Hello.
Please excuse me for my poor english.

I am trying to write a program, and one of its functions will be manipulations with windowses of other programs.
In particular, moving them and making its screenshots.

I am trying to make screenshot with code like this one:
Qt Code: 
  1. for (const auto& screen : QGuiApplication::screens()) {
  2.    if (screen) {
  3.       QPixmap screenshot = screen->grabWindow(window_id);
  4.       if (!screenshot.isNull() && screenshot.save("screenshot.png")) {
  5.          cout << "saved" << endl;
  6.       }
  7.    }
  8. }
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However, to make it work, I have to create a Q*Application object:
Qt Code: 
  1. QApplication a(argc, argv);
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Without it, nothing works (QGuiApplication::screens() is empty).

In case where a program activelu uses Qt it is not a problem.
However, I am trying to make a small library, which can manipulate with windovs via qt, and use the library in my program.

So I want to make my program qt-independent (with exception of the manipulating library ofc).
In this case making global object of a qt type is looking bad.

So what is correct way to solve the task?
Make a singleton with QApplication inside the library?