Deleting a Vertex

AI-generated Key Takeaways

• This example showcases deleting vertices (points) from a polyline on a Google Map by right-clicking to reveal a "Delete" menu.

• A custom DeleteMenu class handles the menu's appearance, behavior, and vertex removal logic.

• The polyline is initialized with editable vertices, allowing users to interact with them.

• Right-clicking a vertex triggers the DeleteMenu, enabling users to remove that specific point from the polyline's path.

This example demonstrates how a user can delete a vertex, or a point on the line, by right-clicking on a vertex to show a "Delete" menu.

TypeScript

function initialize() {
  const mapOptions = {
    zoom: 3,
    center: new google.maps.LatLng(0, -180),
    mapTypeId: "terrain",
  };

  const map = new google.maps.Map(
    document.getElementById("map") as HTMLElement,
    mapOptions
  );

  const flightPlanCoordinates = [
    new google.maps.LatLng(37.772323, -122.214897),
    new google.maps.LatLng(21.291982, -157.821856),
    new google.maps.LatLng(-18.142599, 178.431),
    new google.maps.LatLng(-27.46758, 153.027892),
  ];

  const flightPath = new google.maps.Polyline({
    path: flightPlanCoordinates,
    editable: true,
    strokeColor: "#FF0000",
    strokeOpacity: 1.0,
    strokeWeight: 2,
    map: map,
  });

  /**
   * A menu that lets a user delete a selected vertex of a path.
   */
  class DeleteMenu extends google.maps.OverlayView {
    private div_: HTMLDivElement;
    private divListener_?: google.maps.MapsEventListener;

    constructor() {
      super();
      this.div_ = document.createElement("div");
      this.div_.className = "delete-menu";
      this.div_.innerHTML = "Delete";

      const menu = this;

      google.maps.event.addDomListener(this.div_, "click", () => {
        menu.removeVertex();
      });
    }

    onAdd() {
      const deleteMenu = this;
      const map = this.getMap() as google.maps.Map;

      this.getPanes()!.floatPane.appendChild(this.div_);

      // mousedown anywhere on the map except on the menu div will close the
      // menu.
      this.divListener_ = google.maps.event.addDomListener(
        map.getDiv(),
        "mousedown",
        (e: Event) => {
          if (e.target != deleteMenu.div_) {
            deleteMenu.close();
          }
        },
        true
      );
    }

    onRemove() {
      if (this.divListener_) {
        google.maps.event.removeListener(this.divListener_);
      }

      (this.div_.parentNode as HTMLElement).removeChild(this.div_);

      // clean up
      this.set("position", null);
      this.set("path", null);
      this.set("vertex", null);
    }

    close() {
      this.setMap(null);
    }

    draw() {
      const position = this.get("position");
      const projection = this.getProjection();

      if (!position || !projection) {
        return;
      }

      const point = projection.fromLatLngToDivPixel(position)!;

      this.div_.style.top = point.y + "px";
      this.div_.style.left = point.x + "px";
    }

    /**
     * Opens the menu at a vertex of a given path.
     */
    open(
      map: google.maps.Map,
      path: google.maps.MVCArray<google.maps.LatLng>,
      vertex: number
    ) {
      this.set("position", path.getAt(vertex));
      this.set("path", path);
      this.set("vertex", vertex);
      this.setMap(map);
      this.draw();
    }

    /**
     * Deletes the vertex from the path.
     */
    removeVertex() {
      const path = this.get("path");
      const vertex = this.get("vertex");

      if (!path || vertex == undefined) {
        this.close();
        return;
      }

      path.removeAt(vertex);
      this.close();
    }
  }

  const deleteMenu = new DeleteMenu();

  google.maps.event.addListener(flightPath, "contextmenu", (e: any) => {
    // Check if click was on a vertex control point
    if (e.vertex == undefined) {
      return;
    }

    deleteMenu.open(map, flightPath.getPath(), e.vertex);
  });
}

declare global {
  interface Window {
    initialize: () => void;
  }
}
window.initialize = initialize;
index.ts

Note: Read the guide on using TypeScript and Google Maps.

