constructor(rgba, format, originalText) {
    this._rgba = rgba;
    this._originalText = originalText || null;
    this._originalTextIsValid = !!this._originalText;
    this._format = format;
    if (typeof this._rgba[3] === 'undefined')
      this._rgba[3] = 1;

    for (let i = 0; i < 4; ++i) {
      if (this._rgba[i] < 0) {
        this._rgba[i] = 0;
        this._originalTextIsValid = false;
      }
      if (this._rgba[i] > 1) {
        this._rgba[i] = 1;
        this._originalTextIsValid = false;
      }
    }
  }
@param {!Array.<number>} rgba
@param {!Color.Format} format
@param {string=} originalText