| public seek ( int off ) : void | ||
| off | int | The offset where to move to. /// /// |
| return | void | |
/// <summary> This method reads and buffers the tile headers, packet headers and
/// packet data.
///
/// </summary>
/// <param name="fi">The file to read the headers and data from
///
/// </param>
/// <exception cref="IOException">If an I/O error ocurred.
///
/// </exception>
private void readAndBuffer(BufferedRandomAccessFile fi)
{
int p, prem, length, t, markIndex;
// Buffer main header
fi.seek(0);
length = ((System.Int32) positions[0]) - 2;
mainHeader = new byte[length];
fi.readFully(mainHeader, 0, length);
markIndex = 0;
for (t = 0; t < nt; t++)
{
prem = ppt[t];
packetHeaders[t] = new byte[prem][];
packetData[t] = new byte[prem][];
sopMarkSeg[t] = new byte[prem][];
// Read tile header
length = positions[markIndex + 1] - positions[markIndex];
tileHeaders[t] = new byte[length];
fi.readFully(tileHeaders[t], 0, length);
markIndex++;
for (p = 0; p < prem; p++)
{
// Read packet header
length = positions[markIndex + 1] - positions[markIndex];
if (tempSop)
{
// SOP marker is skipped
length -= CSJ2K.j2k.codestream.Markers.SOP_LENGTH;
fi.skipBytes(CSJ2K.j2k.codestream.Markers.SOP_LENGTH);
}
else
{
// SOP marker is read and buffered
length -= CSJ2K.j2k.codestream.Markers.SOP_LENGTH;
sopMarkSeg[t][p] = new byte[CSJ2K.j2k.codestream.Markers.SOP_LENGTH];
fi.readFully(sopMarkSeg[t][p], 0, CSJ2K.j2k.codestream.Markers.SOP_LENGTH);
}
if (!tempEph)
{
// EPH marker is kept in header
length += CSJ2K.j2k.codestream.Markers.EPH_LENGTH;
}
packetHeaders[t][p] = new byte[length];
fi.readFully(packetHeaders[t][p], 0, length);
markIndex++;
// Read packet data
length = positions[markIndex + 1] - positions[markIndex];
length -= CSJ2K.j2k.codestream.Markers.EPH_LENGTH;
if (tempEph)
{
// EPH marker is used and is skipped
fi.skipBytes(CSJ2K.j2k.codestream.Markers.EPH_LENGTH);
}
packetData[t][p] = new byte[length];
fi.readFully(packetData[t][p], 0, length);
markIndex++;
}
}
}
/// <summary> This method parses the codestream for SOT, SOP and EPH markers and
/// removes header header bits signalling SOP and EPH markers if packed
/// packet headers are used
///
/// </summary>
/// <param name="fi">The file to parse the markers from
///
/// </param>
/// <exception cref="IOException">If an I/O error ocurred.
///
/// </exception>
private void parseAndFind(BufferedRandomAccessFile fi)
{
int length, pos, i, t, sop = 0, eph = 0;
short marker;
int halfMarker;
int tileEnd;
System.Collections.Generic.List<System.Int32> markPos = new List<int>(10);
// Find position of first SOT marker
marker = (short) fi.readUnsignedShort(); // read SOC marker
marker = (short) fi.readUnsignedShort();
while (marker != CSJ2K.j2k.codestream.Markers.SOT)
{
pos = fi.Pos;
length = fi.readUnsignedShort();
// If SOP and EPH markers were only used for parsing in this
// class remove SOP and EPH markers from Scod field
if (marker == CSJ2K.j2k.codestream.Markers.COD)
{
int scod = fi.readUnsignedByte();
if (tempSop)
scod &= 0xfd; // Remove bits indicating SOP
if (tempEph)
scod &= 0xfb; // Remove bits indicating SOP
fi.seek(pos + 2);
fi.write(scod);
}
fi.seek(pos + length);
marker = (short) fi.readUnsignedShort();
}
pos = fi.Pos;
fi.seek(pos - 2);
// Find all packet headers, packed data and tile headers
for (t = 0; t < nt; t++)
{
// Read SOT marker
fi.readUnsignedShort(); // Skip SOT
pos = fi.Pos;
markPos.Add((System.Int32) fi.Pos);
fi.readInt(); // Skip Lsot and Isot
length = fi.readInt(); // Read Psot
fi.readUnsignedShort(); // Skip TPsot & TNsot
tileEnd = pos + length - 2; // Last byte of tile
// Find position of SOD marker
marker = (short) fi.readUnsignedShort();
while (marker != CSJ2K.j2k.codestream.Markers.SOD)
{
pos = fi.Pos;
length = fi.readUnsignedShort();
// If SOP and EPH markers were only used for parsing in this
// class remove SOP and EPH markers from Scod field
if (marker == CSJ2K.j2k.codestream.Markers.COD)
{
int scod = fi.readUnsignedByte();
if (tempSop)
scod &= 0xfd; // Remove bits indicating SOP
if (tempEph)
scod &= 0xfb; // Remove bits indicating SOP
fi.seek(pos + 2);
fi.write(scod);
}
fi.seek(pos + length);
marker = (short) fi.readUnsignedShort();
}
// Find all SOP and EPH markers in tile
sop = 0;
eph = 0;
i = fi.Pos;
while (i < tileEnd)
{
halfMarker = (short) fi.readUnsignedByte();
if (halfMarker == (short) 0xff)
{
marker = (short) ((halfMarker << 8) + fi.readUnsignedByte());
i++;
if (marker == CSJ2K.j2k.codestream.Markers.SOP)
{
markPos.Add((System.Int32) fi.Pos);
ppt[t]++;
sop++;
fi.skipBytes(4);
i += 4;
}
if (marker == CSJ2K.j2k.codestream.Markers.EPH)
{
markPos.Add((System.Int32) fi.Pos);
eph++;
}
}
i++;
}
}
markPos.Add((System.Int32) (fi.Pos + 2));
positions = new System.Int32[markPos.Count];
markPos.CopyTo(positions);
}