JavaScript

function initialize() {
  const mapOptions = {
    zoom: 3,
    center: new google.maps.LatLng(0, -180),
    mapTypeId: "terrain",
  };
  const map = new google.maps.Map(document.getElementById("map"), mapOptions);
  const flightPlanCoordinates = [
    new google.maps.LatLng(37.772323, -122.214897),
    new google.maps.LatLng(21.291982, -157.821856),
    new google.maps.LatLng(-18.142599, 178.431),
    new google.maps.LatLng(-27.46758, 153.027892),
  ];
  const flightPath = new google.maps.Polyline({
    path: flightPlanCoordinates,
    editable: true,
    strokeColor: "#FF0000",
    strokeOpacity: 1.0,
    strokeWeight: 2,
    map: map,
  });

  /**
   * A menu that lets a user delete a selected vertex of a path.
   */
  class DeleteMenu extends google.maps.OverlayView {
    div_;
    divListener_;
    constructor() {
      super();
      this.div_ = document.createElement("div");
      this.div_.className = "delete-menu";
      this.div_.innerHTML = "Delete";

      const menu = this;

      google.maps.event.addDomListener(this.div_, "click", () => {
        menu.removeVertex();
      });
    }
    onAdd() {
      const deleteMenu = this;
      const map = this.getMap();

      this.getPanes().floatPane.appendChild(this.div_);
      // mousedown anywhere on the map except on the menu div will close the
      // menu.
      this.divListener_ = google.maps.event.addDomListener(
        map.getDiv(),
        "mousedown",
        (e) => {
          if (e.target != deleteMenu.div_) {
            deleteMenu.close();
          }
        },
        true,
      );
    }
    onRemove() {
      if (this.divListener_) {
        google.maps.event.removeListener(this.divListener_);
      }

      this.div_.parentNode.removeChild(this.div_);
      // clean up
      this.set("position", null);
      this.set("path", null);
      this.set("vertex", null);
    }
    close() {
      this.setMap(null);
    }
    draw() {
      const position = this.get("position");
      const projection = this.getProjection();

      if (!position || !projection) {
        return;
      }

      const point = projection.fromLatLngToDivPixel(position);

      this.div_.style.top = point.y + "px";
      this.div_.style.left = point.x + "px";
    }
    /**
     * Opens the menu at a vertex of a given path.
     */
    open(map, path, vertex) {
      this.set("position", path.getAt(vertex));
      this.set("path", path);
      this.set("vertex", vertex);
      this.setMap(map);
      this.draw();
    }
    /**
     * Deletes the vertex from the path.
     */
    removeVertex() {
      const path = this.get("path");
      const vertex = this.get("vertex");

      if (!path || vertex == undefined) {
        this.close();
        return;
      }

      path.removeAt(vertex);
      this.close();
    }
  }

  const deleteMenu = new DeleteMenu();

  google.maps.event.addListener(flightPath, "contextmenu", (e) => {
    // Check if click was on a vertex control point
    if (e.vertex == undefined) {
      return;
    }

    deleteMenu.open(map, flightPath.getPath(), e.vertex);
  });
}

window.initialize = initialize;
index.js

Note: The JavaScript is compiled from the TypeScript snippet.

CSS

/* 
 * Always set the map height explicitly to define the size of the div element
 * that contains the map. 
 */
#map {
  height: 100%;
}

/* 
 * Optional: Makes the sample page fill the window. 
 */
html,
body {
  height: 100%;
  margin: 0;
  padding: 0;
}

.delete-menu {
  position: absolute;
  background: white;
  padding: 3px;
  color: #666;
  font-weight: bold;
  border: 1px solid #999;
  font-family: sans-serif;
  font-size: 12px;
  box-shadow: 1px 3px 3px rgba(0, 0, 0, 0.3);
  margin-top: -10px;
  margin-left: 10px;
  cursor: pointer;
}

.delete-menu:hover {
  background: #eee;
}
style.css

HTML

<html>
  <head>
    <title>Deleting a Vertex</title>

    <link rel="stylesheet" type="text/css" href="./style.css" />
    <script type="module" src="./index.js"></script>
  </head>
  <body>
    <div id="map"></div>

    <!-- 
      The `defer` attribute causes the script to execute after the full HTML
      document has been parsed. For non-blocking uses, avoiding race conditions,
      and consistent behavior across browsers, consider loading using Promises. See
      https://developers.google.com/maps/documentation/javascript/load-maps-js-api
      for more information.
      -->
    <script
      src="https://maps.googleapis.com/maps/api/js?key=AIzaSyB41DRUbKWJHPxaFjMAwdrzWzbVKartNGg&callback=initialize&v=weekly"
      defer
    ></script>
  </body>
</html>
index.html

Try Sample

JSFiddle.net Google Cloud Shell

Clone Sample

Git and Node.js are required to run this sample locally. Follow these instructions to install Node.js and NPM. The following commands clone, install dependencies and start the sample application.

  git clone -b sample-delete-vertex-menu https://github.com/googlemaps/js-samples.git
  cd js-samples
  npm i
  npm start

Other samples can be tried by switching to any branch beginning with sample-SAMPLE_NAME.

  git checkout sample-SAMPLE_NAME
  npm i
  npm start