Silverlight DataStateBehavior,初始价值不用
-
22-09-2019 - |
题
我正尝试使用控DataStateBehavior,它的工作现在大多数情况下,我按一下按钮这套说'选择财产的视图模型,无论是虚假的或正确的。该DataStateBehavior然后告诉VisualStateManager去相关国家。
是这样的:
<Button...>
<i:Interaction.Behaviors>
<id:DataStateBehavior Binding="{Binding Selected}" Value="True" TrueState="SelectedVisualState" FalseState="DeselectedVisualState"/>
</i:Interaction.Behaviors>
</Button>
上述工作的罚款。我想要做的不过是把它设置的正确状态,当应用程序负荷,如果我设定的'选择财产上的视图模型的真正的默认情况下我不会看到任何改变UI直到我点击按钮改变模型的财产。
我知道有几种类参与DataState的东西,其中包括:
- BindingListener.cs
- ConverterHelper.cs
- DataStateBehavior.cs
- DataStateSwitchBehavior.cs
- DataTrigger.cs
任何线索就是良好的, 感谢
解决方案
我实际上要增加一个第二次答案,我只是尝试,似乎是清洁的,因为它可以做到的所有反馈,而不一定义的行为。我会把其他的答案只是作为参考,用于替代解决方案,因为他们两个的工作。
<i:Interaction.Triggers>
<i:EventTrigger EventName="Loaded">
<ic:GoToStateAction StateName="SelectedVisualState"/>
</i:EventTrigger>
</i:Interaction.Triggers>
你会需要的只是在增加一个参考Microsoft。表达。相互作用的组件,一部分混合SDK。
xmlns:ic="clr-namespace:Microsoft.Expression.Interactivity.Core;assembly=Microsoft.Expression.Interactions"
其他提示
试试这个扩展的DataStateBehavior类。当目标件载荷,DataStateBehavior将评估,如果该财产已被更新。
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));
}
}
}
一个我已经解决了这个问题是使一个行为可以添加到控制,把它变成一个初始些国家在加载。这是一个简单的例子:
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);
}
}
你将只是添加这种行为的用户控件-水平键
<i:Interaction.Behaviors>
<myi:InitialVisualStateBehavior InitialState="SelectedVisualState" />
</i:Interaction.Behaviors>
你也可以很容易地修改这种接受一个逗号分隔的列表的初步的国家然后可以分和循环过如果你需要把控制在一堆不同的相互排斥的国家后装载。
这也可能重构成TriggerAction,你可能只是引发的事件加载的控制,我不确定哪种方式,将吸尘器。
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