newbe question about signals / slots

**Walsi** · 20th April 2007, 06:18

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** · 20th April 2007, 06:30

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** · 20th April 2007, 06:42

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** · 20th April 2007, 07:05

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.

**Walsi** · 20th April 2007, 07:48

I think it is the same, I want to emit a signal, when callback function from my SIP client (non Qt, only C++) is called.

How can I do this?

**marcel** · 20th April 2007, 07:53

In the Qt app, the callback will be a static function. Given this, you cannot emit a signal from this function when it is called ( it is static, non-QObject ), but you can call a function from the interface ( you will have to make possible the access to the main window or another widget from this callback ). Another solution would be QApplication:: postEvent to post an event that when received by the app will answer the phone or whatever....

Regards

**Walsi** · 20th April 2007, 08:39

Okay that sounds good! I try if understand it in the right way:

I call a function in the callback function from the PJSIP (on_incoming_Call);
This function has access to any Widget or to the main window of Qt;
And in this Function I emit a signal;

Have a look at my Pseudo Source Code

uscsippart.cpp: This is the file where the Callbackfunctions of PJSIP are. This callback function is called when someona calls me. And in this function a call another function (incomingCallFunc).

Qt Code:

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/* 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);
     incomingCallFunc();
}

/* 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);
     incomingCallFunc();
}

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uscinterface.h: here is a "DummyObject" which should has a signal and further here is the prototyp of the function incomingCallFunc();

Qt Code:

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#ifndef INTERFACE_H
#define INTERFACE_H
 
#include <QObject>
 
class IncomingCall : public QObject
{
	Q_OBJECT
 
	public:
		IncomingCall(QObject *parent = 0);
 
 
	signals:
		void incomingCallsignal();
};
 
void incomingCallFunc(void);
#endif

#ifndef INTERFACE_H
#define INTERFACE_H

#include <QObject>

class IncomingCall : public QObject
{
	Q_OBJECT
	
	public:
		IncomingCall(QObject *parent = 0);


	signals:
		void incomingCallsignal();
};

void incomingCallFunc(void);
#endif

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uscinterface.cpp: looks like this!

Qt Code:

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#include "uscinterface.h"
 
IncomingCall::IncomingCall (QObject *parent)
	: QObject(parent)
{
}
 
void incomingCallFunc()
{
	// QT Code to emit a signal
}

#include "uscinterface.h"

IncomingCall::IncomingCall (QObject *parent)
	: QObject(parent)
{
}

void incomingCallFunc()
{
	// QT Code to emit a signal
}

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uscgui.h:

Qt Code:

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#ifndef USCGUI_H
#define USCGUI_H
 
#include <QWidget>
 
class QLabel;
class QPushButton;
 
class UscGuiES01 : public QWidget
{
	Q_OBJECT
 
public:
	UscGuiES01(QWidget *parent = 0);
 
signals:
 
private slots:
 
	void makeCall();
	void incomingCall();
private:
	QLabel *statusLabel;
	QPushButton *acceptButton;
	QPushButton *hangupButton;
	QPushButton *dialButton;
};
 
class UscStatusDisplay : public QWidget
{
	Q_OBJECT
 
	public:
		UscStatusDisplay(QWidget *parent = 0);
};
#endif

#ifndef USCGUI_H
#define USCGUI_H

#include <QWidget>

class QLabel;
class QPushButton;

class UscGuiES01 : public QWidget
{
	Q_OBJECT

public:
	UscGuiES01(QWidget *parent = 0);

signals:

private slots:

	void makeCall();
	void incomingCall();
private:
	QLabel *statusLabel;
	QPushButton *acceptButton;
	QPushButton *hangupButton;
	QPushButton *dialButton;
};

class UscStatusDisplay : public QWidget
{
	Q_OBJECT

	public:
		UscStatusDisplay(QWidget *parent = 0);
};
#endif

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and now uscgui.cpp: Here I generate my GUI I connect Signals and Slots.

