protected override string GetTileAddress(TileIndex.Full tileIndex)
{
var level = this.LOD.MaxLODLevel - tileIndex.LODLevel;
return
($"https://a.tile.openstreetmap.org/{level}/{tileIndex.Column}/{tileIndex.Row}.png");
}
public DownloadImageTask(WebImageSource owner, TileIndex.Full index, string url)
{
this.Owner = owner;
this.TileIndex = index;
this.Url = url;
this.WebClient = new WebClient();
Task.Run(() =>
{
if (!this.TryLoadCache())
{
this.StartDownloading();
}
});
}
public Task <BitmapSource> LoadTileAsync(TileIndex.Full index, IProgress <double> progress, CancellationToken cancellationToken)
{
if (!this.DownloadTasks.TryGetValue(index, out var downloadTask) ||
!downloadTask.Status.IsAlive())
{
var url = this.GetTileAddress(index);
downloadTask = new DownloadImageTask(this, index, url);
lock (this.DownloadTasks)
{
this.DownloadTasks.Add(index, downloadTask);
}
}
downloadTask.HandleObserver(progress, cancellationToken);
return(downloadTask.CompletionSource.Task);
}
public UpdateTileRequest(TileIndex.Full tileIndex, Rect worldRect)
{
this.TileIndex = tileIndex;
this.WorldRect = worldRect;
}
protected abstract string GetTileAddress(TileIndex.Full tileIndex);
