public MBTilesTileSource(TileSetConfiguration configuration)
{
this.configuration = configuration;
this.contentType = Utils.GetContentType(this.configuration.Format); // TODO: from db metadata
if (this.configuration.UseCoordinatesCache)
{
var filePath = GetLocalFilePath(this.configuration.Source);
if (File.Exists(filePath))
{
// TODO: not the best placement in constructor
Task.Run(() =>
{
var connectionString = GetMBTilesConnectionString(this.configuration.Source);
var db = new MBTilesRepository(connectionString);
db.ReadTileCoordinatesAsync(this.tileKeys).Wait(); // TODO: check presence of rowid
this.isTileKeysReady = true;
});
}
}
}
async Task <byte[]> ITileSource.GetTileAsync(int x, int y, int z)
{
if (!this.configuration.Tms)
{
y = Utils.FromTmsY(y, z);
}
var connectionString = GetMBTilesConnectionString(this.configuration.Source);
var db = new MBTilesRepository(connectionString);
// TODO: if database contents were changed, coordinates cache should be invalidated
if (this.configuration.UseCoordinatesCache)
{
var key = MBTilesRepository.CreateTileCoordinatesKey(z, x, y);
if (tileKeys.ContainsKey(key))
{
// Get rowid from cache, read table record by rowid (very fast, compared to selecting by three columns)
return(await db.ReadTileAsync(tileKeys[key]));
}
else
{
if (this.isTileKeysReady)
{
// Assuming there is no tile in database, if it not exists in cache
return(null);
}
else
{
// While cache is not ready, allow simple database read
return(await db.ReadTileAsync(x, y, z));
}
}
}
else
{
return(await db.ReadTileAsync(x, y, z));
}
}
