Program.cs

using System;
using System.IO;
using System.Windows.Forms;
using System.Collections.Generic;
using Microsoft.FSharp.Core;
using Microsoft.FSharp.Collections;
using N2O;
using TWAIN32;

namespace INFOTECH
{   
    class WTwain : Scan.ITwain {
        public static TWAINI self = Program.global.twain;

        public int State { get { return (int)self.Twain.GetState();} }
        public bool Exit{
            get { return self.Exit; }
            set { self.Exit = value; }
        }
        public Scan.Callback ScanCallback {
            get { return new Scan.Callback((b) => (int)self.Twain.m_scancallback(b)); }
            set { self.Twain.m_scancallback = new TWAIN.ScanCallback((b) => (TWAIN.STS)value(b)); }
        }
        public void NativeCallback(bool close) { Program.global.ScanCallbackNative(close); }
        
        public FSharpList<string> GetDataSources() { 
            Func<string,string> conv = s => CSV.Parse(s)[11].ToString();
            return ListModule.OfSeq(self.GetDataSources().ConvertAll(new Converter<string,string>(conv)));
        }
        public int OpenDSM()                { return (int) self.OpenManager(); }
        public int CloseDSM()               {
            IntPtr handle = Program.global.Handle;//IntPtr.Zero
            TWAIN.STS sts = self.Twain.DatParent(TWAIN.DG.CONTROL, TWAIN.MSG.CLOSEDSM, ref handle);
            Console.WriteLine("Close status {0} {1}", sts, handle);
            Program.global.SetButtons(FormScan.EBUTTONSTATE.CLOSED);
            if (Program.global.m_formsetup!=null) {
                Program.global.m_formsetup.Dispose();
            };
            return (int) sts;
        }
        public string DefaultIdentity()     { return self.GetDefault(); }
        public string OpenScanner(string id){ return self.OpenScanner(id); }
        public void Init()                  { self.Init(Program.global.Handle); }
        public void Rollback(int state)     { self.Rollback((TWAIN.STATE) state);}
        //public bool NativeTransfer()        { self.NativeTransfer(); return self.Exit; }
        public bool AutoFeed()              { self.AutoFeed(); return self.Exit; }
        public bool AutoScan()              { self.AutoScan(); return self.Exit; }
        public bool ProgressDriverUi(bool p){ self.ProgressDriverUI(p); return self.Exit; }
        public bool EnableDuplex()          { self.EnableDuplex(); return self.Exit; }
        public int EnableDS() {
            string szTwmemref = "FALSE,FALSE,0"; //hide windows and reset handle
            TWAIN.TW_USERINTERFACE twuserinterface = default(TWAIN.TW_USERINTERFACE);            
            self.Twain.CsvToUserinterface(ref twuserinterface, szTwmemref);
            return (int)self.Twain.DatUserinterface(TWAIN.DG.CONTROL, TWAIN.MSG.ENABLEDS, ref twuserinterface);
        }
        public string FileInfo() {
            string root = Directory.GetCurrentDirectory();
            var files = new DirectoryInfo(root).EnumerateFiles("doc-*.pdf", SearchOption.AllDirectories);
            // the params on which file name is based immidiately updated after save
            // so we can't rely now on real file name just take the last one
            IEnumerator<FileInfo> e = files.GetEnumerator();
            FileInfo current;
            do {
                current = e.Current;
            } while (e.MoveNext());
            return Path.Combine(current.Directory.FullName,current.Name);
        }
        public int Start(int afterStart) {
            self.UseBitmap = 0;
            self.ScanStart = true;
            self.XferReadySent = false;
            self.DisableDsSent = false;
            self.AfterScan = (TWAIN.STATE) afterStart;
            return 0;
        }
        public void Dispose() {self.Dispose();}

        public string Cap(N2O.TwTypes.TwMsg msg, string cap) {
            string status = "";
            TWAIN.TW_CAPABILITY twcap = default(TWAIN.TW_CAPABILITY);

            if(self.Twain.CsvToCapability(ref twcap, ref status, cap)){
                TWAIN.STS sts = self.Twain.DatCapability(TWAIN.DG.CONTROL, (TWAIN.MSG)msg, ref twcap);
                if (sts == TWAIN.STS.SUCCESS) {
                    return self.Twain.CapabilityToCsv(twcap, ((TWAIN.MSG)msg != TWAIN.MSG.QUERYSUPPORT));
                }
                return ((int)sts).ToString();
            }
            return status;
        }
    }

    static class Program
    {
        public static FormScan global;

        public static FSharpFunc<N2O.Types.Msg,N2O.Types.Msg> router(N2O.Types.Req r) {
            return Acquire.proto((Scan.ITwain)new WTwain());
        }

        [STAThread]
        static void Main()
        {
            N2O.Server.proto = FSharpFunc<N2O.Types.Req,FSharpFunc<N2O.Types.Msg,N2O.Types.Msg>>.FromConverter(router);
            N2O.Server.start("0.0.0.0", 40220);

            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(global = new FormScan());
            Application.Exit();
        }
    }
}