[Qt-interest] Problems using postEvent ..plz help

[Neeraj Jhawar]

I tried to implement the postEvent but this code is just not working.

Can any of you please help with the code...

I am trying to accomplish :
Take a number from the thread via postEvent and display is in the
textedit box every 1ms.

Please help me with the code...its been more than 2 days for this
small idea to work:

**************postevent.h*****************************

#ifndef POSTEVENT_H
	#define POSTEVENT_H
	
	#include <qdialog.h>
	#include <qthread.h>
	#include <qevent.h>
	
	class QLineEdit;
	class QPushButton;

		
	class ProdEvent : public QCustomEvent
	{
	public:
		ProdEvent(long s) : QCustomEvent (200), sz(s)
		{;}
		
		long numb() const {return sz;}
		
	private:
		long sz;
	};


	
	class ProdThread : public QThread
	{
	public:
		ProdThread (int);
		void stop();
		void run();

	private:
		int printval;
		bool stopped;
		int finalval;
	};

	
	
	class ThreadForm : public QDialog
	{
		Q_OBJECT
	public:
		ThreadForm (QWidget *parent = 0, const char *name = 0);
		void customEvent (QCustomEvent *e);
	public slots:
		void go();

	protected:

	private:
		ProdThread threadA;
		QPushButton *threadAButton;
		QPushButton *quitButton;
		QLineEdit *textedit;
	};

#endif

******************************end of postevent.h*******************************
*****************************postevent.cpp**********************************

#include <qlayout.h>
#include <qpushbutton.h>
#include <qlineedit.h>

#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <iostream.h>


#include "postevent.h"

static float temp_f;
static char *temp_c;


//the definitions of the thread

ProdThread::ProdThread(int a)			//the constructor
	{
		printval = 0;
		stopped = 0;
		finalval = a;
	}
	
	void ProdThread::stop()
	{
		stopped = 1;
	}
	
	
	void ProdThread::run()
	{
		//		ProdEvent *pe = new ProdEvent(printval);
		stopped = false;
		while(!stopped)
		{
			while (printval < finalval)
			{
				usleep(1000);
				//send the printval via postEvent
				ProdEvent *pe = new ProdEvent(printval);
				QApplication::postEvent(ThreadForm, pe);
				printval++;
			}
		}
	}


//the definitions of the main class

ThreadForm::ThreadForm (QWidget *parent, const char *name) :
QDialog(parent, name)
{
	setCaption(tr("Threads"));
	
	threadAButton = new QPushButton(tr("Start Thread"), this);
	quitButton = new QPushButton (tr("Quit Program"), this);
	quitButton->setDefault(true);
	textedit = new QLineEdit(this);
		
	connect(threadAButton, SIGNAL(clicked()), this, SLOT(go()));
	connect(quitButton, SIGNAL(clicked()), this, SLOT(close()));
	
	QVBoxLayout *layout = new QVBoxLayout(this);
	layout->addWidget(textedit);
	layout->addWidget(threadAButton);
	layout->addWidget(quitButton);
}

void ThreadForm::go()
{
		if (ProdThread.running())
	{
		threadA.stop();
		threadAButton->setText(tr("Start Thread"));
	}
	else
	{
		threadA.start();
		threadBButton->setText(tr("Stop Thread"));
	}

}

void ThreadForm:: customEvent (QCustomEvent *e)
{
	if (e->type() == 200)
	{
		ProdEvent* ce = (ProdEvent*)e;
		temp_f = ce->numb();
		sprintf(temp_c,"%f",temp_f);
		textedit->setText(temp_c);
	}
}

**************************end of
postevent.cpp************************************************
*************************main.cpp*******************************************
#include <qapplication.h>

#include "postevent.h"

int main (int argc, char *argv[])
{
	QApplication app(argc, argv);
	ThreadForm *dialog = new ThreadForm;
	app.setMainWidget(dialog);
	dialog->show();
	return app.exec();
}
*********************************end of main.cpp**************************


Please help with the same




On 1/10/09, Neeraj Jhawar <navderm at gmail.com> wrote:
>>
>> Then why are you using a separate thread at all? If your GUI is supposed
>> to
>> block while you fetch the data just do the data-fetching inside the GUI
>> thread. That'll remove all needs for cross-thread-communication.
>>
>> Andreas
>>
>>
> This is because when I try to update the GUI at this rate, all the buttons
> hang. I just cant get them working smoothly enough. I am fetching the data
> at 100 ms period ( or 1/100 ms freq). at this rate when I try to update GUI
> , the buttons like "STOP OPERATION" and "EXIT" and "SAVE TO FILE" are numb
> and I just cant help them.
>
> Is there a way I could just do this without threads... i.e. take the updates
> from a GUI function and the buttons are still smooth enough??
>
>
>
> Neeraj Jhawar
> Senior Undergraduate
> Mechanical Engineering Department
> Punjab Engineering College
> Chandigarh.
> India
>


-- 
Neeraj Jhawar
Senior Undergraduate
Mechanical Engineering Department
Punjab Engineering College
Chandigarh.
India