Control.Leave 事件

定義

命名空間:

System.Windows.Forms

組件:

System.Windows.Forms.dll

來源:

Control.cs

當輸入焦點離開控制器時會發生。

public:
 event EventHandler ^ Leave;

public event EventHandler? Leave;

member this.Leave : EventHandler 

Public Custom Event Leave As EventHandler 

事件類型

EventHandler

範例

以下程式碼範例利用事件 Leave 將控制項重置至先前狀態。

private:
   void textBox1_Enter( Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      // If the TextBox contains text, change its foreground and background colors.
      if ( textBox1->Text != String::Empty )
      {
         textBox1->ForeColor = Color::Red;
         textBox1->BackColor = Color::Black;

         // Move the selection pointer to the end of the text of the control.
         textBox1->Select(textBox1->Text->Length,0);
      }
   }

   void textBox1_Leave( Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      // Reset the colors and selection of the TextBox after focus is lost.
      textBox1->ForeColor = Color::Black;
      textBox1->BackColor = Color::White;
      textBox1->Select(0,0);
   }

private void textBox1_Enter(object sender, System.EventArgs e)
{
    // If the TextBox contains text, change its foreground and background colors.
    if (!string.IsNullOrEmpty(textBox1.Text))
    {
        textBox1.ForeColor = Color.Red;
        textBox1.BackColor = Color.Black;
        // Move the selection pointer to the end of the text of the control.
        textBox1.Select(textBox1.Text.Length, 0);
    }
}

private void textBox1_Leave(object sender, System.EventArgs e)
{
    // Reset the colors and selection of the TextBox after focus is lost.
    textBox1.ForeColor = Color.Black;
    textBox1.BackColor = Color.White;
    textBox1.Select(0,0);
}

    Private Sub textBox1_Enter(sender As Object, e As System.EventArgs) Handles textBox1.Enter
        ' If the TextBox contains text, change its foreground and background colors.
        If textBox1.Text <> [String].Empty Then
            textBox1.ForeColor = Color.Red
            textBox1.BackColor = Color.Black
            ' Move the selection pointer to the end of the text of the control.
            textBox1.Select(textBox1.Text.Length, 0)
        End If
    End Sub
   
   
    Private Sub textBox1_Leave(sender As Object, e As System.EventArgs) Handles textBox1.Leave
        ' Reset the colors and selection of the TextBox after focus is lost.
        textBox1.ForeColor = Color.Black
        textBox1.BackColor = Color.White
        textBox1.Select(0, 0)
    End Sub
End Class

備註

當你用鍵盤（TAB、SHIFT+TAB 等）、呼叫 Select or SelectNextControl 方法，或將屬性設 ContainerControl.ActiveControl 為當前形式來更改焦點時，焦點事件會依以下順序發生：

1. Enter

2. GotFocus

3. Leave

4. Validating

5. Validated

6. LostFocus

當你用滑鼠或呼叫 Focus 方法改變焦點時，焦點事件會依以下順序發生：

1. Enter

2. GotFocus

3. LostFocus

4. Leave

5. Validating

6. Validated

若 CausesValidation 屬性設為 false，則 Validating 與 Validated 事件會被抑制。

備註

Enter該Leave事件被班級壓Form制。 該類別中 Form 對應的事件是 和 ActivatedDeactivate 事件。 Enter和Leave事件是階層式的，會在母鏈上上下層遞減，直到達到適當的控制。 舉例來說，假設你有一個 Form 有兩個 GroupBox 控制點，每個 GroupBox 控制點都有一個 TextBox 控制點。 當插入點從一個TextBox移到另一個時，Leave事件會被提升到TextBoxEnterGroupBox另一個和，事件也會被提升到另一個GroupBoxTextBox和。

謹慎

不要試圖從 、 GotFocus、 Leave、 LostFocusValidatingValidated 、 或事件處理者中Enter來設定焦點。 這樣做可能會導致你的應用程式或作業系統停止回應。 欲了解更多資訊，請參閱 WM_KILLFOCUS 主題。

如需處理事件的詳細資訊，請參閱 處理和引發事件。

另請參閱

• OnLeave(EventArgs)
• Enter