public void Request(int bandNo, TileId[] tiles)
{
if (tiles == null)
{
return;
}
int count = tiles.Length;
for (int i = 0; i < count; i++)
{
TileTask task = new TileTask();
task.Tile = tiles[i];
task.BandNo = bandNo;
task.Key = GetTileTaskKey(bandNo, tiles[i]);
//插入读取队列
_taskStack.Push(task);
}
//重新启动读取线程
if (_workerIsFinisehd)
{
_isStarted = false;
Start();
}
if (_isDoingLargerTask)
{
_needPauseLargerTask = true;
}
}
private void DoTileTask(TileTask tileTask)
{
TileData data = TryReadFromCacheFile(tileTask);
if (data != null)
{
if (_tileReadedCallback != null)
{
_tileReadedCallback.BeginInvoke(data, null, null);
}
}
else
{
/*
* 缓存文件不存在,选择以下方式：
* 1.直接从IRasterDataProvider中读取
* 2.加入待通知队列,相应的BandLevelTask完成后异步通知内存缓存管理对象
*/
//1.
DirectTileFromDataProvider(tileTask);
//2.
//_needAsyncNotifyTasks.Add(tileTask.Key);
//
//Console.WriteLine(tileTask.Tile.ToString() + ",缓存文件不存在。");
}
}
public void LoadSync(int bandNo, LevelId level)
{
if (level.TileCount == 0 || level.Tiles == null || level.Tiles.Length == 0)
{
return;
}
for (int i = 0; i < level.Tiles.Length; i++)
{
TileTask task = new TileTask();
task.Tile = level.Tiles[i];
task.BandNo = bandNo;
task.Key = GetTileTaskKey(bandNo, level.Tiles[i]);
DoTileTask(task);
}
}
private TileData TryReadFromCacheFile(TileTask tileTask)
{
string fname = _cacheNameHelper.GetCacheFilename(_cacheFolder, tileTask.BandNo, tileTask.Tile.LevelNo);
if (!File.Exists(fname))
{
return(null);
}
int offset = tileTask.Tile.Index * _tileSize * _tileSize * _dataTypeSize;
FileStream fs = null;
//
string key = _cacheNameHelper.GetResourceKey(tileTask.BandNo, tileTask.Tile.LevelNo);
if (_readFileStreams.ContainsKey(key))
{
fs = _readFileStreams[key];
}
else
{
fs = new FileStream(fname, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
_readFileStreams.Add(key, fs);
}
//要请求的块还未写入文件
if (fs.Length < offset)
{
return(null);
}
//
fs.Seek(offset, SeekOrigin.Begin);
byte[] buffer = new byte[_tileSize * _tileSize * _dataTypeSize];
fs.Read(buffer, 0, buffer.Length);
//
TileData data = new TileData();
data.BandNo = tileTask.BandNo;
data.Data = buffer;
data.Tile = tileTask.Tile;
return(data);
}
private unsafe void DirectTileFromDataProvider(TileTask tileTask)
{
byte[] data = new byte[_tileBufferSize];
fixed(byte *ptr = data)
{
IntPtr buffer = new IntPtr(ptr);
TileId tile = tileTask.Tile;
LevelId lv = _tileComputer.Levels[tile.LevelNo];
_dataProvider.GetRasterBand(tileTask.BandNo).Read(
(int)(_tileSize * tile.Col / lv.Scale),
(int)(_tileSize * tile.Row / lv.Scale),
(int)(tile.Width / lv.Scale),
(int)(tile.Height / lv.Scale),
buffer, _dataProvider.DataType, tile.Width, tile.Height);
//
TileData tileData = new TileData();
tileData.BandNo = tileTask.BandNo;
tileData.Tile = tile;
tileData.Data = data;
_tileReadedCallback(tileData);
}
}
