Tile Layer

The basis of any map is a TileLayer, which displays square raster images in a continuous grid, sourced from the Internet or a local file system.

flutter_map supports WMS Usage, but most map tiles are accessed through Slippy Map/CARTO/XYZ URLs.

TileLayer class - flutter_map library - Dart API

TileLayer(
  urlTemplate: 'https://tile.openstreetmap.org/{z}/{x}/{y}.png',
  userAgentPackageName: 'dev.fleaflet.flutter_map.example',
  // Plenty of other options available!
),

You must comply with the appropriate restrictions and terms of service set by your tile server. Failure to do so may lead to any punishment, at the tile server's discretion.

This library and/or the creator(s) are not responsible for any violations you make using this package.

The OpenStreetMap Tile Server (as used above) ToS can be found here. Other servers may have different terms.

URL Template

This parameter must be specified unless wmsOptions is specified.

The URL template is a string that contains placeholders, which, when filled in, create a URL/URI to a specific tile.

Specifically, flutter_map supports the Slippy Map format, sometimes referred to as CARTO or Raster XYZ. Tiles are referred to by their zoom level, and position on the X & Y axis. For more information, read How Does It Work?.

These templates are usually documented by your tile server, and will always include the following placeholders:

• {x}: x axis coordinate

• {y}: y axis coordinate

• {z}: zoom level

Sometimes, they also include:

• {s}: Subdomains

• {r}: Retina Mode

Additional placeholders can also be added freely to the template, and are filled in with the specified values in additionalOptions. This can be used to easier add switchable styles or access tokens, for example.

Subdomains

Some tile servers provide mirrors/redirects of the main tile server on/via subdomains, such as 'a', 'b', 'c'.

These were necessary to bypass browsers' limitations on simultaneous HTTP connections, thus increasing the number of tiles that can load at once.

To use subdomains, add the {s} placeholder, and specify the available subdomains in TileLayer.subdomains. flutter_map will then fill the placeholder with one of these values based on internal logic.

Subdomains are now usually considered redundant due to the usage of HTTP/2 & HTTP/3 which don't have the same restrictions.

Usage of subdomains will also hinder Flutter's ability to cache tiles, potentially leading to increased tile requests and costs.

If the server supports HTTP/2 or HTTP/3 (how to check), avoid using subdomains.

Retina Mode

Retina mode improves the resolution of map tiles, an effect particularly visible on high density displays.

Raster map tiles can look pixelated (especially on high density displays), so some servers support high-resolution "@2x" tiles, which are tiles at twice the resolution of normal tiles. However, not all tile servers support this, so flutter_map can simulate retina behaviour.

It is recommended to enable retina mode on high density displays (especially where the server natively supports retina tiles). This can be done by calling RetinaMode.isHighDensity with the current BuildContext, and passing the result to TileLayer.retinaMode.

If the {r} placeholder is present in the the urlTemplate, and retinaMode is enabled, then it will be filled with "@2x". If it is not present, but retinaMode is enabled, then flutter_map will simulate retina behaviour by requesting four tiles at a larger zoom level and combining them together in place of one.

Note that simulating retina mode will increase tile requests, decrease the effective maximum zoom by 1, and may result in map labels/text/POIs appearing smaller than normal.

Always prefer the server's native retina tiles where available.

Fallback URL Template

It's also possible to specify a fallbackUrl template, used if fetching a tile from the primary urlTemplate fails (which has the same format as this).

Specifying a fallbackUrl does have negative effects on performance and efficiency. Avoid specifying fallbackUrl unless absolutely necessary for your use case.

See in-code documentation and Tile Providers for more information.

userAgentPackageName

Although it is programatically optional, always specify the userAgentPackageName argument to avoid being blocked by your tile server.

This parameter should be passed the application's package name, such as 'com.example.app'. This is important to avoid blocking by tile servers due to high-levels of unidentified traffic. If no value is passed, it defaults to 'unknown'.

This is then formatted into a 'User-Agent' header, and appended to the TileProvider's headers map, if it is not already present.

This is ignored on the web, where the 'User-Agent' header cannot be changed due to a limitation of Dart/browsers.

Tile Providers

If a large proportion of your users use the web platform, it is preferable to use CancellableNetworkTileProvider, instead of the default NetworkTileProvider. It may also be beneficial to use this tile provider on other platforms as well.

See CancellableNetworkTileProvider for more information.

Need more control over how the URL template is interpreted and/or tiles are fetched? You'll need to change the TileProvider.

pageTile Providers