如何知道用户点击了"X"或"关闭"按钮？

Question

在MSDN中我发现CloseReason.UserClosing用户已经决定关闭表单,但我想单击X按钮或单击关闭按钮是相同的.那么如何在我的代码中区分这两者呢？

谢谢大家.

Answer 1

假设您要求WinForms,您可以使用FormClosing()事件.只要表单被关闭,就会触发事件FormClosing().

要检测用户是否单击了X或您的CloseButton,您可以通过sender对象获取它.尝试将发送者转换为Button控件,并验证其名称"CloseButton",例如.

private void Form1_FormClosing(object sender, FormClosingEventArgs e) {
    if (string.Equals((sender as Button).Name, @"CloseButton"))
        // Do something proper to CloseButton.
    else
        // Then assume that X has been clicked and act accordingly.
}

否则,我从来不需要区分是否单击了X或CloseButton,因为我想在FormClosing事件上执行特定的操作,比如在关闭MDIContainerForm之前关闭所有MdiChildren,或者检查未保存的更改的事件.在这种情况下,根据我的说法,我们不需要区别于任何一个按钮.

关闭ALT+ F4也会触发FormClosing()事件,因为它会向表示要关闭的表单发送一条消息.您可以通过设置取消活动

FormClosingEventArgs.Cancel = true. 

在我们的例子中,这将转化为

e.Cancel = true.

注意FormClosing()和FormClosed()事件之间的区别.

FormClosing在表单收到要关闭的消息时发生,并在关闭之前验证它是否有事可做.

FormClosed发生在窗体实际关闭时,因此关闭后.

这有帮助吗？

Answer 2

CloseReason您在MSDN上找到的枚举只是为了检查用户是关闭应用程序,还是由于关闭,或由任务管理器关闭等...

根据原因,你可以采取不同的行动,例如:

void Form_FormClosing(object sender, FormClosingEventArgs e)
{
    if(e.CloseReason == CloseReason.UserClosing)
        // Prompt user to save his data

    if(e.CloseReason == CloseReason.WindowsShutDown)
        // Autosave and clear up ressources
}

但是就像你猜测的那样,点击x按钮,或右键单击任务栏并单击"关闭"或按下Alt F4等等没有区别.这一切都归结为一个CloseReason.UserClosing原因.

Answer 3

"X"按钮注册为DialogResult.Cancel另一个选项是评估DialogResult.

如果表单上有多个按钮,则可能已经将不同的DialogResults 关联到每个按钮,这将为您提供区分每个按钮的方法.

(例如:btnSubmit.DialogResult = DialogResult.OK,btnClose.DialogResult = Dialogresult.Abort)

    public Form1()
    {
        InitializeComponent();

        this.FormClosing += Form1_FormClosing;
    }

    /// <summary>
    /// Override the Close Form event
    /// Do something
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    private void Form1_FormClosing(Object sender, FormClosingEventArgs e)
    {
        //In case windows is trying to shut down, don't hold the process up
        if (e.CloseReason == CloseReason.WindowsShutDown) return;

        if (this.DialogResult == DialogResult.Cancel)
        {
            // Assume that X has been clicked and act accordingly.
            // Confirm user wants to close
            switch (MessageBox.Show(this, "Are you sure?", "Do you still want ... ?", MessageBoxButtons.YesNo, MessageBoxIcon.Question))
            {
                //Stay on this form
                case DialogResult.No:
                    e.Cancel = true;
                    break;
                default:
                    break;
            }
        }
    }

Answer 4

如何通过单击 X 按钮或调用Close()代码来检测表单是否关闭？

您不能依赖表单关闭事件参数的关闭原因，因为：
如果用户单击标题栏上的 X 按钮或
使用 Alt + F4 关闭表单或
使用系统菜单关闭表单或
通过调用Close()方法关闭表单，

对于上述所有情况，关闭原因将是用户关闭( CloseReason.UserClosing)，这不是预期的结果。

要区分表单是按 X 按钮关闭还是按Close方法关闭，您可以使用以下选项之一：

• 处理WM_SYSCOMMAND并检查SC_CLOSE并设置标志。
• 检查StackTrace以查看是否有任何帧包含Close方法调用。

示例 1 - 句柄 WM_SYSCOMMAND

public bool ClosedByXButtonOrAltF4 {get; private set;}
private const int SC_CLOSE = 0xF060;
private const int WM_SYSCOMMAND = 0x0112;
protected override void WndProc(ref Message msg)
{
    if (msg.Msg == WM_SYSCOMMAND && msg.WParam.ToInt32() == SC_CLOSE)
        ClosedByXButtonOrAltF4 = true;
    base.WndProc(ref msg);
}
protected override void OnShown(EventArgs e)
{
    ClosedByXButtonOrAltF4 = false;
}   
protected override void OnFormClosing(FormClosingEventArgs e)
{
    if (ClosedByXButtonOrAltF4)
        MessageBox.Show("Closed by X or Alt+F4");
    else
        MessageBox.Show("Closed by calling Close()");
}

示例 2 - 检查 StackTrace

protected override void OnFormClosing(FormClosingEventArgs e)
{
    if (new StackTrace().GetFrames().Any(x => x.GetMethod().Name == "Close"))
        MessageBox.Show("Closed by calling Close()");
    else
        MessageBox.Show("Closed by X or Alt+F4");
}

Answer 5

如果表单已关闭(如果您的应用程序未附加到特定表单),它将确定何时关闭应用程序.

    private void MyForm_FormClosed(object sender, FormClosedEventArgs e)
    {
        if (Application.OpenForms.Count == 0) Application.Exit();
    }

Answer 6

我总是在我的应用程序中使用Form Close方法，该方法从退出按钮，alt + f4或启动了另一个关闭表单事件中捕获alt + x 。mstrClsTitle = "grmRexcel"在这种情况下，我所有的类都有定义为“私有”字符串的类名，一个调用“表单关闭方法”的Exit方法和一个“表单关闭方法”。我也有一个关于Forms Closing Method-的声明this.FormClosing = My Form Closing Form Closing method name。

此代码：

namespace Rexcel_II
{
    public partial class frmRexcel : Form
    {
        private string mstrClsTitle = "frmRexcel";

        public frmRexcel()
        {
            InitializeComponent();

            this.FormClosing += frmRexcel_FormClosing;
        }

        /// <summary>
        /// Handles the Button Exit Event executed by the Exit Button Click
        /// or Alt + x
        /// 
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btnExit_Click(object sender, EventArgs e)
        {            
            this.Close();        
        }


        /// <summary>
        /// Handles the Form Closing event
        /// 
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void frmRexcel_FormClosing(object sender, FormClosingEventArgs e)
        {

            // ---- If windows is shutting down, 
            // ---- I don't want to hold up the process
            if (e.CloseReason == CloseReason.WindowsShutDown) return;
            {

                // ---- Ok, Windows is not shutting down so
                // ---- either btnExit or Alt + x or Alt + f4 has been clicked or
                // ---- another form closing event was intiated
                //      *)  Confirm user wants to close the application
                switch (MessageBox.Show(this, 
                                    "Are you sure you want to close the Application?",
                                    mstrClsTitle + ".frmRexcel_FormClosing",
                                    MessageBoxButtons.YesNo, MessageBoxIcon.Question))
                {

                    // ---- *)  if No keep the application alive 
                    //----  *)  else close the application
                    case DialogResult.No:
                        e.Cancel = true;
                        break;
                    default:
                        break;
                }
            }
        }
    }
}