Stoping a Qtimer problem...!

[hakermania]

This is the code:

void MainWindow::on_checkBox_clicked()
{
    if ( ui->checkBox->isChecked() ){
        QTimer *timer = new QTimer(this);
        connect(timer, SIGNAL(timeout()), this, SLOT(write_random_image()));
           timer->start(1000);
    }
    else
    timer->stop();
}

void MainWindow::on_checkBox_clicked()
{
    if ( ui->checkBox->isChecked() ){
        QTimer *timer = new QTimer(this);
        connect(timer, SIGNAL(timeout()), this, SLOT(write_random_image()));
           timer->start(1000);
    }
    else
    timer->stop();
}

To copy to clipboard, switch view to plain text mode 

actually, I wanna program , when the checkbox is clicked and checked, the timer must start, and if it is clicked and not checked the timer to stop..
The inly issue is that I get the error:
error: ‘timer’ was not declared in this scope (this goes to timer->stop()
Even if I declare the creation of the timer at the constructor (in a try to use it globally in the program) I cannot call it because of the same error...
So, how can I fix this?

[hobbyist]

I guess you want to declare your QTimer *timer as a private variable in the header of your MainWindow class, initialize it to a new QTimer(this) and connect() in the constructor, and let the click-slot handle start() and stop().

[hakermania]

Ammm I didn't got it...
Step 1: I have to put this at the constructor
connect(timer, SIGNAL(timeout()), this, SLOT(write_random_image()));
Step 2: I have to put this in myfile.h ????????? After the inclusions (#include <QMainWindow>)
QTimer *timer = new QTimer;
Step 3: Let the click-slot handle the start-stop? How do i do this?


Sorry but I am a beginner. Very willing to learn

[Lykurg]

Sorry but I am a beginner. Very willing to learn

class Foo 
{
//...
private:
  QTimer *m_timer;
};
 
Foo::Foo(/*...*/)
{
  m_timer = new QTimer(this);
  connect(m_timer, SIGNAL(timeout()), this, SLOT(write_random_image()));
}
 
void Foo::on_checkBox_clicked(bool checked)
{
    if ( checked )
      m_timer->start(1000);
    else
     m_timer->stop();
}

class Foo 
{
//...
private:
  QTimer *m_timer;
};

Foo::Foo(/*...*/)
{
  m_timer = new QTimer(this);
  connect(m_timer, SIGNAL(timeout()), this, SLOT(write_random_image()));
}

void Foo::on_checkBox_clicked(bool checked)
{
    if ( checked )
      m_timer->start(1000);
    else
     m_timer->stop();
}

To copy to clipboard, switch view to plain text mode 

[hobbyist]

Ok.

In the header file of your class (probably mainwindow.h):

private:
    QTimer *timer;

private:
    QTimer *timer;

To copy to clipboard, switch view to plain text mode 

In the constructor MainWindow::MainWindow() of your class:

timer = new QTimer(this);
connect(timer, SIGNAL(timeout()), this, SLOT(write_random_image()));

timer = new QTimer(this);
connect(timer, SIGNAL(timeout()), this, SLOT(write_random_image()));

To copy to clipboard, switch view to plain text mode 

In the on_checkBox_clicked() slot:

if (ui->checkBox->isChecked())
   timer->start(1000);
else
   timer->stop();

if (ui->checkBox->isChecked())
   timer->start(1000);
else
   timer->stop();

To copy to clipboard, switch view to plain text mode 

Also remember to #include <QTimer> somewhere (e.g. in the header file).

Edit: Too slow..

[hakermania]

Thnk you It works!

[Lykurg]

and also you might want use a unique connection (5th parameter) that the connection is only established once, even if the check box is checked several times.