I have a map with a few base layers. Users can choose the base layer and then save the map. After saving the map, the system loads it with the new base layer. That base layer should be selected in the L.Control.Layers control. However, there's no way in the API to select a base layer.
Anyone knows a way around this, or a different plug in?
UPDATE: Here is the code I use. MapConfigs has the ids in MapBox, and can create the map that L.control.layers requires.
var map = L.mapbox.map( components.mapDivId , MapConfigs.idFor(baseLayerName) );
map.addControl( L.control.layers(
MapConfigs.toBaseLayersControlMap(map)
).setPosition("topright"));
Thanks!
Why not store references to all the base layers available in a hash, then use addLayer or removeLayer (http://leafletjs.com/reference.html#map-addlayer) as needed to programmatically select base layers?. Something like below.
var tileLayers = {light: L.tileLayer('lightUrl'),dark: L.tileLayer('darkUrl')}
Related
I have a LeafletJS map with a GeoJSON layer that contains multiple polygons. If a user enters a latitude/longitude coordinate that falls within the GeoJSON layer, the script should retrieve the feature that contains that point and log some information about it to the console.
I can't simply use Leaflet's built-in event handling because the latitude and longitude coordinates are generated by a separate input field, not by direct interaction with the map. So my question is not a duplicate of this.
I'm looking for something similar to getFeatureContainingLatLng() in the example below:
var map = L.map('map');
var geojson = L.geoJson(myGeojson);
geojson.addTo(map);
$.on('address input changed event', function(lat, lng) {
var myFeature = geojson.getFeatureContainingLatLng(lat, lng);
console.log(myFeature.properties);
});
The plugins Leaflet.CheapLayerAt or Leaflet-pip should help. Both approaches will solve your problem, albeit they have different advantages and disadvantages specially in terms of algorithmic complexity.
Currently I am working on Openlayers 3.
I used custom overlays in Google maps Javascript api v3 to add customized markers as html div on the map. And these markers are grouped and plotted in different custom overlays.
Now I am trying to implement the same in OpenLayers 3, but I couldn't find any solution as the overlays in OpenLayers 3 takes one marker in one overlay.
Can I group overlays in OpenLayers 3 in order to group the markers? Or Is there any other options available?
You have multiple possible options.
A) If you have only one dataset, then you could use a StyleFunction. See this ol3 vector example, more specifically this section of code:
var vectorLayer = new ol.layer.Vector({
source: new ol.source.Vector({
url: 'https://openlayers.org/en/v3.20.1/examples/data/geojson/countries.geojson',
format: new ol.format.GeoJSON()
}),
style: function(feature, resolution) {
style.getText().setText(resolution < 5000 ? feature.get('name') : '');
return style;
}
});
See the style property? It can be a ol.style.Style or a style function, like demonstrated above. The function receives the feature and current resolution of the map view as argument and is called every time the feature gets rendered (or re-rendered). Returning a ol.style.Style or array of style objects will render the feature using the/these styles.
The feature can have unique properties, i.e. feature.getProperties(). Using as many properties within the feature(s), you can return a unique array of unique style objects.
Here's a more complex ol3 example featuring style functions that you can look and have an example of dynamic styling depending on the resolution. That could give you a better idea of what you could do with the feature properties.
B) If you have multiple datasets, then you can create one vector layer per dataset and define a unique style object on the layer, which would render the features all the same.
I'm trying to render Antarctica geojson shape on a map using the HERE maps api.
The geojson is found here: https://github.com/johan/world.geo.json/blob/master/countries/ATA.geo.json
You can see github renders it nicely.
Using the same geojson on geojson.io also renders it nicely.
But somehow it seems to render the 'inverse' of Antarctica when using it in HERE maps.
It colors everything except antarctica.
see: http://imagebin.ca/v/1dZIn5vsEuFx
(I've tried making an expample using jsfiddle, but it's not able to load external json. And the HERE maps api doesn't allow you to load geoJSON from a string)
Is there an issue with the geoJSON? Is there an issue with the HERE maps api?
