Caliburn.Micro + MEF + Modern UI: IContent events

Question

我已经使用Caliburn.Micro和Modern UI(https://mui.codeplex.com(启动了一个项目，并且在使IContent的导航事件在我的视图模型上触发时遇到了一些困难。我已经将两者连接起来，以便通过以下方式相互合作：

CM 引导程序：

public class CMBootstrapper : Bootstrapper<IShell> {
    private CompositionContainer container;
    private DirectoryCatalog catalog;
    public CMBootstrapper() { }
    protected override void Configure() {
        catalog = new DirectoryCatalog(".", "*.*");
        container = new CompositionContainer(catalog);
        var compositionBatch = new CompositionBatch();
        compositionBatch.AddExportedValue<IWindowManager>(new WindowManager());
        compositionBatch.AddExportedValue<IEventAggregator>(new EventAggregator());
        compositionBatch.AddExportedValue(container);
        container.Compose(compositionBatch);
    }
    protected override IEnumerable<Assembly> SelectAssemblies() {
        List<Assembly> assemblies = new List<Assembly>();
        assemblies.Add(Assembly.GetExecutingAssembly());
        return assemblies;
    }
    protected override object GetInstance(Type serviceType, string key) {
        string contract = string.IsNullOrEmpty(key) ? AttributedModelServices.GetContractName(serviceType) : key;
        var exports = container.GetExportedValues<object>(contract);
        if (exports.Count() > 0)
            return exports.First();
        throw new Exception(string.Format("Could not locate any instances of contract {0}.", contract));
    }
    protected override IEnumerable<object> GetAllInstances(Type serviceType) {
        return container.GetExportedValues<object>(AttributedModelServices.GetContractName(serviceType));
    }
    protected override void BuildUp(object instance) {
        container.SatisfyImportsOnce(instance);
    }
}

现代 UI 内容加载器：

[Export]
public class MuiContentLoader : DefaultContentLoader {
    protected override object LoadContent(Uri uri) {
        var content = base.LoadContent(uri);
        if (content == null)
            return null;
        // Locate VM
        var viewModel = ViewModelLocator.LocateForView(content);
        if (viewModel == null)
            return content;
        // Bind VM
        if (content is DependencyObject)
            ViewModelBinder.Bind(viewModel, content as DependencyObject, null);
        return content;
    }
}

MuiView.xaml (Shell(

<mui:ModernWindow x:Class="XMOperations.Views.MuiView"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:mui="http://firstfloorsoftware.com/ModernUI"
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
         mc:Ignorable="d" 
         ContentLoader="{StaticResource ModernContentLoader}"
         d:DesignHeight="300" d:DesignWidth="300">
<mui:ModernWindow.TitleLinks>
    <mui:Link DisplayName="Settings" Source="/Views/SettingsView.xaml" />
</mui:ModernWindow.TitleLinks>
<mui:ModernWindow.MenuLinkGroups>
    <mui:LinkGroupCollection>
        <mui:LinkGroup GroupName="Hello" DisplayName="Hello">
            <mui:LinkGroup.Links>
                <mui:Link Source="/Views/ChildView.xaml" DisplayName="Click me"></mui:Link>
            </mui:LinkGroup.Links>
        </mui:LinkGroup>
    </mui:LinkGroupCollection>
</mui:ModernWindow.MenuLinkGroups>

美景模型

[Export(typeof(IShell))]
public class MuiViewModel : Conductor<IScreen>.Collection.OneActive, IShell {
}

导出每个子视图并实现 IContent，如下所示：

[Export]
[PartCreationPolicy(CreationPolicy.Shared)]
public class SettingsViewModel : Screen, IContent {
    #region IContent Implementation
    public void OnFragmentNavigation(FragmentNavigationEventArgs e) {
        Console.WriteLine("SettingsViewModel.OnFragmentNavigation");
    }
    public void OnNavigatedFrom(NavigationEventArgs e) {
        Console.WriteLine("SettingsViewModel.OnNavigatedFrom");
    }
    public void OnNavigatedTo(NavigationEventArgs e) {
        Console.WriteLine("SettingsViewModel.OnNavigatedTo");
    }
    public void OnNavigatingFrom(NavigatingCancelEventArgs e) {
        Console.WriteLine("SettingsViewModel.OnNavigatingFrom");
    }
    #endregion
}

