Qt5 developed app doesn't display correctly using Cinnamon desktop in VirtualBox

[te777]

I have an app I've developed in Qt 5.3.1 that doesn't display data in output text boxes when using the Linux Cinnamon desktop in VirtualBox with 3D acceleration enabled in the display settings for the virtual machine.

It does this when using the Cinnamon desktop in any Linux Distro (I've tried Cinnamon with Linux Mint, Ubuntu and Debian). The regular Unity desktop in Ubuntu and the Xfce desktops in both Linux Mint and Debian have no problem. Just Cinnamon.

I don't know if this is a Cinnamon, VirtualBox or Qt problem. Months ago I registered a bug with the Cinnamon folks but I never saw a fix, or that the problem was replicated anywhere. If I disable 3D acceleration for any of the Cinnamon virtual machines in VirtualBox the problem doesn't happen.

I'm posting here because maybe some Qt developers have seen similar problems with Cinnamon in either VirtualBox, or a native Linux machine.

Any comments or replies would be welcome. Thanks in advance for any.

[wysota]

What kind of app are we talking about?

[te777]

It's called Lottery Analyzer Expert QL: it can be downloaded at http://tcesoftware.webs.com., follow the link to Linux Downloads.

It's free. My main versions are Windows, but I have both a 32 bit and 64 bit version for Linux developed in Qt 5.3.1. I hope the link I posted is OK. It's a free application, though not open source (because of the nature of the subject).

It does various analyses on the Powerball and Mega Millions lottery games. I developed the programs out of curiosity of how to do it, and offering them for free for all the very useful free software I've used over the years. Again, I hope posting the link is OK. I just want someone to try my program and see if they can replicate the problem in any environment.

Just double click on either Lottery_32 (32 bit) or Lottery_64 (64 bit) in the folder created by downloading and unzipping the tar.gz. Then choose one of the analyze buttons or "drawn" buttons after entering the number of draws to sort. If it runs correctly data will fill the text boxes for the game chosen to sort the totals of. The problem will show if the text boxes are empty except for the last row.

[te777]

The VirtualBox issue post is here:

https://forums.virtualbox.org/viewtopic.php?f=3&t=68650

The Cinnamon issue post is here:

https://github.com/linuxmint/Cinnamon/issues/4389

In case anyone wants to add any replies in replicating the problem in Cinnamon either in VirtualBox or a native Linux machine.

[wysota]

I was rather asking whether it is a widget based app, Qt Quick or Graphics View

[te777]

Widget based I guess. I just created text boxes and my app outputs to them.

[wysota]

Is the text missing only in some of the widgets? Do these include input widgets? Have you tried setting a different font (size/family)?

[te777]

The data doesn't output to the text box widgets. It's just using the system font now I think. I'll try playing with that and see if that makes a difference. I'll report back. Thanks for helping.

---

Added after 58 minutes:

Changing fonts doesn't seem to help. The text boxes use San Serif Medium 9. They're QTextEdit text boxes that I use for output. Maybe that's problem. I have one set of text boxes (4 rows of 17) used for Powerball and another set (4 rows of 20) used for Mega Millions. The data only displays on the last row for each. The other text boxes are left blank when they should have data in them.

[wysota]

What if you place text on QLabel? What about QLineEdit widgets? What about menus?

[te777]

I'm in the process of changing all the QTextEdit boxes to QLineEdit boxes. I'll let you know how it goes.

[wysota]

Change just one or run one of numerous Qt examples that already contain those widgets.

[te777]

I changed all the QTextEdit widgets to QLinEdit widgets. No help. The code that gets run does a sort procedure first in the class I'm using (one class for Powerball and one for Mega Millions). Then an output procedure gets called that passes the references to the widgets to that output procedure from mainwindow.cpp. I tried putting qApp->ProcessEvents() in different places in the button click procedures that call the sort and output sort in the class I'm using, but with no help so far. It's as if data isn't getting flushed to the widgets properly with 3D acceleration enabled.

