我读了一些关于如何将数据从Workerthread传递到主窗口(对话框)的线程,但我仍然不理解,仍然需要帮助。我的工作人员阅读应该处理一些计算,并在每次循环期间将结果显示给GUI上的编辑。我知道,我应该使用PostMessage,但由于我正在进行的计算暗示了一个控制元素,我不知道如何解决这个问题。。。
//CWorkerThreadMgr.h manages the second thread
HRESULT Start (HWND hWnd);// from where the workerthread will be started
HWND m_hWnd ; //Window handle to the UI ;
HANDLE m_hTread; //handle of the worker thread
static UINT WINAPI ThreadProc( LPVOID lptest );
static UINT WINAPI ThreadProc( LPVOID lptest )
{
CWorkerThreadMgr* pCalculateMgr = reinterpret_cast< CWorkerThreadMgr*(lptest);
//The following operation:rand() *m_Slider.GetPos() should
//should be calculated and the result displayed each time in the edit box in the gui
for( UINT uCount = 0; uCount < 40; uCount++ ){
pCalculateMgr->rand() *m_Slider.GetPos();//?don't allowed to touch the gui!!
PostMessage(pCalculateMgr-> m_hWnd, WM_SENDCALCULATED_VALUE,wparam(rand() *m_Slider.GetPos(),0);
}
}
LRESULT CStartCalculationDlg::OnSendCalculatedValue( WPARAM Result, LPARAM )
{
// The resut should be displayed in the edit box
m_Calculation.Format(_T("%d"),???);
SetDlgItemText(IDC_CALCULATION, m_Calculation);
return 1;
}
void CStartCalculationDlg::OnHScroll(UINT nSBCode, UINT nPos,CScrollBar* pScrollBar)
{
m_SliderValue.Format(_T("%d"),m_Slider.GetPos());
SetDlgItemText(IDC_SLIDER_VALUE,m_SliderValue);
}
// Implementation in the CStartCalculationDlg.h
CWorkerThreadMgr m_WorkerThreadMgr //instance of the WorkerThreadMgr
CSliderCtrl m_Slider //member variable of the slider control
CString m_SliderValue // member variable of the edit box, where the current value of the
//slider will be displayed
CString m_Calculation // member variable of the edit box where the calculated
//result from the workerthread will be displayed via PostMessage
afx_msg LRESULT OnSendCalculatedValue( WPARAM, LPARAM );
afx_msg void OnHScroll(UINT nSBCode, UINT nPos, CScrollBar* pScrollBar);
下一个问题是,当我的滑块控件被移动并获得一个新值时,线程过程应该知道它并更新滑块的值。我该怎么做?
与其从工作线程读取滑块位置,不如在UI线程中读取滑块位置并使其对工作线程可用。
我真的不是这个领域的专家,但我已经做了一些工作线程,正如这里所解释的。
在您的情况下,我要做的是创建一个静态变量,如上面链接的文章中使用的"running"标志,以保持滑块的当前位置。然后,在OnHScroll处理程序中将其设置为适当的值。
只要您只从一个线程写入该变量,就不应该出现同步问题。
来自工作线程:
m_data = foo();
PostMessage(hWndMain, UWM_SOME_CUSTOM_MESSAGE, 0, 0);
来自UI线程:
LRESULT CMainFrame::OnSomeCustomMessage(WPARAM wParam, LPARAM lParam)
{
CMyData data = m_pWorker->GetData();
// Do stuff...
return 0;
}
GetData
必须由一个关键部分保护:
CMyData CMyWorker::GetData()
{
// This critical section is used in the worker thread too, whenever m_data is accessed.
m_lock.Lock();
CMyData data = m_data;
m_lock.Unlock();
return data;
}
请参阅MSDN上的C批评部分。