Qt Code:

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#include <pjlib.h>
#include <pjlib-util.h>
#include <pjmedia.h>
#include <pjmedia-codec.h>
#include <pjsip.h>
#include <pjsip_simple.h>
#include <pjsip_ua.h>
#include <pjsua-lib/pjsua.h>
 
#include <QtGui>
#include "uscgui.h"
#include "uscinterface.h"
 
UscGuiES01::UscGuiES01(QWidget *parent)
	: QWidget(parent)
{
 
		statusLabel = new QLabel(tr("???"));
 
		dialButton = new QPushButton(tr("Dial"));
 
		acceptButton = new QPushButton(tr("Accept"));
		acceptButton->setDefault(true);
		acceptButton->setEnabled(false);
 
		hangupButton = new QPushButton(tr("Hang Up"));
		hangupButton->setEnabled(false);
 
		UscStatusDisplay *uscGuiStatusDisplay = new UscStatusDisplay;
		IncomingCall *incomingCall = new IncomingCall;
 
 
/*
 Insert here the connections for the Signals and Slots
 System
*/
 
		connect(dialButton, SIGNAL(clicked()),
				this, SLOT(makeCall()));
 
		connect(incomingCall, SIGNAL(incomingCallsignal()),
				this, SLOT(incomingCall()));
 
		QHBoxLayout *bottomLayout = new QHBoxLayout;
		bottomLayout->addWidget(dialButton);
		bottomLayout->addWidget(acceptButton);
		bottomLayout->addWidget(hangupButton);
 
		QHBoxLayout *topLayout = new QHBoxLayout;
		topLayout->addWidget(statusLabel);
		topLayout->addWidget(uscGuiStatusDisplay);
 
		QVBoxLayout *mainLayout = new QVBoxLayout;
		mainLayout->addLayout(topLayout);
		mainLayout->addLayout(bottomLayout);
		setLayout(mainLayout);
 
		setWindowTitle(tr("Universal SIP Client"));
 
		emit 
}
/*
 Insert here the SLOT Functions
*/
 
void UscGuiES01::makeCall()
{
	pj_str_t uri = pj_str("sip:nb100149@10.17.1.17");
	pjsua_call_make_call(0, &uri, 0, NULL, NULL, NULL);
}
 
void UscGuiES01::incomingCall()
{
	acceptButton->setEnabled(true);
	hangupButton->setEnabled(true);
}
 
UscStatusDisplay::UscStatusDisplay(QWidget *parent)
	: QWidget(parent)
{
	setPalette(QPalette(QColor(Qt::green)));
	setAutoFillBackground(true);
}

#include <pjlib.h>
#include <pjlib-util.h>
#include <pjmedia.h>
#include <pjmedia-codec.h>
#include <pjsip.h>
#include <pjsip_simple.h>
#include <pjsip_ua.h>
#include <pjsua-lib/pjsua.h>

#include <QtGui>
#include "uscgui.h"
#include "uscinterface.h"

UscGuiES01::UscGuiES01(QWidget *parent)
	: QWidget(parent)
{

		statusLabel = new QLabel(tr("???"));

		dialButton = new QPushButton(tr("Dial"));

		acceptButton = new QPushButton(tr("Accept"));
		acceptButton->setDefault(true);
		acceptButton->setEnabled(false);

		hangupButton = new QPushButton(tr("Hang Up"));
		hangupButton->setEnabled(false);

		UscStatusDisplay *uscGuiStatusDisplay = new UscStatusDisplay;
		IncomingCall *incomingCall = new IncomingCall;


/*
 Insert here the connections for the Signals and Slots
 System
*/

		connect(dialButton, SIGNAL(clicked()),
				this, SLOT(makeCall()));

		connect(incomingCall, SIGNAL(incomingCallsignal()),
				this, SLOT(incomingCall()));

		QHBoxLayout *bottomLayout = new QHBoxLayout;
		bottomLayout->addWidget(dialButton);
		bottomLayout->addWidget(acceptButton);
		bottomLayout->addWidget(hangupButton);

		QHBoxLayout *topLayout = new QHBoxLayout;
		topLayout->addWidget(statusLabel);
		topLayout->addWidget(uscGuiStatusDisplay);
	
