How can I emit signal from QRunnable or call callback?

smartcoder.v.arch

Hello. I need your help with such a problem. This is an example of a basic code:

class Runnable : public QRunnable
{
	explicit Runnable(QImage* qimg, uint index):m_qimage(qimg),m_index(index)
	{
        }

	void run()
	{ 
		if(m_qimage->scale(1280,720)->save(QString("%1.jpg").arg(index)))
		{
			// i need to emit a signal in this place
		}
	}
private:
	QImage* m_qimage;
	uint m_index;
} ;


class Controller : public QObject
{
	explicit Controller(QObject* parent = 0)
	{
		m_pool = new QThreadPool(this);
	}

	public slots:
		void slotWithoutName(QImage* qimg,uint index)
		{
			Runnable * m_worker = new Runnable(qimg,index);
			m_pool->start(m_worker);
		}

		void slotAnsverFromRunnableClass(uint index)
		{
			qDebug()<<"Okey , I've done my work!!!\n";
		}
	private:
		QThreadPool* m_pool; 
};

.....and somewhere in the program :

connect(this, SIGNAL(frame(QImage* qimg,uint index)),m_controller,SLOT(slotWithoutName(QImage* qimg,uint index)));

Please, tell me how is right to call the implementation of a slot

			 void slotAnsverFromRunnableClass(uint index)

from class Runnable I tried

QMetaObject::invokeMethod(m_p_controller,"slotAnsverFromRunnableClass",Qt::AutoConnection,Q_ARG(uint,index));

, but it gave no results and no output to the console QtCreator about the mistake too...
Tried this one:

class Runnable : public QObject ,public QRunnable
{
	Q_OBJECT

explicit Runnable(QImage* qimg, uint index):m_qimage(qimg),m_index(index)
{

}

void run()
{ 
	if(m_qimage->scale(1280,720)->save(QString("%1.jpg").arg(index)))
	{
		// i need to emit signal in this place
		emit mySignal(index);
	}
}

signals:
	
	void mySignal(uint index);
	//...
	 other code
	//.....
};

but this method gave no results too. As I understand there is any rule of association between streams using signals or calling callback functions which I don't know... Please, help me to solve this problem. Thanks

? Offline

Hi! There is no "special rule"; everything works as expected:

work.h

#ifndef WORK_H
#define WORK_H

#include <QRunnable>
#include <QDebug>
#include <QObject>

class Work : public QObject, public QRunnable
{
    Q_OBJECT
public:
    void run();
signals:
    void sayHi();
};

#endif // WORK_H

work.cpp

#include "work.h"

#include <QDebug>
#include <QThread>

void Work::run()
{
    qDebug() << "Hello from thread " << QThread::currentThread();
    emit sayHi();
}

main.cpp

#include "mainwindow.h"
#include <QApplication>
#include <QThreadPool>
#include <QDebug>
#include <QObject>
#include "work.h"

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    Work work;
    work.setAutoDelete(false);
    QThreadPool *threadPool = QThreadPool::globalInstance();
    threadPool->start(&work);
    QObject::connect(&work, &Work::sayHi, &app, &QApplication::quit);
    return app.exec();
}

QKelteseth

So just for anyone who still gets errors (like me):
The order of inheritance is very important. Always include the Object first!