我的 DLL 中的虚拟 MouseButtonEventHandler 被调用应用程序覆盖

Question

我有我的 class 库，它在网格中动态创建标签

public class Class1
{
        public virtual event System.Windows.Input.MouseButtonEventHandler label_event;

        public Class1(Grid _grid)
        {
            Label l = new Label();
            l.Content = "label";
            l.Cursor = System.Windows.Input.Cursors.Hand;
            Grid.SetColumn(_grid, 0);
            Grid.SetRow(_grid, 0);
            _grid.Children.Add(l);

            l.MouseLeftButtonUp += label_event;
        }
}

从另一个应用程序创建此 class

Class1 class1 = new Class1(grid);
class1.label_event += l_MouseLeftButtonUp;
...
void l_MouseLeftButtonUp(object sender, System.Windows.Input.MouseButtonEventArgs e)
{
       Title = sender.ToString();
}
...

编译没有错误，但是执行后出现错误 l.MouseLeftButtonUp += label_event; "Cannot be null"

如何覆盖鼠标事件？

Answer 1

您应该在 Class1 中引发一个事件，然后在消费 class:

中处理它

public class Class1
{
    public event System.Windows.Input.MouseButtonEventHandler label_event;

    public Class1(Grid _grid)
    {
        Label l = new Label();
        l.Content = "label";
        l.Cursor = System.Windows.Input.Cursors.Hand;
        Grid.SetColumn(_grid, 0);
        Grid.SetRow(_grid, 0);
        _grid.Children.Add(l);

        l.MouseLeftButtonUp += (s,e) => label_event?.Invoke(this, e);
    }
}

我的 DLL 中的虚拟 MouseButtonEventHandler 被调用应用程序覆盖

Virtual MouseButtonEventHandler in my DLL overridden from calling application

wpf

events

virtual

overriding