Question

我有一个特殊的问题，我必须覆盖 Window 类中的特定方法。

我正在使用 MVVM ，我的ViewModel继承到具有 INotifyPropertyChanged

的BaseVm

我需要的是这个

    public partial class MainWindow : Window
     {
 protected override void OnSourceInitialized(EventArgs e)
        {
                base.OnSourceInitialized(e);

                // Hook up handler for window messages
                var windowSource = PresentationSource.FromVisual(this) as HwndSource;
                if (windowSource == null)
                    return;
                windowSource.AddHook(WiDiOnWindowMessage);

                try
                {
                    _wiDi = new WiDi();
                    _wiDi.ValidateWiDi();

                    //// This is async call so rest of logic handled in OnWiDiWindowMessage
                    //// Pass the window handle which WiDi extensions library uses to send messages back.
                    _wiDi.Initialize((uint)windowSource.Handle.ToInt64());
                }
                catch (WiDiNoWelException)
                {
                    ShowMessageDialog("Warning: The Intel® WiDi auto-connect button is not available.",
                                      "Please use the Intel® WiDi application to connect to your TV.\n" +
                                      "Alternatively you can use an HDMI cable.\n" +
                                      "Issue: The Intel® WiDi Extensions Library (WEL) cannot be found.");
                }
                catch (WiDiNoAppException)
                {
                    ShowMessageDialog("Warning: Intel® WiDi is not available.", 
                                      "Please use an HDMI cable to connect to your TV.\n" +
                                      "Issue: Intel® WiDi cannot be found or this PC may not be Intel® WiDi compatible.");
                }
                catch (WiDiException exception)
                {
                    ShowMessageDialog("Warning: Intel® WiDi is not available.",
                                      "Please use an HDMI cable to connect to your TV.\n" +
                                      "Issue: " + exception.Message);
                }

我的当前代码是

public  class HomeWindowVm : BaseVm
    {
     protected override void OnSourceInitialized(EventArgs e)
       {
            base.OnSourceInitialized(e);

        //    Hook up handler for window messages

         var windowSource = PresentationSource.FromVisual(this) as HwndSource;
           // var windowsource = PresentationSource.FromVisual(this) as HwndSource;
        if (windowSource == null)
             return;
         windowSource.AddHook(WiDiOnWindowMessage);

         try
          {
               _wiDi = new WiDi();
              _wiDi.ValidateWiDi();

                // This is async call so rest of logic handled in OnWiDiWindowMessage
                // Pass the window handle which WiDi extensions library uses to send messages back.
                _wiDi.Initialize((uint)windowSource.Handle.ToInt64());
            }
            catch (WiDiNoWelException)
            {
                ShowMessageDialog("Warning: The Intel® WiDi auto-connect button is not available.",
                                  "Please use the Intel® WiDi application to connect to your TV.\n" +
                                  "Alternatively you can use an HDMI cable.\n" +
                                  "Issue: The Intel® WiDi Extensions Library (WEL) cannot be found.");
            }
            catch (WiDiNoAppException)
            {
                ShowMessageDialog("Warning: Intel® WiDi is not available.",
                                  "Please use an HDMI cable to connect to your TV.\n" +
                                  "Issue: Intel® WiDi cannot be found or this PC may not be Intel® WiDi compatible.");
            }
            catch (WiDiException exception)
            {
                ShowMessageDialog("Warning: Intel® WiDi is not available.",
                                  "Please use an HDMI cable to connect to your TV.\n" +
                                  "Issue: " + exception.Message);
            }
        }

我的问题是，我的课程未继承 Window 。 OnSourceInitialized（EventArgs e）正在提供错误＆gt;

如何在同一代码中继承 Window 类。

Answer 1

您的视图模型可能有一个SourceInitialized方法，您附加到Window的SourceInitialized事件（而不是覆盖OnSourceInitialized方法）：

public class HomeWindowVm : BaseVm
{
    public void SourceInitialized(object sender, EventArgs e)
    {
        var window = (Window)sender;
        var windowSource = PresentationSource.FromVisual(window) as HwndSource;
        ...
    }
}

创建视图模型实例时，您可以像这样附加处理程序：

public MainWindow()
{
    InitializeComponent();

    var vm = new HomeWindowVm();
    SourceInitialized += vm.SourceInitialized;
    DataContext = vm;
}

Answer 2

您无法在ViewModel中执行此操作，因为您可以看到OnSourceInitialized是一个Window函数，因此只能在派生的Window类中重写。从Window派生VM没有意义，因为VM旨在向View提供DataContext（在您的情况下为窗口）。即使您从Window派生VM，也不是要覆盖此功能的Window。

所以在这种情况下，您可以将此代码保存在您的Windows代码中，我不认为这是MVVM的声音。

或者您可以定义附加行为并将其放在Window类上并检查行为本身的所有内容。

无法在MVVM中覆盖

2 个答案: