CancelEventArgs 类

定义

public ref class CancelEventArgs : EventArgs

public class CancelEventArgs : EventArgs

type CancelEventArgs = class
    inherit EventArgs

Public Class CancelEventArgs
Inherits EventArgs

继承

Object

EventArgs

CancelEventArgs

派生

Microsoft.VisualBasic.ApplicationServices.StartupEventArgs

System.ComponentModel.DoWorkEventArgs

System.Configuration.SettingChangingEventArgs

System.Drawing.Printing.PrintEventArgs

System.IdentityModel.Services.ErrorEventArgs

更多…

示例

以下示例使用 CancelEventArgs 和 CancelEventHandler 来处理 Closing 的 Form事件。 此代码假定你已使用名为 isDataSaved的类级Boolean变量创建了 Form 。 它还假定你已添加一个 语句，用于OtherInitialize在调用 InitializeComponent) 后从窗体的 Load 方法或构造函数 (调用方法。

private:
   // Call this method from the InitializeComponent() method of your form
   void OtherInitialize()
   {
      this->Closing += gcnew CancelEventHandler( this, &Form1::Form1_Cancel );
      this->myDataIsSaved = true;
   }

   void Form1_Cancel( Object^ /*sender*/, CancelEventArgs^ e )
   {
      if ( !myDataIsSaved )
      {
         e->Cancel = true;
         MessageBox::Show( "You must save first." );
      }
      else
      {
         e->Cancel = false;
         MessageBox::Show( "Goodbye." );
      }
   }

// Call this method from the constructor of your form
    private void OtherInitialize() {
       this.Closing += new CancelEventHandler(this.Form1_Closing);
       // Exchange commented line and note the difference.
       this.isDataSaved = true;
       //this.isDataSaved = false;
    }

    private void Form1_Closing(Object sender, CancelEventArgs e) {
       if (!isDataSaved) {
          e.Cancel = true;
          MessageBox.Show("You must save first.");
       }
       else {
          e.Cancel = false;
          MessageBox.Show("Goodbye.");
       }
    }

' Call this method from the Load method of your form.
Private Sub OtherInitialize()
    ' Exchange commented line and note the difference.
    Me.isDataSaved = True
    'Me.isDataSaved = False
End Sub

Private Sub Form1_Closing(sender As Object, e As _
   System.ComponentModel.CancelEventArgs) Handles MyBase.Closing
    If Not isDataSaved Then
        e.Cancel = True
        MessageBox.Show("You must save first.")
    Else
        e.Cancel = False
        MessageBox.Show("Goodbye.")
    End If
End Sub

注解

组件在即将执行可取消的操作（例如 Closing 的 事件）时引发可取消事件 Form。

CancelEventArgs Cancel提供 属性以指示是否应取消事件。

构造函数

属性

方法

适用于

另请参阅

• CancelEventHandler