错误:“ResourceDictionary”根元素需要 x:Class 特性来支持 XAML 文件中的事件处理程序。请移除 MouseLeftButtonDown 事件的事件处理程序.

转载于(https://social.msdn.microsoft.com/Forums/windowsapps/zh-CN/af3161ce-f020-4b0b-9b84-95ae597e53fd/resourcedictionary-xclass-xaml-mouseleftbuttondown-xclass?forum=wpfzhchs)

在资源字典中设置listboxItem的鼠标左击的事件样式。

打出这段代码提示“ResourceDictionary”根元素需要 x:Class 特性来支持 XAML 文件中的事件处理程序。请移除 MouseLeftButtonDown 事件的事件处理程序，或将 x:Class 特性添加到根元素。 ”错误，

这句话是什么意思？难道EventSetter 不能在资源字典中写？

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"                    xmlns:local="clr-namespace:WpfApplication1">    <Style x:Key="remenber" TargetType="{x:Type ListBoxItem}"  >        <Setter Property="Margin" Value="1"></Setter><EventSetter Event="MouseLeftButtonDown"  Handler="ProjectMouseLeftButtonDown"/>        <Style.Triggers>            <Trigger Property="IsMouseOver" Value="True">                <Setter Property="Background" Value="#FF569BEE"></Setter>            </Trigger>        </Style.Triggers>    </Style></ResourceDictionary>

解决思路:

1.首先，EventSetter 是可以在资源字典中写的。那句提示意思是需要在ResourceDictionary标签内加上x:Class特性。
你可以写成这样：

ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"                    xmlns:local="clr-namespace:WpfApplication1"                                        x:Class="命名空间.资源字典的名称" ></ResourceDictionary>

命名空间：以你的代码为例，此处应为”WpfApplication1”
资源字典的名称：如果资源字典文件是”Dictionary1.xaml”，这里就是”Dictionary1”
完整写法就是 x:Class=”WpfApplication1. Dictionary1”

2.下面的Demo供你参考：

Dictionary1.xaml：

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"                    xmlns:local="clr-namespace:WriteEventInResourceDictionary"                    x:Class="WriteEventInResourceDictionary.Dictionary1">    <Style  TargetType="{x:Type ListBoxItem}" BasedOn="{StaticResource {x:Type ListBoxItem}}">        <EventSetter Event="PreviewMouseLeftButtonDown" Handler="MyCustomMouseEvent"/>    </Style></ResourceDictionary>

Dictionary1.xaml.cs:

namespace WriteEventInResourceDictionary{    public partial class Dictionary1    {        private void MyCustomMouseEvent(object sender, RoutedEventArgs e)        {            MessageBox.Show("Hello");        }    }}

MainWindow.xaml:

<ListBox>                             <ListBoxItem>Item 1</ListBoxItem>                              <ListBoxItem>Item 2</ListBoxItem>                              <ListBoxItem>Item 3</ListBoxItem>                </ListBox>

App.xaml:

<Application x:Class="WriteEventInResourceDictionary.App"             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"             xmlns:local="clr-namespace:WriteEventInResourceDictionary"             StartupUri="MainWindow.xaml">    <Application.Resources>        <ResourceDictionary>            <ResourceDictionary.MergedDictionaries>                <ResourceDictionary Source="Dictionary1.xaml" />            </ResourceDictionary.MergedDictionaries>        </ResourceDictionary>    </Application.Resources></Application>