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
我找到了这个答案,它几乎满足了我的需求。感谢SwDevMan81的课程。我已经修改了它,以允许抑制和恢复单个方法,我想我应该把它贴在这里。
// This class allows you to selectively suppress event handlers for controls. You instantiate
// the suppressor object with the control, and after that you can use it to suppress all events
// or a single event. If you try to suppress an event which has already been suppressed
// it will be ignored. Same with resuming; you can resume all events which were suppressed,
// or a single one. If you try to resume an un-suppressed event handler, it will be ignored.
//cEventSuppressor _supButton1 = null;
//private cEventSuppressor SupButton1 {
// get {
// if (_supButton1 == null) {
// _supButton1 = new cEventSuppressor(this.button1);
// }
// return _supButton1;
// }
//}
//private void button1_Click(object sender, EventArgs e) {
// MessageBox.Show("Clicked!");
//}
//private void button2_Click(object sender, EventArgs e) {
// SupButton1.Suppress("button1_Click");
//}
//private void button3_Click(object sender, EventArgs e) {
// SupButton1.Resume("button1_Click");
//}
using System;
using System.Collections.Generic;
using System.Text;
using System.Reflection;
using System.Windows.Forms;
using System.ComponentModel;
namespace Crystal.Utilities {
public class cEventSuppressor {
Control _source;
EventHandlerList _sourceEventHandlerList;
FieldInfo _headFI;
Dictionary<object, Delegate[]> suppressedHandlers = new Dictionary<object, Delegate[]>();
PropertyInfo _sourceEventsInfo;
Type _eventHandlerListType;
Type _sourceType;
public cEventSuppressor(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 Dictionary<object, Delegate[]> BuildList() {
Dictionary<object, Delegate[]> retval = 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);
retval = BuildListWalk(retval, head, delegateFI, keyFI, nextFI);
}
return retval;
}
private Dictionary<object, Delegate[]> BuildListWalk(Dictionary<object, Delegate[]> dict,
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);
if (dele != null) {
Delegate[] listeners = dele.GetInvocationList();
if (listeners != null && listeners.Length > 0) {
dict.Add(key, listeners);
}
}
if (next != null) {
dict = BuildListWalk(dict, next, delegateFI, keyFI, nextFI);
}
}
return dict;
}
public void Resume() {
}
public void Resume(string pMethodName) {
//if (_handlers == null)
// throw new ApplicationException("Events have not been suppressed.");
Dictionary<object, Delegate[]> toRemove = new Dictionary<object, Delegate[]>();
// goes through all handlers which have been suppressed. If we are resuming,
// all handlers, or if we find the matching handler, add it back to the
// control's event handlers
foreach (KeyValuePair<object, Delegate[]> pair in suppressedHandlers) {
for (int x = 0; x < pair.Value.Length; x++) {
string methodName = pair.Value[x].Method.Name;
if (pMethodName == null || methodName.Equals(pMethodName)) {
_sourceEventHandlerList.AddHandler(pair.Key, pair.Value[x]);
toRemove.Add(pair.Key, pair.Value);
}
}
}
// remove all un-suppressed handlers from the list of suppressed handlers
foreach (KeyValuePair<object, Delegate[]> pair in toRemove) {
for (int x = 0; x < pair.Value.Length; x++) {
suppressedHandlers.Remove(pair.Key);
}
}
//_handlers = null;
}
public void Suppress() {
Suppress(null);
}
public void Suppress(string pMethodName) {
//if (_handlers != null)
// throw new ApplicationException("Events are already being suppressed.");
Dictionary<object, Delegate[]> dict = BuildList();
foreach (KeyValuePair<object, Delegate[]> pair in dict) {
for (int x = pair.Value.Length - 1; x >= 0; x--) {
//MethodInfo mi = pair.Value[x].Method;
//string s1 = mi.Name; // name of the method
//object o = pair.Value[x].Target;
// can use this to invoke method pair.Value[x].DynamicInvoke
string methodName = pair.Value[x].Method.Name;
if (pMethodName == null || methodName.Equals(pMethodName)) {
_sourceEventHandlerList.RemoveHandler(pair.Key, pair.Value[x]);
suppressedHandlers.Add(pair.Key, pair.Value);
}
}
}
}
}
}
其他回答
斯蒂芬是对的。这很简单:
public event EventHandler<Cles_graph_doivent_etre_redessines> les_graph_doivent_etre_redessines;
public void remove_event()
{
if (this.les_graph_doivent_etre_redessines != null)
{
foreach (EventHandler<Cles_graph_doivent_etre_redessines> F_les_graph_doivent_etre_redessines in this.les_graph_doivent_etre_redessines.GetInvocationList())
{
this.les_graph_doivent_etre_redessines -= F_les_graph_doivent_etre_redessines;
}
}
}
好吧,这里有另一个解决方案来删除关联事件(如果你已经有一个方法来处理控件的事件):
EventDescriptor ed = TypeDescriptor.GetEvents(this.button1).Find("MouseDown",true);
Delegate delegate = Delegate.CreateDelegate(typeof(EventHandler), this, "button1_MouseDownClicked");
if(ed!=null)
ed.RemoveEventHandler(this.button1, delegate);
从删除所有事件处理程序:
Directly no, in large part because you cannot simply set the event to null. Indirectly, you could make the actual event private and create a property around it that tracks all of the delegates being added/subtracted to it. Take the following: List<EventHandler> delegates = new List<EventHandler>(); private event EventHandler MyRealEvent; public event EventHandler MyEvent { add { MyRealEvent += value; delegates.Add(value); } remove { MyRealEvent -= value; delegates.Remove(value); } } public void RemoveAllEvents() { foreach(EventHandler eh in delegates) { MyRealEvent -= eh; } delegates.Clear(); }
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]);
}
}
}
}