how can I get the client's printer list in ASP.NET [closed]

Set postcompilation events (this is to test in your local) in Project properties\Build events\Post-build event command line put

  echo Un-register the components first
  "C:\Windows\Microsoft.NET\Framework\v4.0.30319\RegAsm.exe" "$(TargetDir)$(TargetFileName)" /tlb:ActiveXPrinter.tlb /codebase /u
  echo Register the components
  "C:\Windows\Microsoft.NET\Framework\v4.0.30319 \RegAsm.exe" "$(TargetDir)$(TargetFileName)" /tlb:ActiveXPrinter.tlb /codebase
  echo All done

Now the code of your control.

using System;
using System.Linq;
using System.Management;
using System.Reflection;
using System.Runtime.InteropServices;
using System.Text;
using Microsoft.Win32;

namespace ActiveXPrinter
{
    [ProgId("ActiveXPrinter.PrinterHelper")]
    [ClassInterface(ClassInterfaceType.AutoDual)]
    [Guid("C0167B9D-2987-331A-97F6-3BCEF78E041A")]
    [ComVisible(true)]
    public class PrinterHelper
    {
        #region Register/Unregister

        [ComRegisterFunction()]
        public static void RegisterClass(string key)
        {
            // Strip off HKEY_CLASSES_ROOT\ from the passed key as I don't need it
            StringBuilder sb = new StringBuilder(key);
            sb.Replace(@"HKEY_CLASSES_ROOT\", "");

            // Open the CLSID\{guid} key for write access
            RegistryKey k = Registry.ClassesRoot.OpenSubKey(sb.ToString(), true);

            // And create the 'Control' key - this allows it to show up in 
            // the ActiveX control container 
            RegistryKey ctrl = k.CreateSubKey("Control");
            ctrl.Close();

            // Next create the CodeBase entry - needed if not string named and GACced.
            RegistryKey inprocServer32 = k.OpenSubKey("InprocServer32", true);
            inprocServer32.SetValue("CodeBase", Assembly.GetExecutingAssembly().CodeBase);
            inprocServer32.Close();

            // Finally close the main key
            k.Close();
        }

        [ComUnregisterFunction()]
        public static void UnregisterClass(string key)
        {
            StringBuilder sb = new StringBuilder(key);
            sb.Replace(@"HKEY_CLASSES_ROOT\", "");

            // Open HKCR\CLSID\{guid} for write access
            RegistryKey k = Registry.ClassesRoot.OpenSubKey(sb.ToString(), true);

            // Delete the 'Control' key, but don't throw an exception if it does not exist
            k.DeleteSubKey("Control", false);

            // Next open up InprocServer32
            RegistryKey inprocServer32 = k.OpenSubKey("InprocServer32", true);

            // And delete the CodeBase key, again not throwing if missing 
            k.DeleteSubKey("CodeBase", false);

            // Finally close the main key 
            k.Close();
        }

        #endregion

        [ComVisible(true)]
        public string Devuelve(string mensaje)
        {
            //Método "dummy" que devuelve la entrada. Vale para probar que el ActiveX está bien instalado
            return mensaje;
        }

        [ComVisible(true)]
        public string GetPrinters()
        {
            //Obtenemos las impresoras instaladas en el cliente
            SelectQuery oSelectQuery = new SelectQuery { QueryString = "select * from win32_printer" };

            ManagementObjectSearcher search = new ManagementObjectSearcher(oSelectQuery);
            ManagementObjectCollection results = search.Get();

            //Guardamos el nombre de la impresora que actualmente tiene por defecto el usuario
            string impresoraOriginalPorDefecto = string.Empty;
            foreach (ManagementObject printer in results)
            {
                impresoraOriginalPorDefecto += printer["Name"].ToString() + "|";
            }
            return impresoraOriginalPorDefecto;
        }

        [ComVisible(true)]
        public string GetDefaultPrinter()
        {
            string salida = string.Empty;
            //Obtenemos la impresora instaladas en el cliente que esté marcada como "por defecto"
            SelectQuery oSelectQuery = new SelectQuery { QueryString = "select * from win32_printer where Default = True" };

            ManagementObjectSearcher search = new ManagementObjectSearcher(oSelectQuery);
            ManagementObjectCollection results = search.Get();

            if (results.Count > 0)
            {
                salida = results.OfType<ManagementObject>().First()["Name"].ToString();
            }

            return salida;
        }

        [ComVisible(true)]
        public Boolean SetDefaultPrinter(string printerName)
        {
            bool salida = false;

            //Obtenemos las impresoras instaladas en el cliente con el nombre especificado
            SelectQuery oSelectQuery = new SelectQuery { QueryString = "select * from win32_printer where Name = '"+ printerName + "'" };

            ManagementObjectSearcher search = new ManagementObjectSearcher(oSelectQuery);
            ManagementObjectCollection results = search.Get();


            if (results.Count > 0)
            {
                results.OfType<ManagementObject>().First().InvokeMethod("SetDefaultPrinter", null);
                salida = true;
            }

            return salida;
        }

        [ComVisible(true)]
        public Boolean SetDefaultPrinterMask(string printerMask)
        {
            bool salida = false;

            //Obtenemos las impresoras instaladas en el cliente
            SelectQuery oSelectQuery = new SelectQuery { QueryString = "select * from win32_printer" };

            ManagementObjectSearcher search = new ManagementObjectSearcher(oSelectQuery);
            ManagementObjectCollection results = search.Get();

            //Establecemos la impresora por defecto para imprimir
            foreach (ManagementObject printer in results)
            {
                //Se encuentra la impresora con nombre que contenga lo que nos especifican y se pone por defecto
                if (printer["Name"].ToString().ToUpper().Trim().Contains(printerMask.ToUpper()))
                {
                    printer.InvokeMethod("SetDefaultPrinter", null);
                    salida = true;
                    break;
                }
            }

            return salida;
        }
    }
}