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

[Neeraj Jhawar]

SOME BUGS EXIST

Sorry
This code has some bugs
please dont see it.
I will try to post the new one asap

On 1/11/09, Neeraj Jhawar <navderm at gmail.com> wrote:
> 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
>


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