XAML-Map-Control/MapControl/Shared/WmtsTileMatrixSet.cs

using System.Collections.Generic;
using System.Linq;
#if WPF
using System.Windows;
#elif AVALONIA
using Avalonia;
#endif

namespace MapControl
{
    public class WmtsTileMatrixSet(
        string identifier, string supportedCrsId, string uriTemplate, IEnumerable<WmtsTileMatrix> tileMatrixes)
    {
        public string Identifier => identifier;
        public string SupportedCrsId => supportedCrsId;
        public string UriTemplate { get; } = uriTemplate.Replace("{TileMatrixSet}", identifier);
        public List<WmtsTileMatrix> TileMatrixes { get; } = tileMatrixes.OrderBy(m => m.Scale).ToList();

        public static WmtsTileMatrixSet CreateOpenStreetMapTileMatrixSet(
            string uriTemplate, int minZoomLevel = 0, int maxZoomLevel = 19)
        {
            static WmtsTileMatrix CreateWmtsTileMatrix(int zoomLevel)
            {
                const int tileSize = 256;
                const double origin = 180d * MapProjection.Wgs84MeterPerDegree;

                var matrixSize = 1 << zoomLevel;
                var scale = matrixSize * tileSize / (2d * origin);

                return new WmtsTileMatrix(
                    zoomLevel.ToString(), scale, new Point(-origin, origin),
                    tileSize, tileSize, matrixSize, matrixSize);
            }

            return new WmtsTileMatrixSet(
                null,
                WebMercatorProjection.DefaultCrsId,
                uriTemplate
                    .Replace("{z}", "{0}")
                    .Replace("{x}", "{1}")
                    .Replace("{y}", "{2}"),
                Enumerable
                    .Range(minZoomLevel, maxZoomLevel - minZoomLevel + 1)
                    .Select(CreateWmtsTileMatrix));
        }
    }
}