newbe question about signals / slots

[Walsi]

Hello!

At first a have to say:

.) i am a newb at writing programs in C++
.) i am a newb at Qt
.) i am a newb at OOP

My question: How can I emit a signal out from another function? I think that i have to tedliver someting about the parameters of the functin????

Imagine: I have a SIP Client in C++ (pjsip.org) and I want to build a Application (GUI) on this Client.

So when I (the SIP Client) is called, it comes to a callback function in which the call is handeld. Now i want to see it on the GUI when I get called.

My idea: I program a signal Slot unit:
Signal: --> is in the Callback function --> incomingCall();
and in the Slot: --> I enable some buttons for example.

#include "uscinterface.h"     <-- here in this include it the prototyp of the class which  contains the signal
 
static void on_incoming_call(...)
{
...
...
...
 
 
emit incomingCallsignal();
}

#include "uscinterface.h"     <-- here in this include it the prototyp of the class which  contains the signal

static void on_incoming_call(...)
{
...
...
...


emit incomingCallsignal();
}

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Error message at compiling:

error: 'incomingCallsignal' was not declared in this scope


So what is my mistake, or what is the right way to solve this problem
If you need more information or sourcecode to help me, let me know

Best Regards,...

[marcel]

First of all, signals can only be emitted from objects that inherit QObject.
You should take a look in the Assistant at "Signals and slots" before starting anything.

[Walsi]

Thanks for your quick answer marcel!

I read the information about Signals and Slots in the Assistant again, and now I understand it better. So my I idea to solve this porblem isn't possible.

So, how can I "connect" this Callback function with any element of my GUI???

I am quite desperate about this problem because I am already working about 4 days on it's solution.

So it would be very nice if you could help me!

best Regards,...

[marcel]

The callback is called from another application or from the same application?

[high_flyer]

.) i am a newb at writing programs in C++
.) i am a newb at Qt
.) i am a newb at OOP

Welcome!

Look, if you are new to all three, starting with call back functions is a bit hard.
Maybe you don't even need that.
Explain what it is you what to do, maybe the solution is much simpler.

[Walsi]

I use the PJSIP Opensource. This is a SIP Client without a GUI.

There is a good online support on pjsip.org. There is also an example c file which shows how you could start building your own Applicaiton own it.

I have to build a Application with a GUI (QT4) on it. So I took those sample c file and started modifying and extending it.

There is a callbackfunction which is called when somebody want to call me!

/* Callback called by the library upon receiving incoming call */
static void on_incoming_call(pjsua_acc_id acc_id, pjsua_call_id call_id,
                             pjsip_rx_data *rdata)
{
     pjsua_call_info ci;
 
     PJ_UNUSED_ARG(acc_id);
     PJ_UNUSED_ARG(rdata);
 
     pjsua_call_get_info(call_id, &ci);
 
     PJ_LOG(3,(THIS_FILE, "Incoming call from %.*s!!",
                          (int)ci.remote_info.slen,
                          ci.remote_info.ptr));
 
     /* Automatically answer incoming calls with 200/OK */
     pjsua_call_answer(call_id, 200, NULL, NULL);
     emit incomingCall();
}

/* Callback called by the library upon receiving incoming call */
static void on_incoming_call(pjsua_acc_id acc_id, pjsua_call_id call_id,
                             pjsip_rx_data *rdata)
{
     pjsua_call_info ci;

     PJ_UNUSED_ARG(acc_id);
     PJ_UNUSED_ARG(rdata);

     pjsua_call_get_info(call_id, &ci);

     PJ_LOG(3,(THIS_FILE, "Incoming call from %.*s!!",
                          (int)ci.remote_info.slen,
                          ci.remote_info.ptr));

     /* Automatically answer incoming calls with 200/OK */
     pjsua_call_answer(call_id, 200, NULL, NULL);
     emit incomingCall();
}

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I know that the application comes to this function when I get called.

So my first idea was, to rewrite this function so, that it doesn't automatically answer a incoming call but gives any signal to the GUI that I (the user) can see that I am called.

And afterwards I want to press to button and answer this call.


Best Regards,...

[high_flyer]

Thie issue (external callback and Qt) has been dicussed here quite a bit.
So the basic possiblities are in these threads.
Read a bit, and ask if you need clarifications.
http://www.qtcentre.org/forum/search.php?searchid=61976

[Walsi]

Sorry - no matches. Please try some different terms.

That comes when i use your link - http://www.qtcentre.org/forum/search.php?searchid=61976


??? STRANGE ???


Instead I read and try to understand this thread: http://www.qtcentre.org/forum/f-qt-p...slot-5998.html


Best Regards...

[wysota]

No, it's not strange. Search results are cached for a limited period of time and it just fell out of cache. It's better to give the URL including search terms instead of the result id. I guess the term was probably "callback".

[Walsi]

wysota wrote in this thread:

You might register a callback from the callback api and there either call the slot directly or use a dummy QObject that will emit the signal for you.

Is that the right way to handle my problem?

[wysota]

I have no idea, because I don't know what your problem is Looks like it's something different than what the quoted sentence was about.