Map providers support in SfMaps

3 Sep 2020 / 20 minutes to read

The maps control supports map providers such as OpenStreetMap and Bing Maps that can be added to an imagery layer in maps.

OpenStreetMap

The OpenStreetMap (OSM) is a world map; it was built by a community of mappers. It is free to use under an open license. This allows you view geographical data in a collaborative way from anywhere on the earth. The OSM provides small tile images based on your requests and combines them into a single image to display the map area in the maps control.

Adding OSM in maps

The maps control uses imagery layer to display the tile images from the OSM service. To use OSM, add an imagery layer in maps’ layers collection.

SfMaps maps = new SfMaps(this);
        ImageryLayer layer = new ImageryLayer();
        maps.Layers.Add(layer);

OSM image

NOTE

Both the ShapeFileLayer and ImageryLayer have been derived commonly from MapsLayer.

Bing Maps

The Bing Maps is a world map owned by Microsoft. As OSM, Bing Maps also provides map tile images based on your requests and combines them into a single image to display the map area. To use Bing maps, set the LayerType property of ImageryLayer to “Bing”. Then, set the Bing Maps key, which is obtained from Bing Maps Key.

SfMaps maps = new SfMaps(this);
        ImageryLayer layer = new ImageryLayer();
        layer.LayerType = LayerType.Bing;
        layer.BingMapKey = "Your bing map key";
        maps.Layers.Add(layer);

Bing map image

NOTE

The LayerType property of ImageryLayer provides support to OSM and Bing Maps. The default value of the LayerType property is OSM.

BingMapStyle

The ImageryLayer provides support to the following types of Bing Maps:

  • Road
  • Aerial
  • AerialWithLabels

The desired style for the Bing Maps can be set using the BingMapStyle property of ImageryLayer. The default value of BingMapStyle is “Road”.

Road

The Road view displays the default map view of roads, buildings, and geography. The default value of the BingMapStyle property of imagery layer is “Road”.

Aerial

The Aerial view displays the satellite images to highlight the roads and major landmarks for easy identification. The aerial view can be applied to maps by setting the BingMapStyle to “Aerial”.

SfMaps maps = new SfMaps(this);
    ImageryLayer layer = new ImageryLayer();
    layer.LayerType = LayerType.Bing;
    layer.BingMapStyle = BingMapStyle.Aerial;
    layer.BingMapKey = "Your bing map key ";
    maps.Layers.Add(layer);

aerial view image

AerialWithLabel

The AerialWithLabel view displays the Aerial map with labels for continent, country, ocean, etc. This view can be applied to maps by setting the BingMapStyle to “AerialWithLabel”.

SfMaps maps = new SfMaps(this);
    ImageryLayer layer = new ImageryLayer();
    layer.LayerType = LayerType.Bing;
    layer.BingMapStyle = BingMapStyle.AerialWithLabels;
    layer.BingMapKey = "Your bing map key ";
    maps.Layers.Add(layer);

AerialWithLabel image

Zooming and panning

The maps control provides interactive zooming and panning supports to OSM and Bing Maps.

Zooming helps you get a closer look of an area on maps for in-depth analysis. Panning helps you move a map around to focus the targeted area. You can perform zooming and panning with the pinching gesture in a map area.

Zooming image

ResetOnDoubleTap

The ImageryLayer provides support to reset the maps to the default view when you double tap the imagery layer by setting the ResetOnDoubleTap property to true. The default value of this property is true. This behavior can be restricted by setting the ResetOnDoubleTap property to false.

SfMaps maps = new SfMaps(this);
        ImageryLayer layer = new ImageryLayer();
        layer.ResetOnDoubleTap = true;
        maps.Layers.Add(layer);

GeoCoordinates

The GeoCoordinates property allows you view the desired area at the center on loading. By default, the GeoCoordinates value is (0,0). So, the latitude value “0” and longitude value “0” are shown at the center.

