protected override async Task ExecuteAsync(CancellationToken stoppingToken)
{
Logger.LogInformation("Running OfflineCacheBackgroundTask.");
using (IServiceScope scope = ScopeFactory.CreateScope())
{
TileCacheRepository = scope.ServiceProvider.GetRequiredService <TileCacheRepository>();
TileSourceRepository = scope.ServiceProvider.GetRequiredService <TileSourceRepository>();
Mapper = scope.ServiceProvider.GetRequiredService <IMapper>();
do
{
TileCacheViewModel unfinishedTileCache =
Mapper.Map <TileCacheViewModel>(await TileCacheRepository.GetFirstUnfinishedTileCache());
if (unfinishedTileCache != null)
{
await TileCacheRepository.SetTileCacheStarted(unfinishedTileCache.TileCacheId);
TileCacheManager tileCacheManager = await CreateTileCacheManager(unfinishedTileCache.TileCacheId);
TilesCount = 0;
// Do not remove already downloaded tiles
////tileService.ClearTiles();
try
{
Bounds bounds = GeometryHelper.ToBounds(unfinishedTileCache.Bbox);
TileSource tileSource = await TileSourceRepository.GetTileSourceWithId(unfinishedTileCache.TileSourceId);
TileRangeCalculator calculator = new TileRangeCalculator
{
ValidBounds = GeometryHelper.ToBounds(tileSource.Bbox),
ValidZoomRange = new ZoomRange
{
MinZoom = 0,
MaxZoom = tileSource.ZoomLevelMax,
},
};
TileRangeCollection tiles = new TileRangeCollectionCalculator(calculator).GetTileRanges(bounds, new ZoomRange
{
MinZoom = unfinishedTileCache.ZoomLevelMin ?? 0,
MaxZoom = unfinishedTileCache.ZoomLevelMax,
});
TilesTotal = tiles.TilesTotal;
if (TilesTotal > 30000)
{
await TileCacheRepository.SetTileCacheError(unfinishedTileCache.TileCacheId);
throw new ArgumentException($"Tile cache exceeding the maximum number of 30000 tiles: {TilesTotal}.");
}
TileDownloader tileDownloader =
tileSource.AllowHiDefStitching ? new MergedTileDownloader() : new TileDownloader();
tileDownloader.TileServerUrls = tileSource.TileServerUrls.Select(x => x.Url).ToList();
await tileDownloader.Download(tiles, (zoomLevel, tileRow, tileColumn, tileData) =>
{
// Note that in the TMS tiling scheme, the Y axis is reversed from the "XYZ" coordinate system commonly used in the URLs
int mbtilesRow = (int)Math.Pow(2, zoomLevel) - 1 - tileRow;
lock (OfflineCacheBackgroundTask.lockObject)
{
TilesCount++;
}
if (tileCacheManager.TryGetTile(tileColumn, mbtilesRow, zoomLevel) == null)
{
tileCacheManager.SaveTile(zoomLevel, mbtilesRow, tileColumn, tileData);
}
});
Bounds tileCacheBounds = GeometryHelper.ToBounds(unfinishedTileCache.Bbox);
string metadataBounds = tileCacheBounds.ToCsv();
double centerLon = tileCacheBounds.Center().Lon;
double centerLat = tileCacheBounds.Center().Lat;
string metadataCenter = $"{centerLon},{centerLat},{unfinishedTileCache.ZoomLevelMin}";
string format = tileSource.TileServerUrls[0].Url.EndsWith("png") ? "png" : "jpg";
tileCacheManager.SaveMetadata(unfinishedTileCache.Name, format, metadataBounds, metadataCenter,
unfinishedTileCache.ZoomLevelMin ?? 0, unfinishedTileCache.ZoomLevelMax);
await TileCacheRepository.SetTileCacheFinished(unfinishedTileCache.TileCacheId,
$"{unfinishedTileCache.TileCacheId}.mbtiles");
}
catch (Exception exception)
{
Console.WriteLine(exception);
Logger.LogWarning(exception,
$"OfflineCacheBackgroundTask: Exception when creating tile cache for campaign {unfinishedTileCache.TileCacheId}.");
}
}
await Task.Delay(5 * 1000, stoppingToken);
}while (!stoppingToken.IsCancellationRequested);
Logger.LogInformation("Exiting OfflineCacheBackgroundTask.");
}
}
