How can I connect a signal to Qtimer slot start()

dziko147

Hello ,
I want to start the QTimer in a specific condition .
So I think about send a signal to start() slot .
But I couldn't do it .

Who can suggest a way ?
thank you

Qt embedded developer

you can use signal and slot . so where you condition become true there you have to emit signal. and in constructor you can call start timer slot .

KroMignon

@dziko147 said in How can I connect a signal to Qtimer slot start():

Hello ,
I want to start the QTimer in a specific condition .
So I think about send a signal to start() slot .
But I couldn't do it .
Who can suggest a way ?
thank you

Can you show what you have tried? So it is easier for us to explain what going wrong.

dziko147

@KroMignon

connect(&m_fetchFrameTimer, & QTimer::timeout, this, &Backend::statuspican);

connect(this,SIGNAL(signalgetdataclicked()),this,SLOT(m_fetchFrameTimer.start(2000))); //I thinked about something like this

KroMignon

@dziko147 said in How can I connect a signal to Qtimer slot start():

connect(this,SIGNAL(signalgetdataclicked()),this,SLOT(m_fetchFrameTimer.start(2000))); //I thinked about something like this

This do no made sense.

you can connect a "sender" signal to a "receiver" slot (or signal).
SIGNAL() is used to define the signal to connect (function name and parameter types, not variable names)
SLOT() is used to define the slot to connect (function name and parameter types, not variable names)

What you are trying to do is not allowed.

You could use a lambda function, like this (I suppose the class name is Backend):

connect(this, &Backend::signalgetdataclicked,this, [this](){
    m_fetchFrameTimer.start(2000); 
});

Please, take 1 or 2 minutes to learn how connect() works. It is very well documented here: https://doc.qt.io/qt-5/signalsandslots.html

J.Hilk

@dziko147

connect(this,SIGNAL(signalgetdataclicked()),this,SLOT(m_fetchFrameTimer.start(2000)));

since you're probably trying to start the timer with different times, I would suggest a custom signal for this:

signals:
....
void startFetchFrameTimer(int interval);

and use that in a "regular" connect,

Old syntax:

connect(this, SIGNAL(startFetchFrameTimer(int)), &m_fetchFrameTimer, SLOT(start(int)));

new Syntax

connect( this, &Backend:: startFetchFrameTimer, &m_fetchFrameTimer, qOverload<int>::of(&QTimer::start));

then you just emit the signal wherever you want, and you're fine to go:

emit startFetchFrameTimer(1000);