【WPF】XAML实现按钮背景图片的点击切换

原因：要做一组搜索结果的排序按钮（类似一组RadioButton），效果像下图这样。想法是使用原生的按钮控件，将文字左对齐，整个按钮背景是一张图片，通过样式Trigger控制字体变色、背景图切换。
需求：RadioButton开关按钮，点击后切换自身按钮的背景图片。

MyRadioButton.xaml

<ResourceDictionary  x:Class="HomeDecorationPSD.Presentation.Style.MyRadioButton"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:HomeDecorationPSD.Presentation.Style"
        mc:Ignorable="d">

    <ResourceDictionary.MergedDictionaries>
        <!-- 引入颜色字符串 -->
        <ResourceDictionary Source="/Presentation/Resources/ColorResources.xaml" />
    </ResourceDictionary.MergedDictionaries>

    <Style x:Key="myRadioButton" TargetType="{x:Type RadioButton}">
        <Setter Property="BorderThickness" Value="0"></Setter>
        <Setter Property="Width" Value="80"></Setter>
        <Setter Property="Height" Value="30"></Setter>
        <Setter Property="Foreground" Value="{StaticResource LightGreyColor}"/>

        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type RadioButton}">
                    <Grid x:Name="grid" VerticalAlignment="Center">
                        <Border x:Name="border" BorderThickness="1" BorderBrush="{StaticResource LightGreyColor}" Width="{TemplateBinding Width}" Height="{TemplateBinding Height}"
                                HorizontalAlignment="Center" Background="#E9E9E9" Padding="5,0,0,0">
                            <ContentPresenter Content="{TemplateBinding Content}" VerticalAlignment="Center" HorizontalAlignment="Left" Margin="{TemplateBinding Padding}" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                        </Border>
                    </Grid>

                    <!-- 触发器：设置字体的颜色 -->
                    <ControlTemplate.Triggers>
                        <Trigger Property="IsChecked" Value="true">
                            <Setter Property="Foreground" Value="{StaticResource SoftRedColor}"/> <!-- 被引入的颜色字符串 -->
                            <Setter TargetName="border" Property="Background">
                                <Setter.Value>
                                    <ImageBrush ImageSource="/HomeDecorationPSD;component/Presentation/Resources/Images/down_arrow_selected.png" Stretch="Fill"/>
                                </Setter.Value>
                            </Setter>
                        </Trigger>
                        <Trigger Property="IsChecked" Value="false">
                            <Setter Property="Foreground" Value="{StaticResource LightGreyColor}"/>
                            <Setter TargetName="border" Property="Background"> <!-- 必须指明TargetName -->
                                <Setter.Value>
                                    <ImageBrush ImageSource="/HomeDecorationPSD;component/Presentation/Resources/Images/down_arrow.png" Stretch="Fill"/>
                                </Setter.Value>
                            </Setter>
                        </Trigger>
                    </ControlTemplate.Triggers>

                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</ResourceDictionary>

坑点：

• ControlTemplate必须使用一个Border包裹。
• 在Trigger中给按钮设置文字颜色时，使用Foreground不需要指明TargetName，但是给背景设置图片时，必须要指明TargetName，否则无效果。（非常坑爹，运行无报错，能看到文字变色，不能看到背景图）