Example 7: High-Speed Scanning with Multiple Heads

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Net;
using System.Text;
using System.Threading;
using System.Windows.Forms;
using JoeScan.JCamNet;

namespace Examples
{
    public partial class Form1 : Form
    {
        private Thread scanThread;
        private volatile bool isRunning;
        private Scanner[] scanners; 
        
        public Form1()
        {
            InitializeComponent();
            scanners = SetupScanners();
        }

        private void ScanThreadMain()
        {
            foreach (var scanner in scanners)
            {
                // reset encoders
                scanner.SetEncoder(0);
                // EnterPulsSyncMode() will make all heads trigger on receiving a 
                // Start Scan pulse, that is emitted by the "master" head.
                scanner.EnterPulseSyncMode();                
            }
            // sleep for a millisecond to give all heads to get ready 
            Thread.Sleep(1);
            // and tell the "master" head to send out a pulse train every second
            scanners[0].StartPulseMaster(1000 * 1000);
            
            // this is called on a thread, so it can't manipulate objects on the UI thread, hence the 
            // need to use Invoke()
            this.Invoke(new Action(() => this.textBox.Clear()));
            this.Invoke(new Action(() => this.textBox.AppendText("Scanning Started.\n")));
               
            while (isRunning)
            {
                // This is the recommended way to parallelize the readout from multiple scanners.
                // first, request profiles
                foreach (var scanner in scanners)
                {
                    scanner.BeginGetQueuedProfiles(1);
                }
                // then, read them out
                foreach (var scanner in scanners)
                {
                    List<Profile> received = scanner.EndGetQueuedProfiles();
                    if (received.Count > 0)
                    {
                        // we need to make temp copies because of the way 
                        // captured variables work with lambda expressions
                        int tempShort = scanner.CableID;
                        int tempInt = received[0].Location;
                        this.Invoke(new Action(() =>
                            this.textBox.AppendText(String.Format
                            ("Scanner {0}: Profile measured at Encoder Value {1}\n",
                            tempShort, tempInt))));
                    }   
                }
                // Keep processing time in this loop to a minimum if you want maximum scan speed.
                // Key to a fast system is to only gather the data in this loop, and let another thread 
                // (e.g. your main GUI thread) do heavy processing asynchronously. You must use thread
                //  safe methods of exchanging data or interacting with the UI.
            }
            // and make sure every scanner is out of sync mode again
            foreach (var scanner in scanners)
            {
                scanner.ExitSyncMode();
            }
        }

        private void StartButton_Click(object sender, EventArgs e)
        {
            if (scanThread == null || !scanThread.IsAlive)
            {
                scanThread = new Thread(new ThreadStart(this.ScanThreadMain))
                {                    
                    IsBackground = true,
                    Name = "ScanThreadMain",
                    Priority = ThreadPriority.Highest
                };
                isRunning = true;
                scanThread.Start();
            }
        }

        private void StopButton_Click(object sender, EventArgs e)
        {
            StopScanning();
        }

        private void StopScanning()
        {
            isRunning = false; 
            if (scanThread != null)
            {
                scanThread.Join(100);
                scanThread = null;
            }
        }

        private void QuitButton_Click(object sender, EventArgs e)
        {
            StopScanning();
            Close();
        }

        private Scanner[] SetupScanners()
        {
            // for clarity, no error checking here
            Scanner[] scanners = Scanner.Connect(new IPAddress(new byte[] {192, 168, 1, 150}),
                new short[] {0,1});
            using (TextReader parametersReader = File.OpenText("param.dat"))
            {
                string parametersString = parametersReader.ReadToEnd();
                foreach (var scanner in scanners)
                {                    
                    scanner.SetParameters(parametersString, true);    
                }                
            }
            return scanners;
        }
    }
}