openlayers/examples/snap.js

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

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);