但这些都没有被解雇。经过一些调试，我发现ModernFrame正在检查(SettingsView as IContent)的事件，这些事件不会有它们，因为它只是一个普通的UserControl。因此，我创建了一个自定义 UserControl 类，试图将事件传递给 ViewModel：

MuiContentControl

public delegate void FragmentNavigationEventHandler(object sender, FragmentNavigationEventArgs e);
public delegate void NavigatedFromEventHandler(object sender, NavigationEventArgs e);
public delegate void NavigatedToEventHandler(object sender, NavigationEventArgs e);
public delegate void NavigatingFromEventHandler(object sender, NavigatingCancelEventArgs e);
public class MuiContentControl : UserControl, IContent {
    public event FragmentNavigationEventHandler FragmentNavigation;
    public event NavigatedFromEventHandler NavigatedFrom;
    public event NavigatedToEventHandler NavigatedTo;
    public event NavigatingFromEventHandler NavigatingFrom;
    public MuiContentControl() : base() {
    }
    public void OnFragmentNavigation(FragmentNavigationEventArgs e) {
        if(FragmentNavigation != null)
            FragmentNavigation(this, e);
    }
    public void OnNavigatedFrom(NavigationEventArgs e) {
        if (NavigatedFrom != null)
            NavigatedFrom(this, e);
    }
    public void OnNavigatedTo(NavigationEventArgs e) {
        if(NavigatedTo != null)
            NavigatedTo(this, e);
    }
    public void OnNavigatingFrom(NavigatingCancelEventArgs e) {
        if(NavigatingFrom != null)
            NavigatingFrom(this, e);
    }
}

然后，我修改了视图以使用 Message.Attach 侦听事件：

设置视图

<local:MuiContentControl x:Class="XMOperations.Views.SettingsView"
         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:mui="http://firstfloorsoftware.com/ModernUI" 
         xmlns:cal="http://www.caliburnproject.org"
         xmlns:local="clr-namespace:XMOperations"
         cal:Message.Attach="[Event FragmentNavigation] = [Action OnFragmentNavigation($source, $eventArgs)];
                             [Event NavigatedFrom] = [Action OnNavigatedFrom($source, $eventArgs)];
                             [Event NavigatedTo] = [Action OnNavigatedTo($source, $eventArgs)];
                             [Event NavigatingFrom] = [Action OnNavigatingFrom($source, $eventArgs)]"
         mc:Ignorable="d" 
         d:DesignHeight="300" d:DesignWidth="300">
<Grid Style="{StaticResource ContentRoot}">
    <mui:ModernTab SelectedSource="/Views/Settings/AppearanceView.xaml" Layout="List" ContentLoader="{StaticResource ModernContentLoader}">
        <mui:ModernTab.Links>
            <mui:Link DisplayName="Appearance" Source="/Views/Settings/AppearanceView.xaml" />
        </mui:ModernTab.Links>
    </mui:ModernTab>
</Grid>

唯一不会触发的事件是 NavigatedTo，所以我相信在调度事件之前不会应用 Message.Attach 。我可能以一种非常错误的方式这样做，并且对大规模重建持开放态度。

Answer 1

好的，

这最终并没有那么糟糕 - 它肯定会让尝试将事件传递到 VM 时生活更容易一些

我为ModernWindow控件模板中存在的ModernFrame控件创建了一个导体

您需要在 VM 的OnViewLoaded事件中为您的ModernWindow创建一个指挥体实例，因为这似乎是最佳位置(即尚未发生导航，但控件已完全加载并已解析其模板(

// Example viewmodel:
public class ModernWindowViewModel : Conductor<IScreen>.Collection.OneActive
{
    protected override void OnViewLoaded(object view)
    {
        base.OnViewLoaded(view);
        // Instantiate a new navigation conductor for this window
        new FrameNavigationConductor(this);
    }
}

