截取屏幕并保存为BMP文件

    CDC *pDC;//屏幕DC
    pDC = CDC::FromHandle( ::GetDC(NULL) );//获取当前整个屏幕DC
    int BitPerPixel = pDC->GetDeviceCaps( BITSPIXEL );//获得颜色模式
    int Width = pDC->GetDeviceCaps( HORZRES );
    int Height = pDC->GetDeviceCaps( VERTRES );


    //复制屏幕
    CDC memDC;
    memDC.CreateCompatibleDC( pDC );

    CBitmap memBitmap, *oldmemBitmap;
    memBitmap.CreateCompatibleBitmap( pDC, Width, Height);
    oldmemBitmap = memDC.SelectObject( &memBitmap );//将memBitmap选入内存DC
    memDC.BitBlt( 0, 0, Width, Height, pDC, 0, 0, SRCCOPY);//复制屏幕图像到内存DC

    //保存为bmp文件
    BITMAP bmp;
    memBitmap.GetBitmap( &bmp );//获得位图信息

    FILE *fp = fopen( "c:\\1.bmp", "w+b");

    BITMAPFILEHEADER bfh = {0};//位图文件头
    bfh.bfOffBits = sizeof( BITMAPFILEHEADER) + sizeof( BITMAPINFOHEADER );//到位图数据的偏移量
    bfh.bfSize = bfh.bfOffBits + bmp.bmWidthBytes * bmp.bmHeight;//文件总的大小
    bfh.bfType = (WORD)0x4d42;
    
    BITMAPINFOHEADER bih = {0};//位图信息头
    bih.biBitCount = bmp.bmBitsPixel;//每个像素字节大小
    bih.biCompression = BI_RGB;
    bih.biHeight = bmp.bmHeight;
    bih.biWidth = bmp.bmWidth;
    bih.biPlanes = 1;
    bih.biSize = sizeof( BITMAPINFOHEADER);
    bih.biSizeImage = bmp.bmWidthBytes * bmp.bmHeight;//图像数据大小

    fwrite( &bfh, 1, sizeof(BITMAPFILEHEADER), fp);//写入位图文件头
    fwrite( &bih, 1, sizeof(BITMAPINFOHEADER), fp);//写入位图信息头
     
    byte * p = new byte[bmp.bmWidthBytes * bmp.bmHeight];//申请内存保存位图数据

    GetDIBits( memDC.m_hDC, (HBITMAP)memBitmap.m_hObject, 0, Height, p,
            (LPBITMAPINFO)&bih, DIB_RGB_COLORS);//获取位图数据

    fwrite( p, 1, bmp.bmWidthBytes * bmp.bmHeight, fp);//写入位图数据

    //垃圾处理
    delete [] p;
    fclose(fp);
    memDC.SelectObject( oldmemBitmap );