/// <summary>
/// Instanciates a new Free Object refernce.
/// </summary>
/// <param name="objectId">The <see cref="PdfObjectId"/> to use for the next use of this object number.</param>
/// <param name="nextFreeObjectNumber">The object number of the next free object.</param>
public PdfFreeObjectReference(PdfObjectId objectId, int nextFreeObjectNumber) : base(objectId)
{
if (nextFreeObjectNumber < 0)
{
throw new ArgumentOutOfRangeException(nameof(nextFreeObjectNumber), "Cannot be negative.");
}
this.nextFreeObjectNumber = nextFreeObjectNumber;
}
/// <summary>
/// Instanciates a new PdfObjectReference
/// Reference is marked in use by default
/// </summary>
/// <param name="objectId">The referenced object's <see cref="PdfObjectId"/>.</param>
/// <param name="position">The position of the object</param>
public PdfObjectReference(PdfObjectId objectId, long position) : base(objectId)
{
this.position = position;
}
/// <summary>
/// Reads a section and append entries.
/// </summary>
/// <param name="reader">The <see cref="PdfReader"/> to use.</param>
public static XRefSection FromReader(PdfReader reader)
{
if (reader == null)
{
throw new ArgumentNullException(nameof(reader));
}
reader.ReadToken(StartKeyword);
reader.MoveToNonWhiteSpace();
var entries = new Dictionary <int, PdfObjectReferenceBase>();
string subsectionHeader;
var entryBuffer = new char[20];
while (char.IsDigit(reader.Peek()))
{
int separatorIdx, firstId, count;
try
{
subsectionHeader = reader.ReadLine();
separatorIdx = subsectionHeader.IndexOf(' ');
firstId = Int32.Parse(subsectionHeader.Substring(0, separatorIdx));
count = Int32.Parse(subsectionHeader.Substring(separatorIdx + 1));
}
catch
{
throw new FormatException("Invalid Cross-Reference Table subsection header.");
}
for (int i = firstId; i < firstId + count; i++)
{
// Each entry is exactly 20 bytes long, including the end-of - line marker.
reader.Read(entryBuffer, 0, entryBuffer.Length);
PdfObjectReferenceBase objectReference;
var objectId = new PdfObjectId(i, ushort.Parse(new string(entryBuffer, 11, 5)));
switch (entryBuffer[17])
{
case 'n':
objectReference = new PdfObjectReference(objectId, long.Parse(new string(entryBuffer, 0, 10)));
break;
case 'f':
objectReference = new PdfFreeObjectReference(objectId, int.Parse(new string(entryBuffer, 0, 10)));
break;
default:
throw new FormatException("Invalid Cross-Reference entry");
}
entries.Add(
i,
objectReference
);
}
}
return(new XRefSection(entries, true));
}
