我怎样才能得到一个触发器来改变基于一个DataContext属性TextBlock的颜色？ [英] How can I get a trigger to change the color of a TextBlock based on a DataContext Property?

问题描述

为什么下面的代码得到运行时错误：

触发器集合

成员必须是类型的EventTrigger的

不过的EventTrigger元素没有一个绑定属性。

那么，如何改变？基于DataContext属性TextBlock的颜色

XAML：

 <窗​​口x：类=TestTrigger123345.Window1
的xmlns =htt​​p://schemas.microsoft.com/winfx/2006/xaml/presentation
的xmlns：X =HTTP： //schemas.microsoft.com/winfx/2006/xaml
标题=窗口1HEIGHT =300WIDTH =300> 
< StackPanel中的Horizo​​ntalAlignment =左> 
< TextBlock的文本={绑定状态}> 
< TextBlock.Triggers> 
< D​​ataTrigger绑定={绑定状态}VALUE =关> 
< setter属性=TextBlock.BackgroundVALUE =红/> 
< / DataTrigger> 
< /TextBlock.Triggers> 
< / TextBlock的> 
< / StackPanel的> 
< /窗GT; 
  

代码：

 命名空间TestTriggers 
 {
公共部分类窗口1：窗口
 {
公共窗口1（）
 {
的InitializeComponent（）; 
的DataContext =这一点; 
状态=关; 
} 
 
公共字符串状态{搞定;组; } 
} 
} 
  

解决方案

那是因为你只能将事件直接触发触发属性。

使用样式来实现你想要什么：

 <风格X：键=触发器的TargetType =TextBlock的> 
< Style.Triggers> 
< D​​ataTrigger绑定={绑定状态}VALUE =关> 
< setter属性=TextBlock.BackgroundVALUE =红/> 
< / DataTrigger> 
< /Style.Triggers> 
< /样式和GT; 
  

以下对象具有可以包含触发类型列出的触发器的集合：

  FrameworkElement的样式，控件模板，DataTemplate中
 ---------------- ------- ----------------------------- 
的EventTrigger的EventTrigger 
触发或MultiTrigger 
 DataTrigger或MultiDataTrigger 
  

Why does the following code get the runtime error:

Members of the Triggers collection must be of type EventTrigger

But the EventTrigger element doesn't have a Binding property.

So how do I change the color of the TextBlock based on the DataContext Property?

XAML:

<Window x:Class="TestTrigger123345.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window1" Height="300" Width="300">
    <StackPanel HorizontalAlignment="Left">
        <TextBlock Text="{Binding Status}">
            <TextBlock.Triggers>
                <DataTrigger Binding="{Binding Status}" Value="off">
                    <Setter Property="TextBlock.Background" Value="Red"/>
                </DataTrigger>
            </TextBlock.Triggers>
        </TextBlock>
    </StackPanel>
</Window>

Code:

namespace TestTriggers
{
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();
            DataContext = this;
            Status = "off";
        }

        public string Status { get; set; }    
    }
}

解决方案

That is because you can only set event triggers directly on the Trigger property..

Use a style to achieve what you want:

<Style x:Key="Triggers" TargetType="TextBlock">
    <Style.Triggers>
        <DataTrigger Binding="{Binding Status}" Value="off">
            <Setter Property="TextBlock.Background" Value="Red"/>
        </DataTrigger>
    </Style.Triggers>
</Style>

The following objects have Triggers collections that can contain the trigger types listed:

FrameworkElement     Style, ControlTemplate, DataTemplate
----------------     ------------------------------------
EventTrigger         EventTrigger
                     Trigger or MultiTrigger
                     DataTrigger or MultiDataTrigger

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