C++ Timer difficulties - c++

Question

I'm having issues implementing timing. What i want to do is run this:
//relay 1 power cycle
void MainWindow::relay1PCycle()
{
relay1High();
while (true){
QTimer::singleShot(750, this, SLOT(relay1Low()));
QTimer::singleShot(750, this, SLOT(relay1High()));
}
}
as while a button is pressed.
//power cycle button
void MainWindow::on_pushButton_3_toggled(bool checked)
{
if (checked){
//run relay1PCycle as a thread.
}
else{
//Terminate relay1PCycle thread.
}
}
however, so far everything i've tried so far has been a failure.
What's the correct way to go about this?
Thanks

Answer 1

The task they want to implement is not blocking, so it is not necessary to use threads, only a timer with an adequate logic. To make it simple we will assign that task to the next class:
relaycontroller.h
#ifndef RELAYCONTROLLER_H
#define RELAYCONTROLLER_H
#include <QObject>
#include <QTimer>
#include <QDebug>
class RelayController : public QObject
{
Q_OBJECT
public:
explicit RelayController(QObject *parent = 0):QObject(parent){
timer = new QTimer(this);
state = false;
timer->setInterval(750);
//old style
connect(timer, SIGNAL(timeout()), this, SLOT(onTimeout()));
//new style
//connect(timer, &QTimer::timeout, this, &RelayController::onTimeout);
}
void start(){
qDebug()<<"timer";
timer->start();
}
void stop(){
timer->stop();
}
void relayLow(){
//code here: relay off
qDebug()<<"low";
}
void relayHigh(){
//code here: relay on
qDebug()<<"high";
}
private slots:
void onTimeout(){
if(state)
relayHigh();
else
relayLow();
state = !state;
}
private:
QTimer *timer;
bool state;
};
#endif // RELAYCONTROLLER_H
Then an object is created and used in the slot pressed:
mainwindow.h
private:
RelayController *controller;
mainwindow.cpp
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
controller = new RelayController(this);
ui->pushButton_3->setCheckable(true);
}
void MainWindow::on_pushButton_toggled(bool checked)
{
if(checked)
controller->start();
else
controller->stop();
}