		QVBoxLayout *mainLayout = new QVBoxLayout;
		mainLayout->addLayout(topLayout);
		mainLayout->addLayout(bottomLayout);
		setLayout(mainLayout);

		setWindowTitle(tr("Universal SIP Client"));
		
		emit 
}
/*
 Insert here the SLOT Functions
*/

void UscGuiES01::makeCall()
{
	pj_str_t uri = pj_str("sip:nb100149@10.17.1.17");
	pjsua_call_make_call(0, &uri, 0, NULL, NULL, NULL);
}

void UscGuiES01::incomingCall()
{
	acceptButton->setEnabled(true);
	hangupButton->setEnabled(true);
}

UscStatusDisplay::UscStatusDisplay(QWidget *parent)
	: QWidget(parent)
{
	setPalette(QPalette(QColor(Qt::green)));
	setAutoFillBackground(true);
}

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Now I want to emit the signal of the class Incomingcall(uscinterface.h) by the function incomingCallFunc() in uscinterface.cpp. but I don't now how??

Or, another possibility, I want to set in this function the Buttons (accept, hangup) enabled and leave the signals and slots out for this part.

So, how can I implement that this function has access to the widget (uscgui.cpp)

I have no idea?

Best Regards...

**wysota** · 20th April 2007, 08:49

I think your situation is completely different. You just want to access a method (emit a signal) from an object you don't have a pointer to. Just make the pointer available somewhere so that the callback can access it and that's it. You don't need any special external or additional objects or any other kind of special treatment.

**marcel** · 20th April 2007, 09:18

Yes, juts call the slot from the interface in incomingCallFunc. No need to emit the signal. Make your main window available in incomingCallFunc and simply call the slot (which now doesn't necessarily needs to be a slot ).

Regards

**Walsi** · 20th April 2007, 09:35

OMG

That really sounds very easy for me. But i think it isn't as easy for me to implement.

Okay, let me try:

I generate a pointer which points to my object usc_gui. This object is created in main.

main.cpp

Qt Code:

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#include <pjlib.h>
#include <pjlib-util.h>
#include <pjmedia.h>
#include <pjmedia-codec.h>
#include <pjsip.h>
#include <pjsip_simple.h>
#include <pjsip_ua.h>
#include <pjsua-lib/pjsua.h>
 
#include <QApplication>
 
#include "uscsippart.h"
#include "uscgui.h"
#include "uscinterface.h"
 
int main(int argc, char *argv[])
{
	init_sip();
 
	QApplication uscguiapp(argc, argv);	
	UscGuiES01 usc_gui;
	usc_gui.show();
 
	return uscguiapp.exec();
 
}

#include <pjlib.h>
#include <pjlib-util.h>
#include <pjmedia.h>
#include <pjmedia-codec.h>
#include <pjsip.h>
#include <pjsip_simple.h>
#include <pjsip_ua.h>
#include <pjsua-lib/pjsua.h>

#include <QApplication>

#include "uscsippart.h"
#include "uscgui.h"
#include "uscinterface.h"

int main(int argc, char *argv[])
{
	init_sip();

	QApplication uscguiapp(argc, argv);	
	UscGuiES01 usc_gui;
	usc_gui.show();
	
	return uscguiapp.exec();

}

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Via the parameters I give the callback function the pointer and in the function I can do anything with the object.

For example:

Qt Code:

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void incomingCallFunc(Usc_Gui_ES01 *to_usc_gui)
{
     *to_usc_gui.acceptButton->setEnabled(true);
     *to_usc_gui.hangupButton->setEnabled(true);
}

void incomingCallFunc(Usc_Gui_ES01 *to_usc_gui)
{
     *to_usc_gui.acceptButton->setEnabled(true);
     *to_usc_gui.hangupButton->setEnabled(true);
}

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But where I call this function, the pointer also must be known there?

Qt Code:

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incomingCallFunc(&to_usc_gui);

incomingCallFunc(&to_usc_gui);

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Where and how must I define and/or declarate the pointer that it works?

Best Regards,...

**wysota** · 20th April 2007, 10:23

You should really learn a bit of C++... Your problem is strictly programming language related.

**Walsi** · 20th April 2007, 10:25

Okay!!

Many thanks to you!!

I will learn C++!!!

**wysota** · 20th April 2007, 10:54

Please read about scopes and declarations of external variables. This should allow you to solve the problem yourself.

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