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wpf - 为什么此 DropdownMenu 在 WPF 中不起作用

问题描述

我正在尝试使用 VB 中的代码隐藏在 WPF 中创建 DropdownMenu。由于任何原因，我无法意识到这个 DropdownMenu 没有按我的意愿工作。

这是 MainWindow.xaml 文件：

<Window x:Class="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:materialDesign="http://materialdesigninxaml.net/winfx/xaml/themes"
    mc:Ignorable="d" Height="600" Width="1080" Foreground="White" ResizeMode="NoResize" WindowStartupLocation="CenterScreen" WindowStyle="None">
<Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="auto"/>
        <RowDefinition Height="*"/>
    </Grid.RowDefinitions>
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="250"/>
        <ColumnDefinition Width="*"/>
    </Grid.ColumnDefinitions>

    <materialDesign:ColorZone Mode="PrimaryMid" Grid.ColumnSpan="2" HorizontalAlignment="Stretch">
        <Grid>
            <materialDesign:PopupBox PlacementMode="BottomAndAlignRightEdges" HorizontalAlignment="Right" Margin="10"/>
        </Grid>
    </materialDesign:ColorZone>
    <Grid HorizontalAlignment="Stretch" Grid.Row="1" Background="{StaticResource PrimaryHueMidBrush}">
        <Grid.RowDefinitions>
            <RowDefinition Height="70"/>
            <RowDefinition Height="326*"/>
        </Grid.RowDefinitions>
        <Grid Grid.Row="0" Background="GhostWhite">
            <Image Source="Assets/logo.png"/>
        </Grid>
        <ScrollViewer HorizontalAlignment="Stretch" HorizontalScrollBarVisibility="Disabled" VerticalScrollBarVisibility="Auto" Grid.Row="1">
            <StackPanel x:Name="Menu" Margin="10"/>
        </ScrollViewer>
    </Grid>
</Grid>
</Window>

这是 MainWindow.xaml.vb 文件：

Imports MaterialDesignThemes.Wpf
Imports Project.ViewModel


Partial Public Class MainWindow
Inherits Window

Public Sub New()
    InitializeComponent()
    Dim menuRegister = New List(Of SubItem)()
    menuRegister.Add(New SubItem("Customer"))
    menuRegister.Add(New SubItem("Providers"))
    menuRegister.Add(New SubItem("Employees"))
    menuRegister.Add(New SubItem("Products"))
    Dim item6 = New ItemMenu("Register", menuRegister, PackIconKind.Register)
    Dim menuSchedule = New List(Of SubItem)()
    menuSchedule.Add(New SubItem("Services"))
    menuSchedule.Add(New SubItem("Meetings"))
    Dim item1 = New ItemMenu("Appointments", menuSchedule, PackIconKind.Schedule)
    Dim menuReports = New List(Of SubItem)()
    menuReports.Add(New SubItem("Customers"))
    menuReports.Add(New SubItem("Providers"))
    menuReports.Add(New SubItem("Products"))
    menuReports.Add(New SubItem("Stock"))
    menuReports.Add(New SubItem("Sales"))
    Dim item2 = New ItemMenu("Reports", menuReports, PackIconKind.FileReport)
    Dim menuExpenses = New List(Of SubItem)()
    menuExpenses.Add(New SubItem("Fixed"))
    menuExpenses.Add(New SubItem("Variable"))
    Dim item3 = New ItemMenu("Expenses", menuExpenses, PackIconKind.ShoppingBasket)
    Dim menuFinancial = New List(Of SubItem)()
    menuFinancial.Add(New SubItem("Cash flow"))
    Dim item4 = New ItemMenu("Financial", menuFinancial, PackIconKind.ScaleBalance)
    Dim item0 = New ItemMenu("Dashboard", New UserControl(), PackIconKind.ViewDashboard)
    Menu.Children.Add(New UserControlMenuItem(item0))
    Menu.Children.Add(New UserControlMenuItem(item6))
    Menu.Children.Add(New UserControlMenuItem(item1))
    Menu.Children.Add(New UserControlMenuItem(item2))
    Menu.Children.Add(New UserControlMenuItem(item3))
    Menu.Children.Add(New UserControlMenuItem(item4))
End Sub
End Class

