internal override void Load()
{
base.Load();
_queueSystem = QueueSystem.Instance;
_sync = SynchronizationContext.Current;
_queueSystem.Register(uniqueLayerId, this.LocalStorage, GetImage);
_queueSystem.ImageCompleted += _queueSystem_ImageCompleted;
}
/// <summary>
/// 释放占据的所有资源，不再请求。
/// </summary>
public void Dispose()
{
_executantPool.DownloadImageCompleted -= _executantPool_DownloadImageCompleted;
_executantPool.Dispose();
_howToDownload.Clear();
_memoryCache.ClearAll();
_tilesBuffer.ClearAll();
_storageCache.Clear();
_isStarted = false;
_instance = null;
}