How to load local tiles as overlays in maps application?

PhilipJohn

I'm trying to load a large number of tile overlays from a folder in Assets in my Android project. I can get tiles to load from a remote url, but not from a local folder. Any ideas what I'm doing wrong here?

In my Activity

 public void OnMapReady(GoogleMap map)
        {
            map.MapType = GoogleMap.MapTypeNormal;
            var options = new TileOverlayOptions();
            options.InvokeTileProvider(new LocalTileProvider());
            map.AddTileOverlay(options);
        }

and the UrlTileProvider

public class LocalTileProvider : UrlTileProvider
    {
        public LocalTileProvider() : base(256, 256)
        {
        }

        public override URL GetTileUrl(int x, int y, int z)
        {
            string s = "file:///android_asset/tiles/" + z.ToString() + "/" + y.ToString() + "/" + x.ToString() + ".jpg";
            //string s = "http://b.tile.openstreetmap.org/" + z + "/" + x + "/" + y + ".png"; // <= this works

            return new URL(s);
        }
    }

LandLu

If you want to use a local resource we need to use ITileProvider instead of UrlTileProvider. Make your activity implement the UrlTileProvider. Then apply it like:

public Tile GetTile(int x, int y, int zoom)
{
    var bytes = default(byte[]);
    using (StreamReader reader = new StreamReader(Assets.Open("image.jpg")))
    { 
        using (var memstream = new MemoryStream())
        {
            reader.BaseStream.CopyTo(memstream);
            bytes = memstream.ToArray();
        }
    }
    return new Tile(256, 256, bytes);
}

public void OnMapReady(GoogleMap map)
{
    map.MapType = GoogleMap.MapTypeNormal;
    var tileOverlayOptions = new TileOverlayOptions()
                                .InvokeTileProvider(this);
    map.AddTileOverlay(tileOverlayOptions);
}

LandLu

If you want to use a local resource we need to use ITileProvider instead of UrlTileProvider. Make your activity implement the UrlTileProvider. Then apply it like:

public Tile GetTile(int x, int y, int zoom)
{
    var bytes = default(byte[]);
    using (StreamReader reader = new StreamReader(Assets.Open("image.jpg")))
    { 
        using (var memstream = new MemoryStream())
        {
            reader.BaseStream.CopyTo(memstream);
            bytes = memstream.ToArray();
        }
    }
    return new Tile(256, 256, bytes);
}

public void OnMapReady(GoogleMap map)
{
    map.MapType = GoogleMap.MapTypeNormal;
    var tileOverlayOptions = new TileOverlayOptions()
                                .InvokeTileProvider(this);
    map.AddTileOverlay(tileOverlayOptions);
}

PhilipJohn

@LandLu Many thanks. I was stuck on this for hours. Works fine now.

tnx

@PhilipJohn Would you mind to share your solution code with multiple tile images?

Thanks.

PhilipJohn

@tnx I'm really sorry, but I no longer have access to that code.