public Grib1BitMapSection(FileStream fs)
{
long position = fs.Position;
int[] bitmask = new int[] { 128, 64, 32, 16, 8, 4, 2, 1 };
// octet 1-3 (length of section)
_sectionLength = GribNumberHelper.Uint3(fs);
// octet 4 unused bits
int unused = fs.ReadByte();
// octets 5-6
int bm = GribNumberHelper.Int2(fs);
sbyte[] data = new sbyte[_sectionLength - 6];
StreamReadHelper.ReadInput(fs, data, 0, data.Length);
// 创建新位图, octet 4包含末尾使用过的位数
_bitmap = new bool[(_sectionLength - 6) * 8 - unused];
// 填充位图
for (int i = 0; i < _bitmap.Length; i++)
{
_bitmap[i] = (data[i / 8] & bitmask[i % 8]) != 0;
}
fs.Seek(position + _sectionLength, SeekOrigin.Begin);
}
private bool[] _bitmap = null;//是否是位图
public GRIB2BitMapSection(FileStream fs, int numberPoints)
{
int[] bitmask = new int[] { 128, 64, 32, 16, 8, 4, 2, 1 };
_sectionHeader = new GRIB2SectionHeader(fs);
_bitMapIndicator = fs.ReadByte();
// no bitMap
if (_bitMapIndicator != 0)
{
return;
}
sbyte[] data = new sbyte[_sectionHeader.SectionLength - 6];
StreamReadHelper.ReadInput(fs, data, 0, data.Length);
// create new bit map, octet 4 contains number of unused bits at the end
_bitmap = new bool[numberPoints];
// fill bit map
for (int i = 0; i < _bitmap.Length; i++)
{
_bitmap[i] = (data[i / 8] & bitmask[i % 8]) != 0;
}
}
