Re: MFC Flicker and the Application Framework
Hi C, (sorry couldn't resist)
I agree with most of MrAsm's comments (although the coding commentary is a
matter of preference). I'm not sure you need to use a flicker algorithm for
something this simple. I've done tons of output to views directly and I
don't see any flickering happening. This is a similar example that just
writes a clock on the status bar:
http://www.codeguru.com/cpp/controls/statusbar/article.php/c2975/
It's different than what you're trying to do, but the concept is really the
same. Also, you may consider using a CFormView where you could just have
controls that get updated (like a CStatic or CEdit) instead of trying to
write it to a view. You may find this to be much easier and you don't have
to worry about the flickering stuff so much (although it's still a good idea
to throttle the output so it is readable).
Tom
"C Hill MBSC" <CHillMBSC@discussions.microsoft.com> wrote in message
news:C4D09CC9-745C-4D8D-B7C6-8E60DCDBB1F4@microsoft.com...
Dear All!
I have just written a piece of MFC Code to output a counter value every
second to the screen. Could anyone tell me where I have gone wrong,
because
the text occasionally flickers with white lines through it! It only
happens
occasionally on my machine but is unprofessional! I would like to know
whether there is a problem with MFC, or my code.
P.S. Most of the code was created with AppWizard and message map functions
have been added along with initialisation.
Thank you for your assistance in this matter.
// FlickeringCounterView.cpp : implementation of the
CFlickeringCounterView
class
//
#include "stdafx.h"
#include "FlickeringCounter.h"
#include "FlickeringCounterDoc.h"
#include "FlickeringCounterView.h"
#include ".\flickeringcounterview.h"
#ifdef _DEBUG
#define new DEBUG_NEW
#endif
// CFlickeringCounterView
IMPLEMENT_DYNCREATE(CFlickeringCounterView, CView)
BEGIN_MESSAGE_MAP(CFlickeringCounterView, CView)
// Standard printing commands
ON_COMMAND(ID_FILE_PRINT, CView::OnFilePrint)
ON_COMMAND(ID_FILE_PRINT_DIRECT, CView::OnFilePrint)
ON_COMMAND(ID_FILE_PRINT_PREVIEW, CView::OnFilePrintPreview)
ON_WM_TIMER()
ON_WM_CREATE()
END_MESSAGE_MAP()
// CFlickeringCounterView construction/destruction
CFlickeringCounterView::CFlickeringCounterView()
{
// TODO: add construction code here
Counter = 0;
}
CFlickeringCounterView::~CFlickeringCounterView()
{
}
BOOL CFlickeringCounterView::PreCreateWindow(CREATESTRUCT& cs)
{
// TODO: Modify the Window class or styles here by modifying
// the CREATESTRUCT cs
return CView::PreCreateWindow(cs);
}
// CFlickeringCounterView drawing
void CFlickeringCounterView::OnDraw(CDC* pDC)
{
CFlickeringCounterDoc* pDoc = GetDocument();
ASSERT_VALID(pDoc);
if (!pDoc)
return;
// TODO: add draw code for native data here
CFont MyFont;
MyFont.CreatePointFont(240, "Arial");
pDC->SelectObject(&MyFont);
pDC->TextOut(0, 0, String);
}
// CFlickeringCounterView printing
BOOL CFlickeringCounterView::OnPreparePrinting(CPrintInfo* pInfo)
{
// default preparation
return DoPreparePrinting(pInfo);
}
void CFlickeringCounterView::OnBeginPrinting(CDC* /*pDC*/, CPrintInfo*
/*pInfo*/)
{
// TODO: add extra initialization before printing
}
void CFlickeringCounterView::OnEndPrinting(CDC* /*pDC*/, CPrintInfo*
/*pInfo*/)
{
// TODO: add cleanup after printing
}
// CFlickeringCounterView diagnostics
#ifdef _DEBUG
void CFlickeringCounterView::AssertValid() const
{
CView::AssertValid();
}
void CFlickeringCounterView::Dump(CDumpContext& dc) const
{
CView::Dump(dc);
}
CFlickeringCounterDoc* CFlickeringCounterView::GetDocument() const //
non-debug version is inline
{
ASSERT(m_pDocument->IsKindOf(RUNTIME_CLASS(CFlickeringCounterDoc)));
return (CFlickeringCounterDoc*)m_pDocument;
}
#endif //_DEBUG
// CFlickeringCounterView message handlers
void CFlickeringCounterView::OnTimer(UINT nIDEvent)
{
// TODO: Add your message handler code here and/or call default
Counter++;
String.Format("Counter = %i", Counter);
CPaintDC TmpDC(this);
CFont MyFont;
MyFont.CreatePointFont(240, "Arial");
TmpDC.SelectObject(&MyFont);
CSize MySize = TmpDC.GetTextExtent(String);
CRect MyRect(CPoint(0, 0), CPoint(MySize.cx, MySize.cy));
InvalidateRect(MyRect);
CView::OnTimer(nIDEvent);
}
int CFlickeringCounterView::OnCreate(LPCREATESTRUCT lpCreateStruct)
{
if (CView::OnCreate(lpCreateStruct) == -1)
return -1;
// TODO: Add your specialized creation code here
SetTimer(1, 1000, NULL); // 1Hz Counter Timer
return 0;
}
// FlickeringCounterView.h : interface of the CFlickeringCounterView class
//
#pragma once
class CFlickeringCounterView : public CView
{
private:
CString String;
int Counter;
protected: // create from serialization only
CFlickeringCounterView();
DECLARE_DYNCREATE(CFlickeringCounterView)
// Attributes
public:
CFlickeringCounterDoc* GetDocument() const;
// Operations
public:
// Overrides
public:
virtual void OnDraw(CDC* pDC); // overridden to draw this view
virtual BOOL PreCreateWindow(CREATESTRUCT& cs);
protected:
virtual BOOL OnPreparePrinting(CPrintInfo* pInfo);
virtual void OnBeginPrinting(CDC* pDC, CPrintInfo* pInfo);
virtual void OnEndPrinting(CDC* pDC, CPrintInfo* pInfo);
// Implementation
public:
virtual ~CFlickeringCounterView();
#ifdef _DEBUG
virtual void AssertValid() const;
virtual void Dump(CDumpContext& dc) const;
#endif
protected:
// Generated message map functions
protected:
DECLARE_MESSAGE_MAP()
public:
afx_msg void OnTimer(UINT nIDEvent);
afx_msg int OnCreate(LPCREATESTRUCT lpCreateStruct);
};
#ifndef _DEBUG // debug version in FlickeringCounterView.cpp
inline CFlickeringCounterDoc* CFlickeringCounterView::GetDocument() const
{ return reinterpret_cast<CFlickeringCounterDoc*>(m_pDocument); }
#endif
--
Engineering