Timer control freezing the UI

[steve_rm]

Hello,

CF 3.5 VS 2008

I have a timer control that is being used to do some work. Code below. The timer interval is set for 1 second. However, when the timer is running the UI freezes for a short period.

I understand that the timer control is uses the UI thread, but I didn't think the amount of work was too much to make the UI freeze for short periods.

I couldn't see any server timers for the compact framework.

Any suggestions would be most helpful.

//Get the signal strength of the AP that the adapter is currently connected to
        private void GetSignalStrength()
        {
            try
            {
                //Loop through all the AP nearby and find the one that is currently being connected (Associated)
                if (currentAdapter.NearbyAccessPoints.Count > 0)
                {                 
                    foreach (AccessPoint ap in currentAdapter.NearbyAccessPoints)
                    {
                        if (ap.Name == currentAdapter.AssociatedAccessPoint)
                        {
                           this.DisplaySignalStrength(ap.SignalStrength.ToString());
                           //Break out of for loop when the currently connected AP has been found.
                           break;
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

        //Display the signal strength by filling the bars depending on
        //the strength of the access point.
        private void DisplaySignalStrength(string strength)
        {
            this.pbExcellent.BackColor = Color.Transparent;
            this.pbVeryGood.BackColor = Color.Transparent;
            this.pbGood.BackColor = Color.Transparent;
            this.pbLow.BackColor = Color.Transparent;
            this.pbVeryLow.BackColor = Color.Transparent;

            switch (strength)
            {
                case "Excellent":
                    this.pbExcellent.BackColor = Color.Green;
                    this.pbVeryGood.BackColor = Color.Green;
                    this.pbGood.BackColor = Color.Green;
                    this.pbLow.BackColor = Color.Green;
                    this.pbVeryLow.BackColor = Color.Green;
                    break;
                case "Very Good":
                    this.pbVeryGood.BackColor = Color.Green;
                    this.pbGood.BackColor = Color.Green;
                    this.pbLow.BackColor = Color.Green;
                    this.pbVeryLow.BackColor = Color.Green;
                    break;
                case "Good":
                    this.pbGood.BackColor = Color.Green;
                    this.pbLow.BackColor = Color.Green;
                    this.pbVeryLow.BackColor = Color.Green;
                    break;
                case "Low":
                    this.pbLow.BackColor = Color.Green;
                    this.pbVeryLow.BackColor = Color.Green;
                    break;
                case "Very Low":
                    this.pbVeryLow.BackColor = Color.Green;
                    break;
                default:
                    break;
            }
        }

        //Check the signal strength every 1 second
        private void tmrPollAP_Tick(object sender, EventArgs e)
        {
            this.GetSignalStrength();   
        }

[Shaggy Hiker]

Actually, I would suspect that the amount of time being taken by what you are doing may well be longer than you think. To me, checking signal strength seems like a time-intensive operation. You might write yourself a little profiler to test it. I have one in VB, but they are so easy to write that it's hardly worth passing it out. Just start a stopwatch object at the beginning of the tick event, stop it at the end, and look at the elapsed time. I think you will probably find that the timing is not what you had hoped for. If that is the case, I would say that you should seriously consider checking the signal strength in a background thread. This could either run periodically (you could start it on the timer tick), or run continuously (which might impact performance, too), only updating the display periodically.

[steve_rm]

Hello,

Visual Studio 2008 development edition comes with a profiler that measures the time it takes. I will investigate this.

I was thinking of using a background thread. However, as the picture boxes are on the UI thread then I would have to use the picture boxes to invoke a delegate to marshal the call to the UI thread. Just seems a lot of coding for something that seemed easy.

However, I will try the background thread and post back with the code.

Thanks,

[Shaggy Hiker]

I would do the profiling first. I suspect the signal strength takes a certain amount of time, but I'd want to confirm that it is the cause of the slowdown.