c# - Detect reason for form closing

Question

How can I detect how a windows form is being closed? For example, how do I find out whether the user has clicked on a button which closes the form or if the user clicks on the "X" in the upper-right? Thank you.

Update:

Forgot to mention that the button calls the Application.Exit() method.

Answer 1

As bashmohandes and Dmitriy Matveev already mentioned the solution should be the FormClosingEventArgs. But as Dmitriy also said, this wouldn't make any difference between your button and the X in the right upper corner.

To distinguish between these two options, you can add a boolean property ExitButtonClicked to your form and set it to true in the button Click-Event right before you call Application.Exit().

Now you can ask this property within the FormClosing event and distinguish between those two options within the case UserClosing.

Example:

    public bool UserClosing { get; set; }

    public FormMain()
    {
        InitializeComponent();

        UserClosing = false;
        this.buttonExit.Click += new EventHandler(buttonExit_Click);
        this.FormClosing += new FormClosingEventHandler(Form1_FormClosing);
    }

    void buttonExit_Click(object sender, EventArgs e)
    {
        UserClosing = true;
        this.Close();
    }

    void Form1_FormClosing(object sender, FormClosingEventArgs e)
    {
        switch (e.CloseReason)
        {
            case CloseReason.ApplicationExitCall:
                break;
            case CloseReason.FormOwnerClosing:
                break;
            case CloseReason.MdiFormClosing:
                break;
            case CloseReason.None:
                break;
            case CloseReason.TaskManagerClosing:
                break;
            case CloseReason.UserClosing:
                if (UserClosing)
                {
                    //what should happen if the user hitted the button?
                }
                else
                {
                    //what should happen if the user hitted the x in the upper right corner?
                }
                break;
            case CloseReason.WindowsShutDown:
                break;
            default:
                break;
        }

        // Set it back to false, just for the case e.Cancel was set to true
        // and the closing was aborted.
        UserClosing = false;
    }