private void ReadToDataProvider()
{
if (string.IsNullOrEmpty(fileName))
{
return;
}
if (!File.Exists(fileName))
{
return;
}
_gribFs = new FileStream(fileName, FileMode.Open);
_gribBr = new BinaryReader(_gribFs);
char[] fileFg = _gribBr.ReadChars(4);
string fileFgStr = string.Join("", fileFg);
if (!string.Equals(fileFgStr, "GRIB")) //01-04:GRIB的文件标识
{
throw new Exception("文件错误");
}
byte[] bytes = _gribBr.ReadBytes(3); //05-07:读取3字节的整数
_dataLength = MathHelper.Bytes2Int(bytes); //整个文件的数据长度，bytes[0]*16*16*16+bytes[1]*16*16+bytes[2];
if (_dataLength == 0)
{
return;
}
Byte version = _gribBr.ReadByte(); //08:版本，为1
_pds = new PDSClass(_gribFs, _gribBr);
if (_pds.ThreeSection == enumThreeSection.BMS)
{
_thirdSec = new BMSClass(_gribFs, _gribBr);
}
else
{
_thirdSec = new GDSClass(_gribFs, _gribBr);
_width = (_thirdSec as GDSClass).LatPointsNum;
_height = (_thirdSec as GDSClass).LonPointsNum;
_resolutionX = (_thirdSec as GDSClass).LatResolution;
_resolutionY = (_thirdSec as GDSClass).LonResolution;
}
_bds = new BDSClass(_gribFs, _gribBr, (_thirdSec as GDSClass).LonPointsNum, (_thirdSec as GDSClass).LatPointsNum);
float[] xDatas = _bds.OriginData as float[];
int length = xDatas.Length;
float[] values = new float[length];
for (int i = 0; i < length; i++)
{
values[i] = GribHelper.ComputeActualValue(xDatas[i], _pds.DecimalFactor, _bds.BinaryScale, _bds.ReferenceValue);
}
_values = values;
_coordEnvelope = new CoordEnvelope(-180, 180, -90, 90);
}
internal PDSClass(FileStream fs, BinaryReader br)
{
if (br == null)
{
return;
}
PDSLength = MathHelper.Bytes2Int(br.ReadBytes(3)); //01-03,Length in bytes of PDS
if (PDSLength == 0)
{
return;
}
//04 Parameter table version number - currently 2 for international exchange
fs.Seek(1, SeekOrigin.Current);
//05 Originating Center
OriginatingCenter = GribHelper.GetOringinatingCenter(br.ReadByte());
//06 Generating process or model ID (center dependent)
//07 Grid identification - used for fixed grid types, GDS is used for specific grid definition
//08 Flag specifying the presence or absence of a GDS or a BMS
fs.Seek(2, SeekOrigin.Current);
ThreeSection = GribHelper.GetThreeSection(br.ReadByte());
//09 Parameter and units
object[] objs = GribHelper.GetParameterAndUnits(br.ReadByte());
if (objs != null && objs.Length != 0)
{
Parameter = objs[0].ToString();
Units = objs[1].ToString();
}
//10 Level or Layer Type
//11-12 Level or Layer values
objs = GribHelper.GetLevelOrLayer(br.ReadByte(), MathHelper.Bytes2Int(br.ReadBytes(2)));
//if (objs != null && objs.Length != 0)
//{
// LevelType = objs[0].ToString();
// LevelValue = (int)objs[1];
//}
//13 Reference Time - Year of century
//14 Month of year
//15 Day of month
//16 Hour of day
//17 Minute of hour
byte[] byteVlues = br.ReadBytes(5);
DateTime time = GribHelper.GetDateTime(byteVlues);
TimeString = time.ToString("yyyy-MM-dd hh:mm");
//18 Forecast time unit
//19 P1 - Period of time (Number of time units). 0 for analysis or initialized analysis.
//20 P2 - Period of time (Number of time units) or time interval between successive analyses, successive initialized analyses, or forecasts, undergoing averaging or accumulation.
//21 Time range indicator
//22-23 Number included in average, when octet 21 (Table 5) indicates an average or accumulation; otherwise set to zero.
//24 Number Missing from averages or accumulations.
//25 Century of Initial (Reference) time (=20 until Jan. 1, 2001, 21 afterwards)
//26 Identification of sub-center
//27-28 The decimal scale factor D. A negative value is indicated by setting the high order bit (bit No. 1) in octet 27 to 1 (on).
fs.Seek(9, SeekOrigin.Current);
DecimalFactor = MathHelper.Bytes2Int(br.ReadBytes(2));
//29-40 Reserved (need not be present)
//41-nnn Reserved for originating center use.
fs.Seek(PDSLength - 28, SeekOrigin.Current);
}
