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Snap Interaction

发布于 2022-11-30 23:36:06 字数 7067 浏览 0 评论 0 收藏 0

Example of using the snap interaction together with draw and modify interactions.

Example of using the snap interaction together with draw and modify interactions. The snap interaction must be added last, as it needs to be the first to handle the pointermove event.

main.js

import 'ol/ol.css';
import Map from 'ol/Map';
import View from 'ol/View';
import {Circle as CircleStyle, Fill, Stroke, Style} from 'ol/style';
import {Draw, Modify, Select, Snap} from 'ol/interaction';
import {OSM, Vector as VectorSource} from 'ol/source';
import {Tile as TileLayer, Vector as VectorLayer} from 'ol/layer';

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

const vector = new VectorLayer({
  source: new VectorSource(),
  style: new Style({
    fill: new Fill({
      color: 'rgba(255, 255, 255, 0.2)',
    }),
    stroke: new Stroke({
      color: '#ffcc33',
      width: 2,
    }),
    image: new CircleStyle({
      radius: 7,
      fill: new Fill({
        color: '#ffcc33',
      }),
    }),
  }),
});

const map = new Map({
  layers: [raster, vector],
  target: 'map',
  view: new View({
    center: [-11000000, 4600000],
    zoom: 4,
  }),
});

const ExampleModify = {
  init: function () {
    this.select = new Select();
    map.addInteraction(this.select);

    this.modify = new Modify({
      features: this.select.getFeatures(),
    });
    map.addInteraction(this.modify);

    this.setEvents();
  },
  setEvents: function () {
    const selectedFeatures = this.select.getFeatures();

    this.select.on('change:active', function () {
      selectedFeatures.forEach(function (each) {
        selectedFeatures.remove(each);
      });
    });
  },
  setActive: function (active) {
    this.select.setActive(active);
    this.modify.setActive(active);
  },
};
ExampleModify.init();

const optionsForm = document.getElementById('options-form');

const ExampleDraw = {
  init: function () {
    map.addInteraction(this.Point);
    this.Point.setActive(false);
    map.addInteraction(this.LineString);
    this.LineString.setActive(false);
    map.addInteraction(this.Polygon);
    this.Polygon.setActive(false);
    map.addInteraction(this.Circle);
    this.Circle.setActive(false);
  },
  Point: new Draw({
    source: vector.getSource(),
    type: 'Point',
  }),
  LineString: new Draw({
    source: vector.getSource(),
    type: 'LineString',
  }),
  Polygon: new Draw({
    source: vector.getSource(),
    type: 'Polygon',
  }),
  Circle: new Draw({
    source: vector.getSource(),
    type: 'Circle',
  }),
  getActive: function () {
    return this.activeType ? this[this.activeType].getActive() : false;
  },
  setActive: function (active) {
    const type = optionsForm.elements['draw-type'].value;
    if (active) {
      this.activeType && this[this.activeType].setActive(false);
      this[type].setActive(true);
      this.activeType = type;
    } else {
      this.activeType && this[this.activeType].setActive(false);
      this.activeType = null;
    }
  },
};
ExampleDraw.init();

/**
 * Let user change the geometry type.
 * @param {Event} e Change event.
 */
optionsForm.onchange = function (e) {
  const type = e.target.getAttribute('name');
  const value = e.target.value;
  if (type == 'draw-type') {
    ExampleDraw.getActive() && ExampleDraw.setActive(true);
  } else if (type == 'interaction') {
    if (value == 'modify') {
      ExampleDraw.setActive(false);
      ExampleModify.setActive(true);
    } else if (value == 'draw') {
      ExampleDraw.setActive(true);
      ExampleModify.setActive(false);
    }
  }
};

ExampleDraw.setActive(true);
ExampleModify.setActive(false);

// The snap interaction must be added after the Modify and Draw interactions
// in order for its map browser event handlers to be fired first. Its handlers
// are responsible of doing the snapping.
const snap = new Snap({
  source: vector.getSource(),
});
map.addInteraction(snap);

index.html

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <title>Snap Interaction</title>
    <!-- Pointer events polyfill for old browsers, see https://caniuse.com/#feat=pointer -->
    <script src="https://unpkg.com/elm-pep"></script>
    <!-- The line below is only needed for old environments like Internet Explorer and Android 4.x -->
    <script src="./resources/polyfill.min.js?features=fetch,requestAnimationFrame,Element.prototype.classList,URL,TextDecoder,Number.isInteger"></script>
    <style>
      .map {
        width: 100%;
        height:400px;
      }
    </style>
  </head>
  <body>
    <div id="map" class="map"></div>
    <form id="options-form" autocomplete="off">
      <div class="radio">
        <label>
          <input type="radio" name="interaction" value="draw" id="draw" checked>
          Draw &nbsp;
        </label>
      </div>
      <div class="radio">
        <label>
          <input type="radio" name="interaction" value="modify">
          Modify &nbsp;
        </label>
      </div>
      <div class="form-group">
        <label for="draw-type">Draw type &nbsp;</label>
        <select name="draw-type" id="draw-type">
          <option value="Point">Point</option>
          <option value="LineString">LineString</option>
          <option value="Polygon">Polygon</option>
          <option value="Circle">Circle</option>
        </select>
      </div>
    </form>
    <script src="main.js"></script>
  </body>
</html>

package.json

{
  "name": "snap",
  "dependencies": {
    "ol": "7.1.0"
  },
  "devDependencies": {
    "parcel": "^2.0.0-beta.1"
  },
  "scripts": {
    "start": "parcel index.html",
    "build": "parcel build --public-url . index.html"
  }
}

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