C#

using iTextSharp.text;
using iTextSharp.text.pdf;

 var baseUrl = SecurityContext.BaseUrl;

string urlString = string.Format("{1}Downloads/SalesOrderInvoice.aspx?id={0}", OrderId, baseUrl);

                   Uri url = new Uri(urlString);

                   IDownloader htmlToPDFDownloader = new HtmlToPDFDownloader(url);

                   string fileName = string.Format("Invoice for Order Referecne. {0}", OrderCode);

                   htmlToPDFDownloader.Download(fileName);

public interface IDownloader
    {
        object GetDownloadable();

        void Download(string fileName);
    }

using iTextSharp.text.pdf;
using iTextSharp.text.pdf.draw;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Text.RegularExpressions;
using System.Web;
namespace sampleproj.Client
{
    public class HtmlToPDFDownloader : IDownloader
    {
        private string htmlString;

        public HtmlToPDFDownloader(string htmlString)
        {
            this.htmlString = htmlString;
        }

        private string ImageToBase64(string url)
        {
            WebClient client = new WebClient();
            byte[] bytes ;
            if(url.StartsWith("http"))
            {
                bytes = client.DownloadData(url);
            }
            else
            {
                string physicalPath = HttpContext.Current.Server.MapPath(string.Format("~{0}", url));
                bytes = File.ReadAllBytes(physicalPath);                
            }

            string base64String = Convert.ToBase64String(bytes);

            return "data:image/png;base64," + base64String;
        }

        //private string GetDownloadedContent(Uri url)
        //{   
        //    HttpWebRequest webrequest = (HttpWebRequest)WebRequest.Create(url);
            
        //    webrequest.Method = "GET";

        //    webrequest.ContentType = "text/html";

        //    HttpWebResponse webresponse = (HttpWebResponse)webrequest.GetResponse();

        //    Stream stream = webresponse.GetResponseStream();

        //    StreamReader r = new StreamReader(stream);

        //    return r.ReadToEnd();
        //}

        public HtmlToPDFDownloader(Uri url)
        {
            WebClient client = new WebClient();

            client.Headers.Add("_uidqqweb4324", ConfigurationManager.UserId);

            this.htmlString = client.DownloadString(url);

            //this.htmlString = GetDownloadedContent(url);

            foreach (Match m in Regex.Matches(htmlString, "<img.+?src=[\"'](.+?)[\"'].+?>", RegexOptions.IgnoreCase | RegexOptions.Multiline))
            {
                string src = m.Groups[1].Value;

                //string locaPath = new Uri(src).LocalPath;

                //string physicalPath = HttpContext.Current.Server.MapPath(string.Format("~{0}", locaPath));

                //htmlString = htmlString.Replace(src, physicalPath);

                //string src = m.Groups[1].Value;

                //string locaPath = new Uri(src).ToString();
                //locaPath = HttpContext.Current.Server.MapPath(locaPath);
                string physicalPath = ImageToBase64(src); //Server.MapPath(string.Format("~{0}",locaPath));

                htmlString = htmlString.Replace(src, physicalPath);
            }
        }


        private byte[] GetStream()
        {
            MemoryStream stream = new MemoryStream();

            var htmlContent = this.htmlString;

            var converter = new NReco.PdfGenerator.HtmlToPdfConverter();

            converter.Margins = new NReco.PdfGenerator.PageMargins
            {
                Bottom = 5,
                Left = 2.5f,
                Right = 2.5f,
                Top = 5
            };

            var pdfBytes = converter.GeneratePdf(htmlContent);

            return pdfBytes;
        }

        public object GetDownloadable()
        {
            return GetStream();
        }

        public void Download(string fileName)
        {
            var pdfBytes = GetStream();

            HttpContext.Current.Response.Clear();
            HttpContext.Current.Response.ContentType = "application/pdf; file";
            HttpContext.Current.Response.AddHeader("content-length", pdfBytes.Length.ToString());

            fileName = fileName + "_" + DateTime.Now.ToString("ddMMMyyy") + ".pdf";

            HttpContext.Current.Response.AddHeader("content-disposition", "attachment;" + "filename=" + fileName);
            HttpContext.Current.Response.Cache.SetCacheability(HttpCacheability.NoCache);

