DS-4000系列板卡SDK and Demo Version 5.1 中的错误

错误定位

1，工程名字：Src/NetDemoSource/NetServerDemo 工程名: HKVision。服务器端的demo。
2，文件和错误定位：
1）中断出现在HKVision.cpp中86行的语句： int nResponse = dlg.DoModal();

BOOL CHKVisionApp::InitInstance()
{
if (!AfxSocketInit())
{
AfxMessageBox(IDP_SOCKETS_INIT_FAILED);
return FALSE;
}
AfxEnableControlContainer();
// Standard initialization
// If you are not using these features and wish to reduce the size
//  of your final executable, you should remove from the following
//  the specific initialization routines you do not need.
#ifdef _AFXDLL
Enable3dControls();			// Call this when using MFC in a shared DLL
#else
Enable3dControlsStatic();	// Call this when linking to MFC statically
#endif
int w = GetSystemMetrics(SM_CXSCREEN);
int h = GetSystemMetrics(SM_CYSCREEN);
if((w < 1024)||(h < 768)){
AfxMessageBox("You must set display resolution to 1024x768 or more in order to run the program/n");
return FALSE;
}
CHKVisionDlg dlg;
m_pMainWnd = &dlg;
RegisterLogRecordCallback(LogRecordFunc, &dlg);
int nResponse = dlg.DoModal();
if (nResponse == IDOK)
{
// TODO: Place code here to handle when the dialog is
//  dismissed with OK
}
else if (nResponse == IDCANCEL)
{
// TODO: Place code here to handle when the dialog is
//  dismissed with Cancel
}
// Since the dialog has been closed, return FALSE so that we exit the
//  application, rather than start the application's message pump.
return FALSE;
}

 
2）调试跟踪到了HKVisionDlg.cpp中函数BOOL CHKVisionDlg::OnInitDialog()中语句：
 
if (!MP4_ServerStart(&videoinfo))

{

MessageBox("error","error",MB_OK);

}

具体位置在459行。

 

3）最终错误定位在函数：
int __cdecl StreamDirectReadCallback(ULONG channelNum,void *DataBuf,DWORD Length,int frameType,void *context)
该函数中的：
 
CHKVisionDlg *pMain = (CHKVisionDlg *)AfxGetMainWnd();
pMain->GetDlgItem(IDC_BPS)->SetWindowText((LPCTSTR)str);
 

 

错误分析：

MP4_ServerStart时候，调用回调函数StreamDirectReadCallback函数，估计（源码未公开）是专门开了一个线程调用StreamDirectReadCallback函数。在StreamDirectReadCallback函数中使用了AfxGetMainWnd()。而AfxGetMainWnd函数返回null，可以google “AfxGetMainWnd null” "AfxGetMainWnd 失效"。
http://topic.csdn.net/u/20100430/10/1FF4D768-E1A3-4B4D-8F77-0EFB2A3DFD08.html  

解决方法：

将pMain作为全局的CHKVisionDlg*指针，初始化为NULL，在CHKVisionDlg::OnInitDialog 中，函数结尾处添加：
pMain = this;
最后再StreamDirectReadCallback中可以直接使用pMain了。。。
 

后记

错误定位最为痛苦。步骤1，到步骤2，再到步骤3的跟踪很需要想象力，直接F11根本跟不过去，一个下午才解决。所以写出来~，跟大家分享~