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/*
Author: Viktor Semykin <thesame.ml@gmail.com>
Written for fontello.com project.
*/
'use strict';
var deflate = require('pako/lib/deflate.js').deflate;
function ulong(t) {
/* eslint-disable no-bitwise */
t &= 0xffffffff;
if (t < 0) {
t += 0x100000000;
}
return t;
}
function longAlign(n) {
/* eslint-disable no-bitwise */
return (n + 3) & ~3;
}
function calc_checksum(buf) {
var sum = 0;
var nlongs = buf.length / 4;
for (var i = 0; i < nlongs; ++i) {
var t = buf.readUint32BE(i * 4);
sum = ulong(sum + t);
}
return sum;
}
var WOFF_OFFSET = {
MAGIC: 0,
FLAVOR: 4,
SIZE: 8,
NUM_TABLES: 12,
RESERVED: 14,
SFNT_SIZE: 16,
VERSION_MAJ: 20,
VERSION_MIN: 22,
META_OFFSET: 24,
META_LENGTH: 28,
META_ORIG_LENGTH: 32,
PRIV_OFFSET: 36,
PRIV_LENGTH: 40
};
var WOFF_ENTRY_OFFSET = {
TAG: 0,
OFFSET: 4,
COMPR_LENGTH: 8,
LENGTH: 12,
CHECKSUM: 16
};
var SFNT_OFFSET = {
TAG: 0,
CHECKSUM: 4,
OFFSET: 8,
LENGTH: 12
};
var SFNT_ENTRY_OFFSET = {
FLAVOR: 0,
VERSION_MAJ: 4,
VERSION_MIN: 6,
CHECKSUM_ADJUSTMENT: 8
};
var MAGIC = {
WOFF: 0x774F4646,
CHECKSUM_ADJUSTMENT: 0xB1B0AFBA
};
var SIZEOF = {
WOFF_HEADER: 44,
WOFF_ENTRY: 20,
SFNT_HEADER: 12,
SFNT_TABLE_ENTRY: 16
};
function woffAppendMetadata(src, metadata) {
var zdata = deflate(metadata);
src.writeUint32BE(src.length + zdata.length, WOFF_OFFSET.SIZE);
src.writeUint32BE(src.length, WOFF_OFFSET.META_OFFSET);
src.writeUint32BE(zdata.length, WOFF_OFFSET.META_LENGTH);
src.writeUint32BE(metadata.length, WOFF_OFFSET.META_ORIG_LENGTH);
return Buffer.concat([ src, zdata ]);
}
function ttf2woff(arr, options) {
arr = Buffer.from(arr.buffer, arr.byteOffset, arr.length);
options = options || {};
var version = {
maj: 0,
min: 1
};
var numTables = arr.readUint16BE(4);
//var sfntVersion = arr.readUint32BE(0);
var flavor = 0x10000;
var woffHeader = Buffer.alloc(SIZEOF.WOFF_HEADER);
woffHeader.writeUint32BE(MAGIC.WOFF, WOFF_OFFSET.MAGIC);
woffHeader.writeUint16BE(numTables, WOFF_OFFSET.NUM_TABLES);
woffHeader.writeUint16BE(0, WOFF_OFFSET.RESERVED);
woffHeader.writeUint32BE(0, WOFF_OFFSET.SFNT_SIZE);
woffHeader.writeUint32BE(0, WOFF_OFFSET.META_OFFSET);
woffHeader.writeUint32BE(0, WOFF_OFFSET.META_LENGTH);
woffHeader.writeUint32BE(0, WOFF_OFFSET.META_ORIG_LENGTH);
woffHeader.writeUint32BE(0, WOFF_OFFSET.PRIV_OFFSET);
woffHeader.writeUint32BE(0, WOFF_OFFSET.PRIV_LENGTH);
var entries = [];
var i, tableEntry;
for (i = 0; i < numTables; ++i) {
var data = arr.subarray(SIZEOF.SFNT_HEADER + i * SIZEOF.SFNT_TABLE_ENTRY);
tableEntry = {
Tag: data.subarray(SFNT_OFFSET.TAG, SFNT_OFFSET.TAG + 4),
checkSum: data.readUint32BE(SFNT_OFFSET.CHECKSUM),
Offset: data.readUint32BE(SFNT_OFFSET.OFFSET),
Length: data.readUint32BE(SFNT_OFFSET.LENGTH)
};
entries.push (tableEntry);
}
entries = entries.sort(function (a, b) {
var aStr = String.fromCharCode.apply(null, a.Tag);
var bStr = String.fromCharCode.apply(null, b.Tag);
return aStr === bStr ? 0 : aStr < bStr ? -1 : 1;
});
var offset = SIZEOF.WOFF_HEADER + numTables * SIZEOF.WOFF_ENTRY;
var woffSize = offset;
var sfntSize = SIZEOF.SFNT_HEADER + numTables * SIZEOF.SFNT_TABLE_ENTRY;
var tableBuf = Buffer.alloc(numTables * SIZEOF.WOFF_ENTRY);
for (i = 0; i < numTables; ++i) {
