fonteditor-core
Version:
fonts (ttf, woff, woff2, eot, svg, otf) parse, write, transform, glyph adjust.
244 lines (204 loc) • 6.99 kB
JavaScript
/**
* @file ttf写入器
* @author mengke01(kekee000@gmail.com)
*/
import Writer from './writer';
import Directory from './table/directory';
import supportTables from './table/support';
import checkSum from './util/checkSum';
import error from './error';
// 支持写的表, 注意表顺序
const SUPPORT_TABLES = [
'OS/2',
'cmap',
'glyf',
'head',
'hhea',
'hmtx',
'loca',
'maxp',
'name',
'post'
];
export default class TTFWriter {
constructor(options = {}) {
this.options = {
writeZeroContoursGlyfData: options.writeZeroContoursGlyfData || false, // 不写入空 glyf 数据
hinting: options.hinting || false, // 默认不保留hints信息
kerning: options.kerning || false, // 默认不保留 kernings space 信息
support: options.support // 自定义的导出表结构，可以自己修改某些表项目
};
}
/**
* 处理ttf结构，以便于写
*
* @param {ttfObject} ttf ttf数据结构
*/
resolveTTF(ttf) {
// 头部信息
ttf.version = ttf.version || 0x1;
ttf.numTables = ttf.writeOptions.tables.length;
ttf.entrySelector = Math.floor(Math.log(ttf.numTables) / Math.LN2);
ttf.searchRange = Math.pow(2, ttf.entrySelector) * 16;
ttf.rangeShift = ttf.numTables * 16 - ttf.searchRange;
// 重置校验码
ttf.head.checkSumAdjustment = 0;
ttf.head.magickNumber = 0x5F0F3CF5;
if (typeof ttf.head.created === 'string') {
ttf.head.created = /^\d+$/.test(ttf.head.created)
? +ttf.head.created : Date.parse(ttf.head.created);
}
if (typeof ttf.head.modified === 'string') {
ttf.head.modified = /^\d+$/.test(ttf.head.modified)
? +ttf.head.modified : Date.parse(ttf.head.modified);
}
// 重置日期
if (!ttf.head.created) {
ttf.head.created = Date.now();
}
if (!ttf.head.modified) {
ttf.head.modified = ttf.head.created;
}
const checkUnicodeRepeat = {}; // 检查是否有重复代码点
// 将glyf的代码点按小到大排序
ttf.glyf.forEach((glyf, index) => {
if (glyf.unicode) {
glyf.unicode = glyf.unicode.sort();
glyf.unicode.forEach((u) => {
if (checkUnicodeRepeat[u]) {
error.raise({
number: 10200,
data: index
}, index);
}
else {
checkUnicodeRepeat[u] = true;
}
});
}
});
}
/**
* 写ttf文件
*
* @param {ttfObject} ttf ttf数据结构
* @return {ArrayBuffer} 字节流
*/
dump(ttf) {
// 用来做写入缓存的对象，用完后删掉
ttf.support = Object.assign({}, this.options.support);
// head + directory
let ttfSize = 12 + ttf.numTables * 16;
let ttfHeadOffset = 0; // 记录head的偏移
// 构造tables
ttf.support.tables = [];
ttf.writeOptions.tables.forEach((tableName) => {
const offset = ttfSize;
const TableClass = supportTables[tableName];
const tableSize = new TableClass().size(ttf); // 原始的表大小
let size = tableSize; // 对齐后的表大小
if (tableName === 'head') {
ttfHeadOffset = offset;
}
// 4字节对齐
if (size % 4) {
size += 4 - size % 4;
}
ttf.support.tables.push({
name: tableName,
checkSum: 0,
offset,
length: tableSize,
size
});
ttfSize += size;
});
const writer = new Writer(new ArrayBuffer(ttfSize));
// 写头部
writer.writeFixed(ttf.version);
writer.writeUint16(ttf.numTables);
writer.writeUint16(ttf.searchRange);
writer.writeUint16(ttf.entrySelector);
writer.writeUint16(ttf.rangeShift);
// 写表偏移
new Directory().write(writer, ttf);
// 写支持的表数据
ttf.support.tables.forEach((table) => {
const tableStart = writer.offset;
const TableClass = supportTables[table.name];
new TableClass().write(writer, ttf);
if (table.length % 4) {
// 对齐字节
writer.writeEmpty(4 - table.length % 4);
}
// 计算校验和
table.checkSum = checkSum(writer.getBuffer(), tableStart, table.size);
});
// 重新写入每个表校验和
ttf.support.tables.forEach((table, index) => {
const offset = 12 + index * 16 + 4;
writer.writeUint32(table.checkSum, offset);
});
// 写入总校验和
const ttfCheckSum = (0xB1B0AFBA - checkSum(writer.getBuffer()) + 0x100000000) % 0x100000000;
writer.writeUint32(ttfCheckSum, ttfHeadOffset + 8);
delete ttf.writeOptions;
delete ttf.support;
const buffer = writer.getBuffer();
writer.dispose();
return buffer;
}
/**
* 对ttf的表进行评估，标记需要处理的表
*
* @param {Object} ttf ttf对象
*/
prepareDump(ttf) {
if (!ttf.glyf || ttf.glyf.length === 0) {
error.raise(10201);
}
if (!ttf['OS/2'] || !ttf.head || !ttf.name) {
error.raise(10204);
}
const tables = SUPPORT_TABLES.slice(0);
ttf.writeOptions = {};
// hinting tables direct copy
if (this.options.hinting) {
['cvt', 'fpgm', 'prep', 'gasp', 'GPOS', 'kern', 'kerx'].forEach((table) => {
if (ttf[table]) {
tables.push(table);
}
});
}
// copy kerning space table
if (this.options.kerning) {
['GPOS', 'kern', 'kerx'].forEach((table) => {
if (ttf[table]) {
tables.push(table);
}
});
}
ttf.writeOptions.writeZeroContoursGlyfData = !!this.options.writeZeroContoursGlyfData;
ttf.writeOptions.hinting = !!this.options.hinting;
ttf.writeOptions.kerning = !!this.options.kerning;
ttf.writeOptions.tables = tables.sort();
}
/**
* 写一个ttf字体结构
*
* @param {Object} ttf ttf数据结构
* @return {ArrayBuffer} 缓冲数组
*/
write(ttf) {
this.prepareDump(ttf);
this.resolveTTF(ttf);
const buffer = this.dump(ttf);
return buffer;
}
/**
* 注销
*/
dispose() {
delete this.options;
}
}