如何刪除「按鈕」的「點擊」事件的所有事件處理程序？

Question

我有一個按鈕控件，我需要刪除所有連接到它的Click event的事件處理程序。

這怎麼可能？

Button button = GetButton(); 
button.Click.RemoveAllEventHandlers(); 

Answer 1

你不能，基本上 - 至少不是沒有反思和大量的不滿。

事件嚴格地是「訂閱，取消訂閱」 - 你不能取消訂閱別人的處理程序，除了你可以改變別人對對象的引用。

Answer 2

我在這裏找到這個答案在計算器上：

How to remove all event handlers from a control

private void RemoveClickEvent(Button b) 
{ 
    FieldInfo f1 = typeof(Control).GetField("EventClick", 
     BindingFlags.Static | BindingFlags.NonPublic); 
    object obj = f1.GetValue(b); 
    PropertyInfo pi = b.GetType().GetProperty("Events", 
     BindingFlags.NonPublic | BindingFlags.Instance); 
    EventHandlerList list = (EventHandlerList)pi.GetValue(b, null); 
    list.RemoveHandler(obj, list[obj]); 
} 

其中的原始海報發現here：

Answer 3

注意：由於這個問題上，我貼我的原答案已關閉as a duplicate這個問題，我交叉發佈我的答案的改進版本他回覆。 此答案只適用於WPF。它不適用於Windows窗體或任何其他UI框架。

下面是一個有用的實用程序方法，用於刪除訂閱給定元素上的路由事件的所有事件處理程序。如果你喜歡，你可以簡單地將其轉換爲擴展方法。

/// <summary> 
/// Removes all event handlers subscribed to the specified routed event from the specified element. 
/// </summary> 
/// <param name="element">The UI element on which the routed event is defined.</param> 
/// <param name="routedEvent">The routed event for which to remove the event handlers.</param> 
public static void RemoveRoutedEventHandlers(UIElement element, RoutedEvent routedEvent) 
{ 
    // Get the EventHandlersStore instance which holds event handlers for the specified element. 
    // The EventHandlersStore class is declared as internal. 
    var eventHandlersStoreProperty = typeof(UIElement).GetProperty(
     "EventHandlersStore", BindingFlags.Instance | BindingFlags.NonPublic); 
    object eventHandlersStore = eventHandlersStoreProperty.GetValue(element, null); 

    // If no event handlers are subscribed, eventHandlersStore will be null. 
    // Credit: https://stackoverflow.com/a/16392387/1149773 
    if (eventHandlersStore == null) 
     return; 

    // Invoke the GetRoutedEventHandlers method on the EventHandlersStore instance 
    // for getting an array of the subscribed event handlers. 
    var getRoutedEventHandlers = eventHandlersStore.GetType().GetMethod(
     "GetRoutedEventHandlers", BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic); 
    var routedEventHandlers = (RoutedEventHandlerInfo[])getRoutedEventHandlers.Invoke(
     eventHandlersStore, new object[] { routedEvent }); 

    // Iteratively remove all routed event handlers from the element. 
    foreach (var routedEventHandler in routedEventHandlers) 
     element.RemoveHandler(routedEvent, routedEventHandler.Handler); 
} 

然後，您可以方便地調用您的按鈕的Click情況下，本實用方法：

RemoveRoutedEventHandlers(button, Button.ClickEvent); 

編輯：我已經複製了bug fix implemented by corona，從扔NullReferenceException在任何情況下，停止方法處理程序已訂閱。信用（和upvotes）應該去他們的答案。

Answer 4

我的代碼Jamie Dixon發佈了一個空錯誤問題，並且沒有發生Click事件。

private void RemoveClickEvent(Control control) 
{ 
    // chenged "FieldInfo f1 = typeof(Control)" to "var f1 = b.GetType()". By changing to 
    // the type of the passed in control we can use this for any control with a click event. 
    // using var allows for null checking and lowering the chance of exceptions. 

    var fi = control.GetType().GetField("EventClick", BindingFlags.Static | BindingFlags.NonPublic); 
    if (fi != null) 
    { 
     object obj = fi.GetValue(control); 
     PropertyInfo pi = control.GetType().GetProperty("Events", BindingFlags.NonPublic | BindingFlags.Instance); 
     EventHandlerList list = (EventHandlerList)pi.GetValue(control, null); 
     list.RemoveHandler(obj, list[obj]); 
    } 

} 

然後一個小的改變，它應該是任何事件。

private void RemoveClickEvent(Control control, string theEvent) 
{ 
    // chenged "FieldInfo f1 = typeof(Control)" to "var f1 = b.GetType()". By changing to 
    // the type of the passed in control we can use this for any control with a click event. 
    // using var allows for null checking and lowering the chance of exceptions. 

    var fi = control.GetType().GetField(theEvent, BindingFlags.Static | BindingFlags.NonPublic); 
    if (fi != null) 
    { 
     object obj = fi.GetValue(control); 
     PropertyInfo pi = control.GetType().GetProperty("Events", BindingFlags.NonPublic | BindingFlags.Instance); 
     EventHandlerList list = (EventHandlerList)pi.GetValue(control, null); 
     list.RemoveHandler(obj, list[obj]); 
    } 

} 

我想這可以做得更好，但它適用於我目前的需要。希望這對某人有用。

Answer 5

只是想擴大道格拉斯的例程略，我非常喜歡。 我發現我需要將額外的空檢查添加到eventHandlersStore來處理傳遞的元素沒有附加任何事件的任何情況。

/// <summary> 
/// Removes all event handlers subscribed to the specified routed event from the specified element. 
/// </summary> 
/// <param name="element">The UI element on which the routed event is defined.</param> 
/// <param name="routedEvent">The routed event for which to remove the event handlers.</param> 
public static void RemoveRoutedEventHandlers(UIElement element, RoutedEvent routedEvent) 
{ 
    // Get the EventHandlersStore instance which holds event handlers for the specified element. 
    // The EventHandlersStore class is declared as internal. 
    var eventHandlersStoreProperty = typeof(UIElement).GetProperty(
     "EventHandlersStore", BindingFlags.Instance | BindingFlags.NonPublic); 
    object eventHandlersStore = eventHandlersStoreProperty.GetValue(element, null); 

    if (eventHandlersStore == null) return; 

    // Invoke the GetRoutedEventHandlers method on the EventHandlersStore instance 
    // for getting an array of the subscribed event handlers. 
    var getRoutedEventHandlers = eventHandlersStore.GetType().GetMethod(
     "GetRoutedEventHandlers", BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic); 
    var routedEventHandlers = (RoutedEventHandlerInfo[])getRoutedEventHandlers.Invoke(
     eventHandlersStore, new object[] { routedEvent }); 

    // Iteratively remove all routed event handlers from the element. 
    foreach (var routedEventHandler in routedEventHandlers) 
     element.RemoveHandler(routedEvent, routedEventHandler.Handler); 
}