c# - Caliburn.Micro + MEF + 现代 UI : IContent events

我已经开始了一个使用 Caliburn.Micro 和现代 UI ( https://mui.codeplex.com ) 的项目，并且在让 IContent 的导航事件在我的 View 模型上触发时遇到了一些困难。我已经将两者联系起来，并通过以下方式相互合作:

CM bootstrap :

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>

MuiViewModel

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

}

每个 subview 都被导出并实现 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
}

但这些人都没有开火。经过一些调试后，我发现 ModernFrame 正在检查 (SettingsView as IContent) 的事件，因为它只是一个普通的 UserControl ，所以没有它们。所以我创建了一个自定义的 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 View 以使用 Message.Attach 监听事件:

设置查看

<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 Message.Attach 直到事件被调度后才会被应用。我这样做可能是一种非常错误的方式，并且对大规模重建持开放态度。

最佳答案

好的，这最终还不错 - 它确实使尝试将事件传递给 VM 时的生活更容易一些

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

您需要在 VM 的 OnViewLoaded 事件中为 ModernWindow 创建一个导体实例，因为这似乎是最好的地方(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，任何添加 IContent 接口(interface)的 View 都会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，这适用于出现在 IContent 上的所有 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，或者执行您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 - 窗口中的一行代码并在 VM 上实现接口(interface)，您就完成了:)

编辑:

我唯一可能会添加的是一些异常抛出或调试日志通知时将导体添加到窗口以防万一它由于某种原因找不到框架(也许框架的名称可能会在以后更改发布 m:ui)

关于c# - Caliburn.Micro + MEF + 现代 UI : IContent events，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/16968090/