103 lines
2.9 KiB
Plaintext
103 lines
2.9 KiB
Plaintext
/**
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* @file woff转换ttf
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* @author mengke01(kekee000@gmail.com)
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*/
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import Reader from './reader';
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import Writer from './writer';
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import error from './error';
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/**
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* woff格式转换成ttf字体格式
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*
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* @param {ArrayBuffer} woffBuffer woff缓冲数组
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* @param {Object} options 选项
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* @param {Object} options.inflate 解压相关函数
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*
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* @return {ArrayBuffer} ttf格式byte流
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*/
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export default function woff2ttf(woffBuffer, options = {}) {
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const reader = new Reader(woffBuffer);
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const signature = reader.readUint32(0);
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const flavor = reader.readUint32(4);
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if (signature !== 0x774F4646 || (flavor !== 0x10000 && flavor !== 0x4f54544f)) {
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reader.dispose();
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error.raise(10102);
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}
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const numTables = reader.readUint16(12);
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const ttfSize = reader.readUint32(16);
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const tableEntries = [];
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let tableEntry;
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let i;
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let l;
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// 读取woff表索引信息
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for (i = 0; i < numTables; ++i) {
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reader.seek(44 + i * 20);
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tableEntry = {
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tag: reader.readString(reader.offset, 4),
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offset: reader.readUint32(),
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compLength: reader.readUint32(),
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length: reader.readUint32(),
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checkSum: reader.readUint32()
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};
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// ttf 表数据
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const deflateData = reader.readBytes(tableEntry.offset, tableEntry.compLength);
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// 需要解压
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if (deflateData.length < tableEntry.length) {
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if (!options.inflate) {
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reader.dispose();
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error.raise(10105);
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}
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tableEntry.data = options.inflate(deflateData);
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}
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else {
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tableEntry.data = deflateData;
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}
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tableEntry.length = tableEntry.data.length;
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tableEntries.push(tableEntry);
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}
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const writer = new Writer(new ArrayBuffer(ttfSize));
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// 写头部
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const entrySelector = Math.floor(Math.log(numTables) / Math.LN2);
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const searchRange = Math.pow(2, entrySelector) * 16;
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const rangeShift = numTables * 16 - searchRange;
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writer.writeUint32(flavor);
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writer.writeUint16(numTables);
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writer.writeUint16(searchRange);
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writer.writeUint16(entrySelector);
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writer.writeUint16(rangeShift);
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// 写ttf表索引
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let tblOffset = 12 + 16 * tableEntries.length;
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for (i = 0, l = tableEntries.length; i < l; ++i) {
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tableEntry = tableEntries[i];
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writer.writeString(tableEntry.tag);
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writer.writeUint32(tableEntry.checkSum);
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writer.writeUint32(tblOffset);
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writer.writeUint32(tableEntry.length);
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tblOffset += tableEntry.length
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+ (tableEntry.length % 4 ? 4 - tableEntry.length % 4 : 0);
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}
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// 写ttf表数据
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for (i = 0, l = tableEntries.length; i < l; ++i) {
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tableEntry = tableEntries[i];
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writer.writeBytes(tableEntry.data);
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if (tableEntry.length % 4) {
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writer.writeEmpty(4 - tableEntry.length % 4);
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}
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}
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return writer.getBuffer();
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}
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