/** returns the singleton, creating it if necessary
*/
public static AtomFactory getInstance()
{
if (instance == null)
{
instance = new AtomFactory();
}
return(instance);
}
protected static ParsedAtom[] parseAtoms(RandomAccessFile raf,
long firstOff,
long stopAt)
{
// off is the atom's offset into the file (gets reset
// for next sibling at bottom of loop, after preceding
// sibling's size is read)
long off = firstOff;
ArrayList parsedAtomList = new ArrayList();
// while (raf.getFilePointer() <= stopAt) {
while (off < stopAt)
{
raf.Seek(off, SeekOrigin.Begin);
// 1. first 32 bits are atom size
// use BigInteger to convert bytes to long
// (instead of signed int)
int bytesRead = raf.Read(atomSizeBuf, 0, atomSizeBuf.Length);
if (bytesRead < atomSizeBuf.Length)
{
throw new IOException("couldn't read atom length");
}
BigInteger atomSizeBI = new BigInteger(atomSizeBuf.Reverse().ToArray());
long atomSize = (long)atomSizeBI; //.longValue();
// this is kind of a hack to handle the udta problem
// (see below) when the parent didn't have children,
// meaning we've read 4 bytes of 0 and the atom is
// already over
if (raf.Position == stopAt)
{
break;
}
// 2. next, the atom type
bytesRead = raf.Read(atomTypeBuf, 0, atomTypeBuf.Length);
if (bytesRead != atomTypeBuf.Length)
{
throw new IOException("Couldn't read atom type");
}
String atomType = Encoding.ASCII.GetString(atomTypeBuf);
// 3. if atomSize was 1, then there are 64 bits of extended size
if (atomSize == 1)
{
bytesRead = raf.Read(extendedAtomSizeBuf, 0,
extendedAtomSizeBuf.Length);
if (bytesRead != extendedAtomSizeBuf.Length)
{
throw new IOException("Couldn't read extended atom size");
}
BigInteger extendedSizeBI =
new BigInteger(extendedAtomSizeBuf);
atomSize = (long)extendedSizeBI; //.longValue();
}
// if this atom size is negative, or extends past end
// of file, it's extremely suspicious (ie, we're not
// really in a quicktime file)
if ((atomSize < 0) ||
((off + atomSize) > raf.Length))
{
throw new IOException("atom has invalid size: " +
atomSize);
}
// 4. if a container atom, then parse the children
ParsedAtom parsedAtom = null;
if (ATOM_CONTAINER_TYPES.Contains(atomType))
{
// children run from current point to the end of the atom
ParsedAtom[] children =
parseAtoms(raf,
raf.Position,
off + atomSize);
parsedAtom =
new ParsedContainerAtom(atomSize,
atomType,
children);
}
else
{
parsedAtom =
AtomFactory.getInstance().createAtomFor(atomSize,
atomType,
raf);
ParsedAtom.SetOffset(parsedAtom, off);
}
// add atom to the list
parsedAtomList.Add(parsedAtom);
// now set offset to next atom (or end-of-file
// in special case (atomSize = 0 means atom goes
// to EOF)
if (atomSize == 0)
{
off = raf.Length;
}
else
{
off += atomSize;
}
// if a 'udta' container atom, then jump ahead 4
// to work around Apple's QT 1.0 workaround
// (http://developer.apple.com/technotes/qt/qt_03.html )
if (atomType.Equals("udta"))
{
off += 4;
}
} // while not at stopAt
// convert the array list into an array
//ParsedAtom[] atomArray =
// new ParsedAtom[parsedAtomList.Count];
ParsedAtom[] atomArray = parsedAtomList.Cast <ParsedAtom>().ToArray();
//parsedAtomList.ToArray(typeof(ParsedAtom));
return(atomArray);
} // parseAtoms