我对WPF非常陌生，现在我一直在苦苦思索如何在鼠标离开子菜单时隐藏MenuItem的子菜单。
我尝试直接在父MenuItem上应用触发器，但这仅适用于其标头。我试图操纵MenuItem.ItemsPanel我没有取得任何成功。
我已经设法将子项包装在Menu控件中（在父MenuItem中）并在其上应用触发器，但是有不必要的副作用（比如所有菜单都突出显示而不是一个项目）。
任何帮助将不胜感激，
伊詹
<Menu .... >
<MenuItem .... > // parent MenuItem
<MenuItem .... />
<MenuItem .... />
<MenuItem .... />
<MenuItem .... />
</MenuItem>
</Menu>
答案 0 :(得分：0)
我是 XAML 的新手，这可能并不完美，但它对我有用 - 我需要相同的功能，并在经过数小时的搜索和尝试后想出了这个，这就是我想发布它的原因，因为我不能在任何地方找到答案。有用于样式和对齐的额外代码，但您可以忽略它：
仅 - Xaml 用于在鼠标离开时关闭菜单：
<!--.........Override PopUp so it can close on Mouse Leave + Style ----------------------------------->
<!--#3-Top Menu - MenuItem-->
<Style x:Key="menu_TopMenu_MenuItem_Style" TargetType="{x:Type MenuItem}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate x:Name="menuItem" TargetType="{x:Type MenuItem}">
<Border x:Name="templateRoot" BorderThickness="1" CornerRadius="1" SnapsToDevicePixels="True">
<Grid VerticalAlignment="Center">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="Auto"/>
</Grid.ColumnDefinitions>
<ContentPresenter ContentTemplate="{TemplateBinding HeaderTemplate}" Content="{TemplateBinding Header}" Grid.Column="1" ContentStringFormat="{TemplateBinding HeaderStringFormat}" ContentSource="Header" Margin="{TemplateBinding Padding}" RecognizesAccessKey="True" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
<Popup x:Name="PART_Popup" AllowsTransparency="True" Focusable="False" IsOpen="{Binding IsSubmenuOpen, RelativeSource={RelativeSource TemplatedParent}}" PopupAnimation="None" Placement="Bottom">
<Border x:Name="SubMenuBorder">
<ScrollViewer x:Name="SubMenuScrollViewer"
Style="{DynamicResource {ComponentResourceKey ResourceId=MenuScrollViewer, TypeInTargetAssembly={x:Type FrameworkElement}}}"
Background="Blue" Margin="0" Padding="0">
<Grid RenderOptions.ClearTypeHint="Enabled">
<Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
<Rectangle x:Name="OpaqueRect" Stroke="#8a919c" RadiusX="5" RadiusY="5" StrokeThickness="1" Height="{Binding ActualHeight, ElementName=SubMenuBorder}" Width="{Binding ActualWidth, ElementName=SubMenuBorder}">
<Rectangle.Fill>
<LinearGradientBrush StartPoint="0,0" EndPoint="1,1">
<GradientStop Color="#FF404957" Offset="0.144"/>
<GradientStop Color="#FF2B3F47" Offset="0.994"/>
</LinearGradientBrush>
</Rectangle.Fill>
</Rectangle>
</Canvas>
<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Cycle" Grid.IsSharedSizeScope="True" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" KeyboardNavigation.TabNavigation="Cycle" />
</Grid>
</ScrollViewer>
</Border>
</Popup>
</Grid>
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsSuspendingPopupAnimation" Value="True">
<Setter Property="PopupAnimation" TargetName="PART_Popup" Value="None"/>
</Trigger>
<Trigger Property="IsKeyboardFocusWithin" Value="True">
<Setter TargetName="templateRoot" Property="Background" Value="#FF576DB9" />
</Trigger>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="Background" TargetName="templateRoot" Value="#7F26DACA"/>
<Setter Property="BorderBrush" TargetName="templateRoot" Value="#FF26DAB9"/>
<Setter Property="IsOpen" TargetName="PART_Popup" Value="true"/>
<Setter Property="Cursor" Value="Hand"/>
<Setter Property="Focusable" Value="False"/>
</Trigger>
<!--On - MouseLeave - Close PopUp - "Menu" -->
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="IsKeyboardFocusWithin" Value="false" />
<Condition Property="IsMouseOver" Value="false" />
</MultiTrigger.Conditions>
<MultiTrigger.Setters>
<Setter Property="IsOpen" TargetName="PART_Popup" Value="false"/>
</MultiTrigger.Setters>
</MultiTrigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
================================================ ========================== 详细：
#1 - MainWindow.xaml - 文件 - “下面的菜单代码”：
