如何根据DataContext属性获取更改TextBlock颜色的触发器？

Question

为什么以下代码会出现运行时错误:

Triggers集合的成员必须是EventTrigger类型

但EventTrigger元素没有Binding属性.

那么如何根据DataContext属性更改TextBlock的颜色？

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>

码:

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

        public string Status { get; set; }    
    }
}

Answer 1

那是因为您只能直接在Trigger属性上设置事件触发器.

使用样式来实现您想要的效果:

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

以下对象具有可包含列出的触发器类型的触发器集合:

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

Answer 2

你可以用一种风格来做:

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