本文介绍MFC中图像采集及图像处理的多线程编方法。创建了三个线程，分别为图像采集、图像处理及图像显示线程。线程之间的共享数据有保存的图像链表和图像处理结果存储结构。
图像链表：list<Hobject> imgList；
存储结构体：
struct ResultContainer
{
Hobject result_img;
HTuple time_needed;
HTuple result_handle;
HTuple result_data;
};
创建4个事件保证线程同步性
HANDLE fgStopEvent;
HANDLE newImageEvent;
HANDLE newResultEvent;
HANDLE containerIsFreeEvent;使用2个关键段保证共享数据使用的互斥性
CRITICAL_SECTION newImageMutex;
CRITICAL_SECTION resultDataMutex;同时在头文件中加入私有成员变量：
HANDLE dispThrHandle; //Win32线程句柄
unsigned int dispThreadId; //Win32线程标识符
HANDLE ipThrHandle; //Win32线程句柄
unsigned int ipThreadId; //Win32线程标识符
HANDLE fgThrHandle; //Win32线程句柄
unsigned int fgThreadId; //Win32线程标识符- 在初始化中进行关键段的初始化，创建线程等其他数据初始化过程：
关键段初始化：
InitializeCriticalSection(&newImageMutex);
InitializeCriticalSection(&resultDataMutex);设置事件句柄以同步线程：
fgStopEvent = CreateEvent(NULL,TRUE,FALSE,NULL);
newImageEvent = CreateEvent(NULL,FALSE,FALSE,NULL);
newResultEvent = CreateEvent(NULL,FALSE,FALSE,NULL);
containerIsFreeEvent =CreateEvent(NULL,FALSE,TRUE,NULL);初始化共享数据：
resultData.time_needed = NULL;
resultData.result_img = NULL;
resultData.result_handle = NULL;
resultData.result_data = NULL;其他：
ResetEvent(fgStopEvent); //设置fgStopEvent为无信号状态
InitialGrabOfImage(); //图像采集初始化- 设置一个启动按钮，开启线程，线程开启函数如下：
void CMultiThreading::StartThreads()
{
//所有事件设置为初始状态
ResetEvent(fgStopEvent);
ResetEvent(newImageEvent);
ResetEvent(newResultEvent);
SetEvent(containerIsFreeEvent);
imgList.clear();
// 开启线程
dispThrHandle = (HANDLE)_beginthreadex(NULL，0,
(unsigned (__stdcall *)(void*))&DISPRun,
this,
0,
&dispThreadId);
ipThrHandle = (HANDLE)_beginthreadex(NULL, 0,
(unsigned (__stdcall *)(void*))&IPRun,
this,
0,
&ipThreadId);
fgThrHandle = (HANDLE)_beginthreadex(NULL, 0,
(unsigned (__stdcall *)(void*))&ImgAcqRun,
this,
0,
&fgThreadId);
}- 设置一个停止按钮，停止所有线程，只需将停止事件设置为有信号状态：
SetEvent(fgStopEvent); - 图像采集线程：
void ImgAcqRun(void *pars)
{
HTuple sequenceName;
Hobject grabbedImage;
Hlong FGHandle;
CMultiThreadingDlg *MultiThrDlg = (CMultiThreadingDlg*) pars;
// --------------------- INIT ----------------------
sequenceName = "datacode/ecc200/ecc200.seq";
open_framegrabber("File",1,1,0,0,0,0,"default",-1,
"default",-1,"default",sequenceName,
"default",-1,-1,&FGHandle);
// ----------------- WAIT FOR EVENTS ---------------
while (WAIT_OBJECT_0 != WaitForSingleObject((MultiThrDlg->fgStopEvent),0)) //Stop按钮没有触发
{
grab_image_async(&grabbedImage,FGHandle,-1);
EnterCriticalSection(&MultiThrDlg->newImageMutex); // CriticalSect关键段
if((MultiThrDlg->imgList).size()<MAX_BUFFERS)
{
(MultiThrDlg->imgList).push_back(grabbedImage);
}
LeaveCriticalSection(&MultiThrDlg->newImageMutex); // CriticalSect
SetEvent(MultiThrDlg->newImageEvent); //触发事件
}
// ----------------- RESET/CLOSE ALL HANDLES -------
ResetEvent( MultiThrDlg->newImageEvent);
close_framegrabber(FGHandle);
return;
}- 图像处理线程：
void IPRun(void *pars)
{
HTuple T1,resultHandles,T2;
Hobject result_data, image;
CString sVal;
HANDLE eventHandle[2];
struct ResultContainer ResultDataIP;
