/// <summary>
/// 读取shx索引信息
/// </summary>
/// <param name="stream"></param>
/// <returns></returns>
private static List <ShxRecord> GetAllIndexRecords(Stream stream)
{
List <ShxRecord> records = new List <ShxRecord>();
try
{
stream.Position = 100;
byte[] streamBuffer;
do
{
streamBuffer = ShpUtil.ReadBytesFromStream(stream, 8);
if (streamBuffer.Length < 8)
{
break;
}
else
{
ShxRecord myRecord = new ShxRecord(streamBuffer);
records.Add(myRecord);
}
} while (streamBuffer.Length > 0);
}
catch
{
records.Clear();
}
return(records);
}
/// <summary>
/// 打开shp、shx文件流
/// 读取shp、shx信息时需要首先执行此操作
/// 同时操作头文件读取和ShxRecord、ShpRecord示例化
/// </summary>
/// <param name="ofs"></param>
public void Open(Stream shpStream, Stream shxStream)
{
if (mShpFile != null)
{
Close();
}
mShpFile = shpStream;
mShxFile = shxStream;
mShpFileReader = null;
mShpFileWriter = null;
mShxFileReader = null;
mShxFileWriter = null;
if (mShpFile.CanRead)
{
mShpFileReader = new BinaryReader(mShpFile);
}
if (mShpFile.CanWrite)
{
mShpFileWriter = new BinaryWriter(mShpFile);
}
if (mShxFile.CanRead)
{
mShxFileReader = new BinaryReader(mShxFile);
}
if (mShxFile.CanWrite)
{
mShxFileWriter = new BinaryWriter(mShxFile);
}
//reset position
mRecordsReadCount = 0;
//assume header is not written
mHeaderWritten = false;
//read the header
if (shpStream.CanRead)
{
//try to read the header...
try
{
mHeader.Read(mShpFileReader);
mHeaderWritten = true;
}
catch (EndOfStreamException)
{
//could not read header, file is empty
mHeader = new ShpHeader();
mHeaderWritten = false;
}
}
if (mShpFile != null)
{
mIsReadOnly = !mShpFile.CanWrite;
mIsForwardOnly = !mShpFile.CanSeek;
}
mShxRecord = new ShxRecord(mHeader);
mShpRecord = new ShpRecord(mHeader);
}
/// <summary>
/// 写入shp
/// </summary>
/// <param name="wktList"></param>
public void WriteShp(List <string> wktList)
{
if (mFileCreat)
{
mShpRecord.GetWKTInfo(wktList);
mShxRecord = new ShxRecord(mShpRecord.Header);
mHeader.Write(mShpFileWriter);
mShxRecord.RecordDic = mShpRecord.Write(mShpFileWriter);
}
}
public ShxRecord[] ReadRecordes(int startRecIndex, int count)
{
using (var stream = MMFCache.GetFileReadItems(_FilePath)
.MMF.CreateViewStream(100 + startRecIndex * 8, count * 8))
{
using (var brShapeIndex = new BinaryReader(stream))
{
var records = new ShxRecord[count];
for (int i = 0; i < count; i++)
{
int offset = 2 * Util.SwapByteOrder(brShapeIndex.ReadInt32()); // word to byte
int cLength = 2 * Util.SwapByteOrder(brShapeIndex.ReadInt32());
records[i] = new ShxRecord(offset, cLength);
}
return(records);
}
}
}
