Layer Object

The Layer object is created using either the usingLayer or usingNewLayer methods of the Map Object.

It provides a fluent layer object for chaining methods relating to the layer on the map as per the example below.

Parameters

No parameters.

NOTE: The Layer object is never created directly, rather is is created using either the usingLayer or usingNewLayer methods of the Map Object.

Example

var map = new Mapzania.Map("map-div", "AFRICA", function () {

    map.usingLayer("REGIONS")
        .hide();

    map.usingLayer("COUNTRIES")
        .filterByText("LandLocked=='Y'")
        .convertToCentroids()
        .style({ fillColor: "#0000FF"})
        .update();
});

Methods

addFeature

Adds a feature to the layer.

Parameters

Example

var map = new Mapzania.Map("map-div", "AFRICA");

var feature = {
      type: "Feature",
      geometry: {
        type: "LineString",
        coordinates: [[102.0, 0.0], [103.0, 1.0], [104.0, 0.0], [105.0, 1.0]]
      },
      properties: { streetName: "Markus Street", streetType: "mainroad" }
    };

map.usingNewLayer("MY_FEATURES")
  .addFeature(feature)
  .update();

addFeatureCollection

Adds a feature collection to the layer.

Parameters

Example

var map = new Mapzania.Map("map-div", "AFRICA");

var features = {
    type: "FeatureCollection",
    features: [{
      type: "Feature",
      geometry: {
        type: "LineString",
        coordinates: [[102.0, 0.0], [103.0, 1.0], [104.0, 0.0], [105.0, 1.0]]
      },
      properties: { streetName: "Markus Street", streetType: "mainroad" }
    }]
  };

map.usingNewLayer("MY_FEATURES")
  .addFeatureCollection(features)
  .update();

bringForwards

Brings the layer forwards by one in the layer stack.

This will make the layer more visible as it will be closer to the front/top of the map.

Parameters

No parameters.

Example

map.usingLayer("LAYER2")
	.bringForwards();

bufferGeometry

Creates an filter that buffers geometry. Buffering geometry converts the geometry to the polygon type in the case of points or lines. The geometry is the essentially "inflated" by the factor that is provided. See this for a working example.

Parameters

Options

Example

map.usingLayer("PRIMARY_ROADS")
    .bufferGeometry(0.010, {side:"left", joins:"bevel", end:"flat"})
    .style({
        strokeColor: "#000000",
        fillColor: "#FF0000",
        strokeWidth: 1
    })
    .update();

changeProperties

Creates an filter that restricts, adds or changes the feature properties that are returned from a layer. This is analogous to the SELECT clause of a SQL query.

Parameters

Example

map.usingLayer("COUNTRIES")
  .changeProperties(["Name", "Region", "CALC_AREA"])
  .update();

map.usingLayer("COUNTRIES")
  .changeProperties("Name AS 'Country Name'")
  .update();
  
map.usingLayer("COUNTRIES")
  .changeProperties("Format(Population / Area(), '#,###.0') as Density")
  .update();

map.usingLayer("COUNTRIES")
  .changeProperties("Population / Area()")
  .update();

map.usingLayer("COUNTRIES")
  .changeProperties("Area() As 'MyArea', Length() As 'MyLength'")
  .update();

clearFilters

Removes all filters from a layer.

Parameters

No parameters.

Example

var map = new Mapzania.Map("map-div", "AFRICA");

map.usingLayer("COUNTRIES")
  .clearFilters()
  .update();

clearFeatures

Clears the features from a layer.

Note: this works only for features that have been created client-side.

Layers which have server-side layer-sources will overwrite changes when they are updated (e.g. panning or zooming).

Parameters

No parameters.

Example

var map = new Mapzania.Map("map-div", "AFRICA");

map.usingLayer("MY_FEATURES")
  .clearFeatures()
  .update();

clearStyle

Clears all client-side styles that were applied to a layer.

Parameters

No parameters.

Example

var map = new Mapzania.Map("map-div", "WORLD");

map.usingLayer("COUNTRIES")
    .clearStyle()
    .update()

clipByFeatureCollection

Creates an filter that clips features on the layer based on whether or not they are inside of a GeoJSON FeatureCollection.

