openlayers性能优化——开启图层预加载、减少空白等待时间

 使用切片图层时、地图拖拽会有空白图片，为了减少空白等待时间，我们可以开始图层预加载。

const map_top = new Map({layers: [new TileLayer({preload:Infinity, //预加载source: new StadiaMaps({layer: "outdoors",}),}),],target: "map_top",view: view,});