Method redraw

src/openlayers/overlay/Graph.js:414–421

* @function Graph.prototype.redraw * @description 重绘该图层。

()

     * @description  重绘该图层。
     */
    redraw() {
        this.clearCache();
        if (this.renderer) {
            this.redrawThematicFeatures(this.map.getView().calculateExtent());
            return true;
        }
        return false
    }

    /**
     * @function Graph.prototype.clear