How to properly handle WM_NC* messages.

[amac]

Hey, I've been looking for some information on working with the non-client area, but have been unsuccessful so far. I'm just trying to paint custom window frames, title bar, etc.

For those who have knowledge in this area, where should I start when doing this? Is there certain messages I should handle before trying to paint? I'm looking for any information, or tips...

Thanx

[CornedBee]

I'm currently messing with the NC messages too. I'm now getting a grip on them, but not enough to explain, sorry.

I catch WM_NCCALCRECT (terrible!), WM_NCPAINT, WM_NCLBTNDBLCLK and a few others.

[CornedBee]

Some sample MFC code I use:

void CContentFrameWnd::OnNcCalcSize(BOOL bCalcValidRects, NCCALCSIZE_PARAMS* lpncsp)
{
	RECT& r = lpncsp->rgrc[0];
	r.top += 15;
	r.left += 1;
	r.right -= 1;
	r.bottom -= 1;

	// ignore the bCalcValidRects parameter, client area remains valid except for now
	// uncovered parts, but determining that is the OSs job.
}

UINT CContentFrameWnd::OnNcHitTest(CPoint point)
{
	CRect rect;
	GetWindowRect(&rect);
	point.x -= rect.left;
	point.y -= rect.top;
	
	if(point.x <= 3)
	{
		if(point.y <= 3)
			return HTTOPLEFT;
		if(point.y >= rect.Height() - 3)
			return HTBOTTOMLEFT;
		return HTLEFT;
	}
	if(point.x >= rect.Width() - 3)
	{
		if(point.y <= 3)
			return HTTOPRIGHT;
		if(point.y >= rect.Height() - 3)
			return HTBOTTOMRIGHT;
		return HTRIGHT;
	}

	if(point.y <= 3)
		return HTTOP;
	if(point.y >= rect.Height() - 3)
		return HTBOTTOM;

	if(point.y < 17)
		return HTCAPTION;

	return CWnd::OnNcHitTest(point);
}

void CContentFrameWnd::OnNcPaint()
{
	// CWnd::OnNcPaint() shouldn't be called.
	CRect rect;
	GetWindowRect(&rect);
	rect.SetRect(0, 0, rect.Width(), rect.Height());
	const MSG *pMsg = GetCurrentMessage();
	CDC *pDC = GetWindowDC();
	//pDC->SelectClipRgn(CRgn::FromHandle((reinterpret_cast<HRGN>(pMsg->wParam))), RGN_AND);
	// draw a "window"
	pDC->DrawEdge(rect, EDGE_RAISED, BF_RECT);
	rect.DeflateRect(1,1);
	rect.bottom = 15;
								// support for gradients only win98 and 2k
	::DrawCaption(GetSafeHwnd(), pDC->GetSafeHdc(), &rect,
#if WINVER >= 0x0500
		DC_GRADIENT |
#endif
		DC_TEXT | 
		// Topics are distinguishable from content because they are drawn with an active
		// colored title bar. Need to find a better way as CMiniFrameWnd doesn't support this
		// behaviour.
		(m_bTopic ? DC_ACTIVE : 0));
}

[amac]

Have you tried using GetDCEx() in your WM_NCPAINT message to get a DC with the clipping region? The SDK says to do it that way, but I have yet to get the function to succeed. I've tried getting a DC with it, but without the clipping region... and nothing. I tried using it to get a window DC, but again nothing. However, last night I tried passing DCX_CACHE along with the other parameters... and it worked. Any ideas why it would work with it and not without it?

I got the WM_NCCALCSIZE message down... that one seemed pretty easy.

I guess I've been trying to handle WM_NCPAINT, and I could never get DC using GetDCEx()... I just figured there was something that I was missing...

[CornedBee]

I have tried it. I won't try it again. As you see I even commented out the line where I adjust the clipping region: it clipped out everything, even when the window needed updating.

[amac]

So you found that it didn't work either... hmmm... that's odd.

[jim mcnamara]

Is this of any help?

http://codeguru.earthweb.com/dialog/..._caption.shtml

It plays with the WM_NCPAINT messages successfully - although in a different context.