html2canvas/dist/npm/Font.js

Screenshots with JavaScript

'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.FontMetrics = void 0;

var _Util = require("./Util");

function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }

function _defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } }

function _createClass(Constructor, protoProps, staticProps) { if (protoProps) _defineProperties(Constructor.prototype, protoProps); if (staticProps) _defineProperties(Constructor, staticProps); return Constructor; }

var SAMPLE_TEXT = 'Hidden Text';

var FontMetrics =
/*#__PURE__*/
function () {
  function FontMetrics(document) {
    _classCallCheck(this, FontMetrics);

    this._data = {};
    this._document = document;
  }

  _createClass(FontMetrics, [{
    key: "_parseMetrics",
    value: function _parseMetrics(font) {
      var container = this._document.createElement('div');

      var img = this._document.createElement('img');

      var span = this._document.createElement('span');

      var body = this._document.body;

      if (!body) {
        throw new Error(process.env.NODE_ENV !== "production" ? 'No document found for font metrics' : '');
      }

      container.style.visibility = 'hidden';
      container.style.fontFamily = font.fontFamily;
      container.style.fontSize = font.fontSize;
      container.style.margin = '0';
      container.style.padding = '0';
      body.appendChild(container);
      img.src = _Util.SMALL_IMAGE;
      img.width = 1;
      img.height = 1;
      img.style.margin = '0';
      img.style.padding = '0';
      img.style.verticalAlign = 'baseline';
      span.style.fontFamily = font.fontFamily;
      span.style.fontSize = font.fontSize;
      span.style.margin = '0';
      span.style.padding = '0';
      span.appendChild(this._document.createTextNode(SAMPLE_TEXT));
      container.appendChild(span);
      container.appendChild(img);
      var baseline = img.offsetTop - span.offsetTop + 2;
      container.removeChild(span);
      container.appendChild(this._document.createTextNode(SAMPLE_TEXT));
      container.style.lineHeight = 'normal';
      img.style.verticalAlign = 'super';
      var middle = img.offsetTop - container.offsetTop + 2;
      body.removeChild(container);
      return {
        baseline: baseline,
        middle: middle
      };
    }
  }, {
    key: "getMetrics",
    value: function getMetrics(font) {
      var key = "".concat(font.fontFamily, " ").concat(font.fontSize);

      if (this._data[key] === undefined) {
        this._data[key] = this._parseMetrics(font);
      }

      return this._data[key];
    }
  }]);

  return FontMetrics;
}();

exports.FontMetrics = FontMetrics;