用于关闭Windows窗体应用程序的事件处理程序

Question

我试图创建一个event handler这样的用户,当用户选择close(x)按钮时,它会提示用户保存任何未保存的更改.这是我的C#代码:

private void CloseFileOperation()
{
    // If the Spreadsheet has been changed since the user opened it and
    // the user has requested to Close the window, then prompt him to Save
    // the unsaved changes.
    if (SpreadSheet.Changed)
    {
        DialogResult UserChoice = MessageBox.Show("Would you like to save your changes?", "Spreadsheet Utility",
                MessageBoxButtons.YesNoCancel, MessageBoxIcon.Warning);

        switch (UserChoice)
        {
            case DialogResult.Yes:
                SaveFileOperation();
                this.Close();
                break;
            case DialogResult.No:
                this.Close();
                break;
            case DialogResult.Cancel:
                return;
        }
    }

    // If the Spreadsheet hasn't been changed since the user opened it, then
    // simply Close the window.
    else
        this.Close();
}

我创建MainFram_FormClosing了用户选择close(x)按钮时触发的事件处理程序.

private void MainFrame_FormClosing(object sender, FormClosingEventArgs e)
{
    // Close the Spreadsheet.
    CloseFileOperation();
}

每当我选择关闭按钮时,应用程序崩溃了..我已阅读this帖子中的回复.我想我违反了Windows 7 Program Requirements.我想我不明白为什么这个功能不能轻易完成.

这方面最好的方法是什么？

Answer 1

如果使用事件处理程序本身而不是单独的例程,则可以访问FormClosingEventArgs,这将允许您在必要时取消关闭.您也正在使用this.Close();,它只是重新启动事件,而不是返回并让事件结束.当我使用此代码集作为事件处理程序时,它按预期在Win7上工作:

    private void Form2_FormClosing(object sender, FormClosingEventArgs e)
    {
        if(SpreadSheet.Changed)
        {
            switch(MessageBox.Show("Would you like to save your changes?", "Spreadsheet Utility",
                MessageBoxButtons.YesNoCancel, MessageBoxIcon.Warning))
            {
                case DialogResult.Yes:
                    SaveFileOperation();
                    return;
                case DialogResult.No:
                    return;
                case DialogResult.Cancel:
                    e.Cancel = true;
                    return;
            }
        }
    }