[英]Wpf styles and attached properties
我一直在玩行为,我遇到了一个有趣的问题。 这是我的行为:
public class AddNewBehavior : BaseBehavior<RadGridView, AddNewBehavior>
{
public static readonly DependencyProperty IsEnabledProperty = DependencyProperty.RegisterAttached("IsEnabled", typeof(bool), typeof(AddNewBehavior), new FrameworkPropertyMetadata(false, OnIsEnabledChanged));
public static void SetIsEnabled(DependencyObject obj, bool isEnabled)
{
obj.SetValue(IsEnabledProperty, isEnabled);
}
public static bool GetIsEnabled(DependencyObject obj)
{
return (bool)obj.GetValue(IsEnabledProperty);
} ... OnIsEnabledChanged(...)}
当我设置这样的样式时,这将很有用:
<Style TargetType="telerikGridView:RadGridView">
<Setter Property="Behaviors:AddNewBehavior.IsEnabled" Value="true" />
</Style>
但是,如果我把它放在抽象类中
public abstract class BaseBehavior<TObj, TBehavior> : Behavior<TObj>
where TObj : DependencyObject
where TBehavior : BaseBehavior<TObj, TBehavior>, new()
{
public static readonly DependencyProperty IsEnabledProperty = DependencyProperty.RegisterAttached("IsEnabled", typeof(bool), typeof(TBehavior), new FrameworkPropertyMetadata(false, OnIsEnabledChanged));
public static void SetIsEnabled(DependencyObject obj, bool isEnabled)
{
obj.SetValue(IsEnabledProperty, isEnabled);
}
public static bool GetIsEnabled(DependencyObject obj)
{
return (bool)obj.GetValue(IsEnabledProperty);
}
public static void OnIsEnabledChanged(DependencyObject dpo, DependencyPropertyChangedEventArgs e)
{
BehaviorCollection behaviorCollection = Interaction.GetBehaviors(dpo);
if ((bool)e.NewValue)
{
var firstOrDefault = behaviorCollection.Where(b => b.GetType() == typeof(TBehavior)).FirstOrDefault();
if (firstOrDefault == null)
{
behaviorCollection.Add(new TBehavior());
}
}
}
}
样式声明将粉碎为“值不能为空。属性名称:属性”。
不知道我做错了什么,在基类中使用IsEnabled代码会很棒。
谢谢,
在基类的IsEnabledProperty定义中,尝试将其更改为:
public static readonly DependencyProperty IsEnabledProperty =
DependencyProperty.RegisterAttached(
"IsEnabled",
typeof(bool),
typeof(BaseBehavior<TObj, TBehavior>),
new FrameworkPropertyMetadata(false, OnIsEnabledChanged)
);
也就是说,不是将TBehavior
作为DP OwnerType传递, BaseBehavior<TObj, TBehavior>
传入BaseBehavior<TObj, TBehavior>
。
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