重定向事件按钮委托事件 [英] Redirect event button delegate event

问题描述

我在WinForm上有一个单独的控制器UserControl 1Panel + 2Button



我尝试了什么：

命名空间TestToolBar1 
 {
 public partial class UserControl1：UserControl 
 {
 private System.ComponentModel.Container components = null; 
 
 public UserControl1（）
 {
 InitializeComponent（）; 
} 
 
 //定义一个事件处理程序委托，它基本上重用现有的
 //签名
 public delegate void EventHandler（object sender，System.EventArgs e ）; 
 // decalre事件处理程序委托
 EventHandler EventHandlerDelegate; 
 //重新定义Click事件
新公共事件EventHandler单击
 {
 //这相当于Click + = new EventHandler（...）
添加
 {
 this.EventHandlerDelegate + = value; 
} 
 //这相当于Click  -  = new EventHandler（...）
 remove 
 {
 this.EventHandlerDelegate  -  = value; 
} 
} 
 
 //转发按钮的点击事件
 private void button_Click（object sender，System.EventArgs e）
 {
 if（this.EventHandlerDelegate！= null）
 this.EventHandlerDelegate（sender，e）; 
} 
} 
} 

和表格上的声明

命名空间TestToolBar1 
 {
 public partial class Form2：Form 
 {
 private TestToolBar1.UserControl1 userControl11; 
 private System.ComponentModel.Container components = null; 
 
 public Form2（）
 {
 InitializeComponent（）; 
 
 
 UserControl1 myctrl = new UserControl1（）; 
 myctrl.Top = 0; 
 myctrl.Left = 0; 
 myctrl.Parent = panel1; 
 myctrl.Show（）; 
} 
 .... 
 
 private void userControl_Click1（object sender，System.EventArgs e）
 {
 Control ctrl = sender as Control; 
 MessageBox.Show（message）; 
} 

问题EventHandlerDelegate总是空的而不是重定向

 private void button_Click（object sender，System.EventArgs e）
 {
 if（this.EventHandlerDelegate！= null）
 this.EventHandlerDelegate（sender，e） ; 
} 
 

解决方案

它是null，因为你没有在任何时候为它添加一个处理程序：你提供代码，你创建控件实例，但你不添加处理程序。



如果没有添加处理程序，处理程序中没有任何动作收藏！

我是这样做的：

UserControl1：

 ///< summary> 
 ///表示事情发生的事件
 ///< / summary> 
公共事件EventHandler SomethingHappened; 
 ///< summary> 
 ///被叫来向订阅者发出SomethingHappened 
 ///< / summary> 
 ///< param name =e>< / param> 
 protected virtual void OnSomethingHappened（EventArgs e）
 {
 EventHandler eh = SomethingHappened; 
 if（eh！= null）
 {
 eh（this，e）; 
} 
} 
 
 //转发按钮的点击事件
 private void button1_Click（object sender，System.EventArgs e）
 {
 EventHandler eh = SomethingHappened; 
 if（eh！= null）
 {
 eh（this，e）; 
} 
} 
 

表格：

 UserControl1 myctrl = new UserControl1 （）; 
 myctrl.Top = 0; 
 myctrl.Left = 0; 
 myctrl.Parent = panel1; 
 myctrl.SomethingHappened + = myctrl_SomethingHappened; 
 myctrl.Show（）; 
 

 void myctrl_SomethingHappened（object sender，EventArgs e）
 {
 Console.WriteLine（It happen！）; 
} 
 

如果您看一下：添加事件的简单代码片段 [ ^ ]它会自动添加事件的过程（只需键入evh并按Tab键，它就会填充空白）

I Have a separate contro UserControl 1Panel + 2Button on WinForm

What I have tried:

namespace TestToolBar1
{
    public partial class UserControl1 : UserControl
    {
        private System.ComponentModel.Container components = null;

        public UserControl1()
        {
            InitializeComponent();
        }
      
        // define an event handler delegate which basically re-uses an existing
        // signature
        public delegate void EventHandler(object sender, System.EventArgs e);
        // decalre an event handler delegate
        EventHandler EventHandlerDelegate;
        // re-define the Click event
        new public event EventHandler Click
        {
            // this is the equivalent of Click += new EventHandler(...)
            add
            {
                this.EventHandlerDelegate += value;
            }
            // this is the equivalent of Click -= new EventHandler(...)
            remove
            {
                this.EventHandlerDelegate -= value;
            }
        }

        // forward the button's click event 
        private void button_Click(object sender, System.EventArgs e)
        {
            if (this.EventHandlerDelegate != null)
                this.EventHandlerDelegate(sender, e);
        }       
    }
}

and the declaration on Form

namespace TestToolBar1
{
    public partial class Form2 : Form
    {
        private TestToolBar1.UserControl1 userControl11;
        private System.ComponentModel.Container components = null;

        public Form2()
        {
            InitializeComponent();


            UserControl1 myctrl = new UserControl1();
            myctrl.Top = 0;
            myctrl.Left = 0;
            myctrl.Parent = panel1;
            myctrl.Show();
        }
....

 private void userControl_Click1(object sender, System.EventArgs e)
        {
            Control ctrl = sender as Control;
            MessageBox.Show("message");
        }

problem EventHandlerDelegate is always Null and not redirect

private void button_Click(object sender, System.EventArgs e)
       {
           if (this.EventHandlerDelegate != null)
               this.EventHandlerDelegate(sender, e);
       }

解决方案

It's null because you haven't added a handler to it at any point: you provide the code, you create the control instance, but you don't add a handler.

And if no handler is added, there is nothing to action in the handler collection!
Here is how I'd do it:
UserControl1:

/// <summary>
/// Event to indicate SomethingHappened
/// </summary>
public event EventHandler SomethingHappened;
/// <summary>
/// Called to signal to subscribers that SomethingHappened
/// </summary>
/// <param name="e"></param>
protected virtual void OnSomethingHappened(EventArgs e)
    {
    EventHandler eh = SomethingHappened;
    if (eh != null)
        {
        eh(this, e);
        }
    }

// forward the button's click event
private void button1_Click(object sender, System.EventArgs e)
    {
    EventHandler eh = SomethingHappened;
    if (eh != null)
        {
        eh(this, e);
        }
    }

Form:

UserControl1 myctrl = new UserControl1();
myctrl.Top = 0;
myctrl.Left = 0;
myctrl.Parent = panel1;
myctrl.SomethingHappened += myctrl_SomethingHappened;
myctrl.Show();

void myctrl_SomethingHappened(object sender, EventArgs e)
    {
    Console.WriteLine("It happened!");
    }

If you have a look here: A Simple Code Snippet to Add an Event[^] it automates the process of adding an event (just type "evh" and press tab, and it fills in the blanks)

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