导体代码如下：

public class FrameNavigationConductor
{
    #region Properties
    // Keep a ref to the frame
    private readonly ModernFrame _frame;
    // Keep this to handle NavigatingFrom and NavigatedFrom events as this functionality
    // is usually wrapped in the frame control and it doesn't pass the 'old content' in the
    // event args
    private IContent _navigatingFrom;
    #endregion
    public FrameNavigationConductor(IViewAware modernWindowViewModel)
    {
        // Find the frame by looking in the control template of the window
        _frame = FindFrame(modernWindowViewModel);
        if (_frame != null)
        {
            // Wire up the events
            _frame.FragmentNavigation += frame_FragmentNavigation;
            _frame.Navigated += frame_Navigated;
            _frame.Navigating += frame_Navigating;
        }
    }
    #region Navigation Events
    void frame_Navigating(object sender, NavigatingCancelEventArgs e)
    {
        var content = GetIContent(_frame.Content);
        if (content != null)
        {
            _navigatingFrom = content;
            _navigatingFrom.OnNavigatingFrom(e);
        }
        else
            _navigatingFrom = null;
    }
    void frame_Navigated(object sender, NavigationEventArgs e)
    {
        var content = GetIContent(_frame.Content);
        if (content != null)
            content.OnNavigatedTo(e);
        if (_navigatingFrom != null)
            _navigatingFrom.OnNavigatedFrom(e);
    }
    void frame_FragmentNavigation(object sender, FragmentNavigationEventArgs e)
    {
        var content = GetIContent(_frame.Content);
        if (content != null)
            content.OnFragmentNavigation(e);
    }
    #endregion
    #region Helpers
    ModernFrame FindFrame(IViewAware viewAware)
    {
        // Get the view for the window
        var view = viewAware.GetView() as Control;
        if (view != null)
        {
            // Find the frame by name in the template
            var frame = view.Template.FindName("ContentFrame", view) as ModernFrame;
            if (frame != null)
            {
                return frame;
            }
        }
        return null;
    }
    private IContent GetIContent(object source)
    {
        // Try to cast the datacontext of the attached viewmodel to IContent
        var fe = (source as FrameworkElement);
        if (fe != null)
        {
            var content = fe.DataContext as IContent;
            if (content != null)
                return content;
        }
        return null;
    }
    #endregion
}

现在，您添加IContent接口的任何视图都将在导航发生时自动获取框架调用的方法

public class TestViewModel : Conductor<IScreen>, IContent
{
    public void OnFragmentNavigation(FragmentNavigationEventArgs e)
    {
        // Do stuff
    }
    public void OnNavigatedFrom(NavigationEventArgs e)
    {
        // Do stuff
    }
    public void OnNavigatedTo(NavigationEventArgs e)
    {
        // Do stuff
    }
    public void OnNavigatingFrom(NavigatingCancelEventArgs e)
    {
        // Do stuff
    }
}

我已经测试过，这适用于IContent上出现的所有 4 个导航事件 - 因为它通过EventArgs您可以直接从 VM 取消导航事件或执行通常在仅查看场景中执行的任何

操作

我认为这可能是我能想到的最轻松的方法 - 从字面上看，窗口中的一行代码并在 VM 上实现接口，您就完成了:)

编辑：

我唯一可能添加的是将导体添加到窗口时抛出一些异常或调试日志通知，以防由于某种原因找不到帧(也许帧的名称可能会在以后的 m：ui 版本中更改(

Answer 2

我在IContent Views上做了以下操作，并在ViewModel上实现了IContent。

   public void OnFragmentNavigation(FirstFloor.ModernUI.Windows.Navigation.FragmentNavigationEventArgs e)
    {
        if (this.DataContext != null)
        {
            var viewModel = this.DataContext as IContent;
            if (viewModel != null)
            {
                viewModel.OnFragmentNavigation(e);
            }
        }
    }
    public void OnNavigatedFrom(FirstFloor.ModernUI.Windows.Navigation.NavigationEventArgs e)
    {
        if (this.DataContext != null)
        {
            var viewModel = this.DataContext as IContent;
            if (viewModel != null)
            {
                viewModel.OnNavigatedFrom(e);
            }
        }
    }
    public void OnNavigatedTo(FirstFloor.ModernUI.Windows.Navigation.NavigationEventArgs e)
    {
        if (this.DataContext != null)
        {
            var viewModel = this.DataContext as IContent;
            if (viewModel != null)
            {
                viewModel.OnNavigatedTo(e);
            }
        }
    }
    public void OnNavigatingFrom(FirstFloor.ModernUI.Windows.Navigation.NavigatingCancelEventArgs e)
    {
        if (this.DataContext != null)
        {
            var viewModel = this.DataContext as IContent;
            if (viewModel != null)
            {
                viewModel.OnNavigatingFrom(e);
            }
        }
    }