c# how to have a Timer Close a Winform

Question

Simple C# Winform I have a Timer that close the From. I would like to have a Message box popup saying its closing.
If no response then close if user clicks cancel then the Timer starts. This is what I have so far that closes the Form.

using Timer = System.Windows.Forms.Timer;

 private void Form1_Load(object sender, EventArgs e)
        {        
            // Timer to Close App
            Timer MyTimer = new Timer();   
            MyTimer.Interval = (1 * 60 * 1000); // 1 mins
            MyTimer.Tick += new EventHandler(timer1_Tick);
            MyTimer.Start();
        }


        private void timer1_Tick(object sender, EventArgs e)
        {

            label9.Text = (int.Parse(label9.Text) - 1).ToString();
            if (int.Parse(label9.Text) == 0)  //if the countdown reaches '0', we stop it

            //  MessageBox.Show("The form will now be closed.", "Time Elapsed");

            this.Close();

        }


    }
}

Answer 1

A way with a Countdown =>

(add a Label label1...)

public partial class Form1 : Form  
{  
    [DllImport("User32.dll", SetLastError = true, CharSet = CharSet.Unicode)]  
    public static extern IntPtr FindWindow(string lpClassName, string lpWindowName);  
  
    [DllImport("User32.dll", SetLastError = true, CharSet = CharSet.Unicode)]  
    public static extern bool EndDialog(IntPtr hDlg, int nResult);  
  
    [DllImport("User32.dll", SetLastError = true, CharSet = CharSet.Unicode)]  
    public static extern IntPtr GetWindow(IntPtr hWnd, uint uCmd);  
  
    public const int GW_HWNDFIRST = 0;  
    public const int GW_HWNDLAST = 1;  
    public const int GW_HWNDNEXT = 2;  
    public const int GW_HWNDPREV = 3;  
    public const int GW_OWNER = 4;  
    public const int GW_CHILD = 5;  
    public const int GW_ENABLEDPOPUP = 6;  
  
    [DllImport("User32.dll", SetLastError = true, CharSet = CharSet.Unicode)]  
    private static extern int GetClassName(IntPtr hWnd, StringBuilder lpClassName, int nMaxCount);  
  
    [DllImport("User32.dll", SetLastError = true, CharSet = CharSet.Unicode)]  
    private static extern int GetWindowText(IntPtr hWnd, StringBuilder lpString, int nMaxCount);  
  
    [DllImport("User32.dll", SetLastError = true, CharSet = CharSet.Unicode)]  
    public static extern bool SetWindowText(IntPtr hWnd, string Text);  
  
    [DllImport("User32.dll", EntryPoint = "GetWindowLong", CharSet = CharSet.Unicode)]  
    private static extern long GetWindowLong32(IntPtr hWnd, int nIndex);  
  
    [DllImport("User32.dll", EntryPoint = "GetWindowLongPtr", CharSet = CharSet.Unicode)]  
    private static extern long GetWindowLongPtr64(IntPtr hWnd, int nIndex);  
  
    public static long GetWindowLong(IntPtr hWnd, int nIndex)  
    {  
        if (IntPtr.Size == 4)  
        {  
            return GetWindowLong32(hWnd, nIndex);  
        }  
        return GetWindowLongPtr64(hWnd, nIndex);  
    }  
  
    public const int GWL_STYLE = (-16);  
    public const int GWL_EXSTYLE = (-20);  
  
    public const int SS_ICON  =  0x00000003;  
  
