<!--
 * @Description: 绘制多边形
 * @Author: Dragon
 * @Date: 2020-12-17 16:02:06
 * @LastEditTime: 2020-12-18 17:20:33
 * @LastEditors: Dragon
-->

<template>
 <div>
  <div class="query-wrap">
   <el-button type="primary" @click="drawStart('Polygon')">
    {{ isDraw "绘制区域" : "重新绘制" }}
   </el-button>
  </div>
  <div id="map"></div>
 </div>
</template>

<script>
import "ol/ol.css";
import { Map, View } from "ol";
import { Image as ImageLayer, Vector as VectorLayer } from "ol/layer";
import { ImageStatic, Vector as VectorSource } from "ol/source";
import { getCenter } from "ol/extent";
import { Projection } from "ol/proj";

import Draw from "ol/interaction/Draw";
import { Style, Fill, Stroke } from "ol/style";

import { GeoJSON } from "ol/format";
import staticMap from "@/assets/map.png";

export default {
 data() {
  return {
   map: null, // 地图
   imgx: 0, // 当前地图宽
   imgy: 0, // 当前地图高
   isDraw: true, // 是否绘制
   draw: null,
   source: null,
   vector: null,
   styles: [
    new Style({
     stroke: new Stroke({
      color: "rgba(255,0,0,0.6)",
      width: 2,
     }),
     fill: new Fill({
      color: "rgba(255,0,0,0.3)",
     }),
    }),
   ],
   geojsonObject: {
     'type': 'FeatureCollection',
     'features': [
      {
       'type': 'Feature',
       'geometry': {
        'type': 'Polygon',
        'coordinates': [
         [
          [97.16862961519749, 322.26517247174047],
          [117.3211820327625, 481.9353954724479],
          [1.056456546810466, 489.6863771715114],
          [13.458027265312012, 320.71497613192776],
          [97.16862961519749, 322.26517247174047]
                   ]
        ],
       },
      },
     ],
    },
  };
 },
 methods: {
  // 初始化地图
  initMap() {
   let extent = [0, 0, this.imgx, this.imgy];
   let projection = new Projection({
    code: "xkcd-image",
    units: "pixels",
    extent: extent,
   });
   let $this = this;
   this.map = new Map({
    target: "map",
    layers: [
     new ImageLayer({ // 展示地图层
      source: new ImageStatic({
       url: staticMap,
       projection: projection,
       imageExtent: extent,
      }),
     }),
     new VectorLayer({
      source: new VectorSource({
       features: new GeoJSON().readFeatures($this.geojsonObject),
      }),
      style: $this.styles,
     }),
    ],
    view: new View({
     projection: projection,
     center: getCenter(extent),
     zoom: 2,
     maxZoom: 18,
    }),
   });

   this.source = new VectorSource({ wrapX: false })
   this.vector = new VectorLayer({
    source: this.source,
    style: this.styles
   })
   this.map.addLayer(this.vector)
  },
  
  // 开始绘制多边形
  drawStart(type) {
   let that = this;
   if(this.isDraw) {
    this.isDraw = false
    this.draw = new Draw({
     source: this.source,
     type: type,
    });
    this.map.addInteraction(this.draw);
    this.draw.on("drawend", function (evt) {
     that.drawingEnd(evt);
    });
   } else {
    this.source.clear()
    this.map.removeInteraction(this.draw);
    this.isDraw = true
   }
   
  },

  // 构建多边形结束
  drawingEnd(evt) {
   let that = this
   const geo = evt.feature.getGeometry();
   const t = geo.getType();
   if (t === "Polygon") {
    // 获取坐标点
    const points = geo.getCoordinates();
    console.warn(points, "绘制结束，点坐标")
    this.map.removeInteraction(this.draw); // 移除绘制
   }
  },
 },
 mounted() {
  let that = this;
  let img = new Image();
  setTimeout(function() {
   img.src = staticMap;
   img.onload = function (res) {
    that.imgx = res.target.width;
    that.imgy = res.target.height;
    that.initMap();
   };
  }, 500)
  
 },
};
</script>

<style>
#map {
 width: 100%;
 height: calc(100vh - 50px);
}
</style>