如何在加载或获取数据时取消关闭表单？ [英] How to cancle the closing form when loading or fetch data?

问题描述

大家好，所有



目前，我正在学习vb.net，我正在学习关闭表单的代码，但是在表单处理和结束时遇到了一些问题，我的意思是我需要显示消息（请等待，提取数据将很快完成），如果进程尚未完成，如获取数据



注意：我的英语不是最强的



谢谢

kevin



我尝试了什么：



我需要了解更多信息，我希望这对新人来说是个好消息

Hi, all

Currently, I study vb.net, and I am learning the code about closing the form but I get some issue when form processing and closing, I mean I need to show the message( "please wait , fetching data will complete soon"), If the process not yet to complete such as fetching data

Note: my English not strongest

thank you
kevin

What I have tried:

I need learn more , I hope this will be good information for new guy

推荐答案

订阅表单的结束事件（WindowClosing或FormClosing）。它附带 CancelEventArgs ，其中包含取消属性。当你无法关闭表格时，将该属性设置为 True 。

Subscribe the Closing event (WindowClosing or FormClosing) of the form. It comes with CancelEventArgs which have a Cancel property. Set that property to True when you cannot close the form.

除了解决方案1：



处理 FormClosing 的替代方法，你可以覆盖虚方法 System.Windows.Forms.Form.FormClosing ：

https://msdn.microsoft.com/en-us/library/system.windows.forms.form.onformclosing%28v=vs.110%29.aspx 。



事件参数类型相同， FormClosingEventArgs ，因此您可以通过<$ c控制相同方式的处理取消$ c> FormClosingEventArgs.Cancel ：

FormClosingEventArgs类（System.Windows.Forms） [ ^ ]。



注意你应该更好地检查 FormClosingEventArgs.CloseReason ;通常，只有在用户通过表单的控件关闭时才需要阻止关闭，所以你必须检查原因是 CloseReason.UserClosing ：

FormClosingEventArgs.CloseReason Property（ System.Windows.Forms），

CloseReason Enumeration（System.Windows.Forms）。



覆盖 FormClosing 对事件处理有一定的好处。原因如下：重写的代码更简单，更易于维护，创建派生类型的需求并不麻烦，因为Form类型通常都是在应用程序中派生的。

-SA

In addition to Solution 1:

An alternative to handling FormClosing, you can override the virtual method System.Windows.Forms.Form.FormClosing:
https://msdn.microsoft.com/en-us/library/system.windows.forms.form.onformclosing%28v=vs.110%29.aspx.

The event arguments type is the same, FormClosingEventArgs, so you control the cancellation of processing the same way, via FormClosingEventArgs.Cancel:
FormClosingEventArgs Class (System.Windows.Forms)[^].

Note the you should better check up FormClosingEventArgs.CloseReason; usually, you need to prevent closing only when it's closing by the user via the form's control, so you have to check is the reason is CloseReason.UserClosing:
FormClosingEventArgs.CloseReason Property (System.Windows.Forms),
CloseReason Enumeration (System.Windows.Forms).

Overriding FormClosing has certain benefits over the event handling. Here is why: overridden code is simpler and more maintainable, and the need to create a derived type is not a hassle, because Form types are usually derived in the application anyway.

—SA

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