Intermittent WMTS Service Stalling and Flickering with SharpMap 1.2 and BruTile 2.2.0

[ZohaibWaqarMalik]

I'm encountering an intermittent issue when rendering a WMTS service using SharpMap 1.2 and BruTile 2.2.0. The service works correctly initially, but occasionally, it stops rendering tiles completely, especially during zoom operations. Additionally, I observe flickering of the map layer when zooming in and out.

Here's a breakdown of the problems:

1. Service Stalls/Stucks: The WMTS service sometimes stops working entirely. When this happens, no tiles are rendered on zoom in/out, and the map remains blank. There are no immediate exceptions thrown that I can observe in the catch block.

2. Flickering on Zoom: During zoom in and out operations, the WMS layer visibly flickers before tiles are loaded one by one, leading to a less smooth user experience.

I'm using the following libraries:

• SharpMap: 1.2
• SharpMap.UI: 1.2
• BruTile: 2.2.0

And here's the relevant code snippet for initializing the WMTS layer:

var schema = new BruTile.Predefined.GlobalSphericalMercator();
string urlTemplate = "http://192.168.1.130/core/api/raster-rack/11/WMTS/tiles/png/default/{z}/{x}/{y}.png?end_time=&perma_token=" + _token;

Func<Uri, byte[]> fetcher = (uri) =>
{
    Console.WriteLine(uri.ToString());
    using (var client = new WebClient())
        return client.DownloadData(uri);
};

// Use BruTile.Web.HttpTileSource
var tileSource = new HttpTileSource(
   tileSchema: schema,
   urlFormatter: urlTemplate,
   name: "WMTS Layer",
   tileFetcher: fetcher
);

try
{
    // Create tile layer
    var tileLayer = new TileAsyncLayer(tileSource, "WMTS PNG Layer");

    // Initialize SharpMap
    _mapbox = new Map(mapSize);
    _mapbox.SRID = 3857;
    _mapbox.Center = new GeoAPI.Geometries.Coordinate(8567552.52, 3757032.83);
    _mapbox.Zoom = 19565879.24;
    _mapbox.BackgroundLayer.Add(tileLayer);
}
catch (Exception ex)
{
    Console.WriteLine(ex.Message);
}

Any insights or suggestions on how to diagnose and resolve these problems would be greatly appreciated. Thank you in advance for your time and expertise!