private async Task <IFeature?> ToFeatureAsync(TileInfo tileInfo)
{
var tileData = await _tileSource.GetTileAsync(tileInfo);
var mRaster = ToRaster(tileInfo, tileData);
if (mRaster != null)
{
return(new RasterFeature(mRaster));
}
return(null);
}
private static async Task <List <RasterFeature> > TileIndexToFeaturesAsync(TileIndex[] tileIndexes, ITileSource tileSource)
{
var features = new List <RasterFeature>();
foreach (var tileIndex in tileIndexes)
{
var tileInfo = new TileInfo
{
Index = tileIndex,
Extent = TileTransform.TileToWorld(
new TileRange(tileIndex.Col, tileIndex.Row), tileIndex.Level, tileSource.Schema)
};
var raster = new MRaster(await tileSource.GetTileAsync(tileInfo), tileInfo.Extent.ToMRect());
features.Add(new RasterFeature(raster));
}
return(features);
}
private async Task <RasterFeature> TileToFeatureAsync(ITileSource tileProvider, TileInfo tileInfo)
{
var tile = await tileProvider.GetTileAsync(tileInfo);
// A tile layer can return a null value. This indicates the tile is not
// present in the source, permanently. If this is the case no further
// requests should be done. To avoid further fetches a feature should
// be returned with the Geometry set to null. If a null Feature is returned
// this equates to having no tile at all and attempts to fetch the tile will
// continue. TileLayer.ToGeometry() follows the same implementations.
//
// Note, the fact that we have to define this complex method on the outside
// indicates a design flaw.
if (tile == null)
{
return(new RasterFeature((MRaster?)null));
}
return(new RasterFeature(new MRaster(tile, tileInfo.Extent.ToMRect())));
}
private static async Task <List <Models.TileDataset> > GetSourceTilesAsync(
ITileSource source,
IList <Models.TileCoordinates> tileCoordinates)
{
var sourceTiles = new List <Models.TileDataset>(tileCoordinates.Count);
foreach (var tc in tileCoordinates)
{
// 180 degrees
var tileCount = U.WebMercator.TileCount(tc.Z);
var x = tc.X % tileCount;
var tileData = await source.GetTileAsync(x, U.WebMercator.FlipYCoordinate(tc.Y, tc.Z), tc.Z);
if (tileData != null)
{
sourceTiles.Add(new Models.TileDataset(tc.X, tc.Y, tc.Z, tileData));
}
}
return(sourceTiles);
}