            HttpContext.Current.Response.BinaryWrite(pdfBytes);
            HttpContext.Current.Response.Flush();
            HttpContext.Current.Response.Close();
            HttpContext.Current.Response.End();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace EnergyEngineers.Client
{
    public class SecurityContext
    {
        public int CurrentUserId
        {
            get
            {
                return 1;
            }
        }

        public static string BaseUrl
        {
            get
            {
                return HttpContext.Current.Request.Url.GetLeftPart(UriPartial.Authority) + HttpRuntime.AppDomainAppVirtualPath;
            }
        }
    }
}

if (timer1.Enabled)
{
    MessageBox.Show("Sorry you have already started the Timer");
}

else
     timer1.Start();
     this.StopWatch.Start();

if (timer1.Enabled)
{
    MessageBox.Show("Sorry you have already started the Timer");
}
else
{
     timer1.Start();
     this.StopWatch.Start();
}

private void button1_Click(object sender, EventArgs e)
        {
            if (comboBox1.Text == "4")
            {
                if (textBox1.Text == "0")
                {
                    MessageBox.Show("Otpornost mora biti veca od nule!", "Otpornost", MessageBoxButtons.OK, MessageBoxIcon.Error);
                    return;
                }
                if(comboBox2.Text=="")
                {
                    MessageBox.Show("Izaberi vrednost tolerancije!", "Otpornost", MessageBoxButtons.OK, MessageBoxIcon.Error);
                    return;
                }
                var colours = new string[] { "Black", "Brown", "Red", "Orange", "Yellow", "Green", "Blue", "Violet", "Grey","White", "Silver", "Gold" };
                var factorDictionary = new Dictionary<char, double>() { { 'p', 0.000000000001 }, { 'n', 0.000000001 }, { 'u', 0.000001 }, { 'm', 0.001 }, { 'R', 1 }, { 'K', 1000 }, { 'M', 1000000 }, { 'G', 1000000000 } };
                string res = string.Empty;
 
                while (string.IsNullOrEmpty(res))
                {
                    res = textBox1.Text;
                }
 
                var lastChar = res.Last();
                var isUnitCorrect = factorDictionary.ContainsKey(lastChar);
                var value = res.Substring(0, res.Length - 1);
                var isValueCorrect = !value.Any(x => !char.IsDigit(x));
 
                if (isUnitCorrect && isValueCorrect)
                {
                    double mul = factorDictionary[lastChar];
                    double val = double.Parse(value) * mul;
                    int third = 0;
 
                    if (val < 0.1)
                    {
                        MessageBox.Show("Otpornost ne moze da bude manja od 0.1 oma!", "Otpornost", MessageBoxButtons.OK, MessageBoxIcon.Error);
                        return;
                    }
                    if (val < 1)
                    {
                        val *= 100;
                        third = 10;
                    }
                    else if (val < 10)
                    {
                        val *= 10;
                        third = 11;
                    }
 
                    res = val.ToString();
 
                    if (res.Count() > 24)
                    {
                        MessageBox.Show("Pogresna vrednost!", "Otpornost", MessageBoxButtons.OK, MessageBoxIcon.Error);
                        return;
                    }
 
                    else
                    {
                        label15.BackColor = Color.FromName(colours[res[0] - '0']);
                        label16.BackColor = Color.FromName(colours[res[1] - '0']);
                        label17.BackColor = Color.FromName(colours[third != 0 ? third : res.Count() - 2]);
                        label6.Text = textBox1.Text;
                        textBox2.Text = colours[res[0] - '0'];
                        textBox3.Text = colours[res[1] - '0'];
                        textBox4.Text = colours[third != 0 ? third : res.Count() - 2];
                    }
                    if (comboBox1.Text == "4")
                    {
                        if (comboBox2.Text == "E24 (5%)")
                        {
                            label18.BackColor = Color.Gold;
                            textBox5.Text = "Gold";
                        }
                        if (comboBox2.Text == "E12 (10%)")
                        {
                            label18.BackColor = Color.Silver;
                            textBox5.Text = "Silver";
                        }
                    }
                }
                else
                {
                    MessageBox.Show("Invalid value!", "Otpornost", MessageBoxButtons.OK, MessageBoxIcon.Error);
                    return;
                }
            }