Month: December 2023

void GdiPlusScreenCapture(MONITORINFOEX info, IStream* istream)
{
    HDC DevC = CreateDC(nullptr, info.szDevice, nullptr, nullptr);
    DWORD Width = info.rcMonitor.right - info.rcMonitor.left;
    DWORD Height = info.rcMonitor.bottom - info.rcMonitor.top;

    HDC CaptureDC = CreateCompatibleDC(DevC);
    HBITMAP CaptureBitmap = CreateCompatibleBitmap(DevC, Width, Height);
    HGDIOBJ old_obj = SelectObject(CaptureDC, CaptureBitmap);
    BitBlt(CaptureDC, 0, 0, Width, Height, DevC, 0, 0, SRCCOPY | CAPTUREBLT);

    Gdiplus::Bitmap bitmap(CaptureBitmap, nullptr);

    CLSID pngClsid;
    CLSIDFromString(L"{557cf401-1a04-11d3-9a73-0000f81ef32e}", &pngClsid);

    bitmap.Save(istream, &pngClsid, nullptr);

    SelectObject(CaptureDC, old_obj);
    DeleteDC(CaptureDC);
    ReleaseDC(nullptr, DevC);
    DeleteObject(CaptureBitmap);
    DeleteDC(DevC);
}

void SaveScreenCapture()
{
    std::vector<MONITORINFOEX> monitorInfos;
    GdiplusStartupInput gdiplusStartupInput;
    ULONG_PTR gdiplusToken;
    GdiplusStartup(&gdiplusToken, &gdiplusStartupInput, nullptr);

    // get the bitmap handle to the bitmap screenshot
    HDC hdc = GetDC(nullptr);
    EnumDisplayMonitors(hdc, nullptr, [](HMONITOR hMonitor, HDC hdcMonitor, LPRECT lprcMonitor, LPARAM dwData) -> BOOL {
    std::vector<MONITORINFOEX>* pMonData = reinterpret_cast<std::vector<MONITORINFOEX>*>(dwData);
		MONITORINFOEX info;
		info.cbSize = sizeof(MONITORINFOEX);
		GetMonitorInfo(hMonitor, &info);
		pMonData->push_back(info);
		return true;
	}, reinterpret_cast<LPARAM>(&monitorInfos));
    
    int index = 1;
    for (auto& monitorInfo : monitorInfos)
    {	//Create an empty IStream:
	IStream* pIStream = nullptr;
	if (CreateStreamOnHGlobal(nullptr, true, &pIStream) == S_OK)
        {

            GdiPlusScreenCapture(monitorInfo, pIStream);
	    HGLOBAL hg = nullptr;
	    GetHGlobalFromStream(pIStream, &hg);
	    SIZE_T bufsize = GlobalSize(hg);
	    LPVOID ptr = GlobalLock(hg);
            TCHAR jpegFile[MAX_PATH + 1] = { 0 };
	    _stprintf_s(jpegFile, MAX_PATH, "%d.jpg", index);
	    //write from memory to file for testing:
	    std::ofstream fout(jpegFile, std::ios::binary);
	    fout.write((char*)ptr, bufsize);
	    fout.close();
	    pIStream->Release();
	    GlobalUnlock(hg);
        }
    }

    ReleaseDC(nullptr, hdc);
    GdiplusShutdown(gdiplusToken);
}