Method getEnvelope

src/openlayers/mapping/WebMap.js:5242–5253

* @private * @function WebMap.prototype.createVisibleResolution * @description 图层边界范围 * @param {Array} indexbounds * @param {Object} bounds 图层上下左右范围 * @returns {Object} envelope

(indexbounds, bounds)

   * @returns {Object} envelope
   */
  getEnvelope(indexbounds, bounds) {
    let envelope = {};
    if (indexbounds && indexbounds.length === 4) {
      envelope.left = indexbounds[0];
      envelope.bottom = indexbounds[1];
      envelope.right = indexbounds[2];
      envelope.top = indexbounds[3];
    } else {
      envelope = bounds;
    }
    return envelope;
  }
  /**
   * @private
   * @function WebMap.prototype.createMVTLayer