Question

我正在尝试将C ++库中的事件触发到C＃中的应用程序中。之前的问题：Using unmanaged pointer to callback function on managed C++

感谢我在那个问题评论中收到的帮助，以及Hans Passant回答的前一个问题的这个例子：c++/cli pass (managed) delegate to unmanaged code我思考我得到了它的工作，但是在真实的测试中硬件，事件不会触发。从调试器我可以看到当硬件I / O触发事件时调用函数callback_function，那里的指令打印相应的行，然后调用TriggerEvent（1），但是我没有收到C＃代码中的事件处理它。

我怀疑这与如何在＆＃34;步骤3＆＃34;之前创建新的CppDIOHandler实例有关，而不是在原始代码中创建委托。我尝试获取当前对象的句柄（类似于＆＃34;这个＆＃34;但是使用托管代码，使用GCHandle）来创建CallbackDelegate对象，没有运气。我不明白为什么我不能简单地使用callback = gcnew CallbackDelegate（＆amp; callback_function）而不是那条线。

#include "stdafx.h"
#include <WDT_DIO.H>
#include <string.h>
#include <stdio.h>

using namespace System;
using namespace System::Runtime::InteropServices;

public ref class PinStateChangedEventArgs : public EventArgs
{
public:
    property int Direction;
    property DateTime TimeReached;
};

public ref class CppDIOHandler
{
public:
    CppDIOHandler() {
    }

    delegate void CallbackDelegate(COS_INT_CALLBACK_ARG*);
    static CallbackDelegate^ callback;

    void __stdcall callback_function(COS_INT_CALLBACK_ARG* arg)
    {
        printf("data=0x%02x, flag=0x%02x, seq=%02d\n",
            arg->portData, arg->intrFlag, arg->intrSeq);
        TriggerEvent(1);
    }


    static void StartDIO() {
        //Step 1, initialize DIO library by invoking InitDIO()
        if (!InitDIO())
        {
            Console::WriteLine("InitDIO --> FAILED");
            return;
        }
        Console::WriteLine("InitDIO --> PASSED");

        //Step 2, setup Change-of-State Interrupt mask and level/edge mode
        COS_INT_SETUP setup;
        memset(&setup, 0, sizeof(setup));
        setup.portMask = 0x0f; // 00001111b, enable ch.0~3
        setup.edgeMode = 0x00; // generate interrupt on level change
        setup.edgeType = 0x00; // rising/falling edge, only effective when edgeMode = 1

        if (!SetupDICOS(&setup, sizeof(setup)))
        {
            Console::WriteLine("SetupDICOS --> FAILED");
            return;
        }
        Console::WriteLine("SetupDICOS --> PASSED");

        CppDIOHandler^ cdh = gcnew CppDIOHandler();
        callback = gcnew CallbackDelegate(cdh,&callback_function);
        IntPtr stubPointer = Marshal::GetFunctionPointerForDelegate(callback);
        COS_INT_CALLBACK functionPointer = static_cast<COS_INT_CALLBACK>(stubPointer.ToPointer());
        //TO-DO: Make callback static and remove the GC instruction
        //GC::KeepAlive(callback); 

        //Step 3, register the callback function
        if (!RegisterCallbackDICOS(functionPointer))
        {
            Console::WriteLine("RegisterCallbackDICOS --> FAILED");
            return;
        }
        Console::WriteLine("RegisterCallbackDICOS --> PASSED");
        //Step 4, start the DI Change-of-State Interrupt
        if (!StartDICOS())
        {
            Console::WriteLine("StartDICOS --> FAILED");
            return;
        }
        Console::WriteLine("StartDICOS --> PASSED");
    }

    void StopDIO() {
        //Step 5, stop the DI Change-of-State Interrupt operation
        if (!StopDICOS())
        {
            Console::WriteLine("StopDICOS --> FAILED");
            return;
        }
        Console::WriteLine("StopDICOS --> PASSED");
    }

    void TriggerEvent(int direction)
    {
            PinStateChangedEventArgs^ args = gcnew PinStateChangedEventArgs();
            args->Direction = direction;
            args->TimeReached = DateTime::Now;
            OnPinStateChanged(args);
    }

    event EventHandler<PinStateChangedEventArgs^>^ PinStateChanged;

    virtual void OnPinStateChanged(PinStateChangedEventArgs^ e)
    {
        PinStateChanged(this, e);
    }
};

C＃代码是微不足道的，所以似乎不太可能存在问题，我只是这样做了：

CppDIOHandler cc = new CppDIOHandler();
CppDIOHandler.StartDIO();
cc.PinStateChanged += Cs_PinStateChanged;

但是从不执行Cs_PinstateChanged回调。解决这个问题的正确方法是什么？是否真的有必要使用GCHandle来引用托管代码中的当前对象，否则这与我的问题无关？

在C ++ / CLI中从托管类生成的触发事件

0 个答案: