Update dialog with data from serial port, without flickering

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I have SDI based MFC project, in which I created a dialog by placing code in MainFrame class. The form dialog has a readonly edit box where I want to display data continuously received from serial port. I have the following code in the view class:

void CSerialCommView::OnDraw(CDC* /*pDC*/)
{
	CDC MemDC;
	CSerialCommDoc* pDoc = GetDocument();
	ASSERT_VALID(pDoc);
	if (!pDoc)
	 return;
	CString mystr=SerialPortContinuousRead(); ===> works fine
	mystr += "\r\n";

	CMainFrame *pFrame = (CMainFrame*)AfxGetMainWnd();
	CEdit* DispBox=(CEdit*)pFrame->m_wndDlgBar.GetDlgItem(IDC_DISPLAY_BOX); 
	DispBox->SetWindowTextW(mystr);
}

When I have break points in this function it updates the data in edit box, otherwise I can't see the data. Any help appreciated, thanks

Posted 9-May-10 18:08pm

harinathcau

Updated 15-May-10 22:18pm

Moak

v2

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LittleYellowBird · Answer 1 · 2010-05-09T22:54:00

Solution 1

I don't know if this helps but when I want to update a dialog box with 'real time' data I normally setup a timer to read and display the latest value.

I'm not sure if that's is what you are asking, so I hope that helps. :)

Posted 9-May-10 22:54pm

LittleYellowBird

harinathcau · Answer 2 · 2010-05-10T23:45:00

Hi Alison,

I have added timer to update Edit box. The following code i have in the timer function.

void CSerialCommView::OnTimer(UINT_PTR nIDEvent)
{
// TODO: Add your message handler code here and/or call default
  CMainFrame *pFrame = (CMainFrame*)AfxGetMainWnd();
  CEdit* DispBox=(CEdit*)pFrame->m_wndDlgBar.GetDlgItem(IDC_DISPLAY_BOX); 
  dispstr+=mydatastr+_T("\n");
  DispBox->SetWindowTextW(dispstr);
  DispBox->LineScroll(DispBox->GetLineCount());
  Invalidate(true);
 CView::OnTimer(nIDEvent);
}

The problem is,the dialog flickers because of

Invalidate(true)

.

Is there any other method which will just update without flickering problem. :omg:
Thanks.

krmed · Answer 3 · 2010-05-16T03:45:00

Instead of calling Invalidate() after you set the text, try this:

CMainFrame *pFrame = (CMainFrame*)AfxGetMainWnd();
CEdit* DispBox=(CEdit*)pFrame->m_wndDlgBar.GetDlgItem(IDC_DISPLAY_BOX);
DispBox->SetWindowTextW(mystr);
DispBox->UpdateWindow();

That will cause only the edit control to update - not the entire window.

Hope that helps.

Update dialog with data from serial port, without flickering

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