pLogPal->palVersion = 0x300;
	pLogPal->palNumEntries = nEntries;
	::GetSystemPaletteEntries(hDC, 0, nEntries,
		(LPPALETTEENTRY) ((LPBYTE) pLogPal + 2 * sizeof(WORD)));
	m_hPalette = ::CreatePalette(pLogPal);
	delete pLogPal;
	return TRUE;
}

HBITMAP CDib::CreateBitmap(CDC* pDC)
{
    if (m_dwSizeImage == 0) return NULL;
    HBITMAP hBitmap = ::CreateDIBitmap(pDC->GetSafeHdc(), m_lpBMIH,
            CBM_INIT, m_lpImage, (LPBITMAPINFO) m_lpBMIH, DIB_RGB_COLORS);
    ASSERT(hBitmap);
    return hBitmap;
}

BOOL CDib::Compress(CDC* pDC, BOOL bCompress /* = TRUE */)
{
	// 1. makes GDI bitmap from existing DIB
	// 2. makes a new DIB from GDI bitmap with compression
	// 3. cleans up the original DIB
	// 4. puts the new DIB in the object
	if((m_lpBMIH->biBitCount != 4) && (m_lpBMIH->biBitCount != 8)) return FALSE;
		// compression supported only for 4 bpp and 8 bpp DIBs
	if(m_hBitmap) return FALSE; // can't compress a DIB Section!
	TRACE("Compress: original palette size = %d\n", m_nColorTableEntries); 
	HDC hdc = pDC->GetSafeHdc();
	HPALETTE hOldPalette = ::SelectPalette(hdc, m_hPalette, FALSE);
	HBITMAP hBitmap;  // temporary
	if((hBitmap = CreateBitmap(pDC)) == NULL) return FALSE;
	int nSize = sizeof(BITMAPINFOHEADER) + sizeof(RGBQUAD) * m_nColorTableEntries;
	LPBITMAPINFOHEADER lpBMIH = (LPBITMAPINFOHEADER) new char[nSize];
	memcpy(lpBMIH, m_lpBMIH, nSize);  // new header
	if(bCompress) {
		switch (lpBMIH->biBitCount) {
		case 4:
			lpBMIH->biCompression = BI_RLE4;
			break;
		case 8:
			lpBMIH->biCompression = BI_RLE8;
			break;
		default:
			ASSERT(FALSE);
		}
		// calls GetDIBits with null data pointer to get size of compressed DIB
		if(!::GetDIBits(pDC->GetSafeHdc(), hBitmap, 0, (UINT) lpBMIH->biHeight,
						NULL, (LPBITMAPINFO) lpBMIH, DIB_RGB_COLORS)) {
			AfxMessageBox("Unable to compress this DIB");
			// probably a problem with the color table
	 		::DeleteObject(hBitmap);
			delete [] lpBMIH;
			::SelectPalette(hdc, hOldPalette, FALSE);
			return FALSE; 
		}
		if (lpBMIH->biSizeImage == 0) {
			AfxMessageBox("Driver can't do compression");
	 		::DeleteObject(hBitmap);
			delete [] lpBMIH;
			::SelectPalette(hdc, hOldPalette, FALSE);
			return FALSE; 
		}
		else {
			m_dwSizeImage = lpBMIH->biSizeImage;
		}
	}
	else {
		lpBMIH->biCompression = BI_RGB; // decompress
		// figure the image size from the bitmap width and height
		DWORD dwBytes = ((DWORD) lpBMIH->biWidth * lpBMIH->biBitCount) / 32;
		if(((DWORD) lpBMIH->biWidth * lpBMIH->biBitCount) % 32) {
			dwBytes++;
		}
		dwBytes *= 4;
		m_dwSizeImage = dwBytes * lpBMIH->biHeight; // no compression
		lpBMIH->biSizeImage = m_dwSizeImage;
	} 
	// second GetDIBits call to make DIB
	LPBYTE lpImage = (LPBYTE) new char[m_dwSizeImage];
	VERIFY(::GetDIBits(pDC->GetSafeHdc(), hBitmap, 0, (UINT) lpBMIH->biHeight,
    		lpImage, (LPBITMAPINFO) lpBMIH, DIB_RGB_COLORS));
    TRACE("dib successfully created - height = %d\n", lpBMIH->biHeight);
	::DeleteObject(hBitmap);
	Empty();
	m_nBmihAlloc = m_nImageAlloc = crtAlloc;
	m_lpBMIH = lpBMIH;
	m_lpImage = lpImage;
	ComputePaletteSize(m_lpBMIH->biBitCount);
	ComputeMetrics();
	MakePalette();
	::SelectPalette(hdc, hOldPalette, FALSE);
	TRACE("Compress: new palette size = %d\n", m_nColorTableEntries); 
	return TRUE;
}