<Window x:Class="PaintApp.MainWindow"
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:PaintApp"
mc:Ignorable="d"
Title="MainWindow" Height="450" Width="800">
<!--GRID-->
<Grid x:Name="grid_MainGrid">
<!--..............................The Menu Code....................................................-->
<!--Top Menu-->
<DockPanel x:Name="dockPanel_Menu_TopMenu" Style="{DynamicResource dockPanel_Menu_TopMenu_Style}">
<Menu x:Name="menu_TopMenu" Style="{DynamicResource menu_TopMenu_Style}">
<MenuItem Header="File" Style="{DynamicResource menu_TopMenu_MenuItem_Style}">
<MenuItem Header="New"/>
<Separator Style="{DynamicResource menu_TopMenu_Seperator_Style}"/>
<MenuItem Header="Open"/>
<Separator Style="{DynamicResource menu_TopMenu_Seperator_Style}"/>
<MenuItem Header="Save"/>
</MenuItem>
<MenuItem Header="Close" Style="{DynamicResource menu_TopMenu_MenuItem_Style}"/>
<MenuItem Header="Open" Style="{DynamicResource menu_TopMenu_MenuItem_Style}"/>
</Menu>
</DockPanel>
#2 - 资源字典文件 - 样式- maintheme.xaml - 我将我的样式放在一个单独的文件中，所以我可以动态更换主题
<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
x:Class="PaintApp.maintheme"
xmlns:local="clr-namespace:PaintApp">
<!--..........Only For Style and alignment if you dont care about the style ignore this....................................................-->
<!--#1 - Top Menu-DockPanel-->
<Style x:Key="dockPanel_Menu_TopMenu_Style" TargetType="{x:Type DockPanel}">
<Setter Property="VerticalAlignment" Value="Top"/>
<Setter Property="Height" Value="20"/>
</Style>
<!--..........Only For Style and alignment if you dont care about the style ignore this....................................................-->
<!--#2-Top Menu-Menu-->
<Style x:Key="menu_TopMenu_Style" TargetType="{x:Type Menu}">
<Setter Property="DockPanel.Dock" Value="Top"/>
<Setter Property="Background" Value="#FF3E434B"/>
<Setter Property="Foreground" Value="#FFFFFA9B"/>
<Setter Property="FontFamily" Value="Verdana"/>
</Style>
<!--.........Override PopUp so it can close on Mouse Leave + Style ----------------------------------->
<!--#3-Top Menu - MenuItem-->
<Style x:Key="menu_TopMenu_MenuItem_Style" TargetType="{x:Type MenuItem}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate x:Name="menuItem" TargetType="{x:Type MenuItem}">
<Border x:Name="templateRoot" BorderThickness="1" CornerRadius="1" SnapsToDevicePixels="True">
<Grid VerticalAlignment="Center">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="Auto"/>
</Grid.ColumnDefinitions>
<ContentPresenter ContentTemplate="{TemplateBinding HeaderTemplate}" Content="{TemplateBinding Header}" Grid.Column="1" ContentStringFormat="{TemplateBinding HeaderStringFormat}" ContentSource="Header" Margin="{TemplateBinding Padding}" RecognizesAccessKey="True" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
<Popup x:Name="PART_Popup" AllowsTransparency="True" Focusable="False" IsOpen="{Binding IsSubmenuOpen, RelativeSource={RelativeSource TemplatedParent}}" PopupAnimation="None" Placement="Bottom">
<Border x:Name="SubMenuBorder">
<ScrollViewer x:Name="SubMenuScrollViewer"
Style="{DynamicResource {ComponentResourceKey ResourceId=MenuScrollViewer, TypeInTargetAssembly={x:Type FrameworkElement}}}"
Background="Blue" Margin="0" Padding="0">
<Grid RenderOptions.ClearTypeHint="Enabled">
<Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
<Rectangle x:Name="OpaqueRect" Stroke="#8a919c" RadiusX="5" RadiusY="5" StrokeThickness="1" Height="{Binding ActualHeight, ElementName=SubMenuBorder}" Width="{Binding ActualWidth, ElementName=SubMenuBorder}">
<Rectangle.Fill>
<LinearGradientBrush StartPoint="0,0" EndPoint="1,1">
<GradientStop Color="#FF404957" Offset="0.144"/>
<GradientStop Color="#FF2B3F47" Offset="0.994"/>
</LinearGradientBrush>
