Marker Collision Management

Handle marker collisions

Vector maps provide basic support for marker collision. For example, you can modify the marker API to hide labels. Vector maps also provide support for prioritization of markers.

The following example always displays markers and hides underlying labels:

var marker = new google.maps.Marker({
  position: event.latLng,
  map: map,
  collisionBehavior:
    google.maps.CollisionBehavior.REQUIRED_AND_HIDES_OPTIONAL,
  });

The following example hides markers if they collide with a required marker and hides underlying labels:

var marker = new google.maps.Marker({
  position: event.latLng,
  map: map,
  collisionBehavior:
    google.maps.CollisionBehavior.OPTIONAL_AND_HIDES_LOWER_PRIORITY,
  });

TypeScript

let map: google.maps.Map;

// Initialize and add the map
function initMap(): void {
  let markers: google.maps.Marker[] = [];

  // @ts-ignore Beta functionality
  let collisionBehavior = google.maps.CollisionBehavior.REQUIRED;

  map = new google.maps.Map(
    document.getElementById("map") as HTMLElement,
    {
      mapId: "3a3b33f0edd6ed2a",
      center: { lat: 47.609414458375674, lng: -122.33897030353548 },
      zoom: 17,
    } as google.maps.MapOptions
  );

  const menuList = document.querySelector(".mdc-list") as HTMLUListElement;

  // Add the behaviors to the select options
  // @ts-ignore Beta functionality
  for (const [key, value] of Object.entries(google.maps.CollisionBehavior)) {
    const item = document.createElement("LI");

    item.classList.add("mdc-list-item");
    item.setAttribute("data-value", key);

    const itemText = document.createElement("SPAN") as HTMLSpanElement;

    itemText.classList.add("mdc-list-item__text");
    itemText.innerText = value as string;

    item.appendChild(itemText);
    menuList.appendChild(item);
  }

  // @ts-ignore
  const select = new mdc.select.MDCSelect(
    document.querySelector(".mdc-select") as HTMLElement
  );

  select.listen("MDCSelect:change", () => {
    collisionBehavior = select.value;
    markers.forEach((marker) => {
      marker.set("collisionBehavior", collisionBehavior);
    });
  });

  select.value = collisionBehavior;

  // Create some markers on the map
  markers = [
    [-122.3402, 47.6093],
    [-122.3402, 47.6094],
    [-122.3403, 47.6094],
    [-122.3384, 47.6098],
    [-122.3389, 47.6095],
    [-122.3396, 47.6095],
    [-122.3379, 47.6097],
    [-122.3378, 47.6097],
    [-122.3396, 47.6091],
    [-122.3383, 47.6089],
    [-122.3379, 47.6093],
    [-122.3381, 47.6095],
    [-122.3378, 47.6095],
  ].map(
    ([lng, lat]: number[], i: number) =>
      new google.maps.Marker({
        position: new google.maps.LatLng({ lat, lng }),
        map,
        zIndex: i,
        collisionBehavior: collisionBehavior,
      } as google.maps.MarkerOptions)
  );
}

declare global {
  interface Window {
    initMap: () => void;
  }
}
window.initMap = initMap;

JavaScript

let map;

// Initialize and add the map
function initMap() {
  let markers = [];
  // @ts-ignore Beta functionality
  let collisionBehavior = google.maps.CollisionBehavior.REQUIRED;

  map = new google.maps.Map(document.getElementById("map"), {
    mapId: "3a3b33f0edd6ed2a",
    center: { lat: 47.609414458375674, lng: -122.33897030353548 },
    zoom: 17,
  });

  const menuList = document.querySelector(".mdc-list");

  // Add the behaviors to the select options
  // @ts-ignore Beta functionality
  for (const [key, value] of Object.entries(google.maps.CollisionBehavior)) {
    const item = document.createElement("LI");

    item.classList.add("mdc-list-item");
    item.setAttribute("data-value", key);

    const itemText = document.createElement("SPAN");

    itemText.classList.add("mdc-list-item__text");
    itemText.innerText = value;
    item.appendChild(itemText);
    menuList.appendChild(item);
  }

