JarCastingleaflet-image
Export images out of Leaflet maps without a server component, by using Canvas and CORS.
Requirements
- Tile layer providers (OSM, MapBox, etc) must support CORS
- Any markers on the map must also support CORS. The default Leaflet-CDN markers don't, so they aren't supported.
- Your browser must support CORS and Canvas, so
IE >= 10with no exceptions. - This library does not rasterize HTML because browsers cannot rasterize HTML. Therefore, L.divIcon and other HTML-based features of a map, like zoom controls or legends, are not included in the output, because they are HTML.
For Leaflet < 1.0.0: You must set L_PREFER_CANVAS = true; so that vector layers are drawn in Canvas
For Leaflet >= 1.0.0: You must set renderer: L.canvas() for any layer that you want included in the generated image. You can also set this by setting preferCanvas: true in your map's options.
Plugins that will not work with leaflet-image
- Leaflet.label: will not work because it uses HTML to display labels.
- Leaflet.markercluster: will not work because it uses HTML for clusters.
Usage
browserify
npm install --save leaflet-image
web
curl -L https://unpkg.com/leaflet-image@latest/leaflet-image.js > leaflet-image.js
Example
var map = L.mapbox.map('map', 'YOUR.MAPID').setView([38.9, -77.03], 14);
leafletImage(map, function(err, canvas) {
// now you have canvas
// example thing to do with that canvas:
var img = document.createElement('img');
var dimensions = map.getSize();
img.width = dimensions.x;
img.height = dimensions.y;
img.src = canvas.toDataURL();
document.getElementById('images').innerHTML = '';
document.getElementById('images').appendChild(img);
});
Plugin CDN
leaflet-image is available through the Mapbox Plugin CDN so you don't need to download & copy it. Just include the following script tag:
<script src='//api.tiles.mapbox.com/mapbox.js/plugins/leaflet-image/v0.0.4/leaflet-image.js'></script>
API
leafletImage(map, callback)
map is a L.map or L.mapbox.map, callback takes (err, canvas).
Attribution
Any images you generate from maps that require attribution - which is most, including all from commercial sources and those that include any data from OpenStreetMap - will require the same attribution as the map did. Remember to attribute.
See Also
- The Mapbox Static Image API is simpler to use and faster than this approach.
