QSerialPort's read buffer is always empty while running another func.

[Gokhan]

@J-Hilk Yes. it gives the "Crashed" error and "Destroyed while process ("cmd.exe") is still running." What can I do to solve this?
@SGaist I know they are a local variable, I can't use a global variable. I tried to use a global variable instead of them, this time it never gave the finished event. I guess I didn't completely connect this signal. Also, this argument list is running like I want, if I write the waiting function...

[SGaist]

There's no need for global variables. Since you'll be using these commands several times, just keep them as member variables and setup them once in your dialog constructor.

Then you can re-use them as needed.

[J.Hilk]

@Gokhan said in QSerialPort's read buffer is always empty while running another func.:

@J-Hilk Yes. it gives the "Crashed" error and "Destroyed while process ("cmd.exe") is still running." What can I do to solve this?
@SGaist I know they are a local variable, I can't use a global variable. I tried to use a global variable instead of them, this time it never gave the finished event. I guess I didn't completely connect this signal. Also, this argument list is running like I want, if I write the waiting function...

Actually, that are to be expected error messages, for reasons, @SGaist explained!

QProgress does not have to be global to work e.g:

QString com=QString("/k img_cvt  -i  %1   -f   0").arg(img_down[idxProcess].image_with_ext);
  arguments <<com;
  QDir dir;
  dir.setCurrent("D:/conv");
  QProcess *proc = new QProcess();

   connect(proc, & QProcess::errorOccurred, proc,[=](QProcess::ProcessError error){qDebug() <<"Process had an error:" <<  error; });
   connect(proc, SIGNAL(finished(int, QProcess::ExitStatus)),
                this, SLOT(finishProcess(int, QProcess::ExitStatus)) );
  connect(proc, SIGNAL(finished(int, QProcess::ExitStatus)), proc, SLOT(deleteLater()));
   proc->start("cmd.exe",arguments);

[Gokhan]

@SGaist and @J-Hilk many thank your reply.
I'm using the proc variable as a member variable that is decelerated and initialized in class. "QProcess *proc = new QProcess();" like you said. However, it never gave the finish event. Why don't I get any event?
And when I re-click the button, it gives an error that is "QProcess::start: Process is already running",

void image_down_dialog::on_convertButton_clicked()
{
    idxProcess = 0;
    find_all_imgs();

    QStringList arguments;
    QString com=QString("/k img_cvt  -i  %1   -f   0").arg(img_down[0].image_with_ext);
    arguments <<com;
    QDir::setCurrent("D:/User Interface/GUI_660_HMI/conv");

    connect(proc, & QProcess::errorOccurred, proc,[=](QProcess::ProcessError error){qDebug() <<"Process had an error:" <<  error; });
    connect(proc, SIGNAL(finished(int, QProcess::ExitStatus)),
            this, SLOT(finishProcess(int, QProcess::ExitStatus)) );
    connect(proc, SIGNAL(finished(int, QProcess::ExitStatus)), proc, SLOT(deleteLater()));

    proc->start("cmd.exe",arguments);
}

[J.Hilk]

@Gokhan
ok first, if you make QProcess a member variable, move the connects into the constructor:

QProcess *proc = new QProcess();
connect(proc, & QProcess::errorOccurred, proc,[=](QProcess::ProcessError error){qDebug() <<"Process had an error:" <<  error; });
connect(proc, SIGNAL(finished(int, QProcess::ExitStatus)),
            this, SLOT(finishProcess(int, QProcess::ExitStatus)) );

or you get problems when you press the button more than once.

also the deleteLater has to be moved to the destructor or you can use your QProcess object only once.

~MyClass(){
   proc->deleteLater();
}

Why don't I get any event?
And when I re-click the button, it gives an error that is "QProcess::start: Process is already running",

it would seem your process is still running right?

[VRonin]

@J.Hilk said in QSerialPort's read buffer is always empty while running another func.:

also the deleteLater has to be moved to the destructor

If you pass the parent in the constructor there is no need to manually do this

[J.Hilk]

@VRonin true, but @Gokhan said

I'm using the proc variable as a member variable that is decelerated and initialized in class. "QProcess *proc = new QProcess();"

So in this particular case the deleteLater() is needed. More convenient would of course be to give QProcess a parent.

