关于rederbuffer

// gdi gdi+ 使用的双缓存class RenderBuffer{public:RenderBuffer();~RenderBuffer();public:    void   Resize(unsigned int width, unsigned int height);    void   Clear(DWORD dwColor, RECT* prc);void   Destroy();    void   Dump();void   GetImageData(ImageData*  pData);public:    GRAPHICS_RENDER_LIBRARY_TYPE  m_eGraphicsType;  // 同时支持gdi/gdi+HBITMAP  m_hBitmap;    HDC      m_hDC;    unsigned int  m_nWidth;    unsigned int  m_nHeight;};

这个类的实质就是封装了一下HBITMAP和GDI,对HBITMAP的数据进行操作，有点像mfc的memdc的概念。只是这里多了提取hbitmap内存数据的接口。

RenderBuffer::RenderBuffer(){    m_eGraphicsType= GRAPHICS_RENDER_LIBRARY_TYPE_GDI;    m_hDC = NULL;    m_nWidth = 0;    m_nHeight = 0;    m_hBitmap = NULL;}RenderBuffer::~RenderBuffer(){Destroy();}void  RenderBuffer::Destroy(){SAFE_DELETE_GDIOBJECT(m_hBitmap);    DeleteDC(m_hDC);    m_hDC = NULL;    m_nHeight = m_nWidth = 0;}void  RenderBuffer::Clear(DWORD dwColor, RECT* prc){    if (!m_hBitmap)        return;    HBRUSH hBrush = CreateSolidBrush(dwColor);    if (prc)    {        ::FillRect(m_hDC, prc, hBrush);    }    else    {        RECT rc = {0, 0, m_nWidth, m_nHeight};        ::FillRect(m_hDC, &rc, hBrush);    }        SAFE_DELETE_GDIOBJECT(hBrush);}void   RenderBuffer::Resize(unsigned int width, unsigned int height){    if (width == 0 || height == 0)    {        Destroy();        return;    }    if (width == m_nWidth && height == m_nHeight)    {        return;    }    if (m_hBitmap)    {        SAFE_DELETE_GDIOBJECT(m_hBitmap);    }    Image image;image.Create(width, -(int)height, 32, Image::createAlphaChannel);    m_hBitmap = image.Detach();    if (!m_hDC)    {        m_hDC = CreateCompatibleDC(NULL);        SetBkMode(m_hDC, TRANSPARENT);        SetStretchBltMode(m_hDC, HALFTONE);    }    HBITMAP hOldBitmap = (HBITMAP)SelectObject(m_hDC, m_hBitmap);    m_nWidth = width;    m_nHeight = height;}// void  RenderBuffer::Draw(HDC hDC)// {//     if (m_bAlphaBlend)//     {//         if (255 == m_nOpcity)//         {//             m_image.Draw(hDC, 0, 0);//         }//         else//         {//             m_image.Draw(hDC, 0, 0, m_nOpcity);//         }//     }//     else//     {//         m_image.BitBlt(hDC, 0, 0);//     }// }void  RenderBuffer::Dump(){    if (m_hBitmap)    {        Image image;        image.Attach(m_hBitmap, Image::DIBOR_TOPDOWN);        image.Save(L"C:\\aaa.bmp", Gdiplus::ImageFormatBMP);        image.Save(L"C:\\aaa.png", Gdiplus::ImageFormatPNG);        image.Detach();    }}void  RenderBuffer::GetImageData(ImageData*  pData){BITMAP  bm;<span style="background-color: rgb(204, 0, 0);">::GetObject(m_hBitmap, sizeof(bm), &bm);</span>pData->m_nbpp = bm.bmBitsPixel;pData->m_nWidth = bm.bmWidth;pData->m_nHeight = bm.bmHeight;pData->m_nStride = bm.bmWidthBytes;pData->m_pScan0 = (BYTE*)bm.bmBits;pData->m_ptr = (BYTE*)bm.bmBits;}