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Google Maps GoogleMap Toolbox icon

You can display interactive Google Maps on your Anvil Form with the GoogleMap component. Drag and drop onto your Form, or create one in code with the GoogleMap constructor.

map = GoogleMap()

map.center = GoogleMap.LatLng(52.2053, 0.1218)
map.zoom = 13
A GoogleMap showing Cambridge UK.

Markers and other overlays

GoogleMap components are containers. You can add various Map Overlay components to a map. In this example, we add a marker at a particular position and with a ‘drop’ animation.

marker = GoogleMap.Marker(
  animation=GoogleMap.Animation.DROP,
  position=GoogleMap.LatLng(52.2053, 0.1218)
)

map.add_component(marker)
A GoogleMap showing Cambridge UK with a pin dropped in the centre.

Customising markers

You can customise Markers using their icon property. This can be set to a GoogleMap.Symbol or GoogleMap.Icon object:

green_icon = GoogleMap.Icon(
      url="http://maps.google.com/mapfiles/kml/paddle/grn-blank.png"
    )

marker = GoogleMap.Marker(
  animation=GoogleMap.Animation.DROP,
  position=GoogleMap.LatLng(52.2053, 0.1218),
  icon = green_icon
)

map.add_component(marker)
A GoogleMap showing Cambridge UK with a green icon pin dropped in the centre.

You can find all sorts of useful icon images here.

Overlays and mouse events

Markers (and other overlays) can respond to mouse events. In the code snippet below, we display an InfoWindow anchored to the marker when the marker is clicked.

InfoWindows have a content property, which can be set to a string or an Anvil Component such as a Label or an entire Form - in this case we use a Label saying “This is Cambridge!”.

def marker_click(sender, **event_args):
  i =GoogleMap.InfoWindow(content=Label(text="This is Cambridge!"))
  i.open(map, sender)

marker.add_event_handler("click", marker_click)
A GoogleMap showing Cambridge UK with a message saying 'This is Cambridge' marked at a particular location (roughly where the bus station is).

Clicking on the marker brings up the message.

Drawing lines

To draw a line between positions on a map, add a GoogleMap.Polyline component to the map. In this example, we also add an arrow icon.

  p = GoogleMap.Polyline(
    path=[
      GoogleMap.LatLng(52.215, 0.14),
      GoogleMap.LatLng(52.195, 0.12),
      GoogleMap.LatLng(52.21, 0.10),
    ],
    stroke_color='blue',
    stroke_weight=2,
    icons=[
      GoogleMap.IconSequence(
        icon=GoogleMap.Symbol(
          path=GoogleMap.SymbolPath.FORWARD_OPEN_ARROW,
          scale=2
        )
      )
    ]
  )
A GoogleMap showing Cambridge UK with two lines joined at an angle. One line ends in an arrowhead.

Complete list of overlay components

Here is a complete list of the available map overlay components, and their most important properties and methods. See the API Docs for complete lists of properties and events.

Each property is listed in the format property_name: argument_type

GoogleMap.Marker

Mark a particular point on the map. Draws a red pin by default.

Properties

  • animation: GoogleMap.Animation - Specifies the animation of this marker. Set to GoogleMap.Animation.DROP, or GoogleMap.Animation.BOUNCE.

  • icon: can be either of the following:

    • GoogleMap.Symbol - Specifies the shape to display. If unset, a red pin is displayed.
    • GoogleMap.Icon - Specifies a custom icon, constructed using the url property.

  • label: GoogleMap.MarkerLabel | String - Describes the text label of this marker.

  • position: GoogleMap.LatLng - Specifies the position of this marker.

Learn more about Markers in the Google Maps documentation

GoogleMap.InfoWindow

Display a popup on the map at a particular position.

Properties

  • position: GoogleMap.LatLng - Specifies the position of the popup. Not required if this popup is anchored to a component (see the open method, below).
  • content: anvil.Component | string - The content of the popup. Can be a string, or an Anvil Component.

Methods

  • open(map, [anchor]) - Display this InfoWindow on the specified map. If anchor is specified, the InfoWindow does not need to have its own position property set.
  • close() - Hide this InfoWindow. The user can also cause this to happen by clicking the close button in the top-right of the popup.

Learn more about InfoWindows in the Google Maps documentation

GoogleMap.Polyline

Draw a line on the map.

Properties

  • icons: list of GoogleMap.IconSequence - Specifies the icons to display along this line.
  • path: list of GoogleMap.LatLng - A list of points along the line.
  • geodesic: boolean - Whether this line should follow the curvature of the Earth. Default False.

Learn more about Polylines in the Google Maps documentation

GoogleMap.Polygon

Draw a closed polygon on the map.

Properties

  • path: list of GoogleMap.LatLng - A list of vertices.
  • geodesic: boolean - Whether the outline of this polygon should follow the curvature of the Earth. Default False.

Learn more about Polygons in the Google Maps documentation

GoogleMap.Rectangle

Draw a rectangle on the map.

Properties

  • bounds: GoogleMap.LatLngBounds - Specifies the position and size of this rectangle.

Learn more about Rectangles in the Google Maps documentation

GoogleMap.Circle

Draw a circle on the map.

Properties

  • center: GoogleMap.LatLng - The position of the circle.
  • radius: number - The radius of the circle, in meters.

Learn more about Circles in the Google Maps documentation

In addition to the properties specified above, all overlays have clickable, draggable, and visible properties. Overlays with outlines also have editable, stroke_color, stroke_weight and stroke_opacity properties.

Those with area have fill_color and fill_opacity properties.

See the official Google Maps documentation for more details.

