要在控件上创建新的事件处理程序,可以这样做
c.Click += new EventHandler(mainFormButton_Click);
或者这个
c.Click += mainFormButton_Click;
要删除事件处理程序,可以这样做
c.Click -= mainFormButton_Click;
但是如何从事件中删除所有事件处理程序呢?
要在控件上创建新的事件处理程序,可以这样做
c.Click += new EventHandler(mainFormButton_Click);
或者这个
c.Click += mainFormButton_Click;
要删除事件处理程序,可以这样做
c.Click -= mainFormButton_Click;
但是如何从事件中删除所有事件处理程序呢?
当前回答
我在MSDN论坛上找到了一个解决方案。下面的示例代码将删除button1中的所有Click事件。
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
button1.Click += button1_Click;
button1.Click += button1_Click2;
button2.Click += button2_Click;
}
private void button1_Click(object sender, EventArgs e) => MessageBox.Show("Hello");
private void button1_Click2(object sender, EventArgs e) => MessageBox.Show("World");
private void button2_Click(object sender, EventArgs e) => RemoveClickEvent(button1);
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]);
}
}
其他回答
我刚刚发现如何在设置WinForms控件的属性时挂起事件。它将删除控件中的所有事件:
namespace CMessWin05
{
public class EventSuppressor
{
Control _source;
EventHandlerList _sourceEventHandlerList;
FieldInfo _headFI;
Dictionary<object, Delegate[]> _handlers;
PropertyInfo _sourceEventsInfo;
Type _eventHandlerListType;
Type _sourceType;
public EventSuppressor(Control control)
{
if (control == null)
throw new ArgumentNullException("control", "An instance of a control must be provided.");
_source = control;
_sourceType = _source.GetType();
_sourceEventsInfo = _sourceType.GetProperty("Events", BindingFlags.Instance | BindingFlags.NonPublic);
_sourceEventHandlerList = (EventHandlerList)_sourceEventsInfo.GetValue(_source, null);
_eventHandlerListType = _sourceEventHandlerList.GetType();
_headFI = _eventHandlerListType.GetField("head", BindingFlags.Instance | BindingFlags.NonPublic);
}
private void BuildList()
{
_handlers = new Dictionary<object, Delegate[]>();
object head = _headFI.GetValue(_sourceEventHandlerList);
if (head != null)
{
Type listEntryType = head.GetType();
FieldInfo delegateFI = listEntryType.GetField("handler", BindingFlags.Instance | BindingFlags.NonPublic);
FieldInfo keyFI = listEntryType.GetField("key", BindingFlags.Instance | BindingFlags.NonPublic);
FieldInfo nextFI = listEntryType.GetField("next", BindingFlags.Instance | BindingFlags.NonPublic);
BuildListWalk(head, delegateFI, keyFI, nextFI);
}
}
private void BuildListWalk(object entry, FieldInfo delegateFI, FieldInfo keyFI, FieldInfo nextFI)
{
if (entry != null)
{
Delegate dele = (Delegate)delegateFI.GetValue(entry);
object key = keyFI.GetValue(entry);
object next = nextFI.GetValue(entry);
Delegate[] listeners = dele.GetInvocationList();
if(listeners != null && listeners.Length > 0)
_handlers.Add(key, listeners);
if (next != null)
{
BuildListWalk(next, delegateFI, keyFI, nextFI);
}
}
}
public void Resume()
{
if (_handlers == null)
throw new ApplicationException("Events have not been suppressed.");
foreach (KeyValuePair<object, Delegate[]> pair in _handlers)
{
for (int x = 0; x < pair.Value.Length; x++)
_sourceEventHandlerList.AddHandler(pair.Key, pair.Value[x]);
}
_handlers = null;
}
public void Suppress()
{
if (_handlers != null)
throw new ApplicationException("Events are already being suppressed.");
BuildList();
foreach (KeyValuePair<object, Delegate[]> pair in _handlers)
{
for (int x = pair.Value.Length - 1; x >= 0; x--)
_sourceEventHandlerList.RemoveHandler(pair.Key, pair.Value[x]);
}
}
}
}
如果你真的要这么做……这需要深思熟虑和相当长的时间。事件处理程序在控件内的事件委托映射中进行管理。你需要
在控件实例中反射并获取此映射。 迭代每个事件,获取委托 每个委托可以依次是一系列链接的事件处理程序。调用obControl。RemoveHandler(事件处理程序)
简而言之,工作量很大。在理论上是可能的。我从没试过这样的东西。
看看是否可以对订阅-退订阶段有更好的控制/纪律。
我讨厌这里展示的任何完整的解决方案,我现在做了一个混合和测试,为任何事件处理程序工作:
public class MyMain()
public void MyMethod() {
AnotherClass.TheEventHandler += DoSomeThing;
}
private void DoSomething(object sender, EventArgs e) {
Debug.WriteLine("I did something");
AnotherClass.ClearAllDelegatesOfTheEventHandler();
}
}
public static class AnotherClass {
public static event EventHandler TheEventHandler;
public static void ClearAllDelegatesOfTheEventHandler() {
foreach (Delegate d in TheEventHandler.GetInvocationList())
{
TheEventHandler -= (EventHandler)d;
}
}
}
简单!感谢Stephen Punak。
我使用它是因为我使用一个通用的本地方法来删除委托,当设置不同的委托时,在不同的情况下调用本地方法。
删除按钮的所有处理程序: save.RemoveEvents ();
public static class EventExtension
{
public static void RemoveEvents<T>(this T target) where T : Control
{
var propInfo = typeof(T).GetProperty("Events", BindingFlags.NonPublic | BindingFlags.Instance);
var list = (EventHandlerList)propInfo.GetValue(target, null);
list.Dispose();
}
}
有时我们不得不使用第三方控件,我们需要构建这些尴尬的解决方案。基于@Anoop Muraleedharan的答案,我创建了这个具有推理类型和ToolStripItem支持的解决方案
public static void RemoveItemEvents<T>(this T target, string eventName)
where T : ToolStripItem
{
RemoveObjectEvents<T>(target, eventName);
}
public static void RemoveControlEvents<T>(this T target, string eventName)
where T : Control
{
RemoveObjectEvents<T>(target, eventName);
}
private static void RemoveObjectEvents<T>(T target, string Event) where T : class
{
var typeOfT = typeof(T);
var fieldInfo = typeOfT.BaseType.GetField(
Event, BindingFlags.Static | BindingFlags.NonPublic);
var provertyValue = fieldInfo.GetValue(target);
var propertyInfo = typeOfT.GetProperty(
"Events", BindingFlags.NonPublic | BindingFlags.Instance);
var eventHandlerList = (EventHandlerList)propertyInfo.GetValue(target, null);
eventHandlerList.RemoveHandler(provertyValue, eventHandlerList[provertyValue]);
}
你可以这样使用它
var toolStripButton = new ToolStripButton();
toolStripButton.RemoveItemEvents("EventClick");
var button = new Button();
button.RemoveControlEvents("EventClick");