Advanced MFC Programming

Chapter 10. Bitmap
……
(
)
{
(
hRes=::FindResource
(
AfxGetResourceHandle(),
MAKEINTRESOURCE(IDB_BITMAP),
RT_BITMAP
)
) != NULL &&
(
hData=::LoadResource
(
AfxGetResourceHandle(),
hRes
)
) != NULL
lpBi=(LPBITMAPINFO)::LockResource(hData);
ASSERT(lpBi);
We call funcitons ::FindResource(…) and ::LoadResource(…) to load the bitmap resource. Function
::FindResource(…) will return a handle to the specified resource block, which can be passed to
::LoadResource(…) for loading the resource. This function returns a global memory handle. We can call
::LockResource(…) to lock the resource. This function will return an address that can be used to access the
bitmap data. In the sample, we use pointer lpBi to store this address.
Next, we must calculate the size of color table and allocate enough memory for creating logical palette.
The color table size can be calculated from “bit count per pixel” information of the bitmap as follows:
……
……
switch(lpBi->bmiHeader.biBitCount)
{
case 1:
{
nSizeCT=2;
break;
}
case 4:
{
nSizeCT=16;
break;
}
case 8:
{
nSizeCT=256;
break;
}
default: nSizeCT=0;
}
The color table size is stored in variable nSizeCT. Next, the logical palette is created from the color
table stored in the DIB data:
……
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;
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