dib.cpp

opengl 编程环境设置,详细的减少了如何在VC下进行OPENGL的设置

 * NumColors()
 *
 * Return Value:
 *
 * WORD             - number of colors in the color table
 *
 * Description:
 *
 * This function calculates the number of colors in the DIB's color table
 * by finding the bits per pixel for the DIB (whether Win3.0 or other-style
 * DIB). If bits per pixel is 1: colors=2, if 4: colors=16, if 8: colors=256,
 * if 24, no colors in color table.
 *
 ************************************************************************/

WORD CDib::NumColors() const
{
	if (!m_pBMI)
		return 0;

	WORD wBitCount;  // DIB bit count

	/*  The number of colors in the color table can be less than 
	 *  the number of bits per pixel allows for (i.e. lpbi->biClrUsed
	 *  can be set to some value).
	 *  If this is the case, return the appropriate value.
	 */

	DWORD dwClrUsed;

	dwClrUsed = m_pBMI->bmiHeader.biClrUsed;
	if (dwClrUsed != 0)
		return (WORD)dwClrUsed;

	/*  Calculate the number of colors in the color table based on
	 *  the number of bits per pixel for the DIB.
	 */
	wBitCount = m_pBMI->bmiHeader.biBitCount;

	/* return number of colors based on bits per pixel */
	switch (wBitCount)
	{
		case 1:
			return 2;

		case 4:
			return 16;

		case 8:
			return 256;

		default:
			return 0;
	}
}

/*************************************************************************
 *
 * Save()
 *
 * Saves the specified DIB into the specified CFile.  The CFile
 * is opened and closed by the caller.
 *
 * Parameters:
 *
 * CFile& file - open CFile used to save DIB
 *
 * Return value: Number of saved bytes or CFileException
 *
 *************************************************************************/

DWORD CDib::Save(CFile& file) const
{
	BITMAPFILEHEADER bmfHdr; // Header for Bitmap file
	DWORD dwDIBSize;

	if (m_pBMI == NULL)
		return 0;

	// Fill in the fields of the file header

	// Fill in file type (first 2 bytes must be "BM" for a bitmap)
	bmfHdr.bfType = DIB_HEADER_MARKER;  // "BM"

	// Calculating the size of the DIB is a bit tricky (if we want to
	// do it right).  The easiest way to do this is to call GlobalSize()
	// on our global handle, but since the size of our global memory may have
	// been padded a few bytes, we may end up writing out a few too
	// many bytes to the file (which may cause problems with some apps).
	//
	// So, instead let's calculate the size manually (if we can)
	//
	// First, find size of header plus size of color table.  Since the
	// first DWORD in both BITMAPINFOHEADER and BITMAPCOREHEADER conains
	// the size of the structure, let's use this.
	dwDIBSize = *(LPDWORD)&m_pBMI->bmiHeader + PaletteSize();  // Partial Calculation

	// Now calculate the size of the image
	if ((m_pBMI->bmiHeader.biCompression == BI_RLE8) || (m_pBMI->bmiHeader.biCompression == BI_RLE4))
	{
		// It's an RLE bitmap, we can't calculate size, so trust the
		// biSizeImage field
		dwDIBSize += m_pBMI->bmiHeader.biSizeImage;
	}
	else
	{
		DWORD dwBmBitsSize;  // Size of Bitmap Bits only

		// It's not RLE, so size is Width (DWORD aligned) * Height
		dwBmBitsSize = WIDTHBYTES((m_pBMI->bmiHeader.biWidth)*((DWORD)m_pBMI->bmiHeader.biBitCount)) * m_pBMI->bmiHeader.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).
		m_pBMI->bmiHeader.biSizeImage = dwBmBitsSize;
	}

	// Calculate the file size by adding the DIB size to sizeof(BITMAPFILEHEADER)
	bmfHdr.bfSize = dwDIBSize + sizeof(BITMAPFILEHEADER);
	bmfHdr.bfReserved1 = 0;
	bmfHdr.bfReserved2 = 0;

	/*
	 * Now, calculate the offset the actual bitmap bits will be in
	 * the file -- It's the Bitmap file header plus the DIB header,
	 * plus the size of the color table.
	 */
	bmfHdr.bfOffBits = (DWORD)sizeof(BITMAPFILEHEADER) + m_pBMI->bmiHeader.biSize + PaletteSize();

	// Write the file header
	file.Write((LPSTR)&bmfHdr, sizeof(BITMAPFILEHEADER));
	DWORD dwBytesSaved = sizeof(BITMAPFILEHEADER); 

