Control.BackgroundImageChanged Control.BackgroundImageChanged Control.BackgroundImageChanged Control.BackgroundImageChanged Event

定義

發生於 BackgroundImage 屬性的值變更時。Occurs when the value of the BackgroundImage property changes.

public:
 event EventHandler ^ BackgroundImageChanged;
public event EventHandler BackgroundImageChanged;
member this.BackgroundImageChanged : EventHandler 
Public Custom Event BackgroundImageChanged As EventHandler 

範例

下列程式碼範例是當Text屬性值變更時,所執行的事件處理常式。The following code example is an event handler that is executed when the Text property value changes. Changed當對應的propertyname值變更(PropertyName代表對應屬性的名稱)時, 類別有數個名稱模式為PropertyName的方法,會Control引發。The Control class has several methods with the name pattern PropertyNameChanged that are raised when the corresponding PropertyName value changes (PropertyName represents the name of the corresponding property).

下列程式碼範例會變更ForeColor TextBox顯示貨幣資料的。The following code example changes the ForeColor of a TextBox displaying currency data. 此範例會將文字轉換成十進位數, ForeColor Color.Red如果Color.Black數位為負數,則會將變更為,如果數位是正數,則會變更為。The example converts the text to a decimal number and changes the ForeColor to Color.Red if the number is negative and to Color.Black if the number is positive. 這個範例需要您具有Form TextBox包含的。This example requires that you have a Form that contains a TextBox.

private:
   void currencyTextBox_TextChanged( Object^ /*sender*/, EventArgs^ /*e*/ )
   {
      try
      {
         // Convert the text to a Double and determine if it is a negative number.
         if ( Double::Parse( currencyTextBox->Text ) < 0 )
         {
            // If the number is negative, display it in Red.
            currencyTextBox->ForeColor = Color::Red;
         }
         else
         {
            // If the number is not negative, display it in Black.
            currencyTextBox->ForeColor = Color::Black;
         }
      }
      catch ( Exception^ ) 
      {
         // If there is an error, display the text using the system colors.
         currencyTextBox->ForeColor = SystemColors::ControlText;
      }
   }
private void currencyTextBox_TextChanged(object sender, EventArgs e)
{
   try
   {
      // Convert the text to a Double and determine if it is a negative number.
      if(double.Parse(currencyTextBox.Text) < 0)
      {
         // If the number is negative, display it in Red.
         currencyTextBox.ForeColor = Color.Red;
      }
      else
      {
         // If the number is not negative, display it in Black.
         currencyTextBox.ForeColor = Color.Black;
      }
   }
   catch
   {
      // If there is an error, display the text using the system colors.
      currencyTextBox.ForeColor = SystemColors.ControlText;
   }
}
Private Sub currencyTextBox_TextChanged(sender As Object, _ 
  e As EventArgs) Handles currencyTextBox.TextChanged
   Try
      ' Convert the text to a Double and determine if it is a negative number.
      If Double.Parse(currencyTextBox.Text) < 0 Then
         ' If the number is negative, display it in Red.
         currencyTextBox.ForeColor = Color.Red
      Else
         ' If the number is not negative, display it in Black.
         currencyTextBox.ForeColor = Color.Black
      End If
   Catch
      ' If there is an error, display the text using the system colors.
      currencyTextBox.ForeColor = SystemColors.ControlText
   End Try
End Sub 

備註

如果以程式設計方式修改BackgroundImage或使用者互動來變更屬性,就會引發這個事件。This event is raised if the BackgroundImage property is changed by either a programmatic modification or user interaction.

如需處理事件的詳細資訊, 請參閱處理和引發事件For more information about handling events, see Handling and Raising Events.

適用於

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