Silverlight DataStateBehavior,未使用初始值

Silverlight DataStateBehavior,未使用初始值,silverlight,triggers,behavior,vsm,Silverlight,Triggers,Behavior,Vsm,我尝试使用Silverlight DataStateBehavior,它在大多数情况下都可以正常工作,我单击一个按钮,将视图模型中的“Selected”属性设置为false或true。DataStateBehavior然后告诉VisualStateManager转到相关状态 像这样: <Button...> <i:Interaction.Behaviors> <id:DataStateBehavior Binding="{Bin

我尝试使用Silverlight DataStateBehavior,它在大多数情况下都可以正常工作,我单击一个按钮,将视图模型中的“Selected”属性设置为false或true。DataStateBehavior然后告诉VisualStateManager转到相关状态

像这样:

   <Button...>
   <i:Interaction.Behaviors>
             <id:DataStateBehavior Binding="{Binding Selected}" Value="True" TrueState="SelectedVisualState" FalseState="DeselectedVisualState"/>
          </i:Interaction.Behaviors>
   </Button>

以上方法很好。不过,我要做的是让它在应用程序加载时设置正确的状态,如果我在默认情况下将视图模型上的“Selected”属性设置为true,则在单击按钮更改viewmodel属性之前,我不会在UI中看到任何更改

我知道有几个类涉及DataState内容,包括:

  • BindingListener.cs
  • ConverterHelper.cs
  • DataStateBehavior.cs
  • DataStateSwitchBehavior.cs
  • DataTrigger.cs
任何线索都是好的,
谢谢

我解决这个问题的一个方法是,在加载控件时,创建一个可以添加到控件中的行为,使其进入初始视觉状态。下面是一个简单的例子:

public class InitialVisualStateBehavior : Behavior<Control>
{
    public static readonly DependencyProperty InitialStateProperty = DependencyProperty.Register(
        "InitialState",
        typeof(string),
        typeof(InitialVisualStateBehavior),
        null);

    public string InitialState
    {
        get { return (string)GetValue(InitialStateProperty); }
        set { SetValue(InitialStateProperty, value); }
    }

    protected override void OnAttached()
    {
        base.OnAttached();

        if (this.AssociatedObject != null)
        {
            this.AssociatedObject.Loaded += new RoutedEventHandler(AssociatedObject_Loaded);
        }
    }

    protected override void OnDetaching()
    {
        base.OnDetaching();

        if (this.AssociatedObject != null)
        {
            this.AssociatedObject.Loaded -= AssociatedObject_Loaded;
        }
    }

    private void AssociatedObject_Loaded(object sender, RoutedEventArgs e)
    {
        VisualStateManager.GoToState(this.AssociatedObject, this.InitialState, false);
    }
}
公共类InitialVisualStateBehavior:行为
{
公共静态只读DependencyProperty InitialStateProperty=DependencyProperty.Register(
“初始状态”,
类型(字符串),
类型(初始行为),
无效);
公共字符串初始状态
{
get{return(string)GetValue(InitialStateProperty);}
set{SetValue(InitialStateProperty,value);}
}
受保护的覆盖无效附加()
{
base.onatached();
if(this.AssociatedObject!=null)
{
this.AssociatedObject.Loaded+=新路由EventHandler(AssociatedObject\u Loaded);
}
}
附加时受保护的覆盖无效()
{
base.OnDetaching();
if(this.AssociatedObject!=null)
{
this.AssociatedObject.Loaded-=AssociatedObject\u Loaded;
}
}
已加载关联对象的私有无效(对象发送方,路由目标)
{
VisualStateManager.goState(this.AssociatedObject,this.InitialState,false);
}
}
然后,只需将该行为添加到XAML中的UserControl级别:

<i:Interaction.Behaviors>
    <myi:InitialVisualStateBehavior InitialState="SelectedVisualState" />
</i:Interaction.Behaviors>

您还可以轻松地修改它,以接受以逗号分隔的初始状态列表,如果需要在加载后将控件置于一组不同的互斥状态,则可以拆分并循环该列表


这也可能会被重构成一个触发动作,您可以直接触发控件的已加载事件,我不确定哪种方式会更干净。

我解决这个问题的一种方法是,在加载时向控件添加一个行为,使其进入初始可视状态。下面是一个简单的例子:

public class InitialVisualStateBehavior : Behavior<Control>
{
    public static readonly DependencyProperty InitialStateProperty = DependencyProperty.Register(
        "InitialState",
        typeof(string),
        typeof(InitialVisualStateBehavior),
        null);

    public string InitialState
    {
        get { return (string)GetValue(InitialStateProperty); }
        set { SetValue(InitialStateProperty, value); }
    }

    protected override void OnAttached()
    {
        base.OnAttached();

        if (this.AssociatedObject != null)
        {
            this.AssociatedObject.Loaded += new RoutedEventHandler(AssociatedObject_Loaded);
        }
    }

    protected override void OnDetaching()
    {
        base.OnDetaching();

        if (this.AssociatedObject != null)
        {
            this.AssociatedObject.Loaded -= AssociatedObject_Loaded;
        }
    }

