opentype.js
Version:
OpenType font parser
51 lines (46 loc) • 2.04 kB
JavaScript
// The `hhea` table contains information for horizontal layout.
// https://www.microsoft.com/typography/OTSPEC/hhea.htm
import parse from '../parse';
import table from '../table';
// Parse the horizontal header `hhea` table
function parseHheaTable(data, start) {
const hhea = {};
const p = new parse.Parser(data, start);
hhea.version = p.parseVersion();
hhea.ascender = p.parseShort();
hhea.descender = p.parseShort();
hhea.lineGap = p.parseShort();
hhea.advanceWidthMax = p.parseUShort();
hhea.minLeftSideBearing = p.parseShort();
hhea.minRightSideBearing = p.parseShort();
hhea.xMaxExtent = p.parseShort();
hhea.caretSlopeRise = p.parseShort();
hhea.caretSlopeRun = p.parseShort();
hhea.caretOffset = p.parseShort();
p.relativeOffset += 8;
hhea.metricDataFormat = p.parseShort();
hhea.numberOfHMetrics = p.parseUShort();
return hhea;
}
function makeHheaTable(options) {
return new table.Table('hhea', [
{name: 'version', type: 'FIXED', value: 0x00010000},
{name: 'ascender', type: 'FWORD', value: 0},
{name: 'descender', type: 'FWORD', value: 0},
{name: 'lineGap', type: 'FWORD', value: 0},
{name: 'advanceWidthMax', type: 'UFWORD', value: 0},
{name: 'minLeftSideBearing', type: 'FWORD', value: 0},
{name: 'minRightSideBearing', type: 'FWORD', value: 0},
{name: 'xMaxExtent', type: 'FWORD', value: 0},
{name: 'caretSlopeRise', type: 'SHORT', value: 1},
{name: 'caretSlopeRun', type: 'SHORT', value: 0},
{name: 'caretOffset', type: 'SHORT', value: 0},
{name: 'reserved1', type: 'SHORT', value: 0},
{name: 'reserved2', type: 'SHORT', value: 0},
{name: 'reserved3', type: 'SHORT', value: 0},
{name: 'reserved4', type: 'SHORT', value: 0},
{name: 'metricDataFormat', type: 'SHORT', value: 0},
{name: 'numberOfHMetrics', type: 'USHORT', value: 0}
], options);
}
export default { parse: parseHheaTable, make: makeHheaTable };