How can i use 2 QTimer? One is for counting and the other one is displaying

koahnig

Guest said in How can i use 2 QTimer? One is for counting and the other one is displaying:

I want to Timer with c++ usin qt. I have one timer in my code, but the time display on the screen is slow. timer -> start(500) must update every 20 seconds i guess.

I want to use 2 timer for it. One is for update and count the time, the other timer will display on the screen. How can i do that, I would be very happy if you can help. Here is my code for it
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QTimer>
#include <QPushButton>


QTimer *timer = new QTimer();

 QTimer *timer2 = new QTimer();

int Count = 0;

MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent)
, ui(new Ui::MainWindow)
{
ui->setupUi(this);

// QTimer *timer = new QTimer(this);
//timer->start(5);
connect(timer,
        SIGNAL(timeout()),
        this,
        SLOT(functionstart())
            );

connect(timer2,
            SIGNAL(timeout()),
            this,
            SLOT(functionstart2())
                );

timer2->start(20000);
}

void MainWindow::functionStart()
{

// int count;   
// count = ui->lcdNumber->value();
Count++;
 }


void MainWindow::functionStart2()
 {
 ui->lcdNumber->display(Count);
 }

MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::on_pushButton_clicked()
{
if(timer->isActive()){
timer->stop();
ui->pushButton->setText("Start");
}
else {
timer->start(500);
ui->pushButton->setText("Stop");

}
}


With minimal changes that should work in your case. 

Note: Not tested brain to keyboard only ;)

? Offline

@koahnig im new on this platform and qt. Sorry for my mistakes. I run the code but when i clicked the start it didnt count :(

koahnig

@suslucoder

You would need to publish all files.

Probably your push button is not connected to the slot function.

? Offline

I've solved to problem. Thanks a lot. What if i want to connect my timer to a chart, which is read the data from txt file and according to timer create a chart

mrjj

@suslucoder
Hi
You dont really connect the timer to a chart.
You connect it to a slot.
In that slot you can access a chart you have on your main window to add new data for it to plot.

So the plan is to only read a line from the file each timer triggers ?
Im asking as normally one would read whole file and plot at once so i
wonder what the goal/task is.

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@mrjj actually i want to a real time chart. Datas can read at once. But they should add into chart in a time interval. For example, in every sec, add 20 data on chart. On, in 20 sec add 20 data to the chart. It should be real time

mrjj

@suslucoder
Hi
How big is this file ?

You could read it to a StringList and then use a variable to keep track of how far into the list you are
so each time , timer triggers, then you take next 20 from list and give to the chart.

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@mrjj it is not so big. It has 20 or 40 line at all. Here is my reading file and creating a chart code. I have a timer but it is another project. I cannot create a connection between them :(

#include <QtWidgets/QApplication>
#include <QtWidgets/QMainWindow>
#include <QtCharts/QChartView>
#include <QtCharts/QLineSeries>
#include <QtCore/QDateTime>
#include <QtCharts/QDateTimeAxis>
#include <QtCore/QFile>
#include <QtCore/QTextStream>
#include <QtCore/QDebug>
#include <QtCharts/QValueAxis>
#include <QQueue>

QT_CHARTS_USE_NAMESPACE

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);  //QApplication ana olay döngüsünü içeren bir QT sınıfıdır. Bu kodu çağırdığımızda, yapıcısını argc ve argv olarak çağırıp
                                 //yeni bir nesne oluşturuyoruz.


    QLineSeries *series = new QLineSeries(); //



    QFile sunSpots(":sun");
    if (!sunSpots.open(QIODevice::ReadOnly | QIODevice::Text)) {
        return 1;
    }

    QTextStream stream(&sunSpots);
    while (!stream.atEnd()) {
        QString line = stream.readLine(); //satır satır okuma yap
        if (line.startsWith("#") || line.startsWith(":")) //# veya : ile başlayıyorsa devam et, hiçbir şey yapma
            continue;
        QStringList values = line.split(QLatin1Char(' '), Qt::SkipEmptyParts); //boşlukları ayırıyor ve atıyor
        QDateTime momentInTime;
        momentInTime.setDate(QDate(values[0].toInt(), values[1].toInt() , 15)); //?
        qDebug()<< momentInTime;
        series->append(momentInTime.toMSecsSinceEpoch(), values[2].toDouble());
    }
    sunSpots.close(); //açtığımız txt dosyasını kapat


    QChart *chart = new QChart(); //bir chart oluşturabilmek için QChart sınıfından bir instace oluşturuyoruz.
    chart->addSeries(series); //dosyadan okuduğumuz verileri chart'a ekliyoruz.
    chart->legend()->hide();  //show ile de olur, set,
    chart->setTitle("Sunspots count (by Space Weather Prediction Center)");



  QDateTimeAxis *axisX = new QDateTimeAxis; //eksenleri ayarlıyoruz. QLineSeries
  axisX->setTickCount(10); //x ekseninde gösterilecek veri sayısı.
  axisX->setFormat("MMM yyyy"); //format ay ve yıl olacak.
  axisX->setTitleText("Date"); //x ekseninin altndaki başlık date olacak.
  chart->addAxis(axisX, Qt::AlignBottom);
 series->attachAxis(axisX); //seriye eklediğimiz bilgileri x eksenine koyuyoruz.

 QValueAxis *axisY = new QValueAxis;
 axisY->setLabelFormat("%i");
  axisY->setTitleText("Sunspots count");
  chart->addAxis(axisY, Qt::AlignLeft);
 series->attachAxis(axisY);

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



  QMainWindow window;
    window.setCentralWidget(chartView);
   window.resize(820, 600);
   window.show();


    return a.exec();
}

mrjj

Hi
Well you already read the file and add the data.
in
series->append(momentInTime.toMSecsSinceEpoch(), values[2].toDouble());

so instead of this, you want to do it in steps ?

? Offline

yes, exactly

mrjj

@suslucoder
Hi
Well then instead of appending to the series object,
then make a list and add to that list instead.
So we read file to a list.
do you know std::vector ?

Then make a new timer and connect to a lambda slot .
in the slot, you call series->append to add the data in steps.
make sure you dont run out of list end.

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do you know std::vector ?
I dont know but im trying to do this.
Thank you

mrjj

@suslucoder
Hi
well i was thinking something like

struct Data {
qint64 timestamp;
double value;
};

std::vector<Data> thelist;

would allow you to store what you now add directly.
i mean this line
series->append(momentInTime.toMSecsSinceEpoch(), values[2].toDouble());

Im only guessing since you seems to read timestamp from file too. but not sure what you do with momentInTime variable.

Once in a list, you can take data from that and add step by step.

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@mrjj I will try

mrjj

@suslucoder
Ok so instead fo this line
series->append(momentInTime.toMSecsSinceEpoch(), values[2].toDouble());
you do
Data tmp;
tmp.timestamp = momentInTime.toMSecsSinceEpoch();
tmp.value = values[2].toDouble();
thelist.push_back(tmp);

To store in list.