Method getScaleFromRes

src/openlayers/mapping/WebMap.js:518–523

* @private * @function WebMap.prototype.getScaleFromRes * @description 将分辨率转换为比例尺 * @param {number} resolution - 分辨率 * @param {string} coordUnit - 比例尺单位 * @param {number} dpi

(resolution, coordUnit = 'DEGREE', dpi = 96)

   * @param {number} dpi
   */
  getScaleFromRes(resolution, coordUnit = 'DEGREE', dpi = 96) {
    let scale,
      mpu = metersPerUnit[coordUnit.toUpperCase()];
    scale = (resolution * dpi * mpu) / 0.0254;
    return '1:' + scale;
  }
  /**
   * @private
   * @function WebMap.prototype.formatScale