LVMQUpdater.cs

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using System;
using System.Collections.Generic;
using System.Text;
using System.Threading;
using System.ComponentModel;

namespace Seci.LabView
{
    class LvmqUpdater : IDisposable
    {
        private BackgroundWorker _backgroundUpdater;
        private Timer _updateTimer;
        private TimerCallback _updateCallBack;
        private int _updateRate = 3000;

        private Boolean _messagesChanged;

        public event EventHandler OnChangeToLVMessages;
        public event EventHandler OnLabviewNotThere;

        public LvmqUpdater(int updateRate)
        {
            if (updateRate <= 0)
            {
                _updateRate = 3000;
            }

            if (_backgroundUpdater == null)
            {
                //Initialise the background worker
                _backgroundUpdater = new BackgroundWorker();
                _backgroundUpdater.DoWork += new DoWorkEventHandler(backgroundUpdater_DoWork);
                _backgroundUpdater.RunWorkerCompleted += new RunWorkerCompletedEventHandler(backgroundUpdater_RunWorkerCompleted);
            }
        }

        public void StartUpdater()
        {
            if (_updateCallBack == null && _updateTimer == null)
            {
                _updateCallBack = new TimerCallback(updateTimer_Tick);
                _updateTimer = new Timer(_updateCallBack, null, 0, _updateRate);
            }
        }

        public void PauseUpdater()
        {
            if (_updateTimer != null)
            {
                _updateTimer.Change(System.Threading.Timeout.Infinite, System.Threading.Timeout.Infinite);
            }
        }

        public void ResumeUpdater()
        {
            if (_updateTimer != null)
            {
                _updateTimer.Change(0, _updateRate);
            }
        }

        private void updateTimer_Tick(object obj)
        {
            //Only update if not already running background thread
            try
            {
                if (!_backgroundUpdater.IsBusy)
                {
                    _backgroundUpdater.RunWorkerAsync();
                }
            }
            catch (Exception err)
            {
                Seci.Helpers.ErrorLogger.SeciError("LvmqUpdater:updateTimer_Tick", err);
            }
        }

        private void backgroundUpdater_DoWork(object sender, System.ComponentModel.DoWorkEventArgs e)
        {
            try
            {
                //Check that LabVIEW exists
                if (!LabViewApp.AreYouThere())
                {
                    //Raise an event to notify the user
                    if (OnLabviewNotThere != null)
                    {
                        OnLabviewNotThere(sender, e);
                    }
                }
                else
                {
                    _messagesChanged = Standard.MessageQueue.UpdateMessages();
                }

            }
            catch(Exception err)
            {
                Seci.Helpers.ErrorLogger.SeciError("LvmqUpdater:backgroundUpdater_DoWork", err);
            }
        }

        private void backgroundUpdater_RunWorkerCompleted(object sender, System.ComponentModel.RunWorkerCompletedEventArgs e)
        {
            //Raise an event so the GUI can tell when new messages are received.
            if (_messagesChanged && OnChangeToLVMessages != null)
            {
                OnChangeToLVMessages(sender, e);
            }
        }


        #region IDisposable Members

        public void Dispose()
        {
            try
            {
                Dispose(true);
            }
            finally
            {
                GC.SuppressFinalize(this);
            }
        }

        protected virtual void Dispose(bool disposing)
        {
            if (disposing)
            {
                // Dispose managed resources.
                if (_backgroundUpdater != null) _backgroundUpdater.Dispose();
                if (_updateTimer != null) _updateTimer.Dispose();
            }

            _backgroundUpdater = null;
            _updateTimer = null;
        }

        #endregion
    }
}