QApplication not working as expected with 3rd paramaeter(GUIMode)

seetharam

Hi ,

I have used QApplication (argc, argv, bool GUIMode ) to run application in non gui mode. With this functionality I could run my application in command mode without connecting to Xserver.
Now I have installed Qt 5.6 in my machine and , I am not able to run application in command mode , Apllication is getting crashed with below error.
QXcbConnection: Could not connect to display

Could you please let me know , if you have any idea , how to run QT application in non gui mode without using X server.

With QCoreApplication I can solve this problem but , my application should support both GUI and commnad mode.
Kindly Help me to resolve this issue.

Thansks in advance
Seetharam

jsulm

@seetharam QApplication does not have a constructor with 3 parameters: http://doc.qt.io/qt-5/qapplication.html#QApplication
Do you use a modified Qt version? Your own QApplication class?

seetharam

Yes , in QT 5.6 it is not available .

VRonin

#include <memory>
int main(int argc, char **argv)
{
bool useGui = false;
std::unique_ptr<QCoreApplication> pApp(nullptr);
if(useGui)
pApp.reset(new QApplication(argc,argv));
else
pApp.reset(new QCoreApplication(argc,argv));

return  pApp->exec();
}

seetharam

@seetharam in Qt5 .6 version of QT , we do not have the QApplication constructor with third paramter to disbale GUI mode.
Hi VRonin,
Thanks for reply.
but actually , my application is implemented in a differnet way .

I am using class which is inherited from QApplication . I have passed false to third argument for non gui mode.
now as per QT 5.6 , I could see only a way that I need to duplicate the class which need to be inheriited from QCore Application.

before:
class myClass : public AQpplciation
{
};

Now it should be like
class myguiclass : public QApplication
{
};
class myclass : public QCoreApplication
{
};

Is there any other way instead of writing two separate classes for QApplication and QCore application?

Regards,
Seetharam

SGaist

Hi,

Out of curiosity, why did you need to subclass QApplication ?

seetharam

Hi SGaist,
Thanks for the reply.
In my application I am inheriting a class from QApplication and initially I will show a logo in a separate thread and then close that logo after my application is launched and also I am doing many other configurations which are related to my application.
To do these things I need to inherite a class from QApplication.
To make it work for console mode I did guimode false in QApplication constructor before .
but it is not working for me in QT 5.6

Regards,
Seetharam

JonB

@seetharam
I see this is the 3rd identical post for this question. So I have wasted my time posting a solution in one of the others... :@ Please just don't!

Maddineni

Hi , Sorry for the inconvienience .
I could not delete the duplicate posts.
Could you please delete duplicates except the the post in which the query was answered? Answered one is locked I guess.

Thanks in advance.
Seetharam