Parameters

Example

var featureCollection = {
  type:"FeatureCollection",
  features: [
    {
      type: "Feature",    
      geometry: {
        coordinates: [
          [
            [4.88922, 52.37072],
            [4.89526, 52.37114],
            [4.89209, 52.36931],
            [4.88925, 52.37072]
          ]
        ],
        type: "Polygon"
      }
    }
  ]
};

map.usingLayer("COUNTRIES")
  .clipByFeatureCollection(featureCollection)
  .update();

convertToCentroids

Creates an filter that converts all geometry to a point that represents its centroid. See this for a working example.

Parameters

No parameters.

Example

map.usingLayer("COUNTRIES")
    .convertToCentroids()
    .style({ fillColor: "#0000FF"})
    .update();

filterByBoundingBox

Creates an filter that filters features based on a bounding box.

Parameters

Example

map.usingLayer("COUNTRIES")
  .filterByBoundingBox([12.4, 9.5, 24.6, 41.2])
  .update(); 

filterByFeatureCollection

Creates an filter that filters features based on whether or not they are contained by a GeoJSON FeatureCollection.

Parameters

Options

Example

var featureCollection = {
  type:"FeatureCollection",
  features: [
    {
      type: "Feature",    
      geometry: {
        coordinates: [
          [
            [4.88922, 52.37072],
            [4.89526, 52.37114],
            [4.89209, 52.36931],
            [4.88925, 52.37072]
          ]
        ],
        type: "Polygon"
      }
    }
  ]
};

map.usingLayer("COUNTRIES")
  .filterByFeatureCollection(featureCollection);
  .update();

filterByNearest

Creates an filter that filters features based on their proximity to a point (latitude, longitude).

Parameters

Options

Example

map.usingLayer("COUNTRIES")
  .filterByNearest({type:"Point", coordinates:[10.2, -12.5]}, {take:3})
  .update();

filterByText

Creates an filter that filters features based on a text-based query statement. This is analogous to the WHERE clause of a SQL query.

Parameters

Example

var map = new Mapzania.Map("map-div", "AFRICA");

map.usingLayer("COUNTRIES")
  .filterByText("LandLocked=='Y'")
  .update();

getFeatureCollection

Returns a feature-collection in GeoJSON format of all the local features shown on the map.

Parameters

No Parameters

Example

var map = new Mapzania.Map("map-div", "AFRICA");

var geojson = map.usingLayer("COUNTRIES")
  .getFeatureCollection();

hide

Sets the visibility of a layer to false.

Parameters

No parameters.

Example

var map = new Mapzania.Map("map-div", "WORLD");

map.usingLayer("COUNTRIES")
    .hide();

sendBackwards

Sends the layer backwards by one in the layer stack.

This will make the layer less visible as it will be further from the front/top of the map.

Parameters

No parameters.

Example

map.usingLayer("LAYER2")
	.sendBackwards();

show

Sets the visibility of a layer to true and loads the content for the layer if it has not been done yet.

Parameters

No parameters.

Example

var map = new Mapzania.Map("map-div", "WORLD");

map.usingLayer("COUNTRIES")
    .show(); 

style

Adds a style to a layer. This style will replace any styles that have already been applied using this method and will supercede any styles that have been configured by the MapStyler.

Parameters

Example

var map = new Mapzania.Map("map-div", "WORLD");

map.usingLayer("COUNTRIES")
    .style({ fillColor: "#0000FF"})
    .update();

update

Causes the layer to redraw after its underlying data has changed. This might be due to database changes, styling changes or features being added to the layer on the client.

Parameters

No parameters.

Example

var map = new Mapzania.Map("map-div", "AFRICA");

map.usingLayer("COUNTRIES")
  .filterByText("LandLocked=='Y'")
  .style({ fillColor: "#CCCCCC"})
  .update();

usingFeature

Get a Feature Object from the map based on an id parameter.

This feature object is a fluent object and can be used to chain method calls to the feature as per the example below.

Parameters

Example

var map = new Mapzania.Map("map-div", "AFRICA");

map.usingLayer("COUNTRIES")
  .usingFeature("107")
    .show()
    .style({ fillColor: "#FF0000"})
    .update();