timer

Question

hello everyone,

so im working on a project where the user enters time in mm:ss format in a editable listview, then the program is sapposed to do some math to countdown the amount of time entered ounce the start button is pressed. my problem is im doing the timer calcualtion in background worker and everytime the backround worker runs it rereads the input from the listview causing the math to always be wrong. 

here is my code

que is set to 1 when a button is pressed       my thinking was that i could only set the value for the timer when the program starts then stop rereading it from the listview when a press a button which sets que to 1 but the program will not compile if i dont set some value "end" in every part of the switch statement, i tried the same thing with a "if else" statement

 private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            
            string Time = listView1.Items[0].Text;

            DateTime dateTime = DateTime.ParseExact(Time, "mm:ss",
                                        CultureInfo.InvariantCulture);
          
            
            DateTime end;
            DateTime start;
            int min, sec;
         switch(que)
            {
                case 1:

                    start = DateTime.Now;
                end = DateTime.Now.AddMinutes(dateTime.Minute);
                end = end.AddSeconds(dateTime.Second);

                    break;
            case 2:

                    end = DateTime.Now.AddMinutes(dateTime.Minute);
                    end = end.AddSeconds(dateTime.Second);
                    break;
                default:
            
                end = DateTime.Now.AddMinutes(dateTime.Minute);
                end = end.AddSeconds(dateTime.Second);
                    break;
            }
                min = (int)(dateTime - end).Minutes;
                sec = (int)(dateTime - end).Seconds;
          
            label1.Text = min + ":" + sec;// dateTime.ToString("mm:ss", CultureInfo.CurrentCulture);
        } 

thanks everyone!

Answer 1

Do you need a backgroundworker?

As this is a windows forms application, it might be easiest to use a System.Windows.Forms.Timer. You can set it up to do something every second (as in below example).

public partial class Form1 : Form
{
    // aa timer for count down
    Timer tmr = new Timer();

    public Form1()
    {
        // this is standard in a Windows form
        InitializeComponent();

        // setup timer with interval of one second
        tmr.Interval = 1000;
        // and add event handler
        tmr.Tick += tmr_Tick;

    }

    // timer event handler
    void tmr_Tick(object sender, EventArgs e)
    {
        // split the time specified in a textbox
        string[] time = textBox1.Text.Split(':');
        // convert minutes and seconds
        int minutes = Convert.ToInt32(time[0]);
        int seconds = Convert.ToInt32(time[1]);
        // create a timespan from it
        TimeSpan ts = new TimeSpan(0, minutes,seconds);
        // create a timespan representing one second
        TimeSpan tsOnesecond = new TimeSpan(0,0,1);
        // subtract one second from current timespan
        ts = ts.Add(tsOnesecond.Negate());
        // display new time in textbox
        textBox1.Text = String.Format("{0:D2}:{1:D2}", ts.Minutes, ts.Seconds);

        // check if there is still time left
        if (ts.Ticks == 0)
        {
            // we're done, stop timer, inform user and re-enable start button
            tmr.Stop();
            MessageBox.Show("Done");
            btnStart.Enabled = true;
        }
    }

    // start button event handler
    private void btnStart_Click(object sender, EventArgs e)
    {
        // set a duration value
        textBox1.Text = "00:30";
        // start timer
        tmr.Start();
        // disable start button
        btnStart.Enabled = false;
    }
}

This just shows the basics;

You probably need a global variable to remember the time left (use the TimeSpan for that); the above code remembers it by using the textbox what is more than likely not what you want. In that case you can initialize a global TimeSpan variable in the start button's event handler and subtract a second in the timer's event handler.

Answer 2

i am exactly not sure following you.

do you want to like as below i guess?

1. if user press the the button and set the variable  que to 1 

2.do the time calculation operation in the background-work process event when variable que == 1

if that is your expect for. you just need do like below using if statement

       string Time = listView1.Items[0].Text;

       DateTime dateTime = DateTime.ParseExact(Time, "mm:ss",
                                        CultureInfo.InvariantCulture);
         if(que==1)
            {
                DateTime start = DateTime.Now;
                DateTime end = start;
                end = end.AddMinutes(dateTime.Minute);
                end = end.AddSeconds(dateTime.Second);
                int min = (int)(dateTime - end).Minutes;
                int sec = (int)(dateTime - end).Seconds;
            	label1.Text = min + ":" + sec;// dateTime.ToString("mm:ss", CultureInfo.CurrentCulture);
            }

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DON'T TRY SO HARD,THE BEST THINGS COME WHEN YOU LEAST EXPECT THEM TO.