如何使用反射从自定义控件中删除单击事件？

Question

我在 WPF 中有一个订阅 Click 事件的自定义控件 (MenuButton)。我现在想使用反射来取消订阅该事件。这是我的代码目前的样子：

private void RemoveClickEvent(MenuButton mbButton)
{
    FieldInfo fiFieldInfo = mbButton.GetType().GetField("Click", BindingFlags.Public | BindingFlags.NonPublic |
                                                        BindingFlags.Instance |BindingFlags.Static | BindingFlags.GetField);
    object objValue = fiFieldInfo.GetValue(mbButton);
    PropertyInfo piProprtyInfo = mbButton.GetType().GetProperty("Events", BindingFlags.Public | BindingFlags.NonPublic |
                                                                BindingFlags.Instance | BindingFlags.Static | BindingFlags.GetField | BindingFlags.GetProperty);

    EventHandlerList ehEventHandlers = (EventHandlerList)piProprtyInfo.GetValue(mbButton, null);
    ehEventHandlers.RemoveHandler(objValue, ehEventHandlers[objValue]);
}

我可以成功获取 FieldInfo 对象，但 PropertyInfo 对象显示为空。如何修复我的代码以使该方法正常工作？作为记录，我的目标是 .NET Framework 4。

编辑：

这是我订阅事件的方式。

private void PageStart()
{
    //Subscribe to the necessary event when a page is first loaded
    foreach (MenuButton mbItem in mbMenuButtonsList)
    {
        if (mbItem.HideExtraInfo == true)
        {
            mbButton.Click += (sender, e) => ShowOrHideControls(sender, e, true);
        }
        else
        {
            mbButton.Click += (sender, e) => ShowOrHideControls(sender, e, false);
        }
    }
}

private void PageEnd()
{
    //When moving to the next page, unsubscribe from the events
    foreach (MenuButton mbItem in mbMenuButtonsList)
    {
        RemoveClickEvent(mbItem);
    }
}

编辑#2：

我忽略了一点，我在项目中使用的一些事件也需要传入 MenuButton，如下所示：

UIElementCollection ctrlControls = MainCanvas.Children;
mbButton.Click += (sender, e) => ChangeControls(sender, e, mbButton, ctrlControls, false);

如果我停止使用 Lambda 表达式，我该如何解决这个问题？

Answer 1

如果您不使用 lambda 订阅您的事件，而是使用方法，那么取消订阅很容易：

if (mbItem.HideExtraInfo == true)
{
    mbButton.Click += ShowControls;
}
else
{
    mbButton.Click += HideControls;
}

private void ShowControls(object sender, EventArgs e) => ShowOrHideControls(sender, e, true);
private void HideControls(object sender, EventArgs e) => ShowOrHideControls(sender, e, false);

private void PageEnd()
{
    //When moving to the next page, unsubscribe from the events
    foreach (MenuButton mbItem in mbMenuButtonsList)
    {
        mbItem.Click -= ShowControls;
        mbItem.Click -= HideControls;
    }
}

Answer 2

这很容易处理，不要使用 lambda 表达式！

private void PageStart()
{
    //Subscribe to the necessary event when a page is first loaded
    foreach (MenuButton mbItem in mbMenuButtonsList)
    {
        if (mbItem.HideExtraInfo == true)
        {
            mbButton.Click += true_handler;
        }
        else
        {
            mbButton.Click += false_handler;
        }
    }
}

void true_handler(object sender, EventArgs args)
{
    ShowOrHideControls(sender, e, true);
}

void false_handler(object sender, EventArgs args)
{
    ShowOrHideControls(sender, e, false);
}

private void PageEnd()
{
    //When moving to the next page, unsubscribe from the events
    foreach (MenuButton mbItem in mbMenuButtonsList)
    {
        if (mbItem.HideExtraInfo == true)
        {
            mbButton.Click -= true_handler;
        }
        else
        {
            mbButton.Click -= false_handler;
        }
    }
}