The button click procedure code is below:

void MainWindow::on_pushButton_clicked()
{
 
    int range = 1;
 
    bool dooutput;
 
    int drawstosort;
 
    bool ok;
 
 
    Powerball* p = new Powerball();
 
    p->readnums();
 
    if (p->inputfilefound)  {
 
        dooutput = p->sort_input_validate( ui->textEdit_5 );
 
          if (dooutput) {
 
              drawstosort = ui->textEdit_5->toPlainText().toInt(&ok,10);
 
              p->sort(drawstosort);
 
         //     qApp->processEvents();
 
     p->outputsort (ui->lineEdit , ui->lineEdit_2 , ui->lineEdit_4 , ui->lineEdit_3 ,
                  ui->lineEdit_8 , ui->lineEdit_6 , ui->lineEdit_5 , ui->lineEdit_7 ,
                  ui->lineEdit_13 , ui->lineEdit_10 , ui->lineEdit_9 , ui->lineEdit_12 ,
                  ui->lineEdit_11 , ui->lineEdit_14 , ui->lineEdit_16 , ui->lineEdit_15 ,
                  ui->lineEdit_17 , ui->lineEdit_29 , ui->lineEdit_21 , ui->lineEdit_20 ,
                  ui->lineEdit_26 , ui->lineEdit_23 , ui->lineEdit_31 , ui->lineEdit_34 ,
                  ui->lineEdit_32 , ui->lineEdit_19 , ui->lineEdit_22 , ui->lineEdit_33 ,
                  ui->lineEdit_18 , ui->lineEdit_24 , ui->lineEdit_29 , ui->lineEdit_27 ,
                  ui->lineEdit_25 , ui->lineEdit_30 , ui->lineEdit_58 , ui->lineEdit_37 ,
                  ui->lineEdit_66 , ui->lineEdit_44 , ui->lineEdit_46 , ui->lineEdit_63 ,
                  ui->lineEdit_47 , ui->lineEdit_32 , ui->lineEdit_39 , ui->lineEdit_41 ,
                  ui->lineEdit_49 , ui->lineEdit_55 , ui->lineEdit_40 , ui->lineEdit_56 ,
                  ui->lineEdit_52 , ui->lineEdit_57 , ui->lineEdit_43 , ui->lineEdit_61 ,
                  ui->lineEdit_54 , ui->lineEdit_68 , ui->lineEdit_50 , ui->lineEdit_35 ,
                  ui->lineEdit_59 , ui->lineEdit_67 , ui->lineEdit_60 , ui->lineEdit_38 ,
                  ui->lineEdit_62 , ui->lineEdit_48 , ui->lineEdit_45 , ui->lineEdit_53 ,
                  ui->lineEdit_36 , ui->lineEdit_51 , ui->lineEdit_64 , ui->lineEdit_65 ,
                  range
                );
      }
   }
 
    qApp->processEvents();
 
 
    delete p;
}

void MainWindow::on_pushButton_clicked()
{

    int range = 1;

    bool dooutput;

    int drawstosort;

    bool ok;


    Powerball* p = new Powerball();

    p->readnums();

    if (p->inputfilefound)  {

        dooutput = p->sort_input_validate( ui->textEdit_5 );

          if (dooutput) {

              drawstosort = ui->textEdit_5->toPlainText().toInt(&ok,10);

              p->sort(drawstosort);