  // @ts-ignore
  const select = new mdc.select.MDCSelect(
    document.querySelector(".mdc-select")
  );

  select.listen("MDCSelect:change", () => {
    collisionBehavior = select.value;
    markers.forEach((marker) => {
      marker.set("collisionBehavior", collisionBehavior);
    });
  });
  select.value = collisionBehavior;
  // Create some markers on the map
  markers = [
    [-122.3402, 47.6093],
    [-122.3402, 47.6094],
    [-122.3403, 47.6094],
    [-122.3384, 47.6098],
    [-122.3389, 47.6095],
    [-122.3396, 47.6095],
    [-122.3379, 47.6097],
    [-122.3378, 47.6097],
    [-122.3396, 47.6091],
    [-122.3383, 47.6089],
    [-122.3379, 47.6093],
    [-122.3381, 47.6095],
    [-122.3378, 47.6095],
  ].map(
    ([lng, lat], i) =>
      new google.maps.Marker({
        position: new google.maps.LatLng({ lat, lng }),
        map,
        zIndex: i,
        collisionBehavior: collisionBehavior,
      })
  );
}

window.initMap = initMap;

CSS

:root {
  --mdc-theme-primary: #1a73e8;
  --mdc-theme-secondary: #rgb(225, 245, 254);
  --mdc-theme-on-primary: #fff;
  --mdc-theme-on-secondary: rgb(1, 87, 155);
}

.mdc-text-field--focused:not(.mdc-text-field--disabled) .mdc-floating-label {
  color: var(--mdc-theme-primary);
}

.mdc-select--focused .mdc-select__dropdown-icon {
  background: url(data:image/svg+xml,%3Csvg%20width%3D%2210px%22%20height%3D%225px%22%20viewBox%3D%227%2010%2010%205%22%20version%3D%221.1%22%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20xmlns%3Axlink%3D%22http%3A%2F%2Fwww.w3.org%2F1999%2Fxlink%22%3E%0A%20%20%20%20%3Cpolygon%20id%3D%22Shape%22%20stroke%3D%22none%22%20fill%3D%22%23000%22%20fill-rule%3D%22evenodd%22%20opacity%3D%220.54%22%20points%3D%227%2010%2012%2015%2017%2010%22%3E%3C%2Fpolygon%3E%0A%3C%2Fsvg%3E) no-repeat center;
}

.mdc-select:not(.mdc-select--disabled).mdc-select--focused .mdc-floating-label {
  color: var(--mdc-theme-primary);
}

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

#container {
  height: 100%;
  display: flex;
}

#sidebar {
  flex-basis: 15rem;
  flex-grow: 1;
  padding: 1rem;
  max-width: 30rem;
  height: 100%;
  box-sizing: border-box;
  overflow: auto;
}

#map {
  flex-basis: 0;
  flex-grow: 4;
  height: 100%;
}

.mdc-select,
.mdc-select__anchor,
.mdc-select__menu {
  width: 100%;
}

HTML

<html>
  <head>
    <title>Marker Collision Management</title>
    <script src="https://polyfill.io/v3/polyfill.min.js?features=default"></script>
    <link
      href="https://unpkg.com/material-components-web@6.0.0/dist/material-components-web.css"
      rel="stylesheet"
    />
    <script src="https://unpkg.com/material-components-web@6.0.0/dist/material-components-web.min.js"></script>
    <link
      rel="stylesheet"
      href="https://fonts.googleapis.com/icon?family=Material+Icons"
    />

    <link rel="stylesheet" type="text/css" href="./style.css" />
    <script type="module" src="./index.js"></script>
  </head>
  <body>
    <div id="container">
      <div id="map"></div>
      <div id="sidebar">
        <div class="mdc-select mdc-select--outlined">
          <div
            class="mdc-select__anchor"
            aria-labelledby="outlined-select-label"
          >
            <input
              type="text"
              disabled
              readonly
              id="demo-selected-text"
              class="mdc-select__selected-text"
            />
            <i class="mdc-select__dropdown-icon"></i>
            <span class="mdc-notched-outline">
              <span class="mdc-notched-outline__leading"></span>
              <span class="mdc-notched-outline__notch">
                <span
                  id="outlined-select-label"
                  class="mdc-floating-label mdc-theme--primary"
                  >Pick a Collision Behavior</span
                >
              </span>
              <span class="mdc-notched-outline__trailing"></span>
            </span>
          </div>
          <div class="mdc-select__menu mdc-menu mdc-menu-surface">
            <ul class="mdc-list"></ul>
          </div>
        </div>
      </div>
    </div>

    <!-- 
     The `defer` attribute causes the callback 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
     with https://www.npmjs.com/package/@googlemaps/js-api-loader.
    -->
    <script
      src="https://maps.googleapis.com/maps/api/js?key=AIzaSyB41DRUbKWJHPxaFjMAwdrzWzbVKartNGg&callback=initMap&v=beta"
      defer
    ></script>
  </body>
</html>

Try Sample

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-marker-collision-management 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