main window doesn't open although program is running

LeoC

Hi,

I have a small gui that should display some voltage values that comes in over a serial port.
The thing is that the gui is not loaded after starting the programm, although I see the values comming in in the debug output. So the programm itself is running somehow.
When I remove the part where I read the serial port the gui is shown.

What is wrong here?

#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{ 
    strVoltages << "Voltage 1" << "Voltage 2" << "Voltage 3";

    ui->setupUi(this);
    this->createLayout();

    this->readValues();
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::readValues() {
    QSerialPort port;
    port.setPortName("COM3");
    port.setBaudRate(115200);
    port.setDataBits(QSerialPort::Data8);
    port.setParity(QSerialPort::NoParity);
    port.setStopBits(QSerialPort::OneStop);
    port.setFlowControl(QSerialPort::NoFlowControl);

    if (!port.open(QSerialPort::ReadWrite)) {
        qDebug() << "Error opening serial port: " << port.errorString() << endl;
    }
    else {
        while(1) {
            while (!port.canReadLine())
                port.waitForReadyRead(-1);

            while (port.canReadLine()) {
                QString strIn(port.readLine());
                QStringList strList = strIn.split(',');

                if(strList.count() == strVoltages.length()) {
                    int iLCDCounter = 0;
                    foreach(QString strTmp, strList) {
                        lLCDNumber.at(iLCDCounter++)->display(strTmp);
                        qDebug() << strTmp;

                    }
                }
            }
        }
    }
}

void MainWindow::createLayout() {

    QVBoxLayout * vBoxLayout = new QVBoxLayout();

    for(int iItr = 0; iItr < strVoltages.length(); iItr++) {
        lDescription.append(new QLabel(strVoltages.at(iItr)));
        lLCDNumber.append(new QLCDNumber());

        QHBoxLayout *hBoxLayout = new QHBoxLayout();
        hBoxLayout->addWidget(lDescription.last());
        hBoxLayout->addWidget(lLCDNumber.last());

        vBoxLayout->addLayout(hBoxLayout);
    }

    QWidget *w = new QWidget();
    w->setLayout(vBoxLayout);

    setCentralWidget(w);
}

Thanks!

JonB

@LeoC said in main window doesn't open although program is running:

while(1) {

That loop never exits.

Your code/GUI might be better written using signals for reading the data instead of waitForReadyRead() etc. Get the main window up & showing without waiting, and display the values as & when they arrive via signals/slots.

arsinte_andrei

why do you use while(1)??? have you heard of signal and slot?? use it!!

while(1) is useful for programming microcontrollers .. In Qt we use signal and slots

Pablo J. Rogina

@LeoC said in main window doesn't open although program is running:

What is wrong here?

It looks like the while() loop... You are supposed to work with signals & slots in Qt.

You may want to look at this example for serial terminal. I guess you'll grasp a good idea about how to work with the serial port

LeoC

Sorry for my late response.

It isn't the first time I use Qt and I heard about signals and slots of course. In this case I needed a very fast (and maybe dirty) solution so that I just copied 'something' from the internet. Shouldn't do this again. After you gave me the right hint I abandoned the above solution (since it didn't worked anyway) and started from scratch again. Not it works as it should do.

If someone is interested:

#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{ 
    strVoltages << "Voltage 1" << "Voltage 2" << "Voltage 3";
    iMinSize = (3 * strVoltages.count() + strVoltages.count() - 1);
    iMaxSize = (4 * strVoltages.count() + strVoltages.count() - 1);
    bInvokedFirstTime = false;
    bInvokedSecondTime = false;

    ui->setupUi(this);
    this->setWindowTitle("Voltmeter");

    connect(&port,SIGNAL(readyRead()),this,SLOT(readValues()));

    this->createLayout();

    this->configureSerialPort();
    this->readValues();
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::configureSerialPort() {
    port.setPortName("COM3");
    port.setBaudRate(115200);
    port.setDataBits(QSerialPort::Data8);
    port.setParity(QSerialPort::NoParity);
    port.setStopBits(QSerialPort::OneStop);
    port.setFlowControl(QSerialPort::NoFlowControl);

    if (!port.open(QSerialPort::ReadWrite)) {
        qDebug() << "Error opening serial port: " << port.errorString() << endl;
    }
    else
        qDebug() << "Serial port is ready";
}

void MainWindow::displayValues(QByteArray baTmp) {
    
    QStringList strListValues = QString(baTmp).split(",");

    int iLoopCounter = 0;
    foreach(QString strTmp, strListValues) {
        lLCDNumber.at(iLoopCounter)->display(strTmp);

        bool bCheck;
        double dNumber = strTmp.toDouble(&bCheck);

        if(dNumber < 10)
            lIndicator.at(iLoopCounter)->setStyleSheet("QLabel { background-color : red; }");

        iLoopCounter++;
    }
}

void MainWindow::readValues() {

    if(bInvokedFirstTime) {
        baDataIn.append(port.readAll());

        if(!bInvokedSecondTime) {
            int iPosOfExlM = baDataIn.indexOf("!");
            if(iPosOfExlM < iMinSize) {
                baDataIn = baDataIn.right(baDataIn.length() - (iPosOfExlM+1));
                bInvokedSecondTime = true;
            }
        }

        int iLengthOfDataIn;
        while(baDataIn.length() > iMaxSize) {
            int iPosOfExlM = baDataIn.indexOf("!");
            QByteArray baTmp;

            if(iPosOfExlM != -1) {
                baTmp = baDataIn.left(iPosOfExlM);
                baDataIn = baDataIn.right(baDataIn.length() - (iPosOfExlM+1));
                iLengthOfDataIn = baDataIn.length();

                if(baTmp.length() >= iMinSize && baTmp.length() <= iMaxSize) {
                    this->displayValues(baTmp);
                }
            }
        }
    }
    if(!bInvokedFirstTime) {
        bInvokedFirstTime = true;
        QByteArray baTmp = port.readAll();
    }
}

void MainWindow::createLayout() {

    QVBoxLayout * vBoxLayout = new QVBoxLayout();
    QFont f( "Arial", 30, QFont::Bold);

    for(int iItr = 0; iItr < strVoltages.length(); iItr++) {
        lDescription.append(new QLabel(strVoltages.at(iItr)));
        lDescription.last()->setFont(f);
        lDescription.last()->setFixedWidth(200);

        lLCDNumber.append(new QLCDNumber());
        lLCDNumber.last()->setFixedHeight(100);

        lIndicator.append(new QLabel());
        lIndicator.last()->setFixedWidth(100);
        lIndicator.last()->setFixedHeight(100);
        lIndicator.last()->setStyleSheet("QLabel { background-color : grey; }");

        QHBoxLayout *hBoxLayout = new QHBoxLayout();
        hBoxLayout->addWidget(lDescription.last());
        hBoxLayout->addWidget(lLCDNumber.last());
        hBoxLayout->addWidget(lIndicator.last());

        vBoxLayout->addLayout(hBoxLayout);
    }

    QPushButton *bReset = new QPushButton("Reset");
    vBoxLayout->addWidget(bReset);
    connect(bReset,SIGNAL(pressed()),this,SLOT(resetMeasurement()));

    QWidget *w = new QWidget();
    w->setLayout(vBoxLayout);

    setCentralWidget(w);
}

void MainWindow::resetMeasurement() {
    foreach(QLabel *lTmp, lIndicator) {
        lTmp->setStyleSheet("QLabel { background-color : grey; }");
    }
}

arsinte_andrei

if is working please mark this as solved from the menu... Many thanks