iTextSharp.text.pdf.PdfReader.ReadXRefStream C# (CSharp) Метод

        protected internal bool ReadXRefStream(int ptr) {
            tokens.Seek(ptr);
            int thisStream = 0;
            if (!tokens.NextToken())
                return false;
            if (tokens.TokenType != PRTokeniser.TK_NUMBER)
                return false;
            thisStream = tokens.IntValue;
            if (!tokens.NextToken() || tokens.TokenType != PRTokeniser.TK_NUMBER)
                return false;
            if (!tokens.NextToken() || !tokens.StringValue.Equals("obj"))
                return false;
            PdfObject objecto = ReadPRObject();
            PRStream stm = null;
            if (objecto.IsStream()) {
                stm = (PRStream)objecto;
                if (!PdfName.XREF.Equals(stm.Get(PdfName.TYPE)))
                    return false;
            }
            else
                return false;
            if (trailer == null) {
                trailer = new PdfDictionary();
                trailer.Merge(stm);
            }
            stm.Length = ((PdfNumber)stm.Get(PdfName.LENGTH)).IntValue;
            int size = ((PdfNumber)stm.Get(PdfName.SIZE)).IntValue;
            PdfArray index;
            PdfObject obj = stm.Get(PdfName.INDEX);
            if (obj == null) {
                index = new PdfArray();
                index.Add(new int[]{0, size});
            }
            else
                index = (PdfArray)obj;
            PdfArray w = (PdfArray)stm.Get(PdfName.W);
            int prev = -1;
            obj = stm.Get(PdfName.PREV);
            if (obj != null)
                prev = ((PdfNumber)obj).IntValue;
            // Each xref pair is a position
            // type 0 -> -1, 0
            // type 1 -> offset, 0
            // type 2 -> index, obj num
            EnsureXrefSize(size * 2);
            if (objStmMark == null && !partial)
                objStmMark = new Hashtable();
            if (objStmToOffset == null && partial)
                objStmToOffset = new IntHashtable();
            byte[] b = GetStreamBytes(stm, tokens.File);
            int bptr = 0;
            int[] wc = new int[3];
            for (int k = 0; k < 3; ++k)
                wc[k] = w.GetAsNumber(k).IntValue;
            for (int idx = 0; idx < index.Size; idx += 2) {
                int start = index.GetAsNumber(idx).IntValue;
                int length = index.GetAsNumber(idx + 1).IntValue;
                EnsureXrefSize((start + length) * 2);
                while (length-- > 0) {
                    int type = 1;
                    if (wc[0] > 0) {
                        type = 0;
                        for (int k = 0; k < wc[0]; ++k)
                            type = (type << 8) + (b[bptr++] & 0xff);
                    }
                    int field2 = 0;
                    for (int k = 0; k < wc[1]; ++k)
                        field2 = (field2 << 8) + (b[bptr++] & 0xff);
                    int field3 = 0;
                    for (int k = 0; k < wc[2]; ++k)
                        field3 = (field3 << 8) + (b[bptr++] & 0xff);
                    int baseb = start * 2;
                    if (xref[baseb] == 0 && xref[baseb + 1] == 0) {
                        switch (type) {
                            case 0:
                                xref[baseb] = -1;
                                break;
                            case 1:
                                xref[baseb] = field2;
                                break;
                            case 2:
                                xref[baseb] = field3;
                                xref[baseb + 1] = field2;
                                if (partial) {
                                    objStmToOffset[field2] = 0;
                                }
                                else {
                                    IntHashtable seq = (IntHashtable)objStmMark[field2];
                                    if (seq == null) {
                                        seq = new IntHashtable();
                                        seq[field3] = 1;
                                        objStmMark[field2] = seq;
                                    }
                                    else
                                        seq[field3] = 1;
                                }
                                break;
                        }
                    }
                    ++start;
                }
            }
            thisStream *= 2;
            if (thisStream < xref.Length)
                xref[thisStream] = -1;
                
            if (prev == -1)
                return true;
            return ReadXRefStream(prev);
        }