获取或设置附加属性的访问器在数据绑定时未触发? WPF
我有一个自定义附加属性,但从未在数据绑定上访问访问器。 这些访问器是否意味着每次附加属性更改时都会被访问?
public static readonly DependencyProperty CharacterColumnNumberProperty =
DependencyProperty.RegisterAttached("CharacterColumnNumber", typeof(int), typeof(DragCanvas), new UIPropertyMetadata(1));
public static int GetCharacterColumnNumber(UIElement uiElement)
{
if (uiElement != null)
return (int)uiElement.GetValue(CharacterColumnNumberProperty);
else return 0;
}
public static void SetCharacterColumnNumber(UIElement uiElement, int value)
{
if (uiElement != null)
{
uiElement.SetValue(CharacterColumnNumberProperty, value);
DragCanvas.SetLeft(uiElement, value * 10);
}
}
XAML:
<Setter Property="local:DragCanvas.CharacterColumnNumber" Value="{Binding Path=CharacterColumnNumber, Mode=TwoWay}" />
I have a custom Attached Property but the Accessors on never being accessed on databinding.
Are theses accessors meant to be accessed everytime the attached property changes?
public static readonly DependencyProperty CharacterColumnNumberProperty =
DependencyProperty.RegisterAttached("CharacterColumnNumber", typeof(int), typeof(DragCanvas), new UIPropertyMetadata(1));
public static int GetCharacterColumnNumber(UIElement uiElement)
{
if (uiElement != null)
return (int)uiElement.GetValue(CharacterColumnNumberProperty);
else return 0;
}
public static void SetCharacterColumnNumber(UIElement uiElement, int value)
{
if (uiElement != null)
{
uiElement.SetValue(CharacterColumnNumberProperty, value);
DragCanvas.SetLeft(uiElement, value * 10);
}
}
XAML:
<Setter Property="local:DragCanvas.CharacterColumnNumber" Value="{Binding Path=CharacterColumnNumber, Mode=TwoWay}" />
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不,他们不是。如果您想知道内部属性引擎何时更改这些值,请传入 PropertyChangedCallback 参数。
每次属性更改时都会调用此委托,无论是通过 CLR 属性还是通过依赖属性引擎(即绑定)内部的更改。
No they are not. If you want to know when the internal property engine is changing these values you pass in a delegate for the PropertyChangedCallback parameter of the UIPropertyMetadata.
This delegate will be invoked each time the property is changed, whether it came through the CLR property or via changes internally in the dependency property engine (i.e. bindings).