Method getLayer

src/common/overlay/levelRenderer/Painter.js:321–367

* @function LevelRenderer.Painter.prototype.getLayer * @description 获取 zlevel 所在层，如果不存在则会创建一个新的层。 * * @param {number} zlevel - zlevel。 * @return {LevelRenderer.Painter} this。

(zlevel)

     * @return {LevelRenderer.Painter} this。
     */
    getLayer(zlevel) {
        // Change draw layer
        var currentLayer = this._layers[zlevel];
        if (!currentLayer) {
            var len = this._zlevelList.length;
            var prevLayer = null;
            var i = -1;
            if (len > 0 && zlevel > this._zlevelList[0]) {
                for (i = 0; i < len - 1; i++) {
                    if (
                        this._zlevelList[i] < zlevel
                        && this._zlevelList[i + 1] > zlevel
                    ) {
                        break;
                    }
                }
                prevLayer = this._layers[this._zlevelList[i]];
            }
            this._zlevelList.splice(i + 1, 0, zlevel);

            // Create a new layer
            //currentLayer = new PaintLayer(zlevel, this);
            currentLayer = new PaintLayer(CommonUtil.createUniqueID("_levelLayer_" + zlevel), this);
            var prevDom = prevLayer ? prevLayer.dom : this._bgDom;
            if (prevDom.nextSibling) {
                prevDom.parentNode.insertBefore(
                    currentLayer.dom,
                    prevDom.nextSibling
                );
            } else {
                prevDom.parentNode.appendChild(
                    currentLayer.dom
                );
            }
            currentLayer.initContext();

            this._layers[zlevel] = currentLayer;

            if (this._layerConfig[zlevel]) {
                new Util().merge(currentLayer, this._layerConfig[zlevel], true);
            }

            currentLayer.updateTransform();
        }

        return currentLayer;
    }


    /**