BOOL CDib::Read(CFile* pFile)
{
	// 1. read file header to get size of info hdr + color table
	// 2. read info hdr (to get image size) and color table
	// 3. read image
	// can't use bfSize in file header
	Empty();
	int nCount, nSize;
	BITMAPFILEHEADER bmfh;
	TRY {
		nCount = pFile->Read((LPVOID) &bmfh, sizeof(BITMAPFILEHEADER));
		if(nCount != sizeof(BITMAPFILEHEADER)) {
			AfxMessageBox("read error 1");
			return FALSE;
		}
		if(bmfh.bfType != 0x4d42) {
			AfxMessageBox("Invalid bitmap file");
			return FALSE;
		}
		nSize = bmfh.bfOffBits - sizeof(BITMAPFILEHEADER);
		m_lpBMIH = (LPBITMAPINFOHEADER) new char[nSize];
		m_nBmihAlloc = m_nImageAlloc = crtAlloc;
		nCount = pFile->Read(m_lpBMIH, nSize); // info hdr & color table
		ComputeMetrics();
		m_lpImage = (LPBYTE) new char[m_dwSizeImage];
		nCount = pFile->Read(m_lpImage, m_dwSizeImage); // image only
	}
	CATCH (CException, e) {
		AfxMessageBox("Read error 1");
		return FALSE;
	}
	END_CATCH
	ComputePaletteSize(m_lpBMIH->biBitCount);
	MakePalette();
	return TRUE;
}

BOOL CDib::Write(CFile* pFile)
{
	BITMAPFILEHEADER bmfh;
	bmfh.bfType = 0x4d42;  // 'BM'
	int nSize =  sizeof(BITMAPINFOHEADER) + sizeof(RGBQUAD) * m_nColorTableEntries +  m_dwSizeImage;
	bmfh.bfSize = nSize + sizeof(BITMAPFILEHEADER);
	// meaning of bfSize open to interpretation (bytes, words, dwords?) -- we won't use it
	bmfh.bfReserved1 = bmfh.bfReserved2 = 0;
	bmfh.bfOffBits = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER) +
			sizeof(RGBQUAD) * m_nColorTableEntries;	
	TRY {
		pFile->Write((LPVOID) &bmfh, sizeof(BITMAPFILEHEADER));
		pFile->Write((LPVOID) m_lpBMIH, nSize);
	}
	CATCH (CException, e) {
		AfxMessageBox("write error");
		return FALSE;
	}
	END_CATCH
	return TRUE;
}

void CDib::Serialize(CArchive& ar)
{
	ar.Flush();
	if(ar.IsStoring()) {
		Write(ar.GetFile());
	}
	else {
		Read(ar.GetFile());
	}
}

// helper functions
void CDib::ComputePaletteSize(int nBitCount)
{
	if(m_lpBMIH == 0 ||

		m_lpBMIH->biClrUsed == 0) {
		switch(nBitCount) {
			case 1:
				m_nColorTableEntries = 2;
				break;
			case 4:
				m_nColorTableEntries = 16;
				break;
			case 8:
				m_nColorTableEntries = 256;
				break;
			case 16:
			case 24:
			case 32:
				m_nColorTableEntries = 0;
				break;
			default:
				ASSERT(FALSE);
		}
	}
	else {
		m_nColorTableEntries = m_lpBMIH->biClrUsed;
	}
	ASSERT(m_nColorTableEntries <= 256); 
}

void CDib::ComputeMetrics()
{
	m_dwSizeImage = m_lpBMIH->biSizeImage;
	if(m_dwSizeImage == 0) {
		DWORD dwBytes = ((DWORD) m_lpBMIH->biWidth * m_lpBMIH->biBitCount) / 32;
		if(((DWORD) m_lpBMIH->biWidth * m_lpBMIH->biBitCount) % 32) {
			dwBytes++;
		}
		dwBytes *= 4;
		m_dwSizeImage = dwBytes * m_lpBMIH->biHeight; // no compression
	}
	m_lpvColorTable = (LPBYTE) m_lpBMIH + sizeof(BITMAPINFOHEADER);
}

void CDib::Empty()
{
	// this is supposed to clean up whatever is in the DIB
	DetachMapFile();
	if(m_nBmihAlloc == crtAlloc) {
		delete [] m_lpBMIH;
	}
	else if(m_nBmihAlloc == heapAlloc) {
		::GlobalUnlock(m_hGlobal);
		::GlobalFree(m_hGlobal);
	}
	if(m_nImageAlloc == crtAlloc) delete [] m_lpImage;
	if(m_hPalette != NULL) ::DeleteObject(m_hPalette);
	if(m_hBitmap != NULL) ::DeleteObject(m_hBitmap);
	m_nBmihAlloc = m_nImageAlloc = noAlloc;
	m_hGlobal = NULL;
	m_lpBMIH = NULL;
	m_lpImage = NULL;
	m_lpvColorTable = NULL;
	m_nColorTableEntries = 0;
	m_dwSizeImage = 0;
	m_lpvFile = NULL;
	m_hMap = NULL;
	m_hFile = NULL;
	m_hBitmap = NULL;
	m_hPalette = NULL;
}

void CDib::DetachMapFile()
{
	if(m_hFile == NULL) return;
	::UnmapViewOfFile(m_lpvFile);
	::CloseHandle(m_hMap);
	::CloseHandle(m_hFile);
	m_hFile = NULL;
}