Other Layers

DG.LayerGroup

Used to group several layers and handle them as one. If you add it to the map, any layers added or removed from the group will be added/removed on the map as well. Extends DG.Layer.

DG.layerGroup([marker1, marker2]).addLayer(polyline).addTo(map);

Creation

Factory	Description
`DG.layerGroup( <Layer[]> layers )`	Create a layer group, optionally given an initial set of layers.

Options

Options inherited from Layer

Events

Events inherited from Layer

Methods

Method	Returns	Description
`toGeoJSON()`	`Object`	Returns a `GeoJSON` representation of the layer group (as a GeoJSON `GeometryCollection`).
`addLayer( <Layer> layer )`	`this`	Adds the given layer to the group.
`removeLayer( <Layer> layer )`	`this`	Removes the given layer from the group.
`removeLayer( <Number> id )`	`this`	Removes the layer with the given internal ID from the group.
`hasLayer( <Layer> layer )`	`Boolean`	Returns `true` if the given layer is currently added to the group.
`clearLayers()`	`this`	Removes all the layers from the group.
`invoke( <string> methodName, … )`	`this`	Calls `methodName` on every layer contained in this group, passing any additional parameters. Has no effect if the layers contained do not implement `methodName`.
`eachLayer( <Function> fn, <Object> context? )`	`this`	Iterates over the layers of the group, optionally specifying context of the iterator function. `group.eachLayer(function (layer) { layer.bindPopup('Hello'); });`
`getLayer( <Number> id )`	`Layer`	Returns the layer with the given internal ID.
`getLayers()`	`Layer[]`	Returns an array of all the layers added to the group.
`setZIndex( <Number> zIndex )`	`this`	Calls `setZIndex` on every layer contained in this group, passing the z-index.
`getLayerId( <Layer> layer )`	`Number`	Returns the internal ID for a layer

Methods inherited from Layer

Methods inherited from Evented

DG.FeatureGroup

Extended DG.LayerGroup that also has mouse events (propagated from members of the group) and a shared bindPopup method.

DG.featureGroup([marker1, marker2, polyline])
    .bindPopup('Hello world!')
    .on('click', function () {
        alert('Clicked on a group!');
    })
    .addTo(map);

Creation

Factory	Description
`DG.featureGroup( <Layer[]> layers )`	Create a feature group, optionally given an initial set of layers.

Options

Options inherited from Layer

Events

Events inherited from Layer

Methods

Method	Returns	Description
`setStyle( <Path options> style )`	`this`	Sets the given path options to each layer of the group that has a `setStyle` method.
`bringToFront()`	`this`	Brings the layer group to the top of all other layers
`bringToBack()`	`this`	Brings the layer group to the top of all other layers
`getBounds()`	`LatLngBounds`	Returns the LatLngBounds of the Feature Group (created from bounds and coordinates of its children).

Methods inherited from LayerGroup

Methods inherited from Layer

Methods inherited from Evented

DG.GeoJSON

Represents a GeoJSON object or an array of GeoJSON objects. Allows you to parse GeoJSON data and display it on the map. Extends DG.FeatureGroup.

DG.geoJson(data, {
    style: function (feature) {
        return { color: feature.properties.color };
    },
})
    .bindPopup(function (layer) {
        return layer.feature.properties.description;
    })
    .addTo(map);

Creation

Factory	Description
`DG.geoJSON( <Object> geojson?, <GeoJSON options> options? )`	Creates a GeoJSON layer. Optionally accepts an object in GeoJSON format to display on the map (you can alternatively add it later with `addData` method) and an `options` object.

Options

Option	Type	Default	Description
`pointToLayer`	`Function`	`*`	A `Function` defining how GeoJSON points spawn maps API layers. It is internally called when data is added, passing the GeoJSON point feature and its `LatLng`. The default is to spawn a default `Marker`: `function(geoJsonPoint, latlng) { return DG.marker(latlng); }`
`style`	`Function`	`*`	A `Function` defining the `Path options` for styling GeoJSON lines and polygons, called internally when data is added. The default value is to not override any defaults: `function (geoJsonFeature) { return {} }`
`onEachFeature`	`Function`	`*`	A `Function` that will be called once for each created `Layer`, after it has been created and styled. Useful for attaching events and popups to features. The default is to do nothing with the newly created layers: `function (layer) {}`
`filter`	`Function`	`*`	A `Function` that will be used to decide whether to show a feature or not. The default is to show all features: `function (geoJsonFeature) { return true; }`
`coordsToLatLng`	`Function`	`*`	A `Function` that will be used for converting GeoJSON coordinates to `LatLng`s. The default is the `coordsToLatLng` static method.

Options inherited from Layer

Events

Events inherited from Layer

Methods

Methods inherited from FeatureGroup

Methods inherited from LayerGroup

Methods inherited from Layer

Methods inherited from Evented

Functions

There are several static functions which can be called without instantiating DG.GeoJSON:

Function	Returns	Description
`geometryToLayer( <Object> featureData, <GeoJSON options> options? )`	`Layer`	Creates a `Layer` from a given GeoJSON feature. Can use a custom `pointToLayer` and/or `coordsToLatLng` functions if provided as options.
`coordsToLatLng( <Array> coords )`	`LatLng`	Creates a `LatLng` object from an array of 2 numbers (longitude, latitude) or 3 numbers (longitude, latitude, altitude) used in GeoJSON for points.
`coordsToLatLngs( <Array> coords, <Number> levelsDeep?, <Function> coordsToLatLng? )`	`Array`	Creates a multidimensional array of `LatLng`s from a GeoJSON coordinates array. `levelsDeep` specifies the nesting level (0 is for an array of points, 1 for an array of arrays of points, etc., 0 by default). Can use a custom `coordsToLatLng` function.
`latLngToCoords( <LatLng> latlng )`	`Array`	Reverse of `coordsToLatLng`
`latLngsToCoords( <Array> latlngs, <Number> levelsDeep?, <Boolean> closed? )`	`Array`	Reverse of `coordsToLatLngs` `closed` determines whether the first point should be appended to the end of the array to close the feature, only used when `levelsDeep` is 0. False by default.
`asFeature( <Object> geojson )`	`Object`	Normalize GeoJSON geometries/features into GeoJSON features.

