注册方法以在引发事件时调用 [英] Method to register method to be called when event is raised

问题描述

我有一个包含 20 个 PictureBox 控件的面板.如果用户单击任何控件，我希望调用 Panel 中的一个方法.

I have a Panel which contains 20 PictureBox controls. If a user clicks on any of the controls, I want a method within the Panel to be called.

我该怎么做?

public class MyPanel : Panel
{
   public MyPanel()
   {
      for(int i = 0; i < 20; i++)
      {
         Controls.Add(new PictureBox());
      }
   }

   // DOESN'T WORK.
   // function to register functions to be called if the pictureboxes are clicked.
   public void RegisterFunction( <function pointer> func )
   {
        foreach ( Control c in Controls )
        {
             c.Click += new EventHandler( func );
        }
   }
}

如何实现RegisterFunction()?另外，如果有很酷的C#特性可以让代码更优雅，请分享.

How do I implement RegisterFunction()? Also, if there are cool C# features that can make the code more elegant, please share.

推荐答案

函数指针"在 C# 中由委托类型表示.Click 事件需要 EventHandler 类型的委托.因此，您可以简单地将 EventHandler 传递给 RegisterFunction 方法并为每个 Click 事件注册它:

A "function pointer" is represented by a delegate type in C#. The Click event expects an delegate of type EventHandler. So you can simply pass an EventHandler to the RegisterFunction method and register it for each Click event:

public void RegisterFunction(EventHandler func)
{
    foreach (Control c in Controls)
    {
         c.Click += func;
    }
}

用法:

public MyPanel()
{
    for (int i = 0; i < 20; i++)
    {
        Controls.Add(new PictureBox());
    }

    RegisterFunction(MyHandler);
}

请注意，这会将 EventHandler 委托添加到 每个 控件，而不仅仅是 PictureBox 控件(如果有其他控件).更好的方法可能是在创建 PictureBox 控件时添加事件处理程序:

Note that this adds the EventHandler delegate to every control, not just the PictureBox controls (if there are any other). A better way is probably to add the event handlers the time when you create the PictureBox controls:

public MyPanel()
{
    for (int i = 0; i < 20; i++)
    {
        PictureBox p = new PictureBox();
        p.Click += MyHandler;
        Controls.Add(p);
    }
}

EventHandler 委托指向的方法如下所示:

The method that the EventHandler delegate points to, looks like this:

private void MyHandler(object sender, EventArgs e)
{
    // this is called when one of the PictureBox controls is clicked
}

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