TransparentBlt

[_T No name]

hi, i have made a derived class from CDialog to customize it with my bitmaps in which some pixels need to be transparent. I am using TransparentBlt() for the same in OnEraseBkgnd() in derived class after calling CDialog::OnEraseBkgnd(). the thing is happening is those pixels are either coming grey so white sometime. not becoming transparent. Can anyone suggest where i am doing wrong !!! thanx

[Naveen]

_T("No name") wrote:

I am using TransparentBlt() for the same in OnEraseBkgnd()

without seeing the code hard to say... hope you calls the CDialog::OnEraseBkgnd() before doing the TransparentBlt().

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[_T No name]

i am calling it before the TransparentBlt() only.. CDialog::OnEraseBkgnd(pDC); CRect rcClient; GetClientRect(rcClient); CDC memDC; memDC.CreateCompatibleDC(pDC); /* TODO : Draw according to state */ /* Title left */ memDC.SelectObject(&m_bmpTitleLeft); pDC->TransparentBlt(rcClient.left,rcClient.top,10,31,&memDC,0,0,10,31,CLR_TRANSPARENT); /* Title Middle */ int i = 0; memDC.SelectObject(&m_bmpTitleMiddle); pDC->StretchBlt(rcClient.left+10,rcClient.top,rcClient.right-10,31,&memDC,0,0,1,31,SRCCOPY); /*Title Right*/ memDC.SelectObject(&m_bmpTitleRight); pDC->TransparentBlt(rcClient.right-10,rcClient.top,10,31,&memDC,0,0,10,31,CLR_TRANSPARENT); /* set Title text */ pDC->SetBkMode(TRANSPARENT); CSize szTitle = pDC->GetTextExtent(m_strTitle); CRect rcTitle(rcClient.left+14,rcClient.top+15-(szTitle.cy/2),rcClient.left+14+szTitle.cx,rcClient.top+15+(szTitle.cy)/2); pDC->DrawText(m_strTitle,-1,&rcTitle,DT_CENTER || DT_SINGLELINE); /* set title box rectangle */ CRect rcTitleBox(rcClient.left,rcClient.top,rcClient.right,rcClient.top+31); m_rcTitleBox = rcTitleBox; /* set main view rectangle */ CRect rcViewDlg(rcClient.left,rcTitle.bottom,rcClient.right,rcClient.bottom); m_rcViewDlg = rcViewDlg; /* Middle right and left area */ memDC.SelectObject(&m_bmpMiddleLeft); pDC->StretchBlt(rcClient.left,rcClient.top+31,10,rcClient.bottom-10,&memDC,0,0,10,1,SRCCOPY); memDC.SelectObject(&m_bmpMiddleRight); pDC->StretchBlt(rcClient.right-10,rcClient.top+31,10,rcClient.bottom-10,&memDC,0,0,10,1,SRCCOPY); /* Middle ares is done by fill rectangle as drawing bitmap in loops makes it slow */ /* Middle area */ CRect rcMiddle(rcClient.left+10,rcClient.top+31+1,rcClient.right-10,rcClient.bottom-10); CBrush brushMiddle(RGB(219,230,244)); pDC->FillRect(&rcMiddle,&brushMiddle); /* Bottom left area */ memDC.SelectObject(&m_bmpBottomLeft); pDC->BitBlt(rcClient.left,rcClient.bottom-50,10,50,&memDC,0,0,SRCCOPY); /* Bottom middle area */ memDC.SelectObject(&m_bmpBottomMiddle); pDC->StretchBlt(rcClient.left+10,rcClient.bottom-50,rcClient.right-10,50,&memDC,0,0,1,50,SRCCOPY); /* Bottom right area */ memDC.SelectObject(&m_bmpBottomRight); pDC->BitBlt(rcClient.right-10,rcClient.bottom-50,10,50

[Ramon F Mendes]

_T("No name") wrote:

CDialog::OnEraseBkgnd(pDC);

When you call the OnEraseBkgnd base method MFC calls the DefWndProc which will fill the dialog with its associated background brush, so remove this line. Also, make sure to set the transparent style of the dialog to TRUE