OnEnter Method
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Control.OnEnter Method (EventArgs)

 

Raises the Enter event.

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

protected virtual void OnEnter(
	EventArgs e
)

Parameters

e
Type: System.EventArgs

An EventArgs that contains the event data.

Raising an event invokes the event handler through a delegate. For more information, see Handling and Raising Events.

The OnEnter method also allows derived classes to handle the event without attaching a delegate. This is the preferred technique for handling the event in a derived class.

Notes to Inheritors:

When overriding OnEnter in a derived class, be sure to call the base class's OnEnter method so that registered delegates receive the event.

The following code example uses the Enter event to change the foreground and background colors of a TextBox under particular conditions.

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);
    }
}

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);
}

.NET Framework
Available since 1.1
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