QT app starting another app in OSX

Question

I'm currently developing an agent "Agent.app" which must scan your usb port and if it detect an usb device, the app start an application called "Filebrowser.app".

I want the Agent.app located inside the Filebrowser.app to avoid multiple apps.

My first app FileBrowser is develop in Qt/c++ under QT creator. I have also develop the Agent.app under Qt Creator but it's just a C++ class no relation with Qt.

I think I would need the agent.pri declared inside the FileBrowser.pri to make sure that the FileBrowser.app will include it.

What I have done in the agent is :

int main()
{
    PulsUsbDetection *MyUSBDevice = new PulsUsbDetection;

    if(MyUSBDevice->isPulsConnected() == true) {
        char *filepath = "/Applications/puls_connect.app";
        string command = "open " + filepath;
        system(command.c_str());
    }

    return 0;
}

That's the worst thing I can do mainly if the app is not in Application.app.

I do have 2 questions:

How to allow the agent.app to start the FileBrowser.app when the agent is inside the FileBrowser.app ?
How to make sure that the agent.app will be included in the FileBrowser.app ?

Thanks a lot

Jeremy Friesner · Answer 1 · 2015-05-06T04:29:52.570

I want the Agent.app located inside the Filebrowser.app to avoid multiple apps.

Have you considered having just a single program that includes the functionality of both applications, and chooses (inside main()) which functionality to execute based on e.g. a command line argument? That would be easier to implement, and would also make your install package a lot smaller. That said...

How to make sure that the agent.app will be included in the FileBrowser.app ?

After compiling both programs, move the agent.app folder into the FileBrowser.app/Contents/Resources folder. You could use a shell command or bash script to do that, or just right-click on the FileBrowser.app icon, choose "Open Package" from the menu, and then open the Contents and Resources sub-folders and drag agent.app in.

How to allow the agent.app to start the FileBrowser.app when the agent is inside the FileBrowser.app ?

The first thing you'll want to do is find the path of the directory that your "agent" executable is in. Fortunately Qt has a method to just that: You can just call QApplication::applicationDirPath().

So, for example, if your FileBrowser.app was placed in /Applications, and agent.app was placed in FileBrowser.app/Contents/Resources (as suggested above), then the above function call would return a string like "/Applications/FileBrowser.app/Contents/Resources/agent.app/Contents/MacOS".

The second step would be to derive from that string the path to your FileBrowser app. That should be straightforward to do:

// This code to be run in the agent app, to launch the FileBrowser app...
QString agentExecutableDirPath = QApplication::applicationDirPath();
QString fileBrowserExecutablePath = agentExecutableDirPath + "../../../../MacOS/FileBrowser";
system(QFile::encodeName(fileBrowserExecutablePath).constData());  // run it

Note that you'd probably get nicer behavior launching the FileBrowser process using Qt's QProcess API than by calling system() -- in particular, the system() call won't return until the FileBrowser process exits, which will have the side effect of freezing up your agent GUI until then.

QT app starting another app in OSX

1 Answers1