cdib.cpp

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	 		::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;
	ComputeMetrics();
	ComputePaletteSize(m_lpBMIH->biBitCount);
	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
	
	// 清除DIB
	Empty();
	
	int nCount, nSize;
	BITMAPFILEHEADER bmfh;
	
	// 尝试读取BMP文件
	try
	{
		// 读BMP文件头
		nCount = pFile->Read((LPVOID) &bmfh, sizeof(BITMAPFILEHEADER));
		
		// 判断读取文件头的大小是否
		if(nCount != sizeof(BITMAPFILEHEADER))
		{
			// 读文件出错
			throw new CException;
		}
		
		// 判断是否是"BM"
		if(bmfh.bfType != 0x4d42)
		{
			// 不是BMP文件，抛出异常
			throw new CException;
		}
		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();
		ComputePaletteSize(m_lpBMIH->biBitCount);
		MakePalette();
		m_lpImage = (LPBYTE) new char[m_dwSizeImage];
		nCount = pFile->Read(m_lpImage, m_dwSizeImage); // image only
	}
	catch(CException* pe)
	{
		AfxMessageBox("Read error");
		pe->Delete();
		return FALSE;
	}
	return TRUE;
}

BOOL CDib::ReadSection(CFile* pFile, CDC* pDC /* = NULL */)
{
	// new function reads BMP from disk and creates a DIB section
	//    allows modification of bitmaps from disk
	// 1. read file header to get size of info hdr + color table
	// 2. read info hdr (to get image size) and color table
	// 3. create DIB section based on header parms
	// 4. read image into memory that CreateDibSection allocates
	Empty();
	int nCount, nSize;
	BITMAPFILEHEADER bmfh;
	try
	{
		nCount = pFile->Read((LPVOID) &bmfh, sizeof(BITMAPFILEHEADER));
		if(nCount != sizeof(BITMAPFILEHEADER))
		{
			throw new CException;
		}
		if(bmfh.bfType != 0x4d42)
		{
			throw new CException;
		}
		nSize = bmfh.bfOffBits - sizeof(BITMAPFILEHEADER);
		m_lpBMIH = (LPBITMAPINFOHEADER) new char[nSize];
		m_nBmihAlloc = crtAlloc;
		m_nImageAlloc = noAlloc;
		nCount = pFile->Read(m_lpBMIH, nSize); // info hdr & color table
		if(m_lpBMIH->biCompression != BI_RGB)
		{
			throw new CException;
		}
		ComputeMetrics();
		ComputePaletteSize(m_lpBMIH->biBitCount);
		MakePalette();
		UsePalette(pDC);
		m_hBitmap = ::CreateDIBSection(pDC->GetSafeHdc(), (LPBITMAPINFO) m_lpBMIH,
			DIB_RGB_COLORS,	(LPVOID*) &m_lpImage, NULL, 0);
		ASSERT(m_lpImage != NULL);
		nCount = pFile->Read(m_lpImage, m_dwSizeImage); // image only
	}
	catch(CException* pe)
	{
		AfxMessageBox("ReadSection error");
		pe->Delete();
		return FALSE;
	}
	return TRUE;
}

BOOL CDib::Write(CFile* pFile)
{
	BITMAPFILEHEADER bmfh;
	bmfh.bfType = 0x4d42;  // 'BM'
	int nSizeHdr = sizeof(BITMAPINFOHEADER) + sizeof(RGBQUAD) * m_nColorTableEntries;
	bmfh.bfSize = 0;
	// bmfh.bfSize = sizeof(BITMAPFILEHEADER) + nSizeHdr + m_dwSizeImage;
	// 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,  nSizeHdr);
		pFile->Write((LPVOID) m_lpImage, m_dwSizeImage);
	}
	catch(CException* pe)
	{
		pe->Delete();
		AfxMessageBox("write error");
		return FALSE;
	}
	return TRUE;
}

void CDib::Serialize(CArchive& ar)
{
	DWORD dwPos;
	dwPos = ar.GetFile()->GetPosition();
	TRACE("CDib::Serialize -- pos = %d\n", dwPos);
	ar.Flush();
	dwPos = ar.GetFile()->GetPosition();
	TRACE("CDib::Serialize -- pos = %d\n", dwPos);
	if(ar.IsStoring())
	{
		Write(ar.GetFile());
	}
	else
	{
		Read(ar.GetFile());
	}
}

// helper functions
void CDib::ComputePaletteSize(int nBitCount)
{
	if((m_lpBMIH == NULL) || (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 >= 0) && (m_nColorTableEntries <= 256)); 
}

void CDib::ComputeMetrics()
{
	if(m_lpBMIH->biSize != sizeof(BITMAPINFOHEADER))
	{
		TRACE("Not a valid Windows bitmap -- probably an OS/2 bitmap\n");
		throw new CException;
	}
	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;
}