这是 ItemMenu 类：

Imports MaterialDesignThemes.Wpf

Namespace ViewModel
Public Class ItemMenu
    Public Sub New(ByVal header As String, ByVal subItems As List(Of SubItem), ByVal icon As PackIconKind)
        header = header
        subItems = subItems
        icon = icon
    End Sub

    Public Sub New(ByVal header As String, ByVal screen As UserControl, ByVal icon As PackIconKind)
        header = header
        screen = screen
        icon = icon
    End Sub

    Public Property Header As String
    Public Property Icon As PackIconKind
    Public Property SubItems As List(Of SubItem)
    Public Property Screen As UserControl
End Class
End Namespace

这是子项类：

Namespace ViewModel
Public Class SubItem
    Public Sub New(ByVal name As String, ByVal Optional screen As UserControl = Nothing)
        name = name
        screen = screen
    End Sub

    Public Property Name As String
    Public Property Screen As UserControl
End Class
End Namespace

这是 UserControlMenuItem.xaml 文件：

<UserControl x:Class="UserControlMenuItem"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
         xmlns:materialDesign="http://materialdesigninxaml.net/winfx/xaml/themes"
         mc:Ignorable="d" >
<Grid>
    <materialDesign:PackIcon Kind="{Binding Path=Icon}" Width="15" Height="15" Margin="10 16" Foreground="White"/>
    <ListBoxItem x:Name="ListViewItemMenu" Content="{Binding Path=Header}" Padding="37 14" FontSize="15" Foreground="White"/>
    <Expander x:Name="ExpanderMenu" Header="{Binding Path=Header}" IsExpanded="False" Width="210" HorizontalAlignment="Right" Background="{x:Null}" Foreground="White">
        <ListView x:Name="ListViewMenu" ItemsSource="{Binding Path=SubItems}" Foreground="White" ScrollViewer.HorizontalScrollBarVisibility="Disabled">
            <ListView.ItemTemplate>
                <DataTemplate>
                    <TextBlock Text="{Binding Path=Name}" Padding="20 5"/>
                </DataTemplate>
            </ListView.ItemTemplate>
        </ListView>
    </Expander>
</Grid>

这是 UserControlMenuItem.xaml.vb 文件：

Imports Project.ViewModel

Partial Public Class UserControlMenuItem
Inherits UserControl

Public Sub New(ByVal itemMenu As ItemMenu)
    InitializeComponent()
    ExpanderMenu.Visibility = If(itemMenu.SubItems Is Nothing, Visibility.Collapsed, Visibility.Visible)
    ListViewItemMenu.Visibility = If(itemMenu.SubItems Is Nothing, Visibility.Visible, Visibility.Collapsed)
    Me.DataContext = itemMenu
End Sub

结束类

这是应用程序运行时的窗口： 在此处输入图像描述

我在这里缺少什么？

从DropDownMenu克隆的设计

标签： wpfvb.netdrop-down-menu

解决方案

我解决了这个问题。这是一个我没有意识到的细节。这些是更正后的类：

ItemMenu班级：

Imports MaterialDesignThemes.Wpf

Namespace ViewModel
Public Class ItemMenu
    Public Sub New(ByVal header As String, ByVal subItems As List(Of SubItem), ByVal icon As PackIconKind)
        Me.Header = header
        Me.SubItems = subItems
        Me.Icon = icon
    End Sub

    Public Sub New(ByVal header As String, ByVal screen As UserControl, ByVal icon As PackIconKind)
        Me.Header = header 
        Me.Screen = screen 
        Me.Icon = icon 
    End Sub

    Public Property Header As String
    Public Property Icon As PackIconKind
    Public Property SubItems As List(Of SubItem)
    Public Property Screen As UserControl
End Class
End Namespace

SubItem班级：

Namespace ViewModel
Public Class SubItem
    Public Sub New(ByVal name As String, ByVal Optional screen As UserControl = Nothing)
        Me.Name = name
        Me.Screen = screen
    End Sub

    Public Property Name As String
    Public Property Screen As UserControl
End Class
End Namespace

只是用“Me”（self在其他语言，如 Python）中引用类，然后为属性赋值：

Me.Header = header 'Example in ItemMenu Class
Me.Name = name     'Example in SubItem Class

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