SfMaps maps = new SfMaps(this);
        maps.ZoomLevel = 2;
        ImageryLayer layer = new ImageryLayer();
        layer.GeoCoordinates = new PointF(69.07f, -37.08f);
        maps.Layers.Add(layer);

Geo-Coordinate image

SfMaps maps = new SfMaps(this);
        maps.ZoomLevel = 2;
        ImageryLayer layer = new ImageryLayer();
        layer.GeoCoordinates = new PointF(0,0);
        maps.Layers.Add(layer);

Center image

Markers

As ShapeFileLayer, markers also can be added to imagery layer. Markers can be customized using the MarkerSettings property in imagery layer.
The detailed explanation of marker and its customization have been provided in Markers section.

SfMaps maps = new SfMaps(this);          
            ImageryLayer layer = new ImageryLayer();        
            layer.MarkerSetting = new MarkerSetting();
            layer.MarkerSetting.MarkerIconColor = Color.Red;
            layer.MarkerSetting.MarkerIcon = MarkerIcon.Diamond;
            layer.MarkerSetting.IconSize = 13;
            MapMarker marker1 = new MapMarker();
            marker1.Label = "United States";
            marker1.Latitude = 40;
            marker1.Longitude = -101;
            layer.Markers.Add(marker1);
            MapMarker marker2 = new MapMarker();
            marker2.Label = "Brazil";
            marker2.Latitude = -15.7833;
            marker2.Longitude = -52;
            layer.Markers.Add(marker2);
            MapMarker marker3 = new MapMarker();
            marker3.Label = "Congo";
            marker3.Latitude = -1.6;
            marker3.Longitude = 24.4;
            layer.Markers.Add(marker3);
            MapMarker marker4 = new MapMarker();
            marker4.Label = "Kazakhstan";
            marker4.Latitude = 49.9;
            marker4.Longitude = 72.23;
            layer.Markers.Add(marker4);
            MapMarker marker5 = new MapMarker();
            marker5.Label = "Australia";
            marker5.Latitude = -20.54;
            marker5.Longitude = 134.10;
            layer.Markers.Add(marker5);
            maps.Layers.Add(layer);

            SetContentView(maps);

Marker image

Cache tiles in application memory

The CanCacheTiles property used to decide whether the tiles should be cached or not.

ImageryLayer imageryLayer = new ImageryLayer();

       imageryLayer.CanCacheTiles = true;

Delete the tiles from cache

The DeleteTilesFromCache method used to delete the cache stored in the applications.

SfMaps maps = new SfMaps(this);          
       ImageryLayer imageryLayer = new ImageryLayer();
       imageryLayer.DeleteTilesFromCache();

Calculate zoom level based on map geo-bounds or distance

This feature is used to calculate the initial zoom level automatically in two ways.

  • Distance in radius(Meter/KiloMeter/Mile)
  • Geo-bounds(Northeast, Southwest)

Distance in radius

Calculate the initial zoom level automatically based on the Radius and DistanceType properties of imagery layer class.

NOTE

DistanceType property default value is KiloMeter.

public class MainActivity : AppCompatActivity
    {
        protected override void OnCreate(Bundle savedInstanceState)
        {
            base.OnCreate(savedInstanceState);
            Xamarin.Essentials.Platform.Init(this, savedInstanceState);
            SfMaps maps = new SfMaps(this);
            ImageryLayer layer = new ImageryLayer();
            layer.GeoCoordinates = new PointF(38.909804f, -77.043442f);
            layer.Radius = 5;
            layer.DistanceType = DistanceType.KiloMeter;
            CustomMarker marker = new CustomMarker(this);
            marker.Label = "Washington";
            marker.Latitude = 38.909804;
            marker.Longitude = -77.043442;
            layer.Markers.Add(marker);
            maps.Layers.Add(layer);
            SetContentView(maps);
        }
    }

    public class CustomMarker : MapMarker
    {
        Android.Content.Context context;
        public CustomMarker(Android.Content.Context con)
        {
            context = con;
        }

        public override void DrawMarker(PointF p0, Canvas p1)
        {
            float density = context.Resources.DisplayMetrics.Density / 1.5f;
            Bitmap bitmap = BitmapFactory.DecodeResource(context.Resources, Resource.Drawable.pin);
            p1.DrawBitmap(bitmap, (float)p0.X - (12 * density), (float)p0.Y - (35 * density), new Paint());
        }
    }

