QT Qapplication stuck in "return a.exec() " in calculation Loop

Question

I simulated a dynamical device like mass spring damper.the QT Solves the equation of motion in Real Time and displays the output. I want to use an Qapplication object,to display Data and the outputs in "Real time". whole problem and display output is inside a loop.Everything is going well, but when the program reaches to command return a.exec() for display output,the GUI window Has come up and remain in the firest iteration." I expect don't gets stuck there and At each loop the program runs And at the end of loop update the GUI window in "Real time". here is my code:

#include "QtWidgets/QApplication"
#include "QtWidgets/QGraphicsScene"
#include "QObject"
#include "QTimer"

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

Motion* ball = new Motion();

// create a scene
QGraphicsScene * scene = new QGraphicsScene();

QGraphicsRectItem* rect = new QGraphicsRectItem();

//show the view
view->show();

The Loop I talked about that.

for (int i = 0; i<int(j); i++)
{
    Sleeper::msleep(50);

double t = time->getTime() + i*0.05;
states2 = world.openLoopSys;

for (int i=0; i<12; i++)
{
    states1(i) = states2(i);
}

ball->run();
return a.exec(); // gets stuck there !!!
}

The Motion class is:

#include "motion.h"

Motion::Motion()
{
// create an item to put into the scene
setRect(0,0,20,30);
setPos(x(),y());

pos_x = 0;
pos_y = 0;
 }


void Motion::run()
{
// connect
 QTimer * timer = new QTimer();
connect(this,SIGNAL(timeout()),this,SLOT(move()));
timer->start(50);
}

void Motion::move()
{
   setPos(x(),y()-5);
 //    setPos(0.01*pos_x,-0.01*pos_y);
}

How can I solve this problem?

That's expected. You should pull `return a.exec()` out of the `for` loop. — vahancho, May 27 '20 at 11:56
@vahancho. By doing this, The results are not displayed real time and are displayed after the calculations — esmaeil, May 27 '20 at 11:59
You can't draw "in real time", painting only happens when the application returns to the event loop. — Frank Osterfeld, May 27 '20 at 12:01
@FrankOsterfeld. What is your suggestion for drawing Results in form of graphical And Real time with QT? — esmaeil, May 27 '20 at 12:06

QT Qapplication stuck in "return a.exec() " in calculation Loop

0 Answers0