c# - 事件处理程序空

Question

在MainWindow构造函数中，我正在注册一个事件处理程序：

public partial class MainWindow : Window, INotifyPropertyChanged
{
    public MainWindow()
    {
        InitializeComponent();
        pageViewDocText = new PageViewDocText();
        framePageDocFieldDetail.Content = pageViewDocText;
        pageViewDocText.NewPageIRPRO += new GabeLib.SearchCls.DocEventHandler(ViewIPRO);
    }

    protected void ViewIPRO(string IRPOlink) // ...
}

public partial class PageViewDocText : Page, INotifyPropertyChanged
{
    public event GabeLib.SearchCls.DocEventHandler NewPageIRPRO;

    private void btn_PageBreakNext(object sender, RoutedEventArgs e)
    {
        // this fires but NewPageIRPRO is null
        if (NewPageIRPRO != null)
        {
            NewPageIRPRO("dummylink");
        }
    }
}

但在 中PageViewDocText，NewPageIRPRO为空

我究竟做错了什么？
从PageViewDocText，我想打电话MainWindow.ViewIPRO。

此事件处理程序触发并注册 pageViewDocText.NewPageIRPRO += 下面的行

App.StaticGabeLib.Search.NewDocIRPRO += new GabeLib.SearchCls.DocEventHandler(ViewIPRO);

Answer 1

看起来您正在从另一个类（未列出）调用一个事件，并且缺少一个委托。

试试这个代码：

public partial class MainWindow : Window, INotifyPropertyChanged
{
    public MainWindow()
    {
        InitializeComponent();
        pageViewDocText = new PageViewDocText();
        framePageDocFieldDetail.Content = pageViewDocText;
        pageViewDocText.PageBreakNext += new PageBreakNext(ViewIPRO);
    }

    protected void ViewIPRO(string IRPOlink) // ...
}

public partial class PageViewDocText : Page, INotifyPropertyChanged
{
    public delegate void PageBreakNext(string IRPOlink);
    public event PageBreakNext PageBreak;

    private void btn_PageBreakNext(object sender, RoutedEventArgs e)
    {
        // this fires but NewPageIRPRO is null
        if (PageBreak != null)
        {
            PageBreak("dummylink");
        }
    }
}