我有一个第三方编辑器,基本上包括一个文本框和一个按钮(DevExpress ButtonEdit控件).我想做一个特定的击键(Alt+ Down)模拟点击按钮.为了避免一遍又一遍地写这个,我想创建一个通用的KeyUp事件处理程序,它将引发ButtonClick事件.不幸的是,控件中似乎没有引发ButtonClick事件的方法,所以...
如何通过反射从外部函数引发事件？
这是使用泛型的演示(省略错误检查):
using System;
using System.Reflection;
static class Program {
private class Sub {
public event EventHandler SomethingHappening;
}
internal static void Raise(this object source, string eventName, TEventArgs eventArgs) where TEventArgs : EventArgs
{
var eventDelegate = (MulticastDelegate)source.GetType().GetField(eventName, BindingFlags.Instance | BindingFlags.NonPublic).GetValue(source);
if (eventDelegate != null)
{
foreach (var handler in eventDelegate.GetInvocationList())
{
handler.Method.Invoke(handler.Target, new object[] { source, eventArgs });
}
}
}
public static void Main()
{
var p = new Sub();
p.Raise("SomethingHappening", EventArgs.Empty);
p.SomethingHappening += (o, e) => Console.WriteLine("Foo!");
p.Raise("SomethingHappening", EventArgs.Empty);
p.SomethingHappening += (o, e) => Console.WriteLine("Bar!");
p.Raise("SomethingHappening", EventArgs.Empty);
Console.ReadLine();
}
}
一般来说,你不能.将事件看作基本上成对AddHandler/ RemoveHandler方法(因为它基本上就是它们是什么).它们如何实施取决于课程.大多数WinForms控件都EventHandlerList用作它们的实现,但是如果它开始获取私有字段和键,你的代码将非常脆弱.
ButtonEdit控件是否公开了一个OnClick可以调用的方法？
脚注:实际上,事件可以 "提升"成员,因此EventInfo.GetRaiseMethod.但是,这从未被C#填充过,我也不相信它在框架中也是如此.
你通常不能提出另一个类事件.事件实际上存储为私有委托字段,以及两个访问器(add_event和remove_event).
要通过反射来完成它,您只需要找到私有委托字段,获取它,然后调用它.
我写了一个类的扩展,它实现了INotifyPropertyChanged以注入RaisePropertyChange
this.RaisePropertyChanged(() => MyProperty);
没有在任何基类中实现该方法.对于我的使用它是慢,但也许源代码可以帮助某人.
所以这里是:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Diagnostics;
using System.Linq.Expressions;
using System.Reflection;
using System.Globalization;
namespace Infrastructure
{
///
/// Adds a RaisePropertyChanged method to objects implementing INotifyPropertyChanged.
///
public static class NotifyPropertyChangeExtension
{
#region private fields
private static readonly Dictionary eventArgCache = new Dictionary();
private static readonly object syncLock = new object();
#endregion
#region the Extension's
///
/// Verifies the name of the property for the specified instance.
///
/// The bindable object.
/// Name of the property.
[Conditional("DEBUG")]
public static void VerifyPropertyName(this INotifyPropertyChanged bindableObject, string propertyName)
{
bool propertyExists = TypeDescriptor.GetProperties(bindableObject).Find(propertyName, false) != null;
if (!propertyExists)
throw new InvalidOperationException(string.Format(CultureInfo.CurrentCulture,
"{0} is not a public property of {1}", propertyName, bindableObject.GetType().FullName));
}
///
/// Gets the property name from expression.
///
/// The notify object.
/// The property expression.
/// a string containing the name of the property.
public static string GetPropertyNameFromExpression(this INotifyPropertyChanged notifyObject, Expression> propertyExpression)
{
return GetPropertyNameFromExpression(propertyExpression);
}
///
/// Raises a property changed event.
///
/// (this INotifyPropertyChanged bindableObject, Expression> propertyExpression)
{
RaisePropertyChanged(bindableObject, GetPropertyNameFromExpression(propertyExpression));
}
#endregion
///
/// Raises the property changed on the specified bindable Object.
///
/// The bindable object.
/// Name of the property.
private static void RaisePropertyChanged(INotifyPropertyChanged bindableObject, string propertyName)
{
bindableObject.VerifyPropertyName(propertyName);
RaiseInternalPropertyChangedEvent(bindableObject, GetPropertyChangedEventArgs(propertyName));
}
///
/// Raises the internal property changed event.
///
/// The bindable object.
/// The
/// Gets the property name from an expression.
///
/// The property expression.
/// The property name as string.
private static string GetPropertyNameFromExpression(Expression> propertyExpression)
{
var lambda = (LambdaExpression)propertyExpression;
MemberExpression memberExpression;
if (lambda.Body is UnaryExpression)
{
var unaryExpression = (UnaryExpression)lambda.Body;
memberExpression = (MemberExpression)unaryExpression.Operand;
}
else memberExpression = (MemberExpression)lambda.Body;
return memberExpression.Member.Name;
}
///
/// Returns an instance of PropertyChangedEventArgs for the specified property name.
///
///
/// The name of the property to create event args for.
///
private static PropertyChangedEventArgs GetPropertyChangedEventArgs(string propertyName)
{
PropertyChangedEventArgs args;
lock (NotifyPropertyChangeExtension.syncLock)
{
if (!eventArgCache.TryGetValue(propertyName, out args))
eventArgCache.Add(propertyName, args = new PropertyChangedEventArgs(propertyName));
}
return args;
}
}
}
我删除了原始代码的一些部分,因此扩展应该按原样工作,而不引用我的库的其他部分.但它并没有真正经过测试.
PS代码的某些部分是从别人那里借来的.对我感到羞耻,我忘记了从哪里得到它.:(
从通过反思提升事件,虽然我认为VB.NET中的答案,即在此之前的两个帖子将为您提供通用方法(例如,我将看一下VB.NET的灵感来源于引用不在同一类中的类型):
public event EventHandlerMyEventToBeFired; public void FireEvent(Guid instanceId, string handler) { // Note: this is being fired from a method with in the same // class that defined the event (that is, "this"). EventArgs e = new EventArgs(instanceId); MulticastDelegate eventDelagate = (MulticastDelegate)this.GetType().GetField(handler, System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.NonPublic).GetValue(this); Delegate[] delegates = eventDelagate.GetInvocationList(); foreach (Delegate dlg in delegates) { dlg.Method.Invoke(dlg.Target, new object[] { this, e }); } } FireEvent(new Guid(), "MyEventToBeFired");
事实证明,我可以做到这一点并没有意识到:
buttonEdit1.Properties.Buttons[0].Shortcut = new DevExpress.Utils.KeyShortcut(Keys.Alt | Keys.Down);
但如果我不能,我将不得不深入研究源代码并找到引发事件的方法.
谢谢你们的帮助.
如果您知道控件是一个按钮,则可以调用其PerformClick()方法.我有其他事件像类似的问题OnEnter,OnExit.如果我不想为每种控件类型派生新类型,则无法引发这些事件.
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