C# - Restart timer when the event handler gets called again

Question

I have a C# WinForms application that has a panel. The panel loads a UserControl and the UserControl contains a DataGridView.

In my UserControl, I have an event handler for the MouseDown event on the DataGrid

private void palletsGrid_MouseDown(object sender, MouseEventArgs e)
{
    try
    {
        EventHandler handler = onScrolling;
        if (handler != null)
        {
            handler(this, new EventArgs());
        }
    }
    Catch (Exception ex)
    {
        Logging.LogWarn("Mouse down error: ", ex);
    }
}

Where onScrolling is a publicly declared EventHandler property.

I deal with this EventHandler in the main form because, I have a timer that auto refreshes every 5 seconds. So I need the main form to know to stop refreshing when this event (scrolling through the DataGridView) happens.

In my main form, this is what I am doing:

private void userControl_ScrollEvent(object sender, EventArgs e)
{
    try
    {
        timer1.Stop();
        Timer pauseTimer = new Timer();
        pauseTimer.Interval = 60000;
        pauseTimer.Start();
        pauseTimer.Tick += new System.EventHandler(pauseTimer_Tick);
    }
    catch (Exception ex)
    {
        Logging.LogFatal("Scroll event capture error: ", ex);
    }
}

What this does is, when the user is scrolling through the DataGridView, the main form stops the auto refresh for 60 seconds. Once the 60 second pauseTimer ticks, the refreshTimer resumes like normal.

Problem:

I need my form to know when I touch the screen twice. As in, if I touch the screen now, the timer starts. Does not refresh for 60 seconds. If I touch it again, the 60 seconds needs to start from the second touch. Not the first. So every time I touch the screen, the pauseTimer needs to restart.

you are creating a Timer every time a user scrolls. bad idea. try creating the timer as member like timer1 and then you can also restart it easily — FrankM, Dec 08 '17 at 14:22
Hmm.. Good point @FrankM. I will modify my application to not do that. — Crazy Cucumber, Dec 08 '17 at 14:24

score 2 · Accepted Answer · answered Dec 08 '17 at 14:59

Like @FrankM points out, you should not create a new timer everytime you scroll. You should always be careful when creating timers (System.Windows.Forms.Timer) in code, if you do, you have to make sure they are disposed properly. The easiest way is to add timers from the designer, this way proper cleanup is taken care of for you. More on disposal of System.Windows.Forms.Timers

Solution 1: Add a pausetimer in the designer and restart it in the scroll event. How to restart a timer may not be obvious, but you do it by first disabling the timer, then enable it:

try
{
    timer1.Enabled = false;
    //Set interval and tick-handler from designer
    pauseTimer.Enabled = false;
    pauseTimer.Enabled = true;
}
catch (Exception ex)
{
    Logging.LogFatal("Scroll event capture error: ", ex);
}

Solution 2: Get rid of the pause timer and just change the interval of your refresh-timer.

try
{
    //Assume that this is the refreshtimer. In the Tick-eventhandler 
    //you reset interval to default refresh intervals
    timer1.Interval = 60000;
    timer1.Enabled = false;
    timer1.Enabled = true;

}
catch (Exception ex)
{
    Logging.LogFatal("Scroll event capture error: ", ex);
}

I like the second solution! I will try either of these and mark as solution if it works out for me. Thanks — Crazy Cucumber, Dec 08 '17 at 15:26
The second solution worked much more elegantly for me. Thank you. Is there a reason why you disable and enable the timer? Is that required? — Crazy Cucumber, Dec 08 '17 at 15:32
Glad to help :) Disabling and then enabling it effectively restarts the timer. If you were to just enable it, the timer would not restart if already enabled on given interval. — TDull, Dec 08 '17 at 15:48

C# - Restart timer when the event handler gets called again

1 Answers1