Understand PreSubclassWindow and DrawItem from debug output

 

 

 

http://www.codeproject.com/Articles/302/Elliptic-Buttons

 

 

 

void CEllepticalButton::PreSubclassWindow() 
{
	CButton::PreSubclassWindow();

	m_bDefault=GetStyle() & (DWORD)BS_DEFPUSHBUTTON; //this is necessary as 
	// the default button style gets removed when u make it ownerdrawn

	ModifyStyle(0, BS_OWNERDRAW);


	CRect rect;
	GetClientRect(rect);
	// Resize the window to make it square
	//commented by Raghav
	//rect.bottom = rect.right = min(rect.bottom,rect.right);

	printf("l = [%d], r = [%d], t = [%d], b = [%d]\n", rect.left, rect.right, rect.top, rect.bottom);

	// Get the vital statistics of the window
	m_ptCentre = rect.CenterPoint();
	m_nHorizontalRadius	= rect.right/2-1;
	m_nVerticalRadius	= rect.bottom/2-1;

	// Set the window region so mouse clicks only activate the round section 
	// of the button
	m_rgn.DeleteObject(); 
	SetWindowRgn(NULL, FALSE);
	m_rgn.CreateEllipticRgnIndirect(rect);
	SetWindowRgn(m_rgn, TRUE);

	// Convert client coords to the parents client coords
	ClientToScreen(rect);


	CWnd* pParent = GetParent();
	if (pParent) pParent->ScreenToClient(rect);

	printf("l = [%d], r = [%d], t = [%d], b = [%d]\n", rect.left, rect.right, rect.top, rect.bottom);

	// Resize the window
	MoveWindow(rect.left, rect.top, rect.Width(), rect.Height(), TRUE);
}

void CEllepticalButton::DrawItem(LPDRAWITEMSTRUCT lpDrawItemStruct) 
{
	ASSERT(lpDrawItemStruct != NULL);
	
	CDC* pDC	 = CDC::FromHandle(lpDrawItemStruct->hDC);
	CRect rect = lpDrawItemStruct->rcItem;
	UINT state = lpDrawItemStruct->itemState;
	UINT nStyle = GetStyle();
	int nHorizontalRadius = m_nHorizontalRadius;
	int nVerticalRadius = m_nVerticalRadius;
	int nSavedDC = pDC->SaveDC();

	printf("drawing item...\n");
	// cout << "di = " << endl;

	pDC->SelectStockObject(NULL_BRUSH);
	pDC->FillSolidRect(rect, ::GetSysColor(COLOR_BTNFACE));

	// Draw the focus circle around the button either if it has the focus
	//or if it is the default button
	if ((state & ODS_FOCUS || m_bDefault)	&& m_bDrawDashedFocusCircle)
		 DrawEllipse(pDC, m_ptCentre, nHorizontalRadius--, nVerticalRadius--, RGB(0,0,0)); 
	


	// Draw the raised/sunken edges of the button (unless flat)
	if (nStyle & BS_FLAT) {
			DrawEllipse(pDC, m_ptCentre, nHorizontalRadius--, nVerticalRadius--, RGB(0,0,0));
			DrawEllipse(pDC, m_ptCentre, nHorizontalRadius--, nVerticalRadius--, ::GetSysColor(COLOR_3DHIGHLIGHT));
			
	} else {
		if ((state & ODS_SELECTED))	{
			DrawEllipse(pDC, m_ptCentre, nHorizontalRadius--, nVerticalRadius--, 
						 ::GetSysColor(COLOR_3DDKSHADOW), ::GetSysColor(COLOR_3DHIGHLIGHT));
			
			DrawEllipse(pDC, m_ptCentre, nHorizontalRadius--, nVerticalRadius--, 
						 ::GetSysColor(COLOR_3DSHADOW), ::GetSysColor(COLOR_3DLIGHT));
		} else {
			DrawEllipse(pDC, m_ptCentre, nHorizontalRadius--, nVerticalRadius--, 
						 ::GetSysColor(COLOR_3DHIGHLIGHT), ::GetSysColor(COLOR_3DDKSHADOW));
							//RGB(255,255,255), ::GetSysColor(COLOR_3DDKSHADOW));
			DrawEllipse(pDC, m_ptCentre, nHorizontalRadius--, nVerticalRadius--, 
						 ::GetSysColor(COLOR_3DHIGHLIGHT), ::GetSysColor(COLOR_3DSHADOW));
			
		}
	}
	
	// draw the text if there is any
	CString strText;
	GetWindowText(strText);

	if (!strText.IsEmpty())
	{
		CRgn rgn;
		rgn.CreateEllipticRgn(m_ptCentre.x-nHorizontalRadius, m_ptCentre.y-nVerticalRadius, 
								m_ptCentre.x+nHorizontalRadius, m_ptCentre.y+nVerticalRadius);
		pDC->SelectClipRgn(&rgn);

		CSize Extent = pDC->GetTextExtent(strText);
		CPoint pt = CPoint( m_ptCentre.x - Extent.cx/2, m_ptCentre.y - Extent.cy/2 );

		if (state & ODS_SELECTED) pt.Offset(1,1);

		pDC->SetBkMode(TRANSPARENT);

		if (state & ODS_DISABLED)
			pDC->DrawState(pt, Extent, strText, DSS_DISABLED, TRUE, 0, (HBRUSH)NULL);
		else
			pDC->TextOut(pt.x, pt.y, strText);

		pDC->SelectClipRgn(NULL);
		rgn.DeleteObject();
	}

	// Draw the focus circle on the inside of the button
	if ((state & ODS_FOCUS) && m_bDrawDashedFocusCircle)
		DrawEllipse(pDC, m_ptCentre, nHorizontalRadius-2, nVerticalRadius-2, RGB(0,0,0), TRUE);
		


	pDC->RestoreDC(nSavedDC);
}