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Control.BackgroundImageChanged-Ereignis

 

Veröffentlicht: Oktober 2016

Tritt auf, wenn sich der Wert der BackgroundImage-Eigenschaft ändert.

Namespace:   System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)

public event EventHandler BackgroundImageChanged

This event is raised if the P:System.Windows.Forms.Control.BackgroundImage property is changed by either a programmatic modification or user interaction.

For more information about handling events, see Handling and Raising Events.

The following code example is an event handler that is executed when the P:System.Windows.Forms.Control.Text property value changes. The T:System.Windows.Forms.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).

The following code example changes the P:System.Windows.Forms.Control.ForeColor of a T:System.Windows.Forms.TextBox displaying currency data. The example converts the text to a decimal number and changes the P:System.Windows.Forms.Control.ForeColor to P:System.Drawing.Color.Red if the number is negative and to P:System.Drawing.Color.Black if the number is positive. This example requires that you have a T:System.Windows.Forms.Form that contains a T:System.Windows.Forms.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
   {
      // If there is an error, display the text using the system colors.
      currencyTextBox.ForeColor = SystemColors.ControlText;
   }
}

.NET Framework
Verfügbar seit 1.1
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