[Gokhan]

@J-Hilk I did them you said, but the result is the same. It never gives the finished event, so it is always running.

[jsulm]

@Gokhan Please read again what @SGaist wrote: each argument should be in its own string. You, instead, put all parameters into one string.

[Gokhan]

@jsulm "/k img_cvt -i %1 -f 0" this is a one line command, so it has to write in one line. While I was also manually using this cmd application before, using it the same. Also, it successfully completes the conversion and creates a new folder within hex code. However, it never gives the finished information, it is continuous running to finish. I can see it's still running when re-click the button.

[jsulm]

@Gokhan said in QSerialPort's read buffer is always empty while running another func.:

/k img_cvt -i %1 -f 0

Wrong it consists of several parameters: "/k" "img_cvt" "-i" "%1" "-f" "0"

[Gokhan]

That is a part of the user manual. I don't know how to use it like you said? However, it's normally running if use the waitforfinish function like I have mentioned above.

The usage is : 
    img_cvt  -i  inputfilename  -f  format

         format is as follow:
            0 : ARGB1555 [default]
            1 : L1
            2 : L4
            3 : L8
            4 : RGB332
            5 : ARGB2
            6 : ARGB4
            7 : RGB565
            8 : PALETTEED [FT80X only]    
            9 : L2 [FT81X only]

Example : 
    img_cvt  -i  lenaface40.png  -f   8

[jsulm]

@Gokhan
Just pass each parameter as one string in the string list (as shown here http://doc.qt.io/qt-5/qprocess.html):

arguments <<"/k"<<"img_cvt"<<"-i"<<QString(%1).arg(img_down[0].image_with_ext)<<"-f"<<"0";

Also you should connect http://doc.qt.io/qt-5/qprocess.html#errorOccurred signal to a slot to check whether something went wrong.

[Gokhan]

@jsulm I just changed my code like you said and connected the signals that are like below in the constructor. The issue isn't solved. ErrorOccurred don't give an error while running.

    proc = new QProcess ();
    connect(proc, & QProcess::errorOccurred, proc,[=](QProcess::ProcessError error){qDebug() <<"Process had an error:" <<  error; });
    connect(proc, SIGNAL(finished(int, QProcess::ExitStatus)),
                this, SLOT(finishProcess(int, QProcess::ExitStatus)) );

[jsulm]

@Gokhan Connect http://doc.qt.io/qt-5/qprocess.html#readyReadStandardError and http://doc.qt.io/qt-5/qprocess.html#readyReadStandardOutput to slots and print out what http://doc.qt.io/qt-5/qprocess.html#readAllStandardError and http://doc.qt.io/qt-5/qprocess.html#readAllStandardOutput return. Maybe you will then see what is going on.

[Gokhan]

@jsulm There is no any readAllStandardError and you can see the output of readAllStandardOutput below. Everything shows normal.

readyReadStandardOutput "image conversion utility for FT8XX V0.7\r\nconvert complete!\r\n"
readyReadStandardOutput "\r\nD:I\\conv>"

[Gokhan]

@jsulm @J-Hilk and @SGaist

I'm trying that it, but I get an error that is "no matching function for call to 'image_down_dialog::connect(QProcess*&, <unresolved overloaded function type>, image_down_dialog*, void (image_down_dialog::*)(int, QProcess::ExitStatus))' " Why do I get this?
^
connect(proc, &QProcess::finished, this, &image_down_dialog::finishProcess);

[SGaist]

How did you declare proc?

[J.Hilk]

@Gokhan
Sadly, Signal finished is overloaded in this class. To connect to this one using the function pointer syntax, you must specify the signal type in a static cast:

connect(process, static_cast<void(QProcess::*)(int, QProcess::ExitStatus)>(&QProcess::finished), [=](int exitCode, QProcess::ExitStatus exitStatus){ /* ... */ });

[Gokhan]

@J-Hilk It should be connected below to compile successfully, so it's static cast. I did it and it can compile and connect now without an issue. However, I haven't solved this problem yet, it isn't still giving the finished event. Can it be a bug with qprocess ? Should I write a bug report?
QObject::connect(proc, (void (QProcess::*)(int,QProcess::ExitStatus))&QProcess::finished, this, &image_down_dialog::finished);