boost.GILを使ってWindowsで画面イメージを取り込み

画面画像をキャプチャしてPNG形式で保存．そのときに，boost::gilを使用した例．

/// 画面をキャプチャする
void CPY_CaptureScreen(const std::wstring &szFilePath) {

    auto pDlg = GetMainDlg(); // 窓(CWnd*)を得る

    CRect rectClient;
    pDlg->GetClientRect( &rectClient );

    CClientDC dc(pDlg);

    CDC dc2;
    dc2.CreateCompatibleDC( &dc );

    CBitmap bitmap;
    bitmap.CreateCompatibleBitmap(&dc, rectClient.Width(), rectClient.Height() );
    
    auto pOldBitmap = dc2.SelectObject( &bitmap );

    dc2.BitBlt(0,0, rectClient.Width(), rectClient.Height(), &dc, 0, 0, SRCCOPY );

    int nWidthAdjust = rectClient.Width();
    if ( nWidthAdjust % 4 ) { nWidthAdjust += 4 - nWidthAdjust % 4;}

    std::vector<BYTE> bitdata( nWidthAdjust * rectClient.Height() * 3 );
    
    dc2.SelectObject( pOldBitmap );

    BITMAPINFO bitmapinfo;
    ZeroMemory(&bitmapinfo, sizeof(BITMAPINFO) );
    bitmapinfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
    bitmapinfo.bmiHeader.biWidth = nWidthAdjust;
    bitmapinfo.bmiHeader.biHeight = rectClient.Height();
    bitmapinfo.bmiHeader.biPlanes = 1;
    bitmapinfo.bmiHeader.biBitCount = 24;
    bitmapinfo.bmiHeader.biCompression = BI_RGB;
    GetDIBits( dc2, bitmap, 0, rectClient.Height(), bitdata.data(), &bitmapinfo, DIB_RGB_COLORS );


    boost::gil::rgb8_image_t img( nWidthAdjust, rectClient.Height() );
    copy_pixels(boost::gil::interleaved_view(nWidthAdjust, rectClient.Height(), (const boost::gil::rgb8_pixel_t*)bitdata.data(), nWidthAdjust*3), view(img));
    png_write_view(CStringA(szFilePath.c_str()), boost::gil::flipped_up_down_view( const_view(img) ) );