Qt QLCDNumber time_t Timer - c++

Question

I have a tool button in one .cpp (i.e. ExerciseControl.cpp). When the button is clicked, it will trigger two timers in another .cpp (i.e. StatusBar.cpp).
However, the following codes does not work. The timers do not start when I click the button in ExerciseControl.cpp to trigger startExercise().
ExerciseControl.cpp:
ExerciseControl::ExerciseControl(void)
{
myStatusBar = new StatusBar;
}
void ExerciseControl::startExercise()
{
myStatusBar ->simulationTimer->start(1000);
myStatusBar ->elapsedTimer->start(1000);
}
StatusBar.cpp:
StatusBar::StatusBar()
{
simulationTimer = new QTimer;
QObject::connect(simulationTimer, SIGNAL(timeout()), this, SLOT(tickSimulation()));
elapsedTimer = new QTimer;
QObject::connect(elapsedTimer, SIGNAL(timeout()), this, SLOT(tickSimulation()));
createButtons();
};
void StatusBar::createButtons()
{
...
}
void StatusBar::tickSimulation()
{
...
}
However, if I declare the following in my constructor, the timers can start automatically, which is not I wanted.
StatusBar::StatusBar()
{
simulationTimer = new QTimer;
simulationTimer->start(1000);
QObject::connect(simulationTimer, SIGNAL(timeout()), this, SLOT(tickSimulation()));
elapsedTimer = new QTimer;
elapsedTimer->start(1000);
QObject::connect(elapsedTimer, SIGNAL(timeout()), this, SLOT(tickSimulation()));
}
I need to trigger the timers through my button in ExerciseControl.cpp.
Please help.
Thanks.

Answer 1

On the example below, ExerciseControl is a specialization of QMainWindow that does 2 things:
Display a QTooButton inside the window;
Allocate a StatusBar object.
Clicking the button invokes the slot _timers_must_start() of the class. This slot is responsible to call start_timers() from the StatusBar object, which in turn starts the timers of that object.
I made each timer call a slot that prints something to the screen when the timeout() is triggered.
Enjoy.
main.cpp:
#include "exercise_control.h"
#include <QApplication>
int main(int argc, char* argv[])
{
QApplication app(argc, argv);
ExerciseControl ec;
ec.show();
return app.exec();
}
exercise_control.h:
#pragma once
#include "status_bar.h"
#include <QMainWindow>
#include <QToolButton>
class ExerciseControl : public QMainWindow
{
Q_OBJECT
public:
ExerciseControl()
{
_button = new QToolButton(this);
_button->setText("Press Me!");
QObject::connect(_button, SIGNAL(clicked()), this, SLOT(_timers_must_start()));
_statusbar = new StatusBar;
// Set the size of the window to the size of the button
setFixedSize(_button->width() ,_button->height());
}
private slots:
/* This slot is called by clicking the button */
void _timers_must_start()
{
qDebug() << "ExerciseControl::_timers_must_start: button clicked! Trying to start timers...";
_statusbar->start_timers();
}
private:
QToolButton* _button;
StatusBar* _statusbar;
};
status_bar.h:
#pragma once
#include <QObject>
#include <QTimer>
#include <QDebug>
class StatusBar : public QObject
{
Q_OBJECT
public:
StatusBar()
{
_timer1 = new QTimer;
QObject::connect(_timer1, SIGNAL(timeout()), this, SLOT(_timer1_task()));
_timer2 = new QTimer;
QObject::connect(_timer2, SIGNAL(timeout()), this, SLOT(_timer2_task()));
}
~StatusBar()
{
_timer1->stop();
delete _timer1;
_timer2->stop();
delete _timer2;
}
void start_timers()
{
if (!_timer1->isActive() && !_timer2->isActive())
{
qDebug() << "StatusBar::start_timers: OK!";
_timer1->start(1000); // 1 second interval
_timer2->start(5000); // 5 seconds interval
return;
}
qDebug() << "StatusBar::start_timers: timers already started, nothing to be done here!";
}
private:
QTimer* _timer1;
QTimer* _timer2;
private slots:
/* These slots are called by the timers of this class, hence PRIVATE SLOTS */
void _timer1_task()
{
qDebug() << "StatusBar::_timer1_task: 1 second has elapsed";
}
void _timer2_task()
{
qDebug() << "StatusBar::_timer2_task: 5 seconds has elapsed";
}
};
test.pro:
QT += widgets
SOURCES += \
main.cpp
HEADERS += \
exercise_control.h \
status_bar.h