从C++中处理事件遇到问题需要在C＃中处理

Question

我正在尝试编写一个使用C++ DLL的基于C＃的WPF应用程序。 C＃应用程序用于用户界面，它具有WPF的所有优点。 C++ DLL使用Win32函数（例如枚举窗口）。

现在我想让C++ DLL引发可以在C＃应用程序中处理的事件。这是我试过（基于this article）：

//cpp file 

#using <System.dll> 

using namespace System; 

struct WIN { 
    HWND Handle; 
    char ClassName; 
    char Title; 
}; 

delegate void wDel(WIN); 
event wDel^ wE; 
void GotWindow(WIN Window) { 
    wE(Window); 
} 

当我尝试编译这段代码，这些错误抛出：

C3708: 'wDel': improper use of 'event'; must be a member of a compatible event source

C2059: syntax error: 'event'

C3861: 'wE': identifier not found

Answer 1

你的事件需要是一些管理成员类，可能是静态的。例如：

#include "stdafx.h" 
#include "windows.h" 

using namespace System; 

struct WIN { 
    HWND Handle; 
    char ClassName; 
    char Title; 
}; 

delegate void wDel(WIN); 

ref class WindowEvents abstract sealed // abstract sealed ref class in c++/cli is like a static class in c# 
{ 
    public: 
     static event wDel^ wE; 

     static void GotWindow(WIN Window) { 
      wE(Window); 
     } 
}; 

更新

如果需要convert your unmanaged HWND to an IntPtr，因为IntPtr是standard P/Invoke signature for an HWND in c#，你可能会考虑类似以下内容：

#include "stdafx.h" 
#include "windows.h" 

using namespace System; 

#pragma managed(push,off) 

struct WIN { // Unmanaged c++ struct encapsulating the unmanaged data. 
    HWND Handle; 
    char ClassName; 
    char Title; 
}; 

#pragma managed(pop) 

public value struct ManagedWIN // Managed c++/CLI translation of the above. 
{ 
public: 
    IntPtr Handle; // Wrapper for an HWND 
    char ClassName; 
    char Title; 
    ManagedWIN(const WIN win) : Handle(win.Handle), ClassName(win.ClassName), Title(win.Title) 
    { 
    } 
}; 

public delegate void wDel(ManagedWIN); 

public ref class WindowEvents abstract sealed // abstract sealed ref class in c++/cli is like a static class in c# 
{ 
    public: 
     static event wDel^ wE; 

    internal: 
     static void GotWindow(WIN Window) { 
      wE(ManagedWIN(Window)); 
     } 
}; 

这里ManagedWIN只包含安全的.Net类型。