  
    System.Timers.Timer timer1;  
    System.Timers.Timer timerMessageBox;  
    double nCurrentTime = 0, nTotalTime = 20 * 1000, nCountDown = 10 * 1000;  
    // Choose an unique title...  
    string sTitle = "Information";  
    int nResult = (int)DialogResult.Cancel;  
  
    public Form1()  
    {  
        InitializeComponent();  
    }  
  
    private void Form1_Load(object sender, EventArgs e)  
    {  
        label1.Text = "";  
        timer1 = new System.Timers.Timer(1 * 1000);  
        timer1.Elapsed += OnTimedEvent;  
        timer1.Start();  
    }  
  
    private void OnTimedEvent(object source, System.Timers.ElapsedEventArgs e)  
    {  
        nCurrentTime += timer1.Interval;  
        label1.Invoke((Action)(() => label1.Text = (nCurrentTime/1000).ToString()));  
        if (nCurrentTime >= nTotalTime - nCountDown)  
        {  
            IntPtr hWndDest = FindWindow(null, sTitle);  
            if (hWndDest == IntPtr.Zero && nResult != (int)DialogResult.OK)  
            {  
                timerMessageBox = new System.Timers.Timer(nCountDown);  
                timerMessageBox.Elapsed += OnTimedMessageBoxEvent;  
                timerMessageBox.Start();                     
                nResult = (int)System.Windows.Forms.MessageBox.Show("The form will close in 10 seconds", sTitle, MessageBoxButtons.OKCancel, MessageBoxIcon.Question);  
                timerMessageBox.Stop();  
                if (nResult == (int)DialogResult.Cancel)  
                {  
                    nCurrentTime = 0;  
                    timer1.Stop();  
                    timer1.Start();  
                }  
                //else if (nResult == (int)DialogResult.OK)  
                //{  
                //    //timer1.Stop();  
                //    //Application.Exit();  
                //}  
            }  
            else  
            {  
                IntPtr hWndChild = GetWindow(hWndDest, GW_CHILD);  
                bool bFound = false;  
                while (!bFound && hWndChild != IntPtr.Zero)  
                {  
                    StringBuilder sbBufferClass = new StringBuilder(260);  
                    GetClassName(hWndChild, sbBufferClass, sbBufferClass.Capacity);  
                    if (sbBufferClass.ToString() == "Static")  
                    {  
                        long nStyle = GetWindowLong(hWndChild, GWL_STYLE);  
                        if ((nStyle & SS_ICON) != 0)  
                        {  
                            StringBuilder sbBufferText = new StringBuilder(260);  
                            GetWindowText(hWndChild, sbBufferText, sbBufferText.Capacity);  
                            if (sbBufferText.ToString() != null)  
                                bFound = true;  
                        }  
                    }                         
                    hWndChild = GetWindow(hWndChild, GW_HWNDNEXT);  
                }  
                if (bFound)  
                {  
                    string sMessage = string.Format("The form will close in {0} seconds", (nTotalTime - nCurrentTime)/1000);  
                    SetWindowText(hWndChild, sMessage);  
                }  
                if (nCurrentTime >= nTotalTime)  
                {  
                    if (nResult == (int)DialogResult.OK)  
                    {  
                        timer1.Stop();  
                        Application.Exit();  
                    }  
                }  
            }  
        }             
    }  
  
    private void OnTimedMessageBoxEvent(object source, System.Timers.ElapsedEventArgs e)  
    {  
        nResult = (int)DialogResult.OK;  
        IntPtr hWndDest = FindWindow(null, sTitle);            
        EndDialog(hWndDest, nResult);             
    }  
}  

Answer 2

Hello,

You can interject in the Closing event and if there is a need to cancel use e.Cancel from the argument in the Closing event.

Code sample from the link above and in this case disregard the TextBox aspect.

private void Form1_Closing(object sender, System.ComponentModel.CancelEventArgs e)  
{  
   // Determine if text has changed in the textbox by comparing to original text.  
   if (textBox1.Text != strMyOriginalText)  
   {  
      // Display a MsgBox asking the user to save changes or abort.  
      if(MessageBox.Show("Do you want to save changes to your text?", "My Application",  
         MessageBoxButtons.YesNo) ==  DialogResult.Yes)  
      {  
         // Cancel the Closing event from closing the form.  
         e.Cancel = true;  
         // Call method to save file...  
      }  
   }  
}