The API doesn't quite understand what to do with the open polygon. Because the polygon is basically just a line around the globe the API doesn't know if you shape closes over the north pole or the south pole. By default it assumes that open polygons close over the north pole. You can change this by using this flag (setNorthPoleCovering):
http://developer.here.com/javascript-apis/documentation/v3/maps/topics_api_nlp/h-map-polygon.html#h-map-polygon__setnorthpolecovering
However, actually getting to that point in the code where this can be done is a bit complicated:
// When you instantiate the geojson.Reader you can specify a function that
// receives all objects the reader parsed. It is called when objects are
// being rendered on the map. At that point we can look into the object and
// check whether it is Antarctica
var reader = new H.data.geojson.Reader('...ATA.geo.json', {
style: function(obj) {
if (obj.getData().properties.name === "Antarctica") {
//AHA! We found Antarctica!
// Since this is a multi-polygon we have a group here which contains
// all polygons. We apply the north-pole-covering flag to each of the
// polygons
obj.forEach(function(polygon) {
polygon.setNorthPoleCovering(false);
});
}
}
});
reader.parse();
map.addLayer(reader.getLayer());
Depending on what you want to accomplish in terms of dynamic behavior, if you are just looking to display or share a map with cards and other metadata about a country with some basic styling -- HERE XYZ can be used to render GeoJSON on a HERE map.
If you want to do it with JavaScript rather than an embedded iframe, the other answer may be what you are looking for.
There is an there an issue with the GeoJSON, and other mapping APIs would have the same problem. It needs to be closed at the 180th meridian, so
[178.277212,-84.472518],[180,-84.71338],[-179.942499,-84.721443]
becomes
[178.277212,-84.472518],[180,-84.71338],[180,-90],[-180,-90],[-180,-84.71338],[-179.942499,-84.721443]
I am displaying two different leaflet maps in the same page. After a certain event. I want a Polyline to appear on both of them. I would like to avoid, if possible, to create a copy and keep two different variables.
I am trying yo use the following:
var line_coordinates = [[1,2],[3,4]];
var my_polyline = L.polyline(line_coordinates);
my_polyline.addTo(map1);
my_polyline.addTo(map2);
However, if I run the above code, the Polyline will be displayed only on the map2.
Afterwords, I will need to change again its coordinates to some new_line_coordinates, and I will run the following:
my_polyline.setLatLngs(new_line_coordinates);
my_polyline.redraw();
The polyline should now appear updated to the new coordinates. However, again, it appears only on map2.
What am I doing wrong? Is it possible to achieve what I am trying to do?
As geocodezip mentioned in a comment, adding a polyline to a map sets the polyline object's this._map instance variable. Therefore, there is no way to have the object rendered on both maps with the way in which it is currently implemented.
You can view the relevant source code here.
You can't add the same layer to multiple Leaflet maps. But I had a similar problem using a more complex GeoJSON layergroup and ultimately solved it by getting the GeoJSON object from the layer using toGeoJSON() and using it to create a new layer for the second map. For a simple polyline, you could use getLatLngs(). So:
var line_coordinates = [[1,2],[3,4]];
var my_polyline = L.polyline(line_coordinates);
my_polyline.addTo(map1);
var new_polyline = L.polyline(line_coordinates);
new_polyline.addTo(map2);
should work, as would:
var line_coordinates = [[1,2],[3,4]];
var my_polyline = L.polyline(line_coordinates);
my_polyline.addTo(map1);
var my_polyline_latlngs = my_polyline.getLatLngs();
var new_polyline = L.polyline(my_polyline_latlngs);
new_polyline.addTo(map2);
I currently have a implementation where some markers coming from JSON list is shown, on a particular area, Now I want to filter these marker depending upon some criteria, I have done the filtering part, and got the filtered list. Now to render this markers on the map again, The current implementation loads the js with a key again, also creates the GMap2 object and draws the list of marker on the newly created map, which is really annoying. I want map to be there and only markers to be added and removed from the map.
Any help is appreciated
You can use addOverlay and removeOverlay to add/remove markers from an already displayed map. See the examples here: http://code.google.com/apis/maps/documentation/overlays.html#Markers
var latlng = new GLatLng(lat, lng);
map.addOverlay(new GMarker(latlng));
You can make drawMap() and drawMarkers() as two separate functions. And after map has been created redefine drawMap to empty function like this:
drawMap = function(){}; After that only drawMarkers() will be executed.
Hope this is what you need. If not, provide some code.