tableEntry = entries[i];
if (String.fromCharCode.apply(null, tableEntry.Tag) !== 'head') {
var algntable = arr.subarray(tableEntry.Offset, tableEntry.Offset + longAlign(tableEntry.Length));
if (calc_checksum(algntable) !== tableEntry.checkSum) {
throw 'Checksum error in ' + String.fromCharCode.apply(null, tableEntry.Tag);
}
}
tableBuf.writeUint32BE(tableEntry.Tag.readUint32BE(0), i * SIZEOF.WOFF_ENTRY + WOFF_ENTRY_OFFSET.TAG);
tableBuf.writeUint32BE(tableEntry.Length, i * SIZEOF.WOFF_ENTRY + WOFF_ENTRY_OFFSET.LENGTH);
tableBuf.writeUint32BE(tableEntry.checkSum, i * SIZEOF.WOFF_ENTRY + WOFF_ENTRY_OFFSET.CHECKSUM);
sfntSize += longAlign(tableEntry.Length);
}
var sfntOffset = SIZEOF.SFNT_HEADER + entries.length * SIZEOF.SFNT_TABLE_ENTRY;
var csum = calc_checksum(arr.subarray(0, SIZEOF.SFNT_HEADER));
for (i = 0; i < entries.length; ++i) {
tableEntry = entries[i];
var b = Buffer.alloc(SIZEOF.SFNT_TABLE_ENTRY);
b.writeUint32BE(tableEntry.Tag.readUint32BE(0), SFNT_OFFSET.TAG);
b.writeUint32BE(tableEntry.checkSum, SFNT_OFFSET.CHECKSUM);
b.writeUint32BE(sfntOffset, SFNT_OFFSET.OFFSET);
b.writeUint32BE(tableEntry.Length, SFNT_OFFSET.LENGTH);
sfntOffset += longAlign(tableEntry.Length);
csum += calc_checksum(b);
csum += tableEntry.checkSum;
}
var checksumAdjustment = ulong(MAGIC.CHECKSUM_ADJUSTMENT - csum);
var len, woffDataChains = [];
for (i = 0; i < entries.length; ++i) {
tableEntry = entries[i];
var sfntData = arr.subarray(tableEntry.Offset, tableEntry.Offset + tableEntry.Length);
if (String.fromCharCode.apply(null, tableEntry.Tag) === 'head') {
version.maj = sfntData.readUint16BE(SFNT_ENTRY_OFFSET.VERSION_MAJ);
version.min = sfntData.readUint16BE(SFNT_ENTRY_OFFSET.VERSION_MIN);
flavor = sfntData.readUint32BE(SFNT_ENTRY_OFFSET.FLAVOR);
sfntData.writeUint32BE(checksumAdjustment, SFNT_ENTRY_OFFSET.CHECKSUM_ADJUSTMENT);
}
var res = deflate(sfntData);
var compLength;
// We should use compression only if it really save space (standard requirement).
// Also, data should be aligned to long (with zeros?).
compLength = Math.min(res.length, sfntData.length);
len = longAlign(compLength);
var woffData = Buffer.alloc(len, 0);
if (res.length >= sfntData.length) {
woffData.set(sfntData);
} else {
woffData.set(res);
}
tableBuf.writeUint32BE(offset, i * SIZEOF.WOFF_ENTRY + WOFF_ENTRY_OFFSET.OFFSET);
offset += woffData.length;
woffSize += woffData.length;
tableBuf.writeUint32BE(compLength, i * SIZEOF.WOFF_ENTRY + WOFF_ENTRY_OFFSET.COMPR_LENGTH);
woffDataChains.push(woffData);
}
woffHeader.writeUint32BE(woffSize, WOFF_OFFSET.SIZE);
woffHeader.writeUint32BE(sfntSize, WOFF_OFFSET.SFNT_SIZE);
woffHeader.writeUint16BE(version.maj, WOFF_OFFSET.VERSION_MAJ);
woffHeader.writeUint16BE(version.min, WOFF_OFFSET.VERSION_MIN);
woffHeader.writeUint32BE(flavor, WOFF_OFFSET.FLAVOR);
var out = Buffer.alloc(woffSize);
var pos = 0;
out.set(woffHeader, pos);
pos += woffHeader.length;
out.set(tableBuf, pos);
pos += tableBuf.length;
for (i = 0; i < woffDataChains.length; i++) {
out.set(woffDataChains[i], pos);
pos += woffDataChains[i].length;
}
if (options.metadata) {
out = woffAppendMetadata(out, options.metadata);
}
return new Uint8Array(out.buffer, out.byteOffset, out.length);
}
module.exports = ttf2woff;