user2365346 user2365346 - 1 month ago 11
C++ Question

An Aero caption title bar issue using DWM API on the windows 10

In order to draw the icon on the caption title bar, I have refereed this MSDN article and used DWM API to create my customize client area by calling DwmExtendFrameIntoClientArea.

my code:

CMainFrame::CMainFrame()
{
Gdiplus::GdiplusStartupInput gdiplusStartupInput;
ULONG_PTR gdiplusToken;
GdiplusStartup(&gdiplusToken, &gdiplusStartupInput, NULL);

BOOL fDwmEnabled = FALSE;
if (SUCCEEDED(DwmIsCompositionEnabled(&fDwmEnabled)))
TRACE0("DWM is enabled\n");

TCHAR szLogoPath[MAX_PATH];
GetModuleFileName ( GetModuleHandle(NULL), szLogoPath, _countof(szLogoPath) );
PathRemoveFileSpec ( szLogoPath );
PathAppend ( szLogoPath, _T("lena.bmp") );
m_pLogoImage = m_pLogoImage->FromFile ( CT2CW(szLogoPath) );
if(NULL == m_pLogoImage)
TRACE0("load image fail\n");
}

void CMainFrame::OnNcCalcSize(BOOL bCalcValidRects, NCCALCSIZE_PARAMS* lpncsp)
{
int xFrame = 2;
int yFrame = 2;
int nTHight = 30;
NCCALCSIZE_PARAMS * p;
RECT * rc;
RECT aRect;
RECT bRect;
RECT acRect;
p = (NCCALCSIZE_PARAMS *)lpncsp;

CopyRect(&bRect,&p->rgrc[1]);
CopyRect(&aRect,&p->rgrc[0]);

acRect.left = aRect.left + xFrame;
acRect.top = aRect.top - nTHight;
acRect.right = aRect.right - xFrame;
acRect.bottom = aRect.bottom - yFrame;
CopyRect(&p->rgrc[0],&acRect);
CopyRect(&p->rgrc[1],&aRect);
CopyRect(&p->rgrc[2],&bRect);
CFrameWnd::OnNcCalcSize(TRUE, lpncsp);
}

LRESULT CMainFrame::OnNcHitTest(CPoint p)
{
BOOL dwm_enabled = FALSE;
if (SUCCEEDED(DwmIsCompositionEnabled(&dwm_enabled)))
{
LRESULT result = 0;
if (!DwmDefWindowProc(m_hWnd, WM_NCHITTEST, 0, MAKELPARAM(p.x, p.y), &result))
result = HitTestNCA(m_hWnd, p);

if (result == HTNOWHERE && GetForegroundWindow() != this)
{
return HTCAPTION;
}

return result;
}

return CWnd::OnNcHitTest(p);
}

BOOL CMainFrame::PreCreateWindow(CREATESTRUCT& cs)
{
if(cs.hMenu!=NULL)
{
::DestroyMenu(cs.hMenu);
cs.hMenu = NULL ;
}
if( !CFrameWnd::PreCreateWindow(cs) )
return FALSE;
// TODO: Modify the Window class or styles here by modifying
// the CREATESTRUCT cs
cs.style = WS_CAPTION | WS_MINIMIZEBOX | WS_MAXIMIZEBOX | WS_OVERLAPPED| WS_SYSMENU | WS_THICKFRAME;
cs.dwExStyle &= ~WS_EX_CLIENTEDGE;
cs.lpszClass = AfxRegisterWndClass(0);

return TRUE;
}

void CMainFrame::OnActivate(UINT nState,CWnd* pWndOther,BOOL bMinimized )
{
CFrameWnd::OnActivate(nState,pWndOther,bMinimized);
BOOL fDwmEnabled = FALSE;
if (SUCCEEDED(DwmIsCompositionEnabled(&fDwmEnabled)))
{
if(nState == WA_ACTIVE )
{
MARGINS margins = {-1};
/*margins.cyTopHeight = 30;
margins.cxLeftWidth = 0;
margins.cxRightWidth = 0;
margins.cyBottomHeight = 0;*/
HRESULT hr = DwmExtendFrameIntoClientArea(m_hWnd, &margins);
if (!SUCCEEDED(hr))
TRACE0("Failed in DwmExtendFrameIntoClientArea\n");
}
}
}

void CMainFrame::OnNcPaint()
{
CFrameWnd::OnPaint();
CDC* dc = GetWindowDC();
RECT rcClient;
GetWindowRect(&rcClient);
dc->FillSolidRect(0,0,RECTWIDTH(rcClient),RECTHEIGHT(rcClient),RGB(255,0,0));