Data visualisation

It is possible to use the Data Layer to visualise location-based data instead of Overlays. In this example, we add point features to the map_data object, then set a rendering styles for all features at once.

map.map_data.add(GoogleMap.Data.Feature(
  geometry=GoogleMap.Data.Point(
    GoogleMap.LatLng(52.2,0.1))))

map.map_data.add(GoogleMap.Data.Feature(
  geometry=GoogleMap.Data.Point(
    GoogleMap.LatLng(52.21,0.12))))

map.map_data.add(GoogleMap.Data.Feature(
  geometry=GoogleMap.Data.Point(
    GoogleMap.LatLng(52.201,0.135))))

map.map_data.style = GoogleMap.Data.StyleOptions(
  icon=GoogleMap.Symbol(
    path=GoogleMap.SymbolPath.CIRCLE,
    scale=30,
    fill_color='red',
    fill_opacity=0.3,
    stroke_opacity=1,
    stroke_weight=1
  )
)
A GoogleMap showing Cambridge UK with three red translucent circles.

We could also generate feature styles dynamically by assigning a ‘styling function’ to the map_data.style property. The function will be called once for every feature, and should return a corresponding style. In this example, we choose the color of the circle based on the longitude of the feature.

def get_style(feature):
  point = feature.geometry.get()
  color = 'red' if point.lng() < 0.12 else 'blue'
  
  return GoogleMap.Data.StyleOptions(
    icon=GoogleMap.Symbol(
      path=GoogleMap.SymbolPath.CIRCLE,
      scale=30,
      fill_color=color,
      fill_opacity=0.3,
      stroke_opacity=1,
      stroke_weight=1
    )
  )

map.map_data.style = get_style
A GoogleMap showing Cambridge UK with on red and two blue translucent circles.

Making circles red or blue based on longitude.

Feature geometries

There are many tools available to define shapes on the map. In the example above, we were interested in points, so we used GoogleMap.Data.Point. There are several others available, listed below.

See the official Google Maps documentation for more information.

GoogleMap.Data.Point(lat_lng)

Features are respresented by a particular position.

GoogleMap.Data.MultiPoint([lat_lng_1, lat_lng_2, ...])

Features are respresented by a set of positions.

GoogleMap.Data.LineString([lat_lng_1, lat_lng_2, ...])

Features are respresented by a line with specified vertices.

GoogleMap.Data.MultiLineString([line_string_1, line_string_2, ...])

Features are respresented by a multiple LineString geometries.

GoogleMap.Data.LinearRing([lat_lng_1, lat_lng_2, ...])

Features are respresented by a closed loop of vertices.

GoogleMap.Data.Polygon([linear_ring_1, linear_ring_2, ...])

Features are respresented by a set of closed loops. Additional loops denote ‘holes’ in the polygon.

GoogleMap.Data.MultiPolygon([polygon_1, polygon_2, ...])

Features are respresented by multiple polygons.

GoogleMap.Data.GeometryCollection([geometry_1, geometry_2, ...])

Features are respresented by an arbitrary set of geometries defined above.

Address lookup (geocoding)

You can look up addresses from locations, and vice-versa, using the GoogleMap.geocode function. This function returns a GoogleMap.GeocoderResult array. In this example, we look up a location from an address, then display a marker.

results = GoogleMap.geocode(address="Cambridge, UK")

m = Marker(position=results[0].geometry.location)
map.add_component(m)

In this example, we look up an address for a given lat/long.

results = GoogleMap.geocode(
  location=GoogleMap.LatLng(52.2053, 0.1218)
)

print(results[0].formatted_address)

There are several other properties available on the GoogleMap.GeocoderResult object. See the official Google documentation for details.

If you want to do geocoding in Server Modules, you can use the geopy library (in a Full Python environment). Here’s a simple server function that does a reverse geocode lookup using a free API:

from geopy.geocoders import ArcGIS

@anvil.server.callable
def geocode(lat, lng):
  geolocator = ArcGIS()
  location = geolocator.reverse((lat, lng))
  print(location.address)

Geocoding API quota

A shared Google Maps API key is provided to allow easy testing of your geocoding code. This is shared between all Anvil users for free, so the request quota may run out. This can cause your request to produce an error like this:

ExternalError: Geocode failed: REQUEST_DENIED

To use your own API key, obtain an API key for your app, add the Google API Service to your app, then enter your API key in the Maps API Key box:

Maps API key section of the Google Service

Maps API key section of the Google Service

Calculating length and area

The GoogleMap Component provides utilities for calculating length and area:

GoogleMap.compute_length([pos_1, pos_2, ...])

Returns the length of the line going through the specified points.

GoogleMap.compute_area([vertex_1, vertex_2, ...])

Returns the area of the polygon with the specified vertices.

# Calculate the length of the line.
GoogleMap.compute_length([
  GoogleMap.LatLng(52.215, 0.14),
  GoogleMap.LatLng(52.195, 0.12),
  GoogleMap.LatLng(52.21, 0.10),
])

# Calculate the area of the polygon.
GoogleMap.compute_length([
  GoogleMap.LatLng(52.215, 0.14),
  GoogleMap.LatLng(52.195, 0.12),
  GoogleMap.LatLng(52.21, 0.10),
])

Google Maps in production

To use Google Maps in production with a custom domain, you should obtain an API key for your app.

To add this API key to your app, add the Google API Service, then expand the ‘Maps API Key’ section:

Maps API key section of the Google Service

Maps API key section of the Google Service

Do you still have questions?

Our Community Forum is full of helpful information and Anvil experts.

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