fonteditor-core/lib/ttf/table/hmtx.js

fonts (ttf, woff, woff2, eot, svg, otf) parse, write, transform, glyph adjust.

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = void 0;
var _table = _interopRequireDefault(require("./table"));
function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
/**
 * @file hmtx 表
 * @author mengke01(kekee000@gmail.com)
 *
 * https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6hmtx.html
 */
var _default = exports.default = _table.default.create('hmtx', [], {
  read: function read(reader, ttf) {
    var offset = this.offset;
    reader.seek(offset);
    var numOfLongHorMetrics = ttf.hhea.numOfLongHorMetrics;
    var hMetrics = [];
    var i;
    var hMetric;
    for (i = 0; i < numOfLongHorMetrics; ++i) {
      hMetric = {};
      hMetric.advanceWidth = reader.readUint16();
      hMetric.leftSideBearing = reader.readInt16();
      hMetrics.push(hMetric);
    }

    // 最后一个宽度
    var advanceWidth = hMetrics[numOfLongHorMetrics - 1].advanceWidth;
    var numOfLast = ttf.maxp.numGlyphs - numOfLongHorMetrics;

    // 获取后续的hmetrics
    for (i = 0; i < numOfLast; ++i) {
      hMetric = {};
      hMetric.advanceWidth = advanceWidth;
      hMetric.leftSideBearing = reader.readInt16();
      hMetrics.push(hMetric);
    }
    return hMetrics;
  },
  write: function write(writer, ttf) {
    var i;
    var numOfLongHorMetrics = ttf.hhea.numOfLongHorMetrics;
    for (i = 0; i < numOfLongHorMetrics; ++i) {
      writer.writeUint16(ttf.glyf[i].advanceWidth);
      writer.writeInt16(ttf.glyf[i].leftSideBearing);
    }

    // 最后一个宽度
    var numOfLast = ttf.glyf.length - numOfLongHorMetrics;
    for (i = 0; i < numOfLast; ++i) {
      writer.writeInt16(ttf.glyf[numOfLongHorMetrics + i].leftSideBearing);
    }
    return writer;
  },
  size: function size(ttf) {
    // 计算同最后一个advanceWidth相等的元素个数
    var numOfLast = 0;
    // 最后一个advanceWidth
    var advanceWidth = ttf.glyf[ttf.glyf.length - 1].advanceWidth;
    for (var i = ttf.glyf.length - 2; i >= 0; i--) {
      if (advanceWidth === ttf.glyf[i].advanceWidth) {
        numOfLast++;
      } else {
        break;
      }
    }
    ttf.hhea.numOfLongHorMetrics = ttf.glyf.length - numOfLast;
    return 4 * ttf.hhea.numOfLongHorMetrics + 2 * numOfLast;
  }
});