</Rectangle.Fill>
</Rectangle>
</Canvas>
<ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Cycle" Grid.IsSharedSizeScope="True" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" KeyboardNavigation.TabNavigation="Cycle" />
</Grid>
</ScrollViewer>
</Border>
</Popup>
</Grid>
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsSuspendingPopupAnimation" Value="True">
<Setter Property="PopupAnimation" TargetName="PART_Popup" Value="None"/>
</Trigger>
<Trigger Property="IsKeyboardFocusWithin" Value="True">
<Setter TargetName="templateRoot" Property="Background" Value="#FF576DB9" />
</Trigger>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="Background" TargetName="templateRoot" Value="#7F26DACA"/>
<Setter Property="BorderBrush" TargetName="templateRoot" Value="#FF26DAB9"/>
<Setter Property="IsOpen" TargetName="PART_Popup" Value="true"/>
<Setter Property="Cursor" Value="Hand"/>
<Setter Property="Focusable" Value="False"/>
</Trigger>
<!--On - MouseLeave - Close PopUp - "Menu" -->
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="IsKeyboardFocusWithin" Value="false" />
<Condition Property="IsMouseOver" Value="false" />
</MultiTrigger.Conditions>
<MultiTrigger.Setters>
<Setter Property="IsOpen" TargetName="PART_Popup" Value="false"/>
</MultiTrigger.Setters>
</MultiTrigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
<!--......SubMenus....Only For Style and alignment if you dont care about the style ignore this....................................................-->
<!--Top - Menu - SUB - MenuItems-->
<Style.Resources>
<Style TargetType="{x:Type MenuItem}">
<Setter Property="OverridesDefaultStyle" Value="True"/>
<Setter Property="SnapsToDevicePixels" Value="True"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type MenuItem}">
<Border x:Name="subMenuitemBorder" BorderThickness="2" CornerRadius="3" SnapsToDevicePixels="True" Uid="Border_38">
<Grid x:Name="bg" Background="{TemplateBinding Background}">
<ContentPresenter x:Name="HeaderHost" ContentSource="Header" RecognizesAccessKey="True">
<ContentPresenter.ContentTemplate>
<DataTemplate>
<!--<Border BorderBrush="#FF60626A" BorderThickness="0, 0, 0, 1" Margin="10, 0, 10, -5">-->
<TextBlock Padding="30, 3,30, 5" Text="{Binding BindsDirectlyToSource=True}"/>
<!--</Border>-->
</DataTemplate>
</ContentPresenter.ContentTemplate>
</ContentPresenter>
</Grid>
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsHighlighted" Value="True">
<Setter Property="BorderBrush" TargetName="subMenuitemBorder" Value="#FF26A0DA"/>
<Setter Property="Background" TargetName="subMenuitemBorder" Value="#7F26A0DA"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Style.Resources>
</Style>
<!--..........Only For Style and alignment if you dont care about the style ignore this....................................................-->
<!--Top - Menu Seperator-->
<Style x:Key="menu_TopMenu_Seperator_Style" TargetType="{x:Type Separator}">
<Setter Property="Background" Value="Red"/>
<Setter Property="Margin" Value="10,1,10,1"/>
<Setter Property="Focusable" Value="false"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type Separator}">
<Border
BorderBrush="#FF6A667E"
BorderThickness="1"
Background="Red"
Height="1"
SnapsToDevicePixels="true"/>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
#3 - App.xaml 文件 - 因为我对样式使用单独的文件
<Application x:Class="PaintApp.App"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:PaintApp"
StartupUri="MainWindow.xaml">
<Application.Resources>
<!--Seperate file for the styles-->
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="maintheme.xaml"></ResourceDictionary>
</ResourceDictionary.MergedDictionaries>
</ResourceDictionary>
<!--Seperate file for the styles-->
</Application.Resources>
</Application>