Leaflet.TileLayer.Fallback
Plugin for Leaflet. Replaces missing Tiles (404 error) by scaled lower zoom Tiles.
Leaflet is the leading open-source JavaScript library for mobile-friendly interactive maps.
Size: 2 kB minified, < 1 kB gzipped.
Requirements
- Leaflet 1.x
- For Leaflet 0.7, use the
v0.1.1release or theleaflet-0.7branch
Demo
TileLayer.Fallback demonstration page
Usage instructions
Quick Guide
HTML:
<!-- add TileLayer.Fallback script after Leaflet -->
<script src="leaflet.tilelayer.fallback.js"></script>JavaScript:
var myTileLayer = L.tileLayer.fallback(url, options);Now missing tiles will be automatically replaced by scaled up tiles from lower zoom levels.
Installing the plugin
Local copy
- Download the "
leaflet.tilelayer.fallback.js" file from thev1.0.4release. - Place the file alongside your page.
- Add the
scripttag (see Quick Guide > HTML) to your page after Leaflet script.
CDN
You can alternatively use the free unpkg CDN service, but keep in mind that it "is a free, best-effort service and cannot provide any uptime or support guarantees".
<!-- After Leaflet script -->
<script src="https://unpkg.com/[email protected]/dist/leaflet.tilelayer.fallback.js"></script>Creation
Simply use the L.tileLayer.fallback factory instead of your regular L.tileLayer:
var myTileLayer = L.tileLayer.fallback(url, options);
myTileLayer.addTo(map);API Reference
Creation
| Factory | Description |
|---|---|
L.tileLayer.fallback( <String> urlTemplate, <TileLayer options> options? ) |
Instantiates a tile layer object given a URL template and optionally an options object. When tile images return a 404 error, they are replaced by a scaled up tile from lower zoom. |
Options
| Option | Type | Default | Description |
|---|---|---|---|
| minNativeZoom | Number |
0 | Minimum zoom number the tiles source has available. If tiles are missing down to that zoom level (included), they will be replaced by the standard Error Tile (specified by errorTileUrl). For zoom lower than minNativeZoom, standard Tile Layer behaviour applies, i.e. tiles are loaded from minNativeZoom and scaled down. |
All other TileLayer options are applicable.
Events
| Event | Data | Description |
|---|---|---|
| tilefallback | TileFallbackEvent |
Fired when a tile is being replaced by a scaled up tile of lower zoom. |
All other TileLayer events are applicable.
TileFallbackEvent
| Property | Type | Description |
|---|---|---|
tile |
HTMLElement |
The tile element (image). |
url |
String |
The original source URL of the tile (before any fallback is applied). |
urlMissing |
String |
The missing source URL of the tile (possibly after a few fallback attempts). |
urlFallback |
String |
The fallback source URL of the tile (which may turn out to be also missing). |
Methods
All regular TileLayer methods are applicable.
Limitations
TileLayer.Fallback plugin tries to replace each missing tile by its immediate
lower zoom equivalent, and if that one is also missing, it goes to lower zoom
again; and so on until a tile image is returned by the server, or it reaches
minNativeZoom.
That means it has to wait for the server to return a 404 error before attempting to replace the tile by a lower zoom equivalent. If several zoom levels are missing, it has to wait as many times as the number of missing zooms. Therefore, the more missing zoom levels, the more time it takes to replace a tile.
License
Leaflet.TileLayer.Fallback is distributed under the Apache 2.0 License.