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MFC Problem

Started by Galileo430 Jan 25, 2001 at 12:15 AM 2 replies 650+ views

Original Post

Jan 25, 2001 at 12:15 AM

Ok so I''m writeing a editor for my game. Basicly it''s a SDI version of Worldcraft. When writeing the grid moving code I encountered a problem. Here is the source for it. NOTE: My grid only consists of a X and Z axis right now.

  
void CVistaEditorView::OnDraw(CDC* pDC)
{
	CVistaEditorDoc* pDoc = GetDocument();
	ASSERT_VALID(pDoc);
	
	CPen	penGrid(PS_SOLID,1, RGB(0x00,0x00,0x00));

	pDC->SelectObject(&penGrid);

        //Fix out of View Grids.

	pDC->MoveTo(((m_iSizeX / 2) - m_lCenterX), 0);
	pDC->LineTo(((m_iSizeX / 2) - m_lCenterX), m_iSizeY);
	pDC->MoveTo( 0, ((m_iSizeY / 2) + m_lCenterZ));
	pDC->LineTo( m_iSizeX, ((m_iSizeY / 2) + m_lCenterZ));


}
void CVistaEditorView::OnRButtonUp(UINT nFlags, CPoint point) 
{
	m_bRightDown = false;
	
	CView::OnRButtonUp(nFlags, point);
}

void CVistaEditorView::OnRButtonDown(UINT nFlags, CPoint point) 
{
	m_bRightDown = true;
	
	CView::OnRButtonDown(nFlags, point);
}

void CVistaEditorView::OnSize(UINT nType, int cx, int cy) 
{
	m_iSizeX = cx;
	m_iSizeY = cy;
	
	CView::OnSize(nType, cx, cy);
}

void CVistaEditorView::OnMouseMove(UINT nFlags, CPoint point) 
{
	if(m_bLeftDown == true && m_bRightDown == true)
	{
		m_lCenterX = m_lCenterX + (m_pntMouseLast.x - point.x);
		m_lCenterZ = m_lCenterZ - (m_pntMouseLast.y - point.y);
		Invalidate(TRUE);
	}



	m_pntMouseLast = point;
	
	CView::OnMouseMove(nFlags, point);
}

void CVistaEditorView::OnLButtonUp(UINT nFlags, CPoint point) 
{
	m_bLeftDown = false;
	
	CView::OnLButtonUp(nFlags, point);
}

void CVistaEditorView::OnLButtonDown(UINT nFlags, CPoint point) 
{
	m_bLeftDown = true;
	
	CView::OnLButtonDown(nFlags, point);
}

I found that after a certain amount of times I Invalidate the view.. I get... Warning: Uncaught exception in WindowProc (returning 0). First-chance exception in VistaEditor.exe (MSVCRTD.DLL): 0xE06D7363: Microsoft C++ Exception. Then the grid dissapears. I scrapped the application once before because of this problem. I can''t seem to find the problem

Gorky

Jan 25, 2001 at 4:11 PM

Try adding this to OnDraw



CVistaEditorDoc* pDoc = GetDocument();	
ASSERT_VALID(pDoc);		

CPen	penGrid(PS_SOLID,1, RGB(0x00,0x00,0x00));	
CPen *pOldPen = pDC->SelectObject(&penGrid);        //Fix out of View Grids.

pDC->MoveTo(((m_iSizeX / 2) - m_lCenterX), 0);	
pDC->LineTo(((m_iSizeX / 2) - m_lCenterX), m_iSizeY);	
pDC->MoveTo( 0, ((m_iSizeY / 2) + m_lCenterZ));	
pDC->LineTo( m_iSizeX, ((m_iSizeY / 2) + m_lCenterZ));

pDC->SelectObject(pOldPen );

What I''m guessing is happening is this.
First time in, all is ok.
But you have selected a local variable pen, to become the pen to use from now on. Not just in this function.

Then when function ends, this pen goes out of scope.
Later OnDraws try to pass back a bad pen in SelectObject.