如何在用户控件中创建事件并在主窗体中处理它？ [英] How do I make an Event in the Usercontrol and have it handled in the Main Form?

问题描述

我有一个自定义的usercontrol，我想做一些相对简单的事情。

I have a custom usercontrol and I want to do something relatively simple.

每当该usercontrol值的上下数字发生变化时，请将主窗体更新为显示窗口。

When ever a numeric up down in that usercontrol's value changes, have the main form update a display window.

如果NUD不在用户控件中，但我似乎无法弄清楚如何由主窗体处理该事件，这不是问题。

This is not a problem if the NUD was not in a usercontrol but I can't seem to figure out how to have the event handled by the mainform and not the usercontrol.

推荐答案

您需要为用户控件创建事件处理程序，该事件处理程序在用户内部发生事件时引发控制被解雇。这将使您能够在事件链上冒泡，以便可以从表单中处理事件。

You need to create an event handler for the user control that is raised when an event from within the user control is fired. This will allow you to bubble the event up the chain so you can handle the event from the form.

在UserControl上单击 Button1 时，我将触发 Button1_Click 会触发 UserControl_ButtonClick 形式：

When clicking Button1 on the UserControl, i'll fire Button1_Click which triggers UserControl_ButtonClick on the form:

用户控件：

[Browsable(true)] [Category("Action")] 
[Description("Invoked when user clicks button")]
public event EventHandler ButtonClick;

protected void Button1_Click(object sender, EventArgs e)
{
    //bubble the event up to the parent
    if (this.ButtonClick!= null)
        this.ButtonClick(this, e);               
}

表格：

UserControl1.ButtonClick += new EventHandler(UserControl_ButtonClick);

protected void UserControl_ButtonClick(object sender, EventArgs e)
{
    //handle the event 
}

注意：

• 较新的Visual Studio版本建议使用 ButtonClick代替 if（this.ButtonClick！= null）this.ButtonClick（this，e）; .invoke（this，e）; ，其功能基本相同，但更短。

• Newer Visual Studio versions suggest that instead of if (this.ButtonClick!= null) this.ButtonClick(this, e); you can use ButtonClick?.Invoke(this, e);, which does essentially the same, but is shorter.

Browsable 属性使事件在Visual Studio的设计器（事件视图）中可见，类别将其显示在操作类别中，而说明提供了对其的描述。您可以完全省略这些属性，但是由于VS可以为您处理，因此可以让设计者轻松使用。

The Browsable attribute makes the event visible in Visual Studio's designer (events view), Category shows it in the "Action" category, and Description provides a description for it. You can omit these attributes completely, but making it available to the designer it is much more comfortable, since VS handles it for you.

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