QPushButton not loading next screen

Vidya H

I am using a Qt5.15 C++ based application on ARM target. I have a QPushButton on my home screen which is gray in color. When clicked, the button color changes to blue. However, the button has to load the menu screen which is not happening.

Background: I have ported the application from Qt5.3 to Qt5.15 and seeing same behavior on both versions.

Since this is a very intermittent issue, I am not able to replicate it.
I am requesting for support to debug this further to understand if this error can occur due to RAM issue on the target platform? Can this issue occur to due Qt framework? Anything specific that I can check on my application code?

Let me know if further details are required.

jsulm

@Vidya-H Without seeing relevant code nobody can tell you why it is not working.
I doubt it is related to RAM - your application would be killed by the OS if there would be not enough RAM.
Also, before thinking about an issue in Qt you need to make sure it is not your code. So, please post the code, or even better a small reproducer.

Vidya H

@jsulm code snippet is below. I added prints to debug further. However, issue has not replicated on the hardware after adding these debug prints. Is there any way to confirm that this issue is due to RAM?

void myWidget::on_pbmyButton_clicked()
{
    if(FALSE == MainWindow::m_bmyButtonDisable)
    {
        MainWindow::m_bmyButtonButtonDisable = TRUE;

        printf("\n******************* myWidget: myButton Pressed. ");

        //do something - my business logic is here
    }

    else
    {
        printf("\n******************* myWidget: Multiple Times myButton Pressed");
    }
}

JonB

@Vidya-H
All this code shows is an if in a function (probably a slot called on signal). It does not show anything at all about "the button has to load the menu screen which is not happening.". It uses a highly inadvisable reference to a variable in the MainWindow class, which is a bad idea. It also uses a static variable, which is odd and quite possibly incorrect.

The issue is likely to be in your code, certainly not "RAM". Is is hard to comment on "intermittent" --- possibly because your code is incorrect and so has "odd" behaviour.

Make a small reproducer if you want help. There should be no need for multiple classes or source files.

Vidya H

@JonB There is a state machine in the code base that causes the button click to move to next state and load the menu screen.

jsulm

@Vidya-H Did you do any debugging to see what is happening? Maybe your state machine is wrong?

JonB

@Vidya-H
Do you think anyone can help you from what you have chosen to say and show?

No matter what, having a class myWidget know about MainWindow is bad architecture, not to mention (apparently) using a static variable in that class which is surely not right. May or may not have something to do with your issue.

As @jsulm writes, don't you think you should debug what happens in your code when the button is clicked?

Vidya H

@jsulm Since this issue came up only twice as of today, once on Qt5.3 and another time on Qt5.15 version of the code, it was not possible to debug further.

JonB

@Vidya-H
Maybe an uninitialized or out-of-scope variable or other programming bug which only shows up sometimes? Nobody can tell from what you have posted. But surely an issue in your code not in Qt.

Vidya H

@JonB yes. I have added debug prints and trying to replicate the issue. If the issue replicates, I will share the logs.

jsulm

@Vidya-H You could also use a debugger to step through the code and see what happens

Vidya H

@jsulm I have a 512MB RAM hardware and app might crash or slow down if I try step by step debugging. For time being, I have added debug prints and trying to replicate the issue.

Axel Spoerl

If you have a bug, you need to debug, as @jsulm and @JonB rightfully say.
There is no need to run your app on a 512MB RAM hardware.
Just compile and reproduce it on your PC.
If you show parts of a strangely designed implementation and ignore the advice you get, please don't expect this forum to be of any help.

Vidya H

@Axel-Spoerl Sure. However, I cannot run the application on the PC as there are several dependencies on the OS layers and several system calls. The issue is reproducing only on the target platform and it has happened only two times almost 3 weeks ago. Hence, I am awaiting and trying to replicate it with additional loggers added. Once I have the logs, I will share the details.

Axel Spoerl

Just to manage expectations: The loggers will tell you what happened, not why it happened. If the application uses a static variable, the initialisation of which you won’t show, if it uses system calls and can’t be compiled on a desktop, there’s a severe architecture problem. Don’t expect more help here. Better fix the application.