	// Write the DIB header
	UINT nCount = sizeof(BITMAPINFO) + (NumColors()-1)*sizeof(RGBQUAD);
	dwBytesSaved += nCount; 
	file.Write(m_pBMI, nCount);
	
	// Write the DIB bits
	DWORD dwBytes = m_pBMI->bmiHeader.biBitCount * Width();
  // Calculate the number of bytes per line
	if (dwBytes%32 == 0)
		dwBytes /= 8;
	else
		dwBytes = dwBytes/8 + (32-dwBytes%32)/8 + (((32-dwBytes%32)%8 > 0) ? 1 : 0); 
	nCount = dwBytes * Height();
	dwBytesSaved += nCount; 
	file.WriteHuge(m_pBits, nCount);

	return dwBytesSaved;
}


/*************************************************************************

  Function:  Read (CFile&)

   Purpose:  Reads in the specified DIB file into a global chunk of
			 memory.

   Returns:  Number of read bytes.

*************************************************************************/

DWORD CDib::Read(CFile& file)
{
	// Ensures no memory leaks will occur
	Free();
	
	BITMAPFILEHEADER bmfHeader;

	// Go read the DIB file header and check if it's valid.
	if (file.Read((LPSTR)&bmfHeader, sizeof(bmfHeader)) != sizeof(bmfHeader))
		return 0;
	if (bmfHeader.bfType != DIB_HEADER_MARKER)
		return 0;
	DWORD dwReadBytes = sizeof(bmfHeader);

	// Allocate memory for DIB
	m_pBMI = (LPBITMAPINFO)GlobalAllocPtr(GHND, bmfHeader.bfOffBits-sizeof(BITMAPFILEHEADER) + 256*sizeof(RGBQUAD));
	if (m_pBMI == 0)
		return 0;

	// Read header.
	if (file.Read(m_pBMI, bmfHeader.bfOffBits-sizeof(BITMAPFILEHEADER)) != (UINT)(bmfHeader.bfOffBits-sizeof(BITMAPFILEHEADER)))
	{
		GlobalFreePtr(m_pBMI);
		m_pBMI = NULL;
		return 0;
	}
	dwReadBytes += bmfHeader.bfOffBits-sizeof(BITMAPFILEHEADER);

	DWORD dwLength = file.GetLength();
	// Go read the bits.
	m_pBits = (LPBYTE)GlobalAllocPtr(GHND, dwLength - bmfHeader.bfOffBits);
	if (m_pBits == 0)
	{
		GlobalFreePtr(m_pBMI);
		m_pBMI = NULL;
		return 0;
	}
	
	if (file.ReadHuge(m_pBits, dwLength-bmfHeader.bfOffBits) != (dwLength - bmfHeader.bfOffBits))
	{
		GlobalFreePtr(m_pBMI);
		m_pBMI = NULL;
		GlobalFreePtr(m_pBits);
		m_pBits = NULL;
		return 0;
	}
	dwReadBytes += dwLength - bmfHeader.bfOffBits;

	CreatePalette();
	return dwReadBytes;
}

#ifdef _DEBUG
void CDib::Dump(CDumpContext& dc) const
{
	CObject::Dump(dc);
}
#endif

//////////////////////////////////////////////////////////////////////////
//// Clipboard support

//---------------------------------------------------------------------
//
// Function:   CopyToHandle
//
// Purpose:    Makes a copy of the DIB to a global memory block.  Returns
//             a handle to the new memory block (NULL on error).
//
// Returns:    Handle to new global memory block.
//
//---------------------------------------------------------------------

HGLOBAL CDib::CopyToHandle() const
{
	CSharedFile file;
	try
	{
		if (Save(file)==0)
			return 0;
	}
	catch (CFileException* e)
	{
		e->Delete();
		return 0;
	}
		
	return file.Detach();
}

//---------------------------------------------------------------------
//
// Function:   ReadFromHandle
//
// Purpose:    Initializes from the given global memory block.  
//
// Returns:    Number of read bytes.
//
//---------------------------------------------------------------------

DWORD CDib::ReadFromHandle(HGLOBAL hGlobal)
{
	CSharedFile file;
	file.SetHandle(hGlobal, FALSE);
	DWORD dwResult = Read(file);
	file.Detach();
	return dwResult;
}

//////////////////////////////////////////////////////////////////////////
//// Serialization support

void CDib::Serialize(CArchive& ar) 
{
	CFile* pFile = ar.GetFile();
	ASSERT(pFile != NULL);
	if (ar.IsStoring())
	{	// storing code
		Save(*pFile);
	}
	else
	{	// loading code
		Read(*pFile);
	}
}