C / C++ / MFC

// The following ifdef block is the standard way of creating macros which make exporting <br />
// from a DLL simpler. All files within this DLL are compiled with the NATIVEDLL_EXPORTS<br />
// symbol defined on the command line. this symbol should not be defined on any project<br />
// that uses this DLL. This way any other project whose source files include this file see <br />
// NATIVEDLL_API functions as being imported from a DLL, whereas this DLL sees symbols<br />
// defined with this macro as being exported.<br />
#ifdef NATIVEDLL_EXPORTS<br />
#define NATIVEDLL_API extern "C" __declspec(dllexport)<br />
#else<br />
#define NATIVEDLL_API __declspec(dllimport)<br />
#endif<br />
<br />
// ********************************************************<br />
// Callback function type definition for a function that is <br />
//  called when the processing performed by the native DLL<br />
//  is complete<br />
// <br />
// Function has no return value & no parameters.<br />
//  Example: void MyWorkCompleteFunction()<br />
typedef void (CALLBACK *NATIVEWORKCOMPLETEPROC)();<br />
<br />
// Callback function type definition for a function that is<br />
//  is called within each iteration of the native processing<br />
//  loop. Native processing will continue until the provided<br />
//  function returns 0;<br />
//<br />
// Function has BOOL return value (int in C#, Integer in VB.NET)<br />
// Function accepts an LPARAM as a parameter (IntPtr in .NET CF)<br />
//  The LPARAM parameter passes application defined data<br />
//  back to the application. The LPARAM is initially provided<br />
//  to the native DLL on the call to StartNativeProcessingWithControlProc<br />
//  function.<br />
typedef BOOL (CALLBACK *NATIVEWORKCONTROLPROC)(LPARAM lParam);<br />
// ********************************************************<br />
<br />
// Initiate processing on a background thread. When processing is complete,<br />
//  the workCompleteProc callback function is called<br />
NATIVEDLL_API void StartNativeProcessing(NATIVEWORKCOMPLETEPROC workCompleteProc);<br />
<br />
// Initiate processing on a background thread. On each iteration of the<br />
//  loop, the workControlProc function is called with the lParam passed<br />
//  as a parameter. The processing on the background thread continues<br />
//  until the workControlProc callback function returns 0. When processing <br />
//  is complete, the workCompleteProc callback function is called<br />
NATIVEDLL_API void StartNativeProcessingWithControlProc(<br />
	NATIVEWORKCONTROLPROC workControlProc, LPARAM lParam, NATIVEWORKCOMPLETEPROC workCompleteProc);<br />

// NativeDLL.cpp : Defines the entry point for the DLL application.<br />
//<br />
<br />
#include "stdafx.h"<br />
#include "NativeDLL.h"<br />
#include <windows.h><br />
#include <commctrl.h><br />
<br />
BOOL APIENTRY DllMain( HANDLE hModule, <br />
                       DWORD  ul_reason_for_call, <br />
                       LPVOID lpReserved<br />
					 )<br />
{<br />
	switch (ul_reason_for_call)<br />
	{<br />
	case DLL_PROCESS_ATTACH:<br />
	case DLL_THREAD_ATTACH:<br />
	case DLL_THREAD_DETACH:<br />
	case DLL_PROCESS_DETACH:<br />
		break;<br />
	}<br />
    return TRUE;<br />
}<br />
<br />
// The reference to the NATIVEWORKCOMPLETEPROC callback function<br />
NATIVEWORKCOMPLETEPROC g_workCompleteProc = NULL;<br />
NATIVEWORKCONTROLPROC g_workControlProc = NULL;<br />
<br />
// Sleep time to simulate work<br />
const int workSleepTimeInMilliseconds = 1500;<br />
<br />
// Forward declerations<br />
DWORD WINAPI ThreadFunc(void* pvThreadParam);<br />
void DoWork();<br />
<br />
// Initiate processing on a background thread. When processing is complete,<br />
//  the workCompleteProc callback function is called<br />
NATIVEDLL_API  void StartNativeProcessing(NATIVEWORKCOMPLETEPROC workCompleteProc)<br />
{<br />
	g_workCompleteProc = workCompleteProc;<br />
	g_workControlProc = NULL;<br />
<br />
	DWORD dwThreadId;<br />
	CreateThread(0, 0, ThreadFunc, NULL, 0, &dwThreadId);	<br />
}<br />
<br />
// Initiate processing on a background thread. On each iteration of the<br />
//  loop, the workControlProc function is called with the lParam passed<br />
//  as a parameter. The processing on the background thread continues<br />
//  until the workControlProc callback function returns 0. When processing <br />
//  is complete, the workCompleteProc callback function is called<br />
NATIVEDLL_API void StartNativeProcessingWithControlProc(<br />
	NATIVEWORKCONTROLPROC workControlProc, LPARAM lParam, NATIVEWORKCOMPLETEPROC workCompleteProc)<br />
{<br />
	g_workCompleteProc = workCompleteProc;<br />
	g_workControlProc = workControlProc;<br />
	<br />
	DWORD dwThreadId;<br />
	CreateThread(0, 0, ThreadFunc, (void*)lParam, 0, &dwThreadId);		<br />
}<br />
<br />
// Functioning running on background thread that simulates<br />
//  some sort of data processing. If only a NATIVEWORKCOMPLETEPROC<br />
//  callback function is provided, ThreadFunc will go through the loop once<br />
// If a NATIVEWORKCONTROLPROC callback function is provided, ThreadFunc will loop<br />
//  until the NATIVEWORKCONTROLPROC callback function returns 0<br />
DWORD WINAPI ThreadFunc(void* pvThreadParam)<br />
{<br />
	int loopControl = 0;<br />
<br />
	do<br />
	{<br />
		DoWork();<br />
		if (g_workControlProc != NULL)<br />
			loopControl = g_workControlProc((LPARAM)pvThreadParam);<br />
	}<br />
	while(loopControl != 0);<br />
<br />
	if (g_workCompleteProc != NULL)<br />
		g_workCompleteProc();<br />
<br />
	return 0;<br />
}<br />
<br />
// Simulate doing work for sleeping the specified period of time<br />
void DoWork()<br />
{<br />
	Sleep(workSleepTimeInMilliseconds);<br />
}