HOW TO：決定 Freezable 是否凍結
下列範例說明如何判斷 Freezable 物件是否凍結。 如果您試著修改凍結的 Freezable 物件，它會擲回 InvalidOperationException。 為避免擲回這個例外狀況，請使用 Freezable 物件的 IsFrozen 屬性，判斷物件是否凍結。
範例
下列範例會凍結 SolidColorBrush，然後使用 IsFrozen 屬性測試它，以判斷它是否凍結。
Dim myButton As New Button()
Dim myBrush As New SolidColorBrush(Colors.Yellow)
If myBrush.CanFreeze Then
' Makes the brush unmodifiable.
myBrush.Freeze()
End If
myButton.Background = myBrush
If myBrush.IsFrozen Then ' Evaluates to true.
' If the brush is frozen, create a clone and
' modify the clone.
Dim myBrushClone As SolidColorBrush = myBrush.Clone()
myBrushClone.Color = Colors.Red
myButton.Background = myBrushClone
Else
' If the brush is not frozen,
' it can be modified directly.
myBrush.Color = Colors.Red
End If
Button myButton = new Button();
SolidColorBrush myBrush = new SolidColorBrush(Colors.Yellow);
if (myBrush.CanFreeze)
{
// Makes the brush unmodifiable.
myBrush.Freeze();
}
myButton.Background = myBrush;
if (myBrush.IsFrozen) // Evaluates to true.
{
// If the brush is frozen, create a clone and
// modify the clone.
SolidColorBrush myBrushClone = myBrush.Clone();
myBrushClone.Color = Colors.Red;
myButton.Background = myBrushClone;
}
else
{
// If the brush is not frozen,
// it can be modified directly.
myBrush.Color = Colors.Red;
}
如需 Freezable 物件的詳細資訊，請參閱 Freezable 物件概觀。