set back ground color for main frame in SDI

[gurucplusplus]

I want to set the back ground color for my SDI main frame using MFC. I don't know how?

[Mark Salsbery]

The easiest way is to add a WM_ERASEBKGND handler to the window class. In response to the message, draw the background in the color of your choice:

BOOL CMyFrameWnd::OnEraseBkgnd(CDC* pDC)
{
// draw background bright red

CBrush bkBrush(RGB(0xFF,0x00,0x00));
pDC->SelectObject(bkBrush);
CRect CliRect;
GetClientRect(&CliRect);
pDC->PatBlt(CliRect.left, CliRect.top, CliRect.Width(), CliRect.Height(), PATCOPY);

return TRUE;
}

Another way is to register a window class (instead of using the default) and in the WNDCLASS struct set the hbrBackground member to a brush of the desired color. Note that if your main frame has a view in it then you need to do this in the view class, not the frame class. Mark

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

[gurucplusplus]

I add OnEraseBkgnd as you suggest in my main frame class, and when I launch my window application I see the red back ground flash quickly and then back to white back ground. Do you know why? Thanks

[Mark Salsbery]

gurucplusplus wrote:

Do you know why?

Yes, because you should have done it in the view class :)

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

[gurucplusplus]

I got it. Thanks. But I have another question. I want to draw lines and rectangle box as overlay to exiting image display on main window frame. How can I do it? I currently can drawing lines, rectangle box on my image as I use mouse left and right mouse buttons. but what I did is to draw onto the image but not on graphic overlay frame. Thanks.

[Mark Salsbery]

As with the background, if you have a view in the frame then you do your drawing there instead of on the frame window - otherwise it will be "covered" by the view window like when you saw the frame background window flash. Typically, you'd do your drawing in response to a WM_PAINT message, after the image has been drawn. If it's a CView-derived class, overriding OnDraw() may be a more appropriate place, especially if the base class draws the image in OnDraw(). Either way, this means you need to store the coordinates (or whatever info is necessary) to redraw everything every time repainting is necessary (when WM_PAINT is received). How is the image being rendered in your case? Mark

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

[gurucplusplus]

I am new to MFC/VisualC++ 6.0. Can you point me few examples of how to draw graphic overlay in MFC?

[Mark Salsbery]

Do you have an image that's already being drawn? If so, how is being done? With a little more specifics I think I can give you a more specific example :) Mark

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

[gurucplusplus]

I load the image from disk using IPicture renderring. This is my OnDraw(CDC* pDC) from CView class: CMyDoc* pDoc = this->GetDocument(); ASSERT_VALID(pDoc); HPALETTE hPal; pDoc->m_pPicture->get_hPal(reinterpret_cast(&hPal)); CPalette *pPalOld = NULL; if (hPal != NULL) { TRACE(_T("CXpiProView::OnDraw - RealizePalette\n")); pPalOld = pDC->SelectPalette(CPalette::FromHandle(hPal), FALSE); pDC->RealizePalette(); } RECT rc; this->GetClientRect(&rc); // display picture using IPicture::Render pDoc->m_pPicture->Render(pDC->GetSafeHdc(),pDoc->m_sizeInPix.cx, pDoc->m_sizeInPix.cy,0,pDoc->m_sizeInHiMetric.cy, pDoc->m_sizeInHiMetric.cx,-pDoc->m_sizeInHiMetric.cy,&rc);