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我正在开发一个使用 React 作为所有其他 UI 内容的包装器的 OpenLayers 地图。因此，我也在尝试对一些特性进行组件化，在本例中是绘图。

下面是重新创建OpenLayers 文档中的示例的尝试。发生的事情是我得到了绘图表面，它进行了绘图，但是一旦绘图完成，地图上什么也没有显示。

我还有一个代码沙盒中行为的活生生的例子。

地图组件

import React, { Component, createRef } from "react";
import ReactDOM from "react-dom";
import Map from "ol/Map";
import View from "ol/View";
import OSM from "ol/source/OSM";
import TileLayer from "ol/layer/Tile";
import DrawingComponent from "./DrawingComponent";

class MapComponent extends Component {
  mapDomRef;
  map;

  constructor(...args) {
    super(...args);
    this.mapDomRef = createRef();
    this.map = new Map();
  }

  componentDidMount() {
    const view = new View({
      center: [-11000000, 4600000],
      zoom: 4
    });

    const rasterLayer = new TileLayer({
      source: new OSM()
    });

    this.map.addLayer(rasterLayer);
    this.map.setTarget(this.mapDomRef.current);
    this.map.setView(view);
  }

  render() {
    return (
      <div className="App">
        <div ref={this.mapDomRef} />

        <DrawingComponent map={this.map} />
      </div>
    );
  }
}

绘图组件

import React, { Component } from "react";
import ReactDOM from "react-dom";
import Draw from "ol/interaction/Draw";
import { Vector as VectorSource } from "ol/source";
import { Vector as VectorLayer } from "ol/layer";

class DrawingComponent extends Component {
  state = {
    geomType: "None"
  };

  constructor(...args) {
    super(...args);
    this.source = new VectorSource({ wrapX: false });
    this.layer = new VectorLayer({ source: this.source });
  }

  handleGeomChange = event => {
    const geomType = event.target.value;
    this.setState(({ draw }) => {
      if (draw) {
        this.props.map.removeInteraction(draw);
      }

      return { geomType, draw: this.addInteraction(geomType) };
    });
  };

  addInteraction(geomType) {
    if (geomType !== "None") {
      const draw = new Draw({
        source: this.source,
        type: geomType
      });

      this.props.map.addInteraction(draw);
      return draw;
    }
  }

  render() {
    return (
      <form class="form-inline">
        <label>Geometry type &nbsp;</label>
        <select
          id="type"
          value={this.state.geomType}
          onChange={this.handleGeomChange}
        >
          <option value="Point">Point</option>
          <option value="LineString">LineString</option>
          <option value="Polygon">Polygon</option>
          <option value="Circle">Circle</option>
          <option value="None">None</option>
        </select>
      </form>
    );
  }
}

export default DrawingComponent;

编辑：应用了使用地图上相同来源的建议，这意味着还要添加我以前没有做过的图层。

4

1 回答 1

0

检查您是否在栅格图层之前添加了矢量图层。如果您先添加矢量图层，则光栅层将渲染在矢量图之上。

于 2020-03-25T21:26:14.300 回答