         //     qApp->processEvents();

     p->outputsort (ui->lineEdit , ui->lineEdit_2 , ui->lineEdit_4 , ui->lineEdit_3 ,
                  ui->lineEdit_8 , ui->lineEdit_6 , ui->lineEdit_5 , ui->lineEdit_7 ,
                  ui->lineEdit_13 , ui->lineEdit_10 , ui->lineEdit_9 , ui->lineEdit_12 ,
                  ui->lineEdit_11 , ui->lineEdit_14 , ui->lineEdit_16 , ui->lineEdit_15 ,
                  ui->lineEdit_17 , ui->lineEdit_29 , ui->lineEdit_21 , ui->lineEdit_20 ,
                  ui->lineEdit_26 , ui->lineEdit_23 , ui->lineEdit_31 , ui->lineEdit_34 ,
                  ui->lineEdit_32 , ui->lineEdit_19 , ui->lineEdit_22 , ui->lineEdit_33 ,
                  ui->lineEdit_18 , ui->lineEdit_24 , ui->lineEdit_29 , ui->lineEdit_27 ,
                  ui->lineEdit_25 , ui->lineEdit_30 , ui->lineEdit_58 , ui->lineEdit_37 ,
                  ui->lineEdit_66 , ui->lineEdit_44 , ui->lineEdit_46 , ui->lineEdit_63 ,
                  ui->lineEdit_47 , ui->lineEdit_32 , ui->lineEdit_39 , ui->lineEdit_41 ,
                  ui->lineEdit_49 , ui->lineEdit_55 , ui->lineEdit_40 , ui->lineEdit_56 ,
                  ui->lineEdit_52 , ui->lineEdit_57 , ui->lineEdit_43 , ui->lineEdit_61 ,
                  ui->lineEdit_54 , ui->lineEdit_68 , ui->lineEdit_50 , ui->lineEdit_35 ,
                  ui->lineEdit_59 , ui->lineEdit_67 , ui->lineEdit_60 , ui->lineEdit_38 ,
                  ui->lineEdit_62 , ui->lineEdit_48 , ui->lineEdit_45 , ui->lineEdit_53 ,
                  ui->lineEdit_36 , ui->lineEdit_51 , ui->lineEdit_64 , ui->lineEdit_65 ,
                  range
                );
      }
   }

    qApp->processEvents();


    delete p;
}

To copy to clipboard, switch view to plain text mode 

Then the class does the sort and output using the widgets passed to the output procedure.

[wysota]

Doing random things will not really help. If text is not painted in a widget then processing events will not help in any way. You need to determine whether the problem is with fonts or something else. Check what happens if you try selecting some text. My nose tells me your problem has something to do with fontconfig. It would be wise to try and reproduce the problem in a different environment (e.g. differently configured VM, different distro, etc.).

[te777]

When I deploy the app to any Linux VM in VirtualBox with 3D accleration, with the Cinnamon desktop, the problem occurs. I tried compiling on Linux Mint Xfce to see if that makes a difference: it doesn't. Only when deployed to Cinnamon desktops (tried with Cinnamon in Ubuntu, Linux Mint and Debian).

Here's the Cinnamon issue post with them:

https://github.com/linuxmint/Cinnamon/issues/3617

[wysota]

What happens if you run your app without Cinnamon, e.g. with bare X?

[te777]

The app works fine. In both Linux Mint and Debian Xfce, and in Ubuntu. I guess I could try some other distros too. Care to suggest any. The app used to work fine in Cinnamon until VirtualBox version 4.3.18. I guess I could try an older version of VirtualBox to to see if the problem occurs.

[wysota]

No, you misunderstood me. Use your virtual machine, just without Cinnamon -- shut down the display manager, login to the console, run X without any desktop environment and start your app with DISPLAY=:0.

[te777]

How do you do that?

[anda_skoa]

You could try forcing a certain Qt widget style to be used.
The problem sounds like it might be caused by different widget styles being used in different environments, or the same widget style picking up different settings depending on environment.

E.g. a qt specific style (plastique for Qt4, fusion for Qt5), or an explicit foreign style (windows)

Cheers,
_

[wysota]

How do you do that?

Ctrl+Alt+F1, login, sudo service sddm stop (or lightdm, depending what your system is using), X &, Ctrl+Alt+F1, DISPLAY=:0 yourapp