This example uses OpenLayers v10.9.0. The latest is v.
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#### topolis integration

draw 17 edit 13 vector 86 topology 3 topolis 1

#####

Example on how to use topolis with OpenLayers.

Example showing the integration of topolis with OpenLayers, enabling creating and editing topological geometry. Standard interaction draws edges, snapping to existing edges. Delete an edge by drawing a new edge crossing the one to delete.

##### main.js

    import Feature from 'ol/Feature.js';
    import Map from 'ol/Map.js';
    import View from 'ol/View.js';
    import MousePosition from 'ol/control/MousePosition.js';
    import LineString from 'ol/geom/LineString.js';
    import Point from 'ol/geom/Point.js';
    import Polygon from 'ol/geom/Polygon.js';
    import Draw from 'ol/interaction/Draw.js';
    import Snap from 'ol/interaction/Snap.js';
    import TileLayer from 'ol/layer/Tile.js';
    import VectorLayer from 'ol/layer/Vector.js';
    import OSM from 'ol/source/OSM.js';
    import VectorSource from 'ol/source/Vector.js';
    import CircleStyle from 'ol/style/Circle.js';
    import Fill from 'ol/style/Fill.js';
    import Stroke from 'ol/style/Stroke.js';
    import Style from 'ol/style/Style.js';
    import Text from 'ol/style/Text.js';

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

    const nodes = new VectorSource({wrapX: false});
    const nodesLayer = new VectorLayer({
      source: nodes,
      style: function (f) {
        const style = new Style({
          image: new CircleStyle({
            radius: 8,
            fill: new Fill({color: 'rgba(255, 0, 0, 0.2)'}),
            stroke: new Stroke({color: 'red', width: 1}),
          }),
          text: new Text({
            text: f.get('node').id.toString(),
            fill: new Fill({color: 'red'}),
            stroke: new Stroke({
              color: 'white',
              width: 3,
            }),
          }),
        });
        return [style];
      },
    });

    const edges = new VectorSource({wrapX: false});
    const edgesLayer = new VectorLayer({
      source: edges,
      style: function (f) {
        const style = new Style({
          stroke: new Stroke({
            color: 'blue',
            width: 1,
          }),
          text: new Text({
            text: f.get('edge').id.toString(),
            fill: new Fill({color: 'blue'}),
            stroke: new Stroke({
              color: 'white',
              width: 2,
            }),
          }),
        });
        return [style];
      },
    });

    const faces = new VectorSource({wrapX: false});
    const facesLayer = new VectorLayer({
      source: faces,
      style: function (f) {
        const style = new Style({
          stroke: new Stroke({
            color: 'black',
            width: 1,
          }),
          fill: new Fill({
            color: 'rgba(0, 255, 0, 0.2)',
          }),
          text: new Text({
            font: 'bold 12px sans-serif',
            text: f.get('face').id.toString(),
            fill: new Fill({color: 'green'}),
            stroke: new Stroke({
              color: 'white',
              width: 2,
            }),
          }),
        });
        return [style];
      },
    });

    const map = new Map({
      layers: [raster, facesLayer, edgesLayer, nodesLayer],
      target: 'map',
      view: new View({
        center: [-11000000, 4600000],
        zoom: 16,
      }),
    });

    const topo = topolis.createTopology();

    topo.on('addnode', nodeToFeature);
    topo.on('removenode', function (e) {
      removeElementFeature(nodes, e);
    });
    topo.on('addedge', edgeToFeature);
    topo.on('modedge', function (e) {
      const feature = edges.getFeatureById(e.id);
      feature.setGeometry(new LineString(e.coordinates));
    });
    topo.on('removeedge', function (e) {
      removeElementFeature(edges, e);
    });
    topo.on('addface', faceToFeature);
    topo.on('removeface', function (e) {
      removeElementFeature(faces, e);
    });

    function removeElementFeature(source, element) {
      const feature = source.getFeatureById(element.id);
      source.removeFeature(feature);
    }

    function nodeToFeature(node) {
      const feature = new Feature({
        geometry: new Point(node.coordinate),
        node: node,
      });
      feature.setId(node.id);
      nodes.addFeature(feature);
    }

    function edgeToFeature(edge) {
      const feature = new Feature({
        geometry: new LineString(edge.coordinates),
        edge: edge,
      });
      feature.setId(edge.id);
      edges.addFeature(feature);
    }

    function faceToFeature(face) {
      const coordinates = topo.getFaceGeometry(face);
      const feature = new Feature({
        geometry: new Polygon(coordinates),
        face: face,
      });
      feature.setId(face.id);
      faces.addFeature(feature);
    }

    function createNode(topo, coord) {
      let node;
      const existingEdge = topo.getEdgeByPoint(coord, 5)[0];
      if (existingEdge) {
        node = topo.modEdgeSplit(existingEdge, coord);
      } else {
        node = topo.addIsoNode(coord);
      }
      return node;
    }

    function onDrawend(e) {
      const edgeGeom = e.feature.getGeometry().getCoordinates();
      const startCoord = edgeGeom[0];
      const endCoord = edgeGeom[edgeGeom.length - 1];
      let start, end;
      try {
        start = topo.getNodeByPoint(startCoord);
        end = topo.getNodeByPoint(endCoord);
        const edgesAtStart = topo.getEdgeByPoint(startCoord, 5);
        const edgesAtEnd = topo.getEdgeByPoint(endCoord, 5);
        const crossing = topo.getEdgesByLine(edgeGeom);
        if (
          crossing.length === 1 &&
          !start &&
          !end &&
          edgesAtStart.length === 0 &&
          edgesAtEnd.length === 0
        ) {
          topo.remEdgeNewFace(crossing[0]);
          start = crossing[0].start;
          if (start.face) {
            topo.removeIsoNode(start);
          }
          end = crossing[0].end;
          if (end.face) {
            topo.removeIsoNode(end);
          }
          return;
        }
        if (!start) {
          start = createNode(topo, startCoord);
          edgeGeom[0] = start.coordinate;
        }
        if (!end) {
          end = createNode(topo, endCoord);
          edgeGeom[edgeGeom.length - 1] = end.coordinate;
        }
        topo.addEdgeNewFaces(start, end, edgeGeom);
      } catch (e) {
        alert(e.toString());
      }
    }

    const draw = new Draw({
      type: 'LineString',
    });
    draw.on('drawend', onDrawend);
    map.addInteraction(draw);
    const snap = new Snap({
      source: edges,
    });
    map.addInteraction(snap);
    map.addControl(new MousePosition());

##### index.html

    <!DOCTYPE html>
    <html lang="en">
      <head>
        <meta charset="UTF-8">
        <title>topolis integration</title>
        <link rel="stylesheet" href="node_modules/ol/ol.css">
        <style>
          .map {
            width: 100%;
            height: 400px;
          }
        </style>
      </head>
      <body>
        <div id="map" class="map"></div>

        <script src="https://cdn.jsdelivr.net/npm/topolis@0.2.5/dist/topolis.js"></script>
        <script type="module" src="main.js"></script>
      </body>
    </html>

##### package.json

    {
      "name": "topolis",
      "dependencies": {
        "ol": "10.9.0"
      },
      "devDependencies": {
        "vite": "^3.2.3"
      },
      "scripts": {
        "start": "vite",
        "build": "vite build"
      }
    }