Ghostscript.NET.Viewer.DSC.DSCTokenizer.ReadContent C# (CSharp) Method

        public string ReadContent(int start, int count)
        {
            long bkpPos = _bufferedStream.Position;

            _bufferedStream.Seek(start, SeekOrigin.Begin);
            byte[] buffer = new byte[count];
            int readCount = _bufferedStream.Read(buffer, 0, count);

            _bufferedStream.Seek(bkpPos, SeekOrigin.Begin);

            return System.Text.Encoding.UTF8.GetString(buffer);
        }

        private void OpenPsFile(string path)
        {
            _tokenizer = new DSCTokenizer(path);

            this.FirstPageNumber = 1;

            DSCToken token = null;

            // loop through all DSC comments based on keyword
            while ((token = _tokenizer.GetNextDSCKeywordToken()) != null)
            {
                switch (token.Text)
                {
                    case DSC_PAGES:        // %%Pages: <numpages> | (atend)
                        {
                            token = _tokenizer.GetNextDSCValueToken(DSCTokenEnding.Whitespace | DSCTokenEnding.LineEnd);
                            
                            // check if we need to ignore this comment because it's set at the end of the file
                            if (!string.IsNullOrWhiteSpace(token.Text) && token.Text != "(atend)" && !token.Text.StartsWith("%"))
                            {
                                // we got it, memorize it
                                this.LastPageNumber = int.Parse(token.Text);
                            }

                            break;
                        }
                    case DSC_BOUNDINGBOX:  // { %%BoundingBox: <llx> <lly> <urx> <ury> } | (atend)
                        {
                            try
                            {
                                DSCToken llx = _tokenizer.GetNextDSCValueToken(DSCTokenEnding.Whitespace | DSCTokenEnding.LineEnd);

                                if (!string.IsNullOrWhiteSpace(llx.Text) && llx.Text != "(atend)" && !llx.Text.StartsWith("%"))
                                {
                                    DSCToken lly = _tokenizer.GetNextDSCValueToken(DSCTokenEnding.Whitespace);
                                    DSCToken urx = _tokenizer.GetNextDSCValueToken(DSCTokenEnding.Whitespace);
                                    DSCToken ury = _tokenizer.GetNextDSCValueToken(DSCTokenEnding.Whitespace | DSCTokenEnding.LineEnd);

                                    this.BoundingBox = new GhostscriptRectangle(
                                        float.Parse(llx.Text, System.Globalization.CultureInfo.InvariantCulture),
                                        float.Parse(lly.Text, System.Globalization.CultureInfo.InvariantCulture),
                                        float.Parse(urx.Text, System.Globalization.CultureInfo.InvariantCulture),
                                        float.Parse(ury.Text, System.Globalization.CultureInfo.InvariantCulture));
                                }
                            }
                            catch { }

                            break;
                        }
                    case DSC_PAGE:         // %%Page: <label> <ordinal>
                        {
                            // label can be anything, we need to get oridinal which is the last
                            // value of the line

                            DSCToken pageNumberToken;
                            
                            // loop through each comment value
                            while ((pageNumberToken = _tokenizer.GetNextDSCValueToken(DSCTokenEnding.Whitespace | DSCTokenEnding.LineEnd)) != null)
                            {
                                // check if this is the last comment value in this line
                                if (pageNumberToken.Ending == DSCTokenEnding.LineEnd)
                                {
                                    // we got it, add this comment keyword to the page list
                                    _pageTokens.Add(int.Parse(pageNumberToken.Text), token);
                                    break;
                                }
                            }

                            break;
                        }
                    case DSC_TRAILER:       // %%Trailer (no keywords)
                        {
                            // if the postscript is well formatted, we should get this one
                            // save this comment so we can know the position when the last page is ending
                            _lastPageEnding = token;

                            break;
                        }
                    case DSC_EOF:           // %%EOF (no keywords)
                        {
                            // check if we already know where the last page is ending
                            if (_lastPageEnding == null)
                            {
                                // we don't know, use start of the %%EOF comment as the last page ending position 
                                _lastPageEnding = token;
                            }

                            break;
                        }
                }
            }

            // check if we didn't find %%Trailer or %%EOF comment
            if (_lastPageEnding == null)
            {
                // it seems that the last page goes to the end of the file, set the last page ending
                // position to the complete file size value
                _lastPageEnding = new DSCToken();
                _lastPageEnding.StartPosition = _tokenizer.FileSize;
            }

            // we did'n find %%Pages comment, set the last page number to 1
            if (this.LastPageNumber == 0)
            {
                this.LastPageNumber = 1;
            }

            // check if we didn't find any %%Page comment
            if (_pageTokens.Count == 0)
            {
                // create dummy one that will point to the first byte in the file
                _pageTokens.Add(1, new DSCToken() { StartPosition = 0 });
            }

            // hpd = Header, Procedure definitions, Document setup
            // start position of the first %%Page: comment is te hpd size
            int hpdSize = (int)_pageTokens[1].StartPosition;
            // get the hpd text
            string hpdContent = _tokenizer.ReadContent(0, hpdSize);

            // process header, procedure definitions and document setup

            if (string.IsNullOrWhiteSpace(hpdContent))
            {
                hpdContent = "%!PS-Adobe-3.0";
            }

            this.Execute(hpdContent);
        }