DG.GridLayer

Generic class for handling a tiled grid of HTML elements. This is the base class for all tile layers and replaces TileLayer.Canvas. GridLayer can be extended to create a tiled grid of HTML Elements like <canvas>, <img> or <div>. GridLayer will handle creating and animating these DOM elements for you.

Synchronous usage

To create a custom layer, extend GridLayer and impliment the createTile() method, which will be passed a Point object with the x, y, and z (zoom level) coordinates to draw your tile.

var CanvasLayer = DG.GridLayer.extend({
    createTile: function (coords) {
        // create a <canvas> element for drawing
        var tile = DG.DomUtil.create('canvas', 'leaflet-tile');
        // setup tile width and height according to the options
        var size = this.getTileSize();
        tile.width = size.x;
        tile.height = size.y;
        // get a canvas context and draw something on it using coords.x, coords.y and coords.z
        var ctx = canvas.getContext('2d');
        // return the tile so it can be rendered on screen
        return tile;
    },
});

Asynchrohous usage

Tile creation can also be asyncronous, this is useful when using a third-party drawing library. Once the tile is finsihed drawing it can be passed to the done() callback.

var CanvasLayer = DG.GridLayer.extend({
    createTile: function (coords, done) {
        var error;
        // create a <canvas> element for drawing
        var tile = DG.DomUtil.create('canvas', 'leaflet-tile');
        // setup tile width and height according to the options
        var size = this.getTileSize();
        tile.width = size.x;
        tile.height = size.y;
        // draw something and pass the tile to the done() callback
        done(error, tile);
    },
});

Creation

Factory	Description
`DG.gridLayer( <GridLayer options> options? )`	Creates a new instance of GridLayer with the supplied options.

Options

Option	Type	Default	Description
`tileSize`	`Number\|Point`	`256`	Width and height of tiles in the grid. Use a number if width and height are equal, or `DG.point(width, height)` otherwise.
`opacity`	`Number`	`1.0`	Opacity of the tiles. Can be used in the `createTile()` function.
`updateWhenIdle`	`Boolean`	`depends`	If `false`, new tiles are loaded during panning, otherwise only after it (for better performance). `true` by default on mobile browsers, otherwise `false`.
`updateInterval`	`Number`	`200`	Tiles will not update more than once every `updateInterval` milliseconds.
`attribution`	`String`	`null`	String to be shown in the attribution control, describes the layer data, e.g. "© 2GIS".
`zIndex`	`Number`	`1`	The explicit zIndex of the tile layer.
`bounds`	`LatLngBounds`	`undefined`	If set, tiles will only be loaded inside inside the set `LatLngBounds`.
`minZoom`	`Number`	`0`	The minimum zoom level that tiles will be loaded at. By default the entire map.
`maxZoom`	`Number`	`undefined`	The maximum zoom level that tiles will be loaded at.
`noWrap`	`Boolean`	`false`	Whether the layer is wrapped around the antimeridian. If `true`, the GridLayer will only be displayed once at low zoom levels.
`pane`	`String`	`'tilePane'`	`Map pane` where the grid layer will be added.

Events

Event	Data	Description
`loading`	`Event`	Fired when the grid layer starts loading tiles
`tileunload`	`TileEvent`	Fired when a tile is removed (e.g. when a tile goes off the screen).
`tileloadstart`	`TileEvent`	Fired when a tile is requested and starts loading.
`tileerror`	`TileEvent`	Fired when there is an error loading a tile.
`tileload`	`TileEvent`	Fired when a tile loads.
`load`	`TileEvent`	Fired when the grid layer loaded all visible tiles.

Events inherited from Layer

Methods

Method	Returns	Description
`bringToFront()`	`this`	Brings the tile layer to the top of all tile layers.
`bringToBack()`	`this`	Brings the tile layer to the bottom of all tile layers.
`getAttribution()`	`String`	Used by the `attribution control`, returns the attribution option.
`getContainer()`	`String`	Returns the HTML element that contains the tiles for this layer.
`setOpacity( <Number> opacity )`	`this`	Changes the opacity of the grid layer.
`setZIndex( <Number> zIndex )`	`this`	Changes the zIndex of the grid layer.
`isLoading()`	`Boolean`	Returns `true` if any tile in the grid layer has not finished loading.
`redraw()`	`this`	Causes the layer to clear all the tiles and request them again.
`getTileSize()`	`Point`	Normalizes the tileSize option into a point. Used by the `createTile()` method.

Extension methods

Layers extending DG.GridLayer shall reimplement the following method.

Method	Returns	Description
`createTile( <Object> coords, <Function> done? )`	`HTMLElement`	Called only internally, must be overriden by classes extending `GridLayer`. Returns the `HTMLElement` corresponding to the given `coords`. If the `done` callback is specified, it must be called when the tile has finished loading and drawing.

Methods inherited from Layer

Methods inherited from Evented