Control.ForeColorChanged 事件
定义
重要
一些信息与预发行产品相关，相应产品在发行之前可能会进行重大修改。 对于此处提供的信息，Microsoft 不作任何明示或暗示的担保。
在 ForeColor 属性值更改时发生。
public:
event EventHandler ^ ForeColorChanged;public event EventHandler ForeColorChanged;public event EventHandler? ForeColorChanged;member this.ForeColorChanged : EventHandler Public Custom Event ForeColorChanged As EventHandler 事件类型
示例
下面的代码示例是属性值更改时 Text 执行的事件处理程序。 当相应的 PropertyName 值更改 (PropertyName 表示相应属性的名称) 时，该Control类具有多个具有名称模式 PropertyNameChanged 的方法。
下面的代码示例更改ForeColorTextBox显示货币数据。 该示例将文本转换为十进制数，并将数字为负数和数字正数时Color.Black更改为ForeColorColor.Red。 此示例要求你有一个Form包含 .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
注解
如果 ForeColor 属性通过编程修改或通过交互更改，则会引发此事件。
有关处理事件的详细信息，请参阅 处理和引发事件。