Custom Overlays

This example creates a custom overlay, containing a U.S. Geological Survey (USGS) image of the relevant area on the map.

Read the documentation.

TypeScript

// This example creates a custom overlay called USGSOverlay, containing
// a U.S. Geological Survey (USGS) image of the relevant area on the map.

// Set the custom overlay object's prototype to a new instance
// of OverlayView. In effect, this will subclass the overlay class therefore
// it's simpler to load the API synchronously, using
// google.maps.event.addDomListener().
// Note that we set the prototype to an instance, rather than the
// parent class itself, because we do not wish to modify the parent class.

// Initialize the map and the custom overlay.
function initMap(): void {
  const map = new google.maps.Map(
    document.getElementById("map") as HTMLElement,
    {
      zoom: 11,
      center: { lat: 62.323907, lng: -150.109291 },
      mapTypeId: "satellite",
    }
  );

  const bounds = new google.maps.LatLngBounds(
    new google.maps.LatLng(62.281819, -150.287132),
    new google.maps.LatLng(62.400471, -150.005608)
  );

  // The photograph is courtesy of the U.S. Geological Survey.
  const srcImage =
    "https://developers.google.com/maps/documentation/" +
    "javascript/examples/full/images/talkeetna.png";

  // The custom USGSOverlay object contains the USGS image,
  // the bounds of the image, and a reference to the map.
  class USGSOverlay extends google.maps.OverlayView {
    private bounds_: google.maps.LatLngBounds;
    private image_: string;
    private div_: HTMLElement | null;

    constructor(bounds: google.maps.LatLngBounds, image: string) {
      super();

      // Initialize all properties.
      this.bounds_ = bounds;
      this.image_ = image;

      // Define a property to hold the image's div. We'll
      // actually create this div upon receipt of the onAdd()
      // method so we'll leave it null for now.
      this.div_ = null;
    }

    /**
     * onAdd is called when the map's panes are ready and the overlay has been
     * added to the map.
     */
    onAdd() {
      this.div_ = document.createElement("div");
      this.div_.style.borderStyle = "none";
      this.div_.style.borderWidth = "0px";
      this.div_.style.position = "absolute";

      // Create the img element and attach it to the div.
      const img = document.createElement("img");

      img.src = this.image_;
      img.style.width = "100%";
      img.style.height = "100%";
      img.style.position = "absolute";
      this.div_.appendChild(img);

      // Add the element to the "overlayLayer" pane.
      const panes = this.getPanes()!;

      panes.overlayLayer.appendChild(this.div_);
    }

    draw() {
      // We use the south-west and north-east
      // coordinates of the overlay to peg it to the correct position and size.
      // To do this, we need to retrieve the projection from the overlay.
      const overlayProjection = this.getProjection();

      // Retrieve the south-west and north-east coordinates of this overlay
      // in LatLngs and convert them to pixel coordinates.
      // We'll use these coordinates to resize the div.
      const sw = overlayProjection.fromLatLngToDivPixel(
        this.bounds_.getSouthWest()
      )!;
      const ne = overlayProjection.fromLatLngToDivPixel(
        this.bounds_.getNorthEast()
      )!;

      // Resize the image's div to fit the indicated dimensions.
      if (this.div_) {
        this.div_.style.left = sw.x + "px";
        this.div_.style.top = ne.y + "px";
        this.div_.style.width = ne.x - sw.x + "px";
        this.div_.style.height = sw.y - ne.y + "px";
      }
    }

    /**
     * The onRemove() method will be called automatically from the API if
     * we ever set the overlay's map property to 'null'.
     */
    onRemove() {
      if (this.div_) {
        (this.div_.parentNode as HTMLElement).removeChild(this.div_);
        this.div_ = null;
      }
    }
  }

  const overlay = new USGSOverlay(bounds, srcImage);

  overlay.setMap(map);
}

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

JavaScript

// This example creates a custom overlay called USGSOverlay, containing
// a U.S. Geological Survey (USGS) image of the relevant area on the map.
// Set the custom overlay object's prototype to a new instance
// of OverlayView. In effect, this will subclass the overlay class therefore
// it's simpler to load the API synchronously, using
// google.maps.event.addDomListener().
// Note that we set the prototype to an instance, rather than the
// parent class itself, because we do not wish to modify the parent class.
// Initialize the map and the custom overlay.
function initMap() {
  const map = new google.maps.Map(document.getElementById("map"), {
    zoom: 11,
    center: { lat: 62.323907, lng: -150.109291 },
    mapTypeId: "satellite",
  });
  const bounds = new google.maps.LatLngBounds(
    new google.maps.LatLng(62.281819, -150.287132),
    new google.maps.LatLng(62.400471, -150.005608)
  );
  // The photograph is courtesy of the U.S. Geological Survey.
  const srcImage =
    "https://developers.google.com/maps/documentation/" +
    "javascript/examples/full/images/talkeetna.png";

  // The custom USGSOverlay object contains the USGS image,
  // the bounds of the image, and a reference to the map.
  class USGSOverlay extends google.maps.OverlayView {
    bounds_;
    image_;
    div_;
    constructor(bounds, image) {
      super();
      // Initialize all properties.
      this.bounds_ = bounds;
      this.image_ = image;
      // Define a property to hold the image's div. We'll
      // actually create this div upon receipt of the onAdd()
      // method so we'll leave it null for now.
      this.div_ = null;
    }
    /**
     * onAdd is called when the map's panes are ready and the overlay has been
     * added to the map.
     */
    onAdd() {
      this.div_ = document.createElement("div");
      this.div_.style.borderStyle = "none";
      this.div_.style.borderWidth = "0px";
      this.div_.style.position = "absolute";

      // Create the img element and attach it to the div.
      const img = document.createElement("img");

      img.src = this.image_;
      img.style.width = "100%";
      img.style.height = "100%";
      img.style.position = "absolute";
      this.div_.appendChild(img);

      // Add the element to the "overlayLayer" pane.
      const panes = this.getPanes();

      panes.overlayLayer.appendChild(this.div_);
    }
    draw() {
      // We use the south-west and north-east
      // coordinates of the overlay to peg it to the correct position and size.
      // To do this, we need to retrieve the projection from the overlay.
      const overlayProjection = this.getProjection();
      // Retrieve the south-west and north-east coordinates of this overlay
      // in LatLngs and convert them to pixel coordinates.
      // We'll use these coordinates to resize the div.
      const sw = overlayProjection.fromLatLngToDivPixel(
        this.bounds_.getSouthWest()
      );
      const ne = overlayProjection.fromLatLngToDivPixel(
        this.bounds_.getNorthEast()
      );

      // Resize the image's div to fit the indicated dimensions.
      if (this.div_) {
        this.div_.style.left = sw.x + "px";
        this.div_.style.top = ne.y + "px";
        this.div_.style.width = ne.x - sw.x + "px";
        this.div_.style.height = sw.y - ne.y + "px";
      }
    }
    /**
     * The onRemove() method will be called automatically from the API if
     * we ever set the overlay's map property to 'null'.
     */
    onRemove() {
      if (this.div_) {
        this.div_.parentNode.removeChild(this.div_);
        this.div_ = null;
      }
    }
  }

  const overlay = new USGSOverlay(bounds, srcImage);

  overlay.setMap(map);
}

window.initMap = initMap;

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;
}

HTML

<html>
  <head>
    <title>Custom Overlays</title>
    <script src="https://polyfill.io/v3/polyfill.min.js?features=default"></script>

    <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 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=weekly"
      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-overlay-simple 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