SingleApplication

This is a replacement of the QSingleApplication for Qt5.

Keeps the Primary Instance of your Application and kills each subsequent instance.

Usage

The SingleApplication class inherits from QApplication. Use it as if you are using the QApplication class.

The library uses your Organization Name and Application Name to set up a Local Socket. The first instance of your Application would start a QLocalServer and then listen for connections on the socket. Every subsequent instance of your application would attempt to connect to that socket. If successful it will be terminated, while in the Primary Instance, SingleApplication would emmit the showUp() signal.

The library uses stdlib to terminate the program with the exit() function.

Here is an example usage of the library:

#include "singleapplication.h"

int main(int argc, char *argv[])
{
    QApplication::setApplicationName("{Your App Name}");
    QApplication::setOrganizationName("{Your Organization Name}");
    
    SingleApplication app(argc, argv);

    return app.exec();
}

The Show Up signal

The SingleApplication class implements a showUp() signal. You can bind to that signal to raise your application's window when a new instance had been started.

Known bugs

The SingleApplication class works really well for the scenario when a user starts your application twice, but the implementation it uses does not garantee it will work if two processes are started simultaniously (with a millisecond delay, which is only done programatically), in which case two instances might coexist on some platforms. The issue is a work in proggress and should be fixed soon.

License

This library and it's supporting documentation are released under The MIT License (MIT).