CMultiThreadingDlg *MultiThrDlg = (CMultiThreadingDlg*) pars;
// -------------------- INIT ------------------------
//图像初始化操作
// ----------------- WAIT FOR EVENTS ---------------
eventHandle[0] = (*MultiThrDlg).newImageEvent;
eventHandle[1] = (*MultiThrDlg).fgStopEvent;
while (WAIT_OBJECT_0 == WaitForMultipleObjects(2,eventHandle,
FALSE,INFINITE))
{
EnterCriticalSection(&MultiThrDlg->newImageMutex); // CriticalSect
image = (MultiThrDlg->imgList).front();
MultiThrDlg->imgList.pop_front();
LeaveCriticalSection(&MultiThrDlg->newImageMutex); // CriticalSect
count_seconds(&T1);
//图像处理过程
count_seconds(&T2);
ResultDataIP.time_needed = 1000*(T2[0].D() - T1[0].D());
ResultDataIP.result_img = image;
ResultDataIP.result_handle = resultHandles;
ResultDataIP.result_data = result_data;
WaitForSingleObject(MultiThrDlg->containerIsFreeEvent,INFINITE);
EnterCriticalSection(&MultiThrDlg->resultDataMutex);
// CriticalSect
MultiThrDlg->resultData = ResultDataIP;
// CriticalSect
LeaveCriticalSection(&MultiThrDlg->resultDataMutex);
ResetEvent(MultiThrDlg->containerIsFreeEvent);
SetEvent( MultiThrDlg->newResultEvent);
}
// ----------------- RESET/CLOSE ALL HANDLES -------
ResetEvent(MultiThrDlg->newResultEvent);
return;
}- 显示线程：
void DISPRun(void *pars)
{
HTuple time,resultHandles,i;
Hobject result_data, image;
CString sVal;
Hlong wWindowID;
CRect rect;
HANDLE eventHandle[2];
struct ResultContainer rData;
CMultiThreadingDlg *MultiThrDlg = (CMultiThreadingDlg*) pars;
wWindowID = (Hlong)MultiThrDlg->ipWinStatic.m_hWnd;
MultiThrDlg->ipWinStatic.GetClientRect(&rect);
// -------------------- INIT -----------------------
set_check("~father");
open_window(0,0,rect.Width(),rect.Height(),wWindowID,
"visible","", &(MultiThrDlg->windowID));
set_check("father");
set_window_attr("border_width",0);
set_part(MultiThrDlg->windowID,0,0,MultiThrDlg->height-1,
MultiThrDlg->width-1);
set_color((MultiThrDlg->windowID),"green");
set_line_width(MultiThrDlg->windowID,3);
eventHandle[0] = ((*MultiThrDlg).newResultEvent);
eventHandle[1] = ((*MultiThrDlg)).fgStopEvent;
// ----------------- WAIT FOR EVENTS ---------------
while (WAIT_OBJECT_0 == WaitForMultipleObjects(2,eventHandle,
FALSE,INFINITE))
{
EnterCriticalSection(&MultiThrDlg->resultDataMutex); // CriticalSect
rData = MultiThrDlg->resultData; // CriticalSect
LeaveCriticalSection(&MultiThrDlg->resultDataMutex);
SetEvent(MultiThrDlg->containerIsFreeEvent);
time = rData.time_needed;
image = rData.result_img;
resultHandles = rData.result_handle;
result_data = rData.result_data;
disp_obj(image,HTuple(MultiThrDlg->windowID));
sVal.Format("%4.2f",time[0].D());
(MultiThrDlg->ipProcTime).SetWindowText(sVal + " ms");
disp_obj(symbolXLDs,HTuple(MultiThrDlg->windowID));
for (i=0; i<=(resultHandles.Num())-1; i+=1)
{
(MultiThrDlg->ipImgLabel).SetWindowText(decodedDataStrings[i]);
}
}
// ----------------- RESET/CLOSE ALL HANDLES ------
close_window(MultiThrDlg->windowID);
SetEvent(MultiThrDlg->containerIsFreeEvent);
MultiThrDlg->ipProcTime.SetWindowText("");
return;
}