Geo-bounds

Calculate the initial zoom level automatically based on the LatLngBounds(Northeast, Southwest) of imagery layer class.

public class MainActivity : AppCompatActivity
    {
        protected override void OnCreate(Bundle savedInstanceState)
        {
            base.OnCreate(savedInstanceState);
            Xamarin.Essentials.Platform.Init(this, savedInstanceState);
            SfMaps maps = new SfMaps(this);
            ImageryLayer layer = new ImageryLayer();
            LatLngBounds bounds = new LatLngBounds();
            bounds.Northeast = new Position(38.909804, -77.043442);
            bounds.Southwest = new Position(38.909804, -77.043442);
            layer.LatLngBounds = bounds;
            CustomMarker marker = new CustomMarker(this);
            marker.Label = "Washington";
            marker.Latitude = 38.909804;
            marker.Longitude = -77.043442;
            layer.Markers.Add(marker);
            maps.Layers.Add(layer);
            SetContentView(maps);
        }
    }

    public class CustomMarker : MapMarker
    {
        Android.Content.Context context;
        public CustomMarker(Android.Content.Context con)
        {
            context = con;
        }

        public override void DrawMarker(PointF p0, Canvas p1)
        {
            float density = context.Resources.DisplayMetrics.Density / 1.5f;
            Bitmap bitmap = BitmapFactory.DecodeResource(context.Resources, Resource.Drawable.pin);
            p1.DrawBitmap(bitmap, (float)p0.X - (12 * density), (float)p0.Y - (35 * density), new Paint());
        }
    }

NOTE

When setting LatLngBounds and DistanceRadius at the same time, the priority is DistanceRadius and calculate zoom level based radius value.

SfMaps zoom level changed image

Get the map tile layer bounds

You can get imagery layer pixel bounds by using MapBounds property while zooming, panning, and changing Geo-Coordinate value in imagery layer.

public class MainActivity : AppCompatActivity
    {
        ImageryLayer layer = new ImageryLayer();

        protected override void OnCreate(Bundle savedInstanceState)
        {
            base.OnCreate(savedInstanceState);
            Xamarin.Essentials.Platform.Init(this, savedInstanceState);
            SfMaps maps = new SfMaps(this);
            layer.GeoCoordinates = new PointF(30.9709225f, -100.2187212f);
            layer.GeoCoordinateChanged += Layer_GeoCoordinateChanged;
            maps.Layers.Add(layer);
            SetContentView(maps);
        }

        private void Layer_GeoCoordinateChanged(object sender, GeoCoordinateChangedEventArgs e)
        {
            var pixelBounds = layer.MapBounds;
        }
    }

Events

ZoomLevelChanging event triggers when zoom level changed. Following arguments can be get from the ZoomLevelChanging event .

  • Cancel - Used to cancel the zooming.

  • PreviousLevel - Returns the previous level after the zooming.

  • CurrentLevel - Returns the current level to be zoomed.

SfMaps maps = new SfMaps(this);          
        ImageryLayer imageryLayer = new ImageryLayer();
        imageryLayer.ZoomLevelChanging += ImageryLayer_ZoomLevelChanging;
		maps.Layers.Add(imageryLayer);
        SetContentView(maps);
		
        private void ImageryLayer_ZoomLevelChanging(object sender, ZoomLevelChangingEventArgs e)
        {
            if (e.PreviousLevel == 10) // Returns the previous zoom level
            {
                e.Cancel = true; // Cancels the zooming event
                var CurrentLevel = e.CurrentLevel; // Returns the current zoomed level
            }
        }