使用ViewModelLocator将WPF绑定到2个ViewModel

Question

在将ViewModelLocator的ApplicationViewModel绑定到MainWindow.xaml以更改应用程序中的页面时，我陷入了困境。

绑定正在工作，显示第一页（LoginPage），但是当我尝试更改它们时，它没有任何作用。看来PropertyChanged事件不起作用。

我的应用程序代码： MainWindow.xaml：

<Window x:Class="DebtDiary.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:DebtDiary"
    xmlns:localization="clr-namespace:DebtDiary.Localization" 
    xmlns:core="clr-namespace:DebtDiary.Core;assembly=DebtDiary.Core"
    mc:Ignorable="d" WindowStyle="None"
    AllowsTransparency="True"
    WindowStartupLocation="CenterScreen"
    Icon="../Images/Logo/DebtDiaryIcon.ico"
    Title="{x:Static localization:Strings.ApplicationName}"
    MinWidth="{Binding MinimumWidth}"
    MinHeight="{Binding MinimumHeight}"
    Width="{Binding MinimumWidth, FallbackValue=1280}"
    Height="{Binding MinimumHeight, FallbackValue=720}">
<Window.Resources>
    <Style TargetType="{x:Type local:MainWindow}">
        <!-- Window Chrome Settings -->
        <Setter Property="WindowChrome.WindowChrome">
            <Setter.Value>
                <WindowChrome ResizeBorderThickness="{Binding ResizeBorderThickness}" CaptionHeight="{Binding TitleBarHeight}"/>
            </Setter.Value>
        </Setter>

        <!-- New window template -->
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type Window}">
                    <!-- Outer border -->
                    <Border Background="Gray">
                        <Grid>
                            <Grid.RowDefinitions>
                                <!-- Title bar -->
                                <RowDefinition Height="{Binding TitleBarHeight, FallbackValue=35}"/>
                                <!-- Window Content -->
                                <RowDefinition Height="*"/>
                            </Grid.RowDefinitions>

                            <!-- Title bar -->
                            <Grid Grid.Row="0" Background="{StaticResource DarkGreyBrush}">
                                <Grid.ColumnDefinitions>
                                    <!-- Icon -->
                                    <ColumnDefinition Width="Auto"/>
                                    <!-- Window title -->
                                    <ColumnDefinition Width="*"/>
                                    <!-- Minimize button -->
                                    <ColumnDefinition Width="Auto"/>
                                    <!-- Maximize / Restore button -->
                                    <ColumnDefinition Width="Auto"/>
                                    <!-- Exit button -->
                                    <ColumnDefinition Width="Auto"/>
                                </Grid.ColumnDefinitions>

                                <!-- Icon -->
                                <Image Grid.Column="0" Source="../Images/Logo/DebtDiarySmallIcon.ico" Margin="3 3 3 4"/>
                                <!-- Title -->
                                <TextBlock Grid.Column="1" Margin="2 9 2 0" Style="{StaticResource TitleBarStyle}" 
                                           Text="{Binding Title, RelativeSource={RelativeSource Mode=TemplatedParent}, FallbackValue='Debt diary'}" />
                                <!-- Minimize button -->
                                <Button Grid.Column="2" Style="{StaticResource WindowControlButton}" Content="{StaticResource MinimizeIcon}" 
                                        Command="{Binding MinimizeCommand}" />
                                <!-- Maximize / Restore button -->
                                <Button Grid.Column="3" Style="{StaticResource WindowControlButton}" 
                                        Content="{TemplateBinding WindowState, Converter={local:WindowStateToIconValueConverter}}" 
                                        Command="{Binding MaximizeCommand}"/>
                                <!-- Close button -->
                                <Button Grid.Column="4" Style="{StaticResource WindowCloseButton}" Content="{StaticResource CloseIcon}" 
                                        Command="{Binding CloseCommand}"/>
                            </Grid>

                            <!-- Page content -->
                            <Border Grid.Row="1">
                                <ContentPresenter Content="{TemplateBinding Content}"/>
                            </Border>

                        </Grid>
                    </Border>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</Window.Resources>

<!-- Window content -->
<Grid DataContext="{Binding ApplicationViewModel, Source={x:Static local:ViewModelLocator.Instance}}">
    <!-- Window background -->
    <Grid.Background>
        <ImageBrush ImageSource="../Images/StartScreenBackground.png" Stretch="UniformToFill" />
    </Grid.Background>

    <!-- Current Page -->
    <Frame Content="{Binding CurrentPage, Converter={local:ApplicationPageValueConverter}}" NavigationUIVisibility="Hidden"/>
</Grid>

ViewModelLocator.cs：

    public class ViewModelLocator
{
    /// <summary>
    /// Singleton instance of the ViewModelLocator
    /// </summary>
    public static ViewModelLocator Instance { get; private set; } = new ViewModelLocator();

    /// <summary>
    /// ApplicationViewModel Property
    /// </summary>
    public ApplicationViewModel ApplicationViewModel
    {
        get
        {
            IKernel kernel = new StandardKernel();
            return kernel.Get<ApplicationViewModel>();
        }
    }
}

ApplicationViewModel.cs

    public class ApplicationViewModel : BaseViewModel
{
    #region Public Properties
    /// <summary>
    /// CurrentPage in the application
    /// </summary>
    public ApplicationPage CurrentPage { get; set; } = ApplicationPage.LoginPage;
    #endregion
}

您是否知道如何解决？