Advanced MFC Programming

Chapter 10. Bitmap
if(hData != NULL)
{
lpBi=(LPBITMAPINFO)::GlobalLock(hData);
ASSERT(lpBi);
nSizeCT=pDoc->GetColorTableSize(lpBi->bmiHeader.biBitCount);
lpLogPal=(LPLOGPALETTE) new BYTE
[
sizeof(LOGPALETTE)+(nSizeCT-1)*sizeof(PALETTEENTRY)
];
lpLogPal->palVersion=0x300;
lpLogPal->palNumEntries=nSizeCT;
for(i=0; ipalPalEntry[i].peRed=lpBi->bmiColors[i].rgbRed;
lpLogPal->palPalEntry[i].peGreen=lpBi->bmiColors[i].rgbGreen;
lpLogPal->palPalEntry[i].peBlue=lpBi->bmiColors[i].rgbBlue;
lpLogPal->palPalEntry[i].peFlags=NULL;
}
pPalDraw=pDoc->GetPalette();
if(pPalDraw->GetSafeHandle() != NULL)pPalDraw->DeleteObject();
VERIFY(pPalDraw->CreatePalette(lpLogPal));
delete [](BYTE *)lpLogPal;
}
::GlobalUnlock(hData);
m_bBitmapLoaded=TRUE;
SetScrollSizes
(
MM_TEXT,
CSize(lpBi->bmiHeader.biWidth, lpBi->bmiHeader.biHeight)
);
Invalidate();
}
else SetScrollSizes(MM_TEXT, CSize(0, 0));
In this functon, DIB handle is obtained from the document and locked. From the global memory
buffers, the color table contained in the DIB is obtained and is used for creating the logical palette. The a
flag is set to indicate that the bitmap is loaded successfully.
In function CGDIView::OnDraw(…), the DIB is painted to the client window:
void CGDIView::OnDraw(CDC *pDC)
{
CPalette *pPal;
CPalette *pPalOld;
HGLOBAL hDib;
LPBITMAPINFO lpBi;
DWORD dwBitOffset;
if(m_bBitmapLoaded == FALSE)return;
CGDIDoc *pDoc=GetDocument();
ASSERT_VALID(pDoc);
hDib=pDoc->GetHDib();
ASSERT(hDib);
lpBi=(LPBITMAPINFO)::GlobalLock(hDib);
ASSERT(lpBi);
pPal=pDoc->GetPalette();
pPalOld=pDC->SelectPalette(pPal, FALSE);
pDC->RealizePalette();
dwBitOffset=
(
sizeof(BITMAPINFOHEADER)+
pDoc->GetColorTableSize
(
lpBi->bmiHeader.biBitCount
)*sizeof(RGBQUAD)
);
::SetDIBitsToDevice
303