Leaflet使用SVG创建动态Legend

接前一篇文章，前一篇文章我们使用 SVG 创建了带有动态文字的图标，今天再看看怎样在地图上根据动态图标生成相关的legend，当然这里也还是使用了 SVG 来生成相关颜色的 legend。

看下面的代码，生成了一个 svg 节点，其中包含了一个带有颜色的圆形图标和一个文字说明。

private generateLegend(name: string, color: string): string {return `<svgversion="1.2"baseProfile="tiny"xmlns="http://www.w3.org/2000/svg"width="16"height="16"viewBox="0 0 30 30"><circle cx="20" cy="20" r="10" fill="${color}" /></svg><span style="margin-left: 4px;">${name}</span>`;
}

完整的 map.component.ts 文件如下，其它代码参考前一篇文章。

import { Component, OnInit, AfterViewInit } from "@angular/core";
import * as leaflet from "leaflet";@Component({selector: "app-map",templateUrl: "./map.component.html",styleUrls: ["./map.component.css"],
})
export class MapComponent implements OnInit, AfterViewInit {map!: leaflet.Map;constructor() {}ngOnInit(): void {}ngAfterViewInit(): void {this.initMap();}private initMap(): void {this.map = leaflet.map("map").setView([51.5, -0.09], 13);const tiles = leaflet.tileLayer("https://tile.openstreetmap.org/{z}/{x}/{y}.png",{maxZoom: 19,attribution:'&copy; <a href="http://www.openstreetmap.org/copyright">OpenStreetMap</a>',},);tiles.addTo(this.map);const clients = [{ name: "Client A", lat: 51.5, lng: -0.09, value: 7, color: "red" },{ name: "Client B", lat: 51.5, lng: -0.07, value: 7, color: "blue" },{ name: "Client C", lat: 51.5, lng: -0.11, value: 7, color: "green" },];clients.forEach((client) => {this.generateMarker(client.lat, client.lng, client.value, client.color);});const generateLegend = this.generateLegend;const legend = leaflet.control.scale({ position: "bottomleft" });legend.onAdd = function () {const div = leaflet.DomUtil.create("div", "info");let html = `<div style="width: 80px; height: 80px; background-color: lightgray;">`;html += `<strong>Categories</strong><br/>`;clients.forEach((client) => {html += generateLegend(client.name, client.color) + "<br/>";});html += `</div>`;div.innerHTML = html;return div;};legend.addTo(this.map);}private generateMarker(lat: number,lng: number,value: number,color: string,) {const circleSVGHtml = `<svg version="1.2" baseProfile="tiny" xmlns="http://www.w3.org/2000/svg" width="250" height="250"><circle cx="125" cy="125" r="100" fill="${color}"/><text x="50%" y="50%" text-anchor="middle" fill="white" font-size="100px" font-family="Arial" dy=".2em">${value}</text></svg>`;const iconURL = "data:image/svg+xml," + encodeURIComponent(circleSVGHtml);const circleIcon = leaflet.icon({iconUrl: iconURL,iconSize: [30, 30],});const marker = leaflet.marker([lat, lng], { icon: circleIcon }).addTo(this.map);return marker;}private generateLegend(name: string, color: string): string {return `<svgversion="1.2"baseProfile="tiny"xmlns="http://www.w3.org/2000/svg"width="16"height="16"viewBox="0 0 30 30"><circle cx="20" cy="20" r="10" fill="${color}" /></svg><span style="margin-left: 4px;">${name}</span>`;}
}