It does not create a chart

[deleted286]

I have 2 different threads. In thread one reading data from txt and in thread 2 copy that file into another txt. I want to create a chart via thread 2(which is writingData() ). I have the following code. But there is no chart when i run the code. I have also mythread.h and myhread.cpp

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QtCore>
#include <QMainWindow>
#include <QtWidgets/QMainWindow>
#include <QtCharts>
#include <QChart>

QT_CHARTS_USE_NAMESPACE
using namespace QtCharts;


MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    initChartView();
    connect(m_timer, SIGNAL(timeout()), SLOT(Timer_Slot()));
    m_timer->setInterval(500);
    m_timer->start();

    myThreadObject = new mythread();
    myQThread = new QThread();

    myThreadObject->moveToThread(myQThread);

    connect(this, &MainWindow::startWriting, myThreadObject, &mythread::writeData);
    connect(myThreadObject, &mythread::writingDone, this, &MainWindow::writingDoneByThread);

    // Start the new thread
    myQThread->start();


}

void MainWindow::writingDoneByThread()
{

}

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

void MainWindow::initChartView()
{
    QChart *chart = new QChart();
    chart->ChartTypeCartesian;
    chart->addSeries(series);
    qDebug()<< series;
    QPen green(Qt::red);
    green.setWidth(2);
    series->setPen(green);
    chart->legend()->hide();
    chart->setTitle("deneme");
    chart->setAnimationOptions(QChart::AllAnimations);

    QValueAxis *axisX=new QValueAxis;
    axisX->setTickCount(10);
    axisX->setRange(0,5);
    axisX->applyNiceNumbers();
    chart->addAxis(axisX, Qt::AlignBottom);
    series->attachAxis(axisX);

    QValueAxis *axisY = new QValueAxis;
    axisY->setTickCount(10);
    axisY->setRange(0, 5);
    axisY->applyNiceNumbers();
    chart->addAxis(axisY, Qt::AlignLeft);
    series->attachAxis(axisY);

    QChartView *chartView = new QChartView(chart);
    chartView->setRenderHint(QPainter::Antialiasing);
    this->setCentralWidget(chartView);
}

void MainWindow::Timer_Slot()
{
    static float q_x;
    if(!queue.isEmpty())
    {
        double num=queue.dequeue();
        q_x += 0.1;
        series->append(q_x, num);
        chart->update();

    }

}

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include "mythread.h"
#include <QMainWindow>
#include <QThread>
#include <QtCharts/QChartView>
#include <QtCharts/QLineSeries>
#include <QtCharts/QLogValueAxis>
#include <QtCharts/QValueAxis>
#include <QTimer>

QT_CHARTS_USE_NAMESPACE

QT_BEGIN_NAMESPACE
namespace Ui {
class MainWindow;
}
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = Q_NULLPTR);
    ~MainWindow();

    void initChartView();
    void Timer_Slot();
private:
    Ui::MainWindow *ui;
    mythread* myThreadObject;    //mythreadden yeni bir obje yaratıyorum
    QThread* myQThread;  //QThreadden bir obje yaratıyorum
    QChart *chart = new QChart();
    QLineSeries *series = new QLineSeries();
    QQueue<double> queue;
    QTimer *m_timer = new QTimer();
signals:
    void startWriting();
public slots:
    void writingDoneByThread();

};
#endif // MAINWINDOW_H

[SGaist]

Hi,

Your queue is empty because nothing fills it.

[deleted286]

In here I thought I was adding the datas into the queue

void mythread::writeData()
{

    QFile::copy("C:/Users/ilknu/Documents/MyThread/deneme.txt", "C:/Users/ilknu/Documents/MyThread/n.txt");
    QFile file2("C:/Users/ilknu/Documents/MyThread/n.txt");

    qDebug() << "im working in writeData part " ;

    if(file2.open(QIODevice::ReadOnly))
    {
        QTextStream in(&file2);
        while(!in.atEnd())
        {
            QString line2 = in.readAll();
            QStringList list2 = line2.split(QLatin1Char(' '), Qt::SkipEmptyParts);
            for(const QString &entry : list2)
            {
                double num = entry.toDouble();
                queue.enqueue(num);
                qDebug() << num;
            }
        }
    }
    file.close();
    emit writingDone();
}

[SGaist]

That queue variable belongs to your mythread class. It's not the same as the one from your MainWindow class even if it has the same name.

[deleted286]

@SGaist can i connect them, or what can i do for this problem? I read and write in mythread.cpp
If i move initChartView and timer_slot, is it true?

[SGaist]

@suslucoder said in It does not create a chart:

If i move initChartView and timer_slot, is it true?

It won't change anything as these two variables will still be unrelated.

@suslucoder said in It does not create a chart:

can i connect them, or what can i do for this problem? I read and write in mythread.cpp

You have to get the data from your mythread object back to your MainWindow.

As I already suggested, you really should start with C++ basics before playing with threading.

[deleted286]

@SGaist said in It does not create a chart:

You have to get the data from your mythread object back to your MainWindow.

What is the way for getting datas from mythread to my mainwindow? I would be very happy if you could show me the way

[SGaist]

Use a signal to transfer the queue. Make it a const reference.

[deleted286]

@SGaist can you show me an example? I did not understand

[SGaist]

What did you not understand ?

[deleted286]

@SGaist if my slot is my queue, what should be the signal. I didnt understand it.

[SGaist]

Your slot is not your queue. Did you read the chapter about signals and slots ?

[deleted286]

@SGaist yes i did. But i cannot understand how can i get datas

[jsulm]

@suslucoder What exactly can't you understand? In the documentation @SGaist posted there is even an example with signal/slot with parameter...