传单中使用VectorGrid的代码效率

Question

我在一个使用VectorGrid的GeoJSON文件中有大约7000个多边形，使用一个层一切都很好，但我需要将这个层划分为10个LayerGroup(10个区域有自己的多边形(。在不重写代码10次的情况下，如何做到这一点？这似乎太浪费了，一定有更聪明的方法，我想不通。这是Im测试的代码，重点必须是使用所有11层。。。

var all_regions = new L.layerGroup();
var region_1 = new L.layerGroup();
var region_2 = new L.layerGroup();
var region_3 = new L.layerGroup();
/* snip */
var region_10 = new L.layerGroup();
var highlight_polygon;
var clearHighlight = function () {
if (highlight_polygon) {
vectorGrid.resetFeatureStyle(highlight_polygon);
}
highlight_polygon = null;
};
var vectorTileOptions_allRegions = {
rendererFactory: L.canvas.tile,
maxNativeZoom: 13,
zIndex: 6,
vectorTileLayerStyles: {
sliced: {
weight: 2,
color: "gray",
opacity: 1,
fill: false,
//fillColor: 'white',
//stroke: true,
fillOpacity: 0,
},
},
interactive: true,
getFeatureId: function (f) {
return f.properties.id;
},
};
var vectorTileOptions_region_1 = {
rendererFactory: L.canvas.tile,
maxNativeZoom: 13,
zIndex: 6,
vectorTileLayerStyles: {
sliced: function (properties, zoom) {
var region = properties.region;
if (region === "region one") {
return {
weight: 2,
color: "gray",
opacity: 1,
fill: false,
//fillColor: 'white',
//stroke: true,
fillOpacity: 0,
};
} else {
return {
weight: 0,
opacity: 0,
fill: false,
stroke: false,
fillOpacity: 0,
interactive: false,
};
}
},
},
interactive: true,
getFeatureId: function (f) {
return f.properties.id;
},
};
// Next vectorTileOptions until all 11 of them....
$.getJSON("/data/regions.geojson", function (json) {
//Not sure this is the correct way doing it...
var vectorGrid = L.vectorGrid
.slicer(json, vectorTileOptions_allRegions, vectorTileOptions_region_1)
.on("click", function (e) {
var properties = e.layer.properties;
L.popup()
.setContent(
"<b>Name</b>: " +
properties.region_name +
"<br><b>Date</b>: " +
"<i>" +
properties.date +
"</i>"
)
.setLatLng(e.latlng)
.openOn(map);
clearHighlight();
highlight_polygon = e.layer.properties.id;
vectorGrid.setFeatureStyle(highlight_polygon, {
weight: 3,
color: "gray",
opacity: 1,
fillColor: "#ff9999",
fill: true,
radius: 6,
fillOpacity: 0.3,
});
L.DomEvent.stop(e);
});
var clearHighlight = function () {
if (highlight_polygon) {
vectorGrid.resetFeatureStyle(highlight_polygon);
}
highlight_polygon = null;
map.on("popupclose", clearHighlight);
};
//This will not work....
vectorGrid.addTo(all_regions);
vectorGrid.addTo(region_1);
});

Answer 1

您可能想做一些类似。。。

var regions = []; // An array that will hold instances of VectorGrid
var vectorGridOptions = {
rendererFactory: L.canvas.tile,
maxNativeZoom: 13,
zIndex: 6,
vectorTileLayerStyles: {
sliced: {}, // Empty, because it shall be overwritten later.
},
};
var defaultStyle = {
stroke: true,
weight: 2,
};
var regionStyles = [];
regionStyles[0] = {
weight: 2,
color: "gray",
};
regionStyles[1] = {
weight: 1,
color: "red",
};
/* ...etc, up to regionStyles[9] */
fetch("/data/regions.geojson")
.then(function (response) { return response.json(); })
.then(function (json) {

// For each number between 0 and 9...
for (var i = 0; i <= 9; i++) {

// Assuming that the GeoJSON data holds a FeatureCollection,
// create a copy of said GeoJSON FeatureCollection, but holding only
// the wanted features.
// See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter
var filteredGeoJSON = {
type: "FeatureCollection",
features: json.features.filter(function (feature) {
// This assumes that each Feature has a "regionID" property with a
// numeric value between 0 and 9.
return feature.properties.regionID === i;
}),
};
// Build up the options for the i-th VectorGrid by merging stuff together.
// See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/assign
var fullRegionStyle = Object.assign({}, defaultStyle, regionStyles[i]);
// Overwrite some stuff in vectorGridOptions. Note that this changes the value of
// a piece of vectorGridOptions at each pass of the loop.
vectorGridOptions.vectorTileLayerStyles.sliced = fullRegionStyle;
regions[i] = L.vectorGrid.slicer(filteredGeoJSON, vectorTileOptions);
regions[i].addTo(map);
}
});

这里的关键点是：

• 使用循环从1到10进行迭代
• 将事物保留在编号数组中，而不是类似名称的变量中
• 过滤FeatureCollection，使每个VectorGrid使用较少的数据。绘制不可见的多边形/多段线所需的计算时间与绘制可见的多边形或多段线的计算时间一样多
• 尽可能多地重构，然后构建具体的数据结构(Object.assign，如果需要，克隆对象(