Set Delay Timer

J.Hilk

Usually during a while loop, all other tasks are suspendet until the loop or more precisely the function returns. That includes the paint/repaint event that is triggered by setStyleSheet().

QCoreApplication::processEvents() is an uncomely way to tell your app, "That with the function, do whatever else is qued".
The Int value you pass to processEvents is a max value in -I believe -ms, you give other Processes to finish their stuff, after that time your code after the call gets processed again.

a While loop now is calling that every eventloop-cycle

My advice, don't use it, if you have other options.

mpergand

A wait function like this:

void wait(float sec)
{
    QElapsedTimer timer;
    timer.start();

    while(! timer.hasExpired(sec*1000))
        QCoreApplication::processEvents();
}

allows you to simpy do that:

b->setStyleSheet("background-color:green");
wait(0.3);
b->setStyleSheet("background-color:red");

Pretty and clean isn't it ?

J.Hilk

@mpergand said in Set Delay Timer:

while(! timer.hasExpired(sec*1000))
    QCoreApplication::processEvents();

Pretty and clean isn't it ?

No, it's not!

Do not use QCoreApplication::processEvents if you can avoid it!

VRonin

@mpergand said in Set Delay Timer:

Pretty and clean isn't it ?

No it is not. it uses 75% of one of my CPU cores for absolutely nothing

mpergand

@j.hilk Do not use QCoreApplication::processEvents if you can avoid it!

Why ?
Explain any good reason to avoid it.

J.Hilk

@mpergand said in Set Delay Timer:

@j.hilk Do not use QCoreApplication::processEvents if you can avoid it!

Why ?
Explain any good reason to avoid it.

At least used in such a loop->
@VRonin said in Set Delay Timer:

No it is not. it uses 75% of one of my CPU cores for absolutely nothing

Its also contrarian to the event-driven programming approach

mpergand

@VRonin said in Set Delay Timer:

No it is not. it uses 75% of one of my CPU cores for absolutely nothing

For .3 sec not a big deal.
I agree, that it's should by used for short period only (< 1 sec)

The main drawback I know (i use the same principle on MacOS) is that it can leading to some reentrant call in some cases.

VRonin

@mpergand said in Set Delay Timer:

For .3 sec not a big deal.

It is. especially on mobile/embedded hardware. it's just bad design especially when alternatives based of QEventLoop exist (but of course use the async is ALWAYS the best design)

mpergand

@VRonin said in Set Delay Timer:

It is. especially on mobile/embedded hardware. it's just bad design especially when alternatives based of QEventLoop exist (but of course use the async is ALWAYS the best design)

Ok, add a small QThread::sleep should do the job as well.

Please, can you post an example of a wait function with a QEventLoop instead.

VRonin

add a small QThread::sleep should do the job as well

it does not, reason in link below

can you post an example of a wait function with a QEventLoop instead.

https://forum.qt.io/topic/78715/why-my-timer-is-not-emit-timeout-signal

Yrandom

WOW. All the discussion :)
First off all, thx for the answer.
I have one more question to fullfill my Project. I dont want to start new Topic.

I have a class GameKonfiguration
and class MainWindow
and the main()

#include "Konfiguration.h"
#include "MainWindow.h"
    
int main(int argc, char *argv[]) {
    // initialize resources, if needed
    // Q_INIT_RESOURCE(resfile);

    QApplication app(argc, argv);
    
    MainWindow *window = new MainWindow(&app);
    window->show();

    Konfiguration *konfiguration = new Konfiguration(&app,window);
    konfiguration->show();

    return app.exec();
}

in main

Now I make this Programm so far, that when i start, both Windows open and i can Change configuration and the gamefield show and user can Play and actually i can quit the game via configuration. everything fine

Now I want to Combine the menu bar from mainwindow and use the menu bar to open my configuration window.
However the Problem i have is now, i cant include Header a in Header b and Header b in Header a.

// mainwindow Header file
#include "ui_MainWindow.h"
#include <QApplication>
//some Header here

//try
#include "Konfiguration.h"
//-- not work because in Konfiguration.h i already include mainwindow.h in oder to use for the Slot etc


using namespace std;

class MainWindow : public QMainWindow {
   Q_OBJECT
private:
    Ui::MainWindow widget;
    QApplication *app;
    // Try
Konfiguration *confi;
    
public:
    MainWindow(QApplication*);
  //some function
    
signals:
    public slots:
      // function etc ........
       void openConfi();
};

 


// in mainwindow.cpp
// Open Game Configuration
    QObject::connect(widget.SpielKonfiguration,SIGNAL(triggered()),this,SLOT(openConfi()));
    
    // End Game
    QObject::connect(widget.SpielBeenden,SIGNAL(triggered()),app,SLOT(quit()));

 // Configuration Window
void MainWindow::openConfi(){
    // in this Slot , the configuration window should open
confi->show();
}

Konfiguration.h and cpp

#ifndef KONFIGURATION_H
#define KONFIGURATION_H


#include <QApplication>
#include "MainWindow.h"
// some Header here....

class Konfiguration : public QDialog{
    Q_OBJECT
    
private:
    QApplication *app;
  // here i create mainwindow pointer to Setup the gamefield
    MainWindow *spielFenster;    
       //some code here
public:
    Konfiguration(QApplication*, MainWindow*);
    virtual ~Konfiguration();     

    public slots:
        void clearText();
//      void updateTextN(QString);
//      void updateTextM(QString);
};


//konfiguration.cpp

// use the mainwindow pointer to set Slot 

  //Set N, M in VerschiebeSpiel
 QObject::connect(editN,SIGNAL(textChanged(QString)),spielFenster,SLOT(setN(QString)));
 QObject::connect(editM,SIGNAL(textChanged(QString)),spielFenster,SLOT(setM(QString)));

So how can I open the Konfiguration Window via the Menu bar of Mainwindow but I can still use the Konfiguration to configure the MainWindow ?

Muss be simple for you guys, but quite hard for newbie :)

thx for your help

mrjj

@Yrandom

the circular includes problem can often be solved with a forward of the class

so instead of ( in the other class header)
#include <myclass>

you just
do

class MyClass; // this is a forward

and you are allowed to have
class Other {
MyClass * mc;

Since all the use of the Myclass functions, are in the CPP file, it works.

In the CPP file you then include the actual header.

Not sure i explained it good :(

Please see
http://stackoverflow.com/questions/625799/resolve-header-include-circular-dependencies

Yrandom

@mrjj
thx for the quick answer.

Now I got build successfull but when I start the Programm and klick on menubar set configuration
I got Windows disconnection and have to quit

here is what i Changed

///////////////////////////////
// in mainwindow.h
// mainclass mainwindow
#include <QMenuBar>
#include <QAction>

class Konfiguration; // this is the other class

using namespace std;

class MainWindow : public QMainWindow {
   Q_OBJECT
private:
Konfiguration *confi;
//code
}

//////////////////////////
//mainwindow.cpp
#include "mainwindow.h"
#include "Konfiguration.h"

 // Configuration Window
void MainWindow::openConfi(){
//
// try to add something like confi = new Konfiguration(&app,this) like in the main() is not working either.
//
    confi->show();
// Debugger stoppt at show()
}

// in Konfiguration.h
#include "MainWindow.h"

class Konfiguration : public QDialog{
    Q_OBJECT
    
private:
code
}

mrjj

@Yrandom said in Set Delay Timer:

Konfiguration *confi;

Did you remeber to new it ?

Konfiguration *confi; is just a pointer :)

you MUST do
confi = new Konfiguration()

before using it for anything

Yrandom

@mrjