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/*
Author: Viktor Semykin <thesame.ml@gmail.com>
Written for fontello.com project.
*/
'use strict'
/**
* Offsets in EOT file structure. Refer to EOTPrefix in OpenTypeUtilities.cpp
*/
var EOT_OFFSET = {
LENGTH: 0,
FONT_LENGTH: 4,
VERSION: 8,
CHARSET: 26,
MAGIC: 34,
FONT_PANOSE: 16,
ITALIC: 27,
WEIGHT: 28,
UNICODE_RANGE: 36,
CODEPAGE_RANGE: 52,
CHECKSUM_ADJUSTMENT: 60
}
/**
* Offsets in different SFNT (TTF) structures. See OpenTypeUtilities.cpp
*/
var SFNT_OFFSET = {
// sfntHeader:
NUMTABLES: 4,
// TableDirectoryEntry
TABLE_TAG: 0,
TABLE_OFFSET: 8,
TABLE_LENGTH: 12,
// OS2Table
OS2_WEIGHT: 4,
OS2_FONT_PANOSE: 32,
OS2_UNICODE_RANGE: 42,
OS2_FS_SELECTION: 62,
OS2_CODEPAGE_RANGE: 78,
// headTable
HEAD_CHECKSUM_ADJUSTMENT: 8,
// nameTable
NAMETABLE_FORMAT: 0,
NAMETABLE_COUNT: 2,
NAMETABLE_STRING_OFFSET: 4,
// nameRecord
NAME_PLATFORM_ID: 0,
NAME_ENCODING_ID: 2,
NAME_LANGUAGE_ID: 4,
NAME_NAME_ID: 6,
NAME_LENGTH: 8,
NAME_OFFSET: 10
}
/**
* Sizes of structures
*/
var SIZEOF = {
SFNT_TABLE_ENTRY: 16,
SFNT_HEADER: 12,
SFNT_NAMETABLE: 6,
SFNT_NAMETABLE_ENTRY: 12,
EOT_PREFIX: 82
}
/**
* Magic numbers
*/
var MAGIC = {
EOT_VERSION: 0x00020001,
EOT_MAGIC: 0x504c,
EOT_CHARSET: 1,
LANGUAGE_ENGLISH: 0x0409
}
/**
* Utility function to convert buffer of utf16be chars to buffer of utf16le
* chars prefixed with length and suffixed with zero
*/
function strbuf (str) {
var arr = Buffer.alloc(str.length + 4)
arr.writeUint16LE(str.length, 0)
for (var i = 0; i < str.length; i += 2) {
arr.writeUint16LE(str.readUint16BE(i), i + 2)
}
arr.writeUint16LE(0, arr.length - 2)
return arr
}
// Takes TTF font on input and returns Uint8Array with EOT font
//
// Params:
//
// - arr(Uint8Array)
//
function ttf2eot (arr) {
arr = Buffer.from(arr.buffer, arr.byteOffset, arr.length)
var out = Buffer.alloc(SIZEOF.EOT_PREFIX, 0)
var i, j
out.writeUint32LE(arr.length, EOT_OFFSET.FONT_LENGTH)
out.writeUint32LE(MAGIC.EOT_VERSION, EOT_OFFSET.VERSION)
out.writeUint8(MAGIC.EOT_CHARSET, EOT_OFFSET.CHARSET)
out.writeUint16LE(MAGIC.EOT_MAGIC, EOT_OFFSET.MAGIC)
var familyName = Buffer.of(0)
var subfamilyName = Buffer.of(0)
var fullName = Buffer.of(0)
var versionString = Buffer.of(0)
var haveOS2 = false
var haveName = false
var haveHead = false
var numTables = arr.readUint16BE(SFNT_OFFSET.NUMTABLES)
for (i = 0; i < numTables; ++i) {
var data = arr.subarray(SIZEOF.SFNT_HEADER + i * SIZEOF.SFNT_TABLE_ENTRY)
var tableEntry = {
tag: String.fromCharCode.apply(null, data.subarray(SFNT_OFFSET.TABLE_TAG, SFNT_OFFSET.TABLE_TAG + 4)),
offset: data.readUint32BE(SFNT_OFFSET.TABLE_OFFSET),
length: data.readUint32BE(SFNT_OFFSET.TABLE_LENGTH)
}
var table = arr.subarray(tableEntry.offset, tableEntry.offset + tableEntry.length)
if (tableEntry.tag === 'OS/2') {
haveOS2 = true
var OS2Version = table.readUint16BE()
for (j = 0; j < 10; ++j) {
out.writeUint8(table.readUint8(SFNT_OFFSET.OS2_FONT_PANOSE + j), EOT_OFFSET.FONT_PANOSE + j)
}
out.writeUint8(table.readUint16BE(SFNT_OFFSET.OS2_FS_SELECTION) & 0x01, EOT_OFFSET.ITALIC)
out.writeUint32LE(table.readUint16BE(SFNT_OFFSET.OS2_WEIGHT), EOT_OFFSET.WEIGHT)
for (j = 0; j < 4; ++j) {
out.writeUint32LE(table.readUint32BE(SFNT_OFFSET.OS2_UNICODE_RANGE + j * 4),
EOT_OFFSET.UNICODE_RANGE + j * 4)
}
if (OS2Version >= 1) {
for (j = 0; j < 2; ++j) {
out.writeUint32LE(table.readUint32BE(SFNT_OFFSET.OS2_CODEPAGE_RANGE + j * 4),
EOT_OFFSET.CODEPAGE_RANGE + j * 4)
}
}
} else if (tableEntry.tag === 'head') {
haveHead = true
out.writeUint32LE(table.readUint32BE(SFNT_OFFSET.HEAD_CHECKSUM_ADJUSTMENT), EOT_OFFSET.CHECKSUM_ADJUSTMENT)
} else if (tableEntry.tag === 'name') {
haveName = true
var nameTable = {
format: table.readUint16BE(SFNT_OFFSET.NAMETABLE_FORMAT),
count: table.readUint16BE(SFNT_OFFSET.NAMETABLE_COUNT),
stringOffset: table.readUint16BE(SFNT_OFFSET.NAMETABLE_STRING_OFFSET)
}
for (j = 0; j < nameTable.count; ++j) {
var nameRecord = table.subarray(SIZEOF.SFNT_NAMETABLE + j * SIZEOF.SFNT_NAMETABLE_ENTRY)
var name = {
platformID: nameRecord.readUint16BE(SFNT_OFFSET.NAME_PLATFORM_ID),
encodingID: nameRecord.readUint16BE(SFNT_OFFSET.NAME_ENCODING_ID),
languageID: nameRecord.readUint16BE(SFNT_OFFSET.NAME_LANGUAGE_ID),
nameID: nameRecord.readUint16BE(SFNT_OFFSET.NAME_NAME_ID),
length: nameRecord.readUint16BE(SFNT_OFFSET.NAME_LENGTH),
offset: nameRecord.readUint16BE(SFNT_OFFSET.NAME_OFFSET)
}
if (name.platformID === 3 && name.encodingID === 1 && name.languageID === MAGIC.LANGUAGE_ENGLISH) {
var s = strbuf(table.subarray(
nameTable.stringOffset + name.offset,
nameTable.stringOffset + name.offset + name.length))
switch (name.nameID) {
case 1:
familyName = s
break
case 2:
subfamilyName = s
break
case 4:
fullName = s
break
case 5:
versionString = s
break
}
}
}
}
if (haveOS2 && haveName && haveHead) { break }
}
if (!(haveOS2 && haveName && haveHead)) {
throw new Error('Required section not found')
}
// Create final buffer with the the same array type as input one.
var eot = Buffer.concat([
out,
familyName,
subfamilyName,
versionString,
fullName,
Buffer.from([0, 0]),
arr
])
eot.writeUint32LE(eot.length, EOT_OFFSET.LENGTH) // Calculate overall length
return new Uint8Array(eot.buffer, eot.byteOffset, eot.length)
}
module.exports = ttf2eot