CPaintDC gdc(this); // device context for painting
Graphics gr(gdc.m_hDC);
gr.DrawImage ( m_pLogoImage, 0, 0 );
ReleaseDC(dc);

}


The result under Windows 7 is fine.
enter image description here

However, my window appears another unknown caption title bar under Windows 10.
enter image description here

enter image description here

I found out the unknown caption is caused by WS_THICKFRAME in the cs.style.
If I remove WS_THICKFRAME, the unknown cation bar will disappear, but I cannot resizing the border of my window. Furthermore, my program cannot capture the minimum, maximum and the close button message on my custom caption bar anymore.
I want to remove the unknown title bar without any side effect.
Does anyone could provide me a good solution or suggestion?

Best Regards,

Answer

When using DwmExtendFrameIntoClientArea, it means frame is extended in to client area. It is no longer in non-client area. So there is no need to override OnNcPaint, you can do all of the painting in OnPaint

void CMainFrame::OnPaint()
{
    CPaintDC dc(this);

    //paint titlebar area (this used to be the non-client area)
    CRect rc;
    GetClientRect(&rc);
    rc.bottom = titlebar_height;

    CDC memdc;
    memdc.CreateCompatibleDC(&dc);
    BITMAPINFOHEADER bmpInfoHeader = { 
        sizeof(BITMAPINFOHEADER), rc.Width(), -rc.Height(), 1, 32 };
    HBITMAP hbitmap = CreateDIBSection(
        dc, (BITMAPINFO*)(&bmpInfoHeader), DIB_RGB_COLORS, NULL, NULL, 0);
    auto oldbitmap = memdc.SelectObject(hbitmap);

    dc.BitBlt(0, 0, rc.Width(), rc.Height(), &memdc, 0, 0, SRCCOPY);
    memdc.SelectObject(oldbitmap);
    DeleteObject(hbitmap);

    //begin normal paint
    //The new client area begins below titlebar_height which we define earlier
    GetClientRect(&rc);
    rc.top = titlebar_height;
    dc.FillSolidRect(&rc, RGB(0, 0, 255));

    Gdiplus::Image *image = Gdiplus::Image::FromFile(L"file.jpg");
    Gdiplus::Graphics gr(dc);
    gr.DrawImage(image, 0, 0);
    delete image;
}

Use a member variable CRect m_border to keep track of border's thickness. You can use AdjustWindowRectEx to find the thickness of the borders.

void CMainFrame::OnActivate(UINT nState, CWnd* pWndOther, BOOL bMinimized)
{
    CFrameWnd::OnActivate(nState, pWndOther, bMinimized);

    titlebar_height = 100;
    //find border thickness
    if (GetWindowLongPtr(m_hWnd, GWL_STYLE) & WS_THICKFRAME)
    {
        m_border = { 0,0,0,0 };
        AdjustWindowRectEx(&m_border, GetWindowLongPtr(m_hWnd,
                GWL_STYLE) & ~WS_CAPTION, FALSE, NULL);
        m_border.left = abs(m_border.left);
        m_border.top = abs(m_border.top);
    }
    else if (GetWindowLongPtr(m_hWnd, GWL_STYLE) & WS_BORDER)
    {
        m_border = { 1,1,1,1 };
    }
    else
    {
        m_border = { 0,0,0,0 };
    }

    //Extend frame in to client area
    MARGINS margins = { 0 };
    margins.cyTopHeight = titlebar_height; //<<=== *** edited
    DwmExtendFrameIntoClientArea(m_hWnd, &margins);
    SetWindowPos(NULL, 0, 0, 0, 0, 
            SWP_SHOWWINDOW | SWP_NOMOVE | SWP_NOSIZE | SWP_FRAMECHANGED);
}

m_border will be for example {7,7,7,7};

Allow Windows to do the painting on left, right, bottom border. The top border is the only one changed

void CMainFrame::OnNcCalcSize(BOOL validate, NCCALCSIZE_PARAMS FAR* lpncsp)
{
    if (validate)
    {
        lpncsp->rgrc[0].left += m_border.left;
        lpncsp->rgrc[0].right -= m_border.right;
        lpncsp->rgrc[0].bottom -= m_border.bottom;
    }
    else
    {
        CFrameWnd::OnNcCalcSize(validate, lpncsp);
    }
}

see also How to glow the minimum. maximum and close button?

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