using System;

using System.IO;

namespace Selenium.Pdf {

class PdfXRefs {

public const int ID_EMPTY = 0;

public const int ID_CATALOGUE = 1;

public const int ID_INFO = 2;

public const int ID_PAGES = 3;

public const int ID_FONTS = 4;

public const int ID_OUTLINES = 5;

public const int ID_START_GENERATE = 6;

private StreamWriter _pdfWriter;

private long[] _buffer = new long[100];

private int _count = ID_START_GENERATE;

public PdfXRefs(StreamWriter writer) {

_pdfWriter = writer;

}

public int Count {

get {

return _count;

}

}

public int CreateObject() {

return _count++;

}

public void RegisterObject(int id) {

_pdfWriter.Flush();

RegisterObject(id, _pdfWriter.BaseStream.Position);

}

public int CreateAndRegisterObject() {

int id = _count++;

RegisterObject(id);

return id;

}

/// <summary>

/// Adds a new position in the reference table.

/// </summary>

public void RegisterObject(int id, long position) {

if (id >= _buffer.Length)

IncreaseCapacity();

_buffer[id] = position;

}

/// <summary>

/// Writes the xref table to the pdf stream.

/// </summary>

/// <returns></returns>

public long Write() {

_pdfWriter.Flush();

long position = _pdfWriter.BaseStream.Position;

int count = _count;

_pdfWriter.WriteLine("xref");

_pdfWriter.WriteLine("0 " + count); //First and last object number

_pdfWriter.Write("0000000000 65535 f\r\n");

for (int i = 1; i < count; i++) {

_pdfWriter.Write(_buffer[i].ToString().PadLeft(10, '0'));

_pdfWriter.Write(" 00000 n\r\n");

}

return position;

}

/// <summary>

/// Increase the capacity of the buffer holding the positions.

/// </summary>

private void IncreaseCapacity() {

long[] newBuffer = new long[_buffer.Length * 2];

Array.Copy(_buffer, newBuffer, _count);

_buffer = newBuffer;

}

}

}