C / C++ / MFC

CString(0xcccccccc) wrote:

More precisely, I want windows to draw the menu and let me do the remaining of the painting.

BEGIN_MSG_MAP(CWtlsdiView)
  MESSAGE_HANDLER(WM_NCPAINT, OnNcPaint)
END_MSG_MAP()

LRESULT OnNcPaint(UINT /*uMsg*/, WPARAM /*wParam*/, LPARAM /*lParam*/, BOOL& /*bHandled*/)
{
   DefWindowProc();
   // Do your painting
   return 0;
}

CRect GetCaptionRect(CWindow& wnd)
{
   // Get size of frame around window
   DWORD dwStyle = wnd.GetStyle();
   CSize szFrame = (dwStyle & WS_THICKFRAME) ?
      CSize(GetSystemMetrics(SM_CXSIZEFRAME),
      GetSystemMetrics(SM_CYSIZEFRAME)) :
   CSize(GetSystemMetrics(SM_CXFIXEDFRAME),
      GetSystemMetrics(SM_CYFIXEDFRAME));

   int cxIcon = GetSystemMetrics(SM_CXSIZE); // width of caption icon/button

   CRect r;
   // Compute rectangle
   wnd.GetWindowRect(&r);		// window rect in screen coords
   r -= CPoint(r.left, r.top);	// shift origin to (0,0)
   r.left  += szFrame.cx;				// frame
   r.right -= szFrame.cx;				// frame
   r.top   += szFrame.cy;				// top = end of frame
   r.bottom = r.top + GetSystemMetrics(SM_CYCAPTION)  // height of caption
      - GetSystemMetrics(SM_CYBORDER);				  // minus gray shadow border
   return r;
}

class MyDialog : public CDialogImpl<MyDialog>
{
public:
   BEGIN_MSG_MAP(MyDialog)
      MESSAGE_HANDLER(WM_NCPAINT, OnNcPaint)
   END_MSG_MAP()

   LRESULT OnNcPaint(UINT nMsg, WPARAM hRgn, LPARAM lParam, BOOL& /*bHandled*/)
   {
      CRect r = GetCaptionRect(*this);
      r.right = r.left + r.Width()/2;
      HRGN onlyRedrawIn = ::CreateRectRgn(r.left, r.top, r.right, r.bottom);

      ::DefWindowProc(m_hWnd, nMsg, (WPARAM)onlyRedrawIn, lParam);
      return 0;
   }
};

void CMainFrame::OnNcPaint()
{
	const MSG* pMsg = GetCurrentMessage();

	CRgn rgnWnd, rgnCli, rgnMenu;
	int iMenuHeight = GetSystemMetrics(SM_CYMENU); //height of the menu bar

	// Compute the NC region as a difference between the window rect and client rect.
	// The region must be relative to top left corner of the window
	CRect rcWnd, rcCli;
	// Get the window rect (relative to the top-left corner of the window)
	GetWindowRect(&rcWnd);
	CPoint ptOffset = - rcWnd.TopLeft();
	rcWnd.OffsetRect(ptOffset);

	// Get the client rect (relative to the top-left corner of the window)
	GetClientRect(&rcCli);
	ClientToScreen(rcCli);
	rcCli.OffsetRect(ptOffset);
	
	// Include de menu bar in the client area
	rcCli.top -= iMenuHeight;

	// Create regions for the window rect and client rect
	rgnWnd.CreateRectRgn(rcWnd.left, rcWnd.top ,rcWnd.right ,rcWnd.bottom);
	rgnCli.CreateRectRgn(rcCli.left, rcCli.top ,rcCli.right ,rcCli.bottom);
	
	// Obtain their difference (that will be the entire non client area without the menu bar)
	rgnWnd.CombineRgn(&rgnWnd, &rgnCli, RGN_DIFF);

	// Create a region for the menu bar
	rgnMenu.CreateRectRgn(rcCli.left, rcCli.top, rcCli.right, rcCli.top + iMenuHeight);

	if(pMsg->wParam != 1) // Is only a part of the nc area requiring repaint ?
	{ // If it's so:
		// Get the region requiring painting:
		CRgn r;
		r.CreateRectRgn(0,0,0,0);
		r.CopyRgn(CRgn::FromHandle((HRGN) pMsg->wParam));
		r.OffsetRgn(ptOffset); // Screen coordinates need to be transformed to window coordinates
		
		// Intersect with the NC area without the menu bar:
		rgnWnd.CombineRgn(&rgnWnd, &r, RGN_AND);
		
		// Intersect with the menu bar:
		rgnMenu.CombineRgn(&rgnMenu, &r, RGN_AND);
	}

	// Paint the nonclient area without the menu bar:
	CWindowDC dc(this);
	CBrush brush;
	brush.CreateSolidBrush(RGB( 255, 0, 0 ));
	dc.FillRgn(&rgnWnd, &brush);

	// Paint the menu bar:
	CRect rcBox;
	rgnMenu.GetRgnBox(&rcBox);
	if(!rcBox.IsRectEmpty()) // Make sure the region is not empty
		::DefWindowProc(m_hWnd, WM_NCPAINT, (WPARAM) rgnMenu.m_hObject, 0); // has no effect
}

CString(0xcccccccc) wrote:

As about your code, first of all thank you for your effort.
Basically you're doing what I'm doing, just my code doesn't work.

Did you test it with VS 2008 ?

CString(0xcccccccc) wrote:

Anyway, there's something wrong with the article, the author wonders about the undocumented wParam = 1 (in WM_NCPAINT), while the MSDN clearly states it stands for "entire NC area needs repainting"

soongez wrote:

hDlg and g_hInst