用createbitmap()生成的bmp图象如何存为文件

BOOL SaveDIB(HDIB hDib, CFile& file)
{
BITMAPFILEHEADER bmfHdr; // Header for Bitmap file
LPBITMAPINFOHEADER lpBI; // Pointer to DIB info structure
DWORD dwDIBSize;

if (hDib == NULL)
return FALSE;
lpBI = (LPBITMAPINFOHEADER) ::GlobalLock((HGLOBAL) hDib);
if (lpBI == NULL)
return FALSE;

if (!IS_WIN30_DIB(lpBI))
{
::GlobalUnlock((HGLOBAL) hDib);
return FALSE; // It's an other-style DIB (save not supported)
}
bmfHdr.bfType = DIB_HEADER_MARKER; // "BM"

dwDIBSize = *(LPDWORD)lpBI + ::PaletteSize((LPSTR)lpBI); // Partial Calculation

// Now calculate the size of the image

if ((lpBI->biCompression == BI_RLE8) || (lpBI->biCompression == BI_RLE4))
{
// It's an RLE bitmap, we can't calculate size, so trust the
// biSizeImage field

dwDIBSize += lpBI->biSizeImage;
}
It is so difficult.
else
{
DWORD dwBmBitsSize; // Size of Bitmap Bits only

// It's not RLE, so size is Width (DWORD aligned) * Height

dwBmBitsSize = WIDTHBYTES((lpBI->biWidth)*((DWORD)lpBI->biBitCount)) * lpBI->biHeight;

dwDIBSize += dwBmBitsSize;

// Now, since we have calculated the correct size, why don't we
// fill in the biSizeImage field (this will fix any .BMP files which
// have this field incorrect).

lpBI->biSizeImage = dwBmBitsSize;
}
bmfHdr.bfSize = dwDIBSize + sizeof(BITMAPFILEHEADER);
bmfHdr.bfReserved1 = 0;
bmfHdr.bfReserved2 = 0;

bmfHdr.bfOffBits = (DWORD)sizeof(BITMAPFILEHEADER) + lpBI->biSize
+ PaletteSize((LPSTR)lpBI);
TRY
{
// Write the file header
file.Write((LPSTR)&bmfHdr, sizeof(BITMAPFILEHEADER));
//
// Write the DIB header and the bits
//
file.WriteHuge(lpBI, dwDIBSize);
}
CATCH (CFileException, e)
{
::GlobalUnlock((HGLOBAL) hDib);
THROW_LAST();
}
END_CATCH
::GlobalUnlock((HGLOBAL) hDib);
return TRUE;
}