QLineEdit update before external method

[Ishtar]

Greetings All

I have something like the following in my project.

MainRoutine doStuff;
 
QLineEdit test = new QLineEdit();
test.setText("Updating...");
 
doStuff.runSTLcppRoutine();

MainRoutine doStuff;

QLineEdit test = new QLineEdit();
test.setText("Updating...");

doStuff.runSTLcppRoutine();

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The call to QLineEdit::setText() does not get updated until doStuff.runSTLCppRoutine() returns despite being physically before it. Can somebody help with this?

Many Thanks.

[NullPointer]

Hi,

You didn't give the time to loop event call the paint() event from QLineEdit...
You can use the QCoreApplication::processEvents() after setting the text.

Hth.

[Ishtar]

Thank you very much for your help

Unfortunately

QCoreApplication::processEvents()

QCoreApplication::processEvents()

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has a bizarre effect.

Here is a snipet of my code.

void Ui_MainGUI::startMainRoutine() {
 
     string errTxt;
     double testValue;
 
      wxParameters wxStn;
 
    if(w->toolBox_WX->currentIndex() == 0){
 
        wxStn.stnName = "Lacrosse WS2300";
        wxStn.stnInterface = "SERIAL";
        wxStn.stnProtocol = "SERIAL";
 
        wxStn.stnPort = w->cmbo_2300Port->currentText().toLocal8Bit().data();
        wxStn.stnDataBit = w->cmbo_2300DataBits->currentText().toLocal8Bit().data();
        wxStn.stnParity = w->cmbo_2300Parity->currentText().toLocal8Bit().data();
        wxStn.stnStopBit = w->cmbo_2300StopBits->currentText().toLocal8Bit().data();
 
        wxStn.stnBaud = w->cmbo_2300Speed->currentText().toInt();
        wxStn.stnPollFreq = w->spin_2300PollFreq->text().toInt();
        wxStn.stnRetries = w->spin_2300Retries->text().toInt();
        wxStn.stnTimeout = w->spin_2300Timeout->text().toInt();
 
    }
 
    w->ledt_2300Status->setText("Connecting...");
    QCoreApplication::processEvents();
 
    if(!(MainRoutine.connStn(wxStn, stnNumber, &errTxt))){
        w->ledt_2300Status->setText("ERROR");
        QString err = QString::fromStdString(errTxt);
        QMessageBox::critical(this, tr("ERROR"), tr("%1").arg(err));
        return;
    }
 
    w->ledt_2300Status->setText("Testing Connection."); 
   QCoreApplication::processEvents();
 
    if(!(MainRoutine.testStn(stnNumber, &testValue, &errTxt))){
        w->ledt_2300Status->setText("ERROR");
        QString err = QString::fromStdString(errTxt);
        QMessageBox::critical(this, tr("ERROR"), tr("%1").arg(err));
        return;
    }
 
    w->ledt_2300Status->setText("ACTIVE");
 
    return;
}

void Ui_MainGUI::startMainRoutine() {

     string errTxt;
     double testValue;
      
      wxParameters wxStn;
    
    if(w->toolBox_WX->currentIndex() == 0){
    
        wxStn.stnName = "Lacrosse WS2300";
        wxStn.stnInterface = "SERIAL";
        wxStn.stnProtocol = "SERIAL";

        wxStn.stnPort = w->cmbo_2300Port->currentText().toLocal8Bit().data();
        wxStn.stnDataBit = w->cmbo_2300DataBits->currentText().toLocal8Bit().data();
        wxStn.stnParity = w->cmbo_2300Parity->currentText().toLocal8Bit().data();
        wxStn.stnStopBit = w->cmbo_2300StopBits->currentText().toLocal8Bit().data();
       
        wxStn.stnBaud = w->cmbo_2300Speed->currentText().toInt();
        wxStn.stnPollFreq = w->spin_2300PollFreq->text().toInt();
        wxStn.stnRetries = w->spin_2300Retries->text().toInt();
        wxStn.stnTimeout = w->spin_2300Timeout->text().toInt();
    
    }

    w->ledt_2300Status->setText("Connecting...");
    QCoreApplication::processEvents();
    
    if(!(MainRoutine.connStn(wxStn, stnNumber, &errTxt))){
        w->ledt_2300Status->setText("ERROR");
        QString err = QString::fromStdString(errTxt);
        QMessageBox::critical(this, tr("ERROR"), tr("%1").arg(err));
        return;
    }
    
    w->ledt_2300Status->setText("Testing Connection."); 
   QCoreApplication::processEvents();

    if(!(MainRoutine.testStn(stnNumber, &testValue, &errTxt))){
        w->ledt_2300Status->setText("ERROR");
        QString err = QString::fromStdString(errTxt);
        QMessageBox::critical(this, tr("ERROR"), tr("%1").arg(err));
        return;
    }
    
    w->ledt_2300Status->setText("ACTIVE");

    return;
}

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1] wxParameters wxStn is a struct which looks like this:

struct wxParameters {
 
    const char *stnName;
    const char *stnInterface;
    const char *stnProtocol;
    const char *stnPort;
    const char *stnDataBit;
    const char *stnParity;
    const char *stnStopBit;    
    int stnBaud;
    int stnPollFreq;
    int stnTimeout;
    int stnRetries;  
 
};

struct wxParameters {

    const char *stnName;
    const char *stnInterface;
    const char *stnProtocol;
    const char *stnPort;
    const char *stnDataBit;
    const char *stnParity;
    const char *stnStopBit;    
    int stnBaud;
    int stnPollFreq;
    int stnTimeout;
    int stnRetries;  
    
};

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2] The call at line 29 fails because wxStn.stnPort is full of garbage.

If I take the processEvents() away then the code works perfectly alas without the QLineEdit being updated until the call returns.

Do you have any idea why my const char *stnPort is full of garbage?

Many thanks
Nikki

[stampede]

Do you have any idea why my const char *stnPort is full of garbage?

Yeah, because you are pointing to a block of memory that is no longer valid:

char * ptr = currentText().toLocal8Bit().data()

char * ptr = currentText().toLocal8Bit().data()

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this is something like:

char * ptr;
{
 QByteArray str = "something";
 ptr = str.data();
}
// is it ok to use ptr here ? not really

char * ptr;
{
 QByteArray str = "something";
 ptr = str.data();
}
// is it ok to use ptr here ? not really

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You should allocate your strings with malloc() and use sprintf or memcpy to initialize it.
Or even better, use QString instead (if you can).

[Ishtar]

Sorry, I was being silly.

In the end I used std::string and then converted to const char later on because QString's are not appropriate for my application.

Many thanks.
Nikki