using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;

namespace Events_Interfaces
{
public delegate void dele();//声明代表 delegate 关键字通知编译器 dele 是一个委托类型
public interface IEvents //定义接口IEvents，包含方法FireEvent事件event1
{
event dele event1;
void FireEvent();
}
public class Form1 : System.Windows.Forms.Form
{
private System.Windows.Forms.Label label1;
private System.Windows.Forms.TextBox textBox1;
private System.Windows.Forms.Label label2;
private System.Windows.Forms.Button button1;
private System.Windows.Forms.Label label3;

private System.ComponentModel.Container components =null;

public Form1()
{
InitializeComponent();
}

protected override void Dispose( bool disposing )
{
if( disposing )
{
if (components != null)
{
components.Dispose();
}
}
base.Dispose( disposing );
}

#region Windows Form Designer generated code

private void InitializeComponent()
{
this.textBox1 = new System.Windows.Forms.TextBox();
this.label1 = new System.Windows.Forms.Label();
this.button1 = new System.Windows.Forms.Button();
this.label2 = new System.Windows.Forms.Label();
this.label3 = new System.Windows.Forms.Label();
this.SuspendLayout();

this.textBox1.Location = new System.Drawing.Point(8, 80);
this.textBox1.Name = "textBox1";
this.textBox1.Size = new System.Drawing.Size(56,23);
this.textBox1.TabIndex = 1;
this.textBox1.Text = "";
this.textBox1.KeyDown += new System.Windows.Forms.KeyEventHandler(this.Key_Press);

this.label1.Location = new System.Drawing.Point(16, 16);
this.label1.Name = "label1";
this.label1.Size = new System.Drawing.Size(256,64);
this.label1.TabIndex = 0;
this.label1.Text = "Whenever you use the arrow keys inside the text box, Corresponding events will be" +"fired to display the label appropriately. Have a try!!";

this.button1.Location = new System.Drawing.Point(240, 112);
this.button1.Name = "button1";
this.button1.Size = new System.Drawing.Size(48,23);
this.button1.TabIndex = 3;
this.button1.Text = "Exit";
this.button1.Click += new System.EventHandler(this.button1_Click);
//
// label2
//
this.label2.Location = new System.Drawing.Point(88, 80);
this.label2.Name = "label2";
this.label2.Size = new System.Drawing.Size(184,23);
this.label2.TabIndex = 2;
this.label2.TextAlign =System.Drawing.ContentAlignment.MiddleCenter;
//
// label3
//
this.label3.Location = new System.Drawing.Point(8, 104);
this.label3.Name = "label3";
this.label3.Size = new System.Drawing.Size(64,23);
this.label3.TabIndex = 4;
this.label3.TextAlign =System.Drawing.ContentAlignment.MiddleCenter;
//
// Form1
//
this.AutoScaleBaseSize = new System.Drawing.Size(6, 16);
this.ClientSize = new System.Drawing.Size(292,141);
this.Controls.AddRange(new System.Windows.Forms.Control[] {this.label3,this.button1,this.label2,this.textBox1,this.label1});

this.Font= new System.Drawing.Font("Comic SansMS",8.25F,System.Drawing.FontStyle.Regular,
System.Drawing.GraphicsUnit.Point,((System.Byte)(0)));
this.Name = "Form1";
this.Text = "Events";
this.ResumeLayout(false);
}
#endregion

static void Main()
{
Application.Run(new Form1());
}

private void Key_Press(object sender,
System.Windows.Forms.KeyEventArgs e)
{
textBox1.Text = "";
label2.Text = "";
string keyId = e.KeyCode.ToString();
switch (keyId)//判断是否按下方向键
{
case "Right":
label3.Text = "";
IEvents id1 = new EventClass1(); //实例化一个接口
id1.event1 += new dele(EventFired1);//定义EventClass1中的事件响应方法
id1.FireEvent();//调用EventClass1中的FireEvent方法，触发event1 事件，事件调用EventFired1方法
break;
case "Left":
label3.Text = "";
IEvents id2 = new EventClass2();
id2.event1 += new
dele(EventFired2);
id2.FireEvent();
break;
case "Down":
label3.Text = "";
IEvents id3 = new EventClass3();
id3.event1 += new
dele(EventFired3);
id3.FireEvent();
break;
case "Up":
label3.Text = "";
IEvents id4 = new EventClass4();
id4.event1 += new
dele(EventFired4);
id4.FireEvent();
break;
default:
label3.Text = keyId;
break;
}
}
//EventFired1方法
public void EventFired1()
{
label2.Text = "";
label2.Text = "You pressed RIGHT arrow key";
}
public void EventFired2()
{
label2.Text = "";
label2.Text = "You pressed LEFT arrow key";
}
public void EventFired3()
{
label2.Text = "";
label2.Text = "You pressed DOWN arrow key";
}
public void EventFired4()
{
label2.Text = "";
label2.Text = "You pressed UP arrow key";
}

private void button1_Click(object sender,
System.EventArgs e)
{
Application.Exit();
}
}
public class EventClass1 : IEvents
{
public event dele event1;
public void FireEvent()
{
event1();
}
}
public class EventClass2 : IEvents
{
public event dele event1;
public void FireEvent()
{
event1();
}
}
public class EventClass3 : IEvents
{
public event dele event1;
public void FireEvent()
{
event1();
}
}
public class EventClass4 : IEvents//EventClass1继承接口IEvents
{
public event dele event1;//定义事件成员event1
//当事件发生时
public void FireEvent()
{
event1();//调用事件处理
}
}

}