    private void AssociatedObject_Loaded(object sender, RoutedEventArgs e)
    {
        VisualStateManager.GoToState(this.AssociatedObject, this.InitialState, false);
    }
}
公共类InitialVisualStateBehavior:行为
{
公共静态只读DependencyProperty InitialStateProperty=DependencyProperty.Register(
“初始状态”,
类型(字符串),
类型(初始行为),
无效);
公共字符串初始状态
{
get{return(string)GetValue(InitialStateProperty);}
set{SetValue(InitialStateProperty,value);}
}
受保护的覆盖无效附加()
{
base.onatached();
if(this.AssociatedObject!=null)
{
this.AssociatedObject.Loaded+=新路由EventHandler(AssociatedObject\u Loaded);
}
}
附加时受保护的覆盖无效()
{
base.OnDetaching();
if(this.AssociatedObject!=null)
{
this.AssociatedObject.Loaded-=AssociatedObject\u Loaded;
}
}
已加载关联对象的私有无效(对象发送方,路由目标)
{
VisualStateManager.goState(this.AssociatedObject,this.InitialState,false);
}
}
然后,只需将该行为添加到XAML中的UserControl级别:

<i:Interaction.Behaviors>
    <myi:InitialVisualStateBehavior InitialState="SelectedVisualState" />
</i:Interaction.Behaviors>

您还可以轻松地修改它,以接受以逗号分隔的初始状态列表,如果需要在加载后将控件置于一组不同的互斥状态,则可以拆分并循环该列表


这也可能被重构成一个触发器操作,您可以直接触发控件的已加载事件,我不确定哪种方式更干净。

我实际上要添加第二个答案,我刚刚尝试过,看起来更干净,因为它可以全部在XAML中完成,而无需自定义行为。我将留下另一个答案作为替代解决方案的参考,因为它们都有效

<i:Interaction.Triggers>
    <i:EventTrigger EventName="Loaded">
        <ic:GoToStateAction StateName="SelectedVisualState"/>
    </i:EventTrigger>
</i:Interaction.Triggers>

实际上,我将添加第二个答案,我刚刚尝试过,而且看起来更简洁,因为它可以在XAML中完成,而无需自定义行为。我将留下另一个答案作为替代解决方案的参考,因为它们都有效

<i:Interaction.Triggers>
    <i:EventTrigger EventName="Loaded">
        <ic:GoToStateAction StateName="SelectedVisualState"/>
    </i:EventTrigger>
</i:Interaction.Triggers>

尝试DataStateBehavior类的此扩展。当加载目标元素时,DataStateBehavior将被评估为属性已更新

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;

namespace Gusdor.Wpf
{
    /// <summary>
    /// Fix for data state behavior. Behavior will trigger transitions when target element loads.
    /// </summary>
    class DataStateBehaviorFix: Microsoft.Expression.Interactivity.Core.DataStateBehavior
    {
        public bool UseTransitionsOnLoad { get; set; }

        protected override void OnAttached()
        {
            base.OnAttached();

            AssociatedObject.Loaded += AssociatedObject_Loaded;
        }

        protected override void OnDetaching()
        {
            base.OnDetaching();

            AssociatedObject.Loaded -= AssociatedObject_Loaded;
        }

        void AssociatedObject_Loaded(object sender, System.Windows.RoutedEventArgs e)
        {
            Evaluate();
        }

        void Evaluate()
        {
            if (Value == null)
            {
                GotoState(Binding == null, this.AssociatedObject);
            }
            else GotoState(Value.Equals(Binding), this.AssociatedObject);
        }

        /// <summary>
        /// Attempts to change to the named state. Walks up tree to first match.
        /// </summary>
        /// <param name="flag"></param>
        /// <param name="element"></param>
        void GotoState(bool flag, FrameworkElement element)
        {          
            string stateName = flag ? TrueState : FalseState;

            if (HasState(element, stateName))
            {
                bool ret = System.Windows.VisualStateManager.GoToElementState(element, stateName, UseTransitionsOnLoad);
            }
            else if (element.Parent as FrameworkElement != null)
                GotoState(flag, element.Parent as FrameworkElement);
        }
        /// <summary>
        /// Checks if an element has the state named
        /// </summary>
        /// <param name="element"></param>
        /// <param name="stateName"></param>
        /// <returns></returns>
        bool HasState(FrameworkElement element, string stateName)
        {
            var groups = Microsoft.Expression.Interactivity.VisualStateUtilities.GetVisualStateGroups(element).Cast<VisualStateGroup>();

            return groups.Any(p => p.States.Cast<VisualState>().Any(s => s.Name == stateName));
        }
    }
}
使用系统;
使用System.Collections.Generic;
使用System.Linq;
使用系统文本;
使用System.Windows;
名称空间Gusdor.Wpf
{
/// 
///修复数据状态行为。当目标元素加载时,该行为将触发转换。
/// 
类DataStateBehaviorFix:Microsoft.Expression.Interactivity.Core.DataStateBehavior
{
public bool UseTransitionsOnLoad{get;set;}
受保护的覆盖无效附加()
{
base.onatached();
AssociatedObject.Loaded+=AssociatedObject\u Loaded;
}
附加时受保护的覆盖无效()
{
base.OnDetaching();
AssociatedObject.Loaded-=AssociatedObject\u Loaded;
}
已加载无效关联对象(对象发送方,System.Windows.RoutedEventArgs e)
{
评估();
}
void Evaluate()