ListView.AfterLabelEdit 事件

定义

命名空间:

System.Windows.Forms

程序集:

System.Windows.Forms.dll

当用户编辑项的标签时发生。

public:
 event System::Windows::Forms::LabelEditEventHandler ^ AfterLabelEdit;

public event System.Windows.Forms.LabelEditEventHandler? AfterLabelEdit;

member this.AfterLabelEdit : System.Windows.Forms.LabelEditEventHandler 

Public Custom Event AfterLabelEdit As LabelEditEventHandler 

事件类型

LabelEditEventHandler

示例

下面的代码示例演示如何使用 AfterLabelEdit 事件将新编辑的标签限制为字母表中的字符。 该示例使用 ASCIIEncoding 类获取新标签的每个字符的 ASCII 字符代码。 如果字符位于表示数字的 ASCII 代码之间，则新标签无法应用于该项。 此示例要求你在窗体上创建了一个 ListView 控件，并为其添加了项。 此示例还要求已将 AfterLabelEdit 事件连接到示例代码中定义的事件处理程序。 若要使用 ASCIIEncoding 类，文件必须包含 System.Text 命名空间。

private:
   void MyListView_AfterLabelEdit( Object^ /*sender*/, System::Windows::Forms::LabelEditEventArgs^ e )
   {
      // Determine if label is changed by checking for 0.
      if ( e->Label == nullptr )
               return;

      // ASCIIEncoding is used to determine if a number character has been entered.
      ASCIIEncoding^ AE = gcnew ASCIIEncoding;

      // Convert the new label to a character array.
      array<Char>^temp = e->Label->ToCharArray();

      // Check each character in the new label to determine if it is a number.
      for ( int x = 0; x < temp->Length; x++ )
      {
         // Encode the character from the character array to its ASCII code.
         array<Byte>^bc = AE->GetBytes( temp[ x ].ToString() );

         // Determine if the ASCII code is within the valid range of numerical values.
         if ( bc[ 0 ] > 47 && bc[ 0 ] < 58 )
         {
            // Cancel the event and return the lable to its original state.
            e->CancelEdit = true;

            // Display a MessageBox alerting the user that numbers are not allowed.
            MessageBox::Show( "The text for the item cannot contain numerical values." );

            // Break out of the loop and exit.
            return;
         }
      }
   }

private void MyListView_AfterLabelEdit(object sender, System.Windows.Forms.LabelEditEventArgs e)
{
 
   // Determine if label is changed by checking for null.
   if (e.Label == null)
      return;

   // ASCIIEncoding is used to determine if a number character has been entered.
   ASCIIEncoding AE = new ASCIIEncoding();
   // Convert the new label to a character array.
   char[] temp = e.Label.ToCharArray();

   // Check each character in the new label to determine if it is a number.
   for(int x=0; x < temp.Length; x++)
   {
      // Encode the character from the character array to its ASCII code.
      byte[] bc = AE.GetBytes(temp[x].ToString());
   
      // Determine if the ASCII code is within the valid range of numerical values.
      if(bc[0] > 47 && bc[0] < 58)
      {
         // Cancel the event and return the lable to its original state.
         e.CancelEdit = true;
         // Display a MessageBox alerting the user that numbers are not allowed.
         MessageBox.Show ("The text for the item cannot contain numerical values.");
         // Break out of the loop and exit.
         return;
      }
   }
}

Private Sub MyListView_AfterLabelEdit(ByVal sender As Object, ByVal e As System.Windows.Forms.LabelEditEventArgs) Handles listView1.AfterLabelEdit

   ' Determine if label is changed by checking to see if it is equal to Nothing.
   If e.Label Is Nothing Then
      Return
   End If
   ' ASCIIEncoding is used to determine if a number character has been entered.
   Dim AE As New ASCIIEncoding()
   ' Convert the new label to a character array.
   Dim temp As Char() = e.Label.ToCharArray()

   ' Check each character in the new label to determine if it is a number.
   Dim x As Integer
   For x = 0 To temp.Length - 1
      ' Encode the character from the character array to its ASCII code.
      Dim bc As Byte() = AE.GetBytes(temp(x).ToString())

      ' Determine if the ASCII code is within the valid range of numerical values.
      If bc(0) > 47 And bc(0) < 58 Then
         ' Cancel the event and return the lable to its original state.
         e.CancelEdit = True
         ' Display a MessageBox alerting the user that numbers are not allowed.
         MessageBox.Show("The text for the item cannot contain numerical values.")
         ' Break out of the loop and exit.
         Return
      End If
   Next x
End Sub

注解

AfterLabelEdit当用户修改完项的文本时，将发生 该事件。 用户为项键入的新字符串将传递给 事件，事件处理程序可以拒绝更改。 如果事件处理程序拒绝更改，则文本将恢复为用户开始编辑项之前的文本。

注意

由于事件 ListView.AfterLabelEdit 发生在提交标签编辑之前，因此在此事件的处理程序中调用 ListView.Sort 方法将使用原始值对项进行排序。

若要 AfterLabelEdit 引发 事件， LabelEdit 必须将 控件的 ListView 属性设置为 true。

可以为事件创建事件处理程序， BeforeLabelEdit 以便在用户编辑项的文本之前执行任务。

有关处理事件的详细信息，请参阅 处理和引发事件。

另请参阅

• OnAfterLabelEdit(LabelEditEventArgs)
• BeforeLabelEdit
• LabelEditEventHandler
• LabelEdit