1. 写在前面
本问下面有矢量图层设置的区域，和热力图层设置的热力图的效果，区域绘制效怎么设置详细内容可以访问 openlayers6【十七】vue VectorLayer矢量图层画地图省市区，多省市区(粤港澳大湾区)效果详解，主要讲解的是热力图层效果实现。区域绘制只是为了效果更好看。好了，继续往下看
在 openlayers 中，图层是使用 layer 对象表示的，主要有 WebGLPoints Layer、热度图(HeatMap Layer)、图片图层(Image Layer)、切片图层(Tile Layer)和 矢量图层(Vector Layer)五种类型，它们都是继承 Layer 类的。
前面两篇文章 我们讲了矢量图层 VectorLayer的常用的场景，这篇我们写一篇 HeatMapLayer 的使用。可以看下图所示的热力图实现效果。 放大缩小地图热力图效果。
2. Heatmap 类实现热力图
2.1 Heatmap 参数
var heatmapLayer = new ol.layer.Heatmap({ source: source, opacity:1, visible:true, zIndex:1, gradient:['#00f','#0ff','#0f0','#ff0','#f00'], blur: 15, radius: 8, extent:[100,30,104,40], });
2.2 实现热力图
2.2.1 addHeatMap()方法详解：
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准备热力图需要的初始化数据，colors 热图的颜色渐变，hatmapData 表示值数量越多显示到页面的热力图颜色越深。codeList 准备的数据的城市对应的经纬度坐标。
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创建热力图图层
HeatmapLayer
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把热力图图层添加到
map 中
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调用添加热力图要素的方法
AppendFeatures()
2.2.2 addHeatMap()方法代码：
addHeatMap() { let colors = [ "#2200FF", "#16D9CC", "#4DEE12", "#E8D225", "#EF1616" ]; let hatmapData = [ { name: "成都市" }, { name: "成都市" }, { name: "成都市" }, { name: "成都市" }, { name: "绵阳市" }, { name: "广安市" }, { name: "雅安市" }, { name: "自贡市" }, { name: "自贡市" }, { name: "自贡市" }, { name: "自贡市" }, { name: "自贡市" }, { name: "自贡市" }, { name: "自贡市" }, { name: "宜宾市" }, { name: "甘孜藏族自治州市" } ]; let codeList = { 成都市: { center: { lng: 104.061902, lat: 30.609503 } }, 广安市: { center: { lng: 106.619126, lat: 30.474142 } }, 绵阳市: { center: { lng: 104.673612, lat: 31.492565 } }, 雅安市: { center: { lng: 103.031653, lat: 30.018895 } }, 自贡市: { center: { lng: 104.797794, lat: 29.368322 } }, 宜宾市: { center: { lng: 104.610964, lat: 28.781347 } }, 甘孜藏族自治州市: { center: { lng: 101.592433, lat: 30.426712 } } }; this.layer = new HeatmapLayer({ source: new VectorSource(), blur: 30, radius: 15, gradient: colors }); this.map.addLayer(this.layer); this.AppendFeatures(hatmapData, colors, codeList, 50); },
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2.2.3 AppendFeatures()方法详解：
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遍历hatmapData和points数据根据名称一致的 循环创建要素
new Feature点new Point信息
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把要素添加到热力图层的数据源中
2.2.4 AppendFeatures()方法代码：
AppendFeatures(hatmapData, colors, points, max) { for (var i in hatmapData) { if (points[hatmapData[i].name]) { var coords = points[hatmapData[i].name]; this.max = max; var f = new Feature({ geometry: new Point( fromLonLat([coords.center.lng, coords.center.lat]) ) }); this.layer.getSource().addFeature(f); } } }
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3. 完整代码
<template> <div id="app"> <div id="Map" ref="map"></div> </div> </template> <script> import "ol/ol.css"; import VectorLayer from "ol/layer/Vector"; import VectorSource from "ol/source/Vector"; import { Tile as TileLayer, Heatmap as HeatmapLayer } from "ol/layer"; import Proj from "ol/proj/Projection"; import XYZ from "ol/source/XYZ"; import { Map, View, Feature, ol } from "ol"; import { Style, Stroke, Fill } from "ol/style"; import { Polygon, Point } from "ol/geom"; import { defaults as defaultControls } from "ol/control"; import { fromLonLat } from "ol/proj"; import areaGeo from "@/geoJson/sichuan.json"; export default { data() { return { map: null }; }, methods: { initMap() { this.map = new Map({ target: "Map", controls: defaultControls({ zoom: true }).extend([]), layers: [ new TileLayer({ source: new XYZ({ url: "http://map.geoq.cn/ArcGIS/rest/services/ChinaOnlineStreetPurplishBlue/MapServer/tile/{z}/{y}/{x}" }) }) ], view: new View({ center: fromLonLat([104.065735, 30.659462]), zoom: 6.5, maxZoom: 19, minZoom: 5 }) }); }, addArea(geo = []) { if (geo.length == 0) { return false; } let features = []; geo.forEach(g => { let lineData = g.features[0]; let routeFeature = ""; if (lineData.geometry.type == "MultiPolygon") { routeFeature = new Feature({ geometry: new MultiPolygon( lineData.geometry.coordinates ).transform("EPSG:4326", "EPSG:3857") }); } else if (lineData.geometry.type == "Polygon") { routeFeature = new Feature({ geometry: new Polygon( lineData.geometry.coordinates ).transform("EPSG:4326", "EPSG:3857") }); } routeFeature.setStyle( new Style({ fill: new Fill({ color: "#4e98f444" }), stroke: new Stroke({ width: 3, color: [71, 137, 227, 1] }) }) ); features.push(routeFeature); }); let routeLayer = new VectorLayer({ source: new VectorSource({ features: features }) }); this.map.addLayer(routeLayer); }, addHeatMap() { let colors = [ "#2200FF", "#16D9CC", "#4DEE12", "#E8D225", "#EF1616" ]; let hatmapData = [ { name: "成都市" }, { name: "成都市" }, { name: "成都市" }, { name: "成都市" }, { name: "绵阳市" }, { name: "广安市" }, { name: "雅安市" }, { name: "自贡市" }, { name: "自贡市" }, { name: "自贡市" }, { name: "自贡市" }, { name: "自贡市" }, { name: "自贡市" }, { name: "自贡市" }, { name: "宜宾市" }, { name: "甘孜藏族自治州市" } ]; let codeList = { 成都市: { center: { lng: 104.061902, lat: 30.609503 } }, 广安市: { center: { lng: 106.619126, lat: 30.474142 } }, 绵阳市: { center: { lng: 104.673612, lat: 31.492565 } }, 雅安市: { center: { lng: 103.031653, lat: 30.018895 } }, 自贡市: { center: { lng: 104.797794, lat: 29.368322 } }, 宜宾市: { center: { lng: 104.610964, lat: 28.781347 } }, 甘孜藏族自治州市: { center: { lng: 101.592433, lat: 30.426712 } } }; this.layer = new HeatmapLayer({ source: new VectorSource(), blur: 30, radius: 15, gradient: colors }); this.map.addLayer(this.layer); this.AppendFeatures(hatmapData, colors, codeList, 50); }, AppendFeatures(hatmapData, colors, points, max) { for (var i in hatmapData) { if (points[hatmapData[i].name]) { var coords = points[hatmapData[i].name]; this.max = max; var f = new Feature({ geometry: new Point( fromLonLat([coords.center.lng, coords.center.lat]) ) }); this.layer.getSource().addFeature(f); } } } }, mounted() { this.initMap(); this.addArea(areaGeo); this.addHeatMap(); } }; </script> <style lang="scss" scoped> // 此处非核心内容，已删除 </style>
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4. 添加删除map图层的方法
this.map.addLayer(this.layer) this.map.removeLayer(this.layer)
5. 热力图自身的get，set方法
heatmapLayer.getBlur() heatmapLayer.setBlur(15) heatmapLayer.getExtent() heatmapLayer.setExtent([100,30,104,40]) heatmapLayer.getGradient() heatmapLayer.setGradient(['#00f','#0ff','#0f0','#ff0','#f00']) heatmapLayer.getMaxZoom() heatmapLayer.setMaxZoom(18) heatmapLayer.getMinZoom() heatmapLayer.setMinZoom(2) heatmapLayer.getOpacity() heatmapLayer.setOpacity(0.5) heatmapLayer.getRadius() heatmapLayer.setRadius(5) heatmapLayer.getSource() heatmapLayer.setSource(source) heatmapLayer.getVisible() heatmapLayer.setVisible(true) heatmapLayer.getZIndex() heatmapLayer.setZIndex(2) heatmapLayer.on(type,listener) heatmapLayer.un(type,listener)
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部分借鉴自：csdn
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这种方法的限制很多，比如你将图片插入修改为“四周紧密型”，那么你插入的图片在编辑器中看不到，实际使用的时候是可以看见的。这就很别扭了，还有就是图片好像会成为附件，如果有你的照片你不想别人每次下载附件将你的照片下载过去吧·······
