanges 1 rangeGaspBehavior', function() {
+        assert.equal(font.tables.gasp.gaspRanges[1].rangeGaspBehavior, 0x0001 + 0x0002 + 0x0004 + 0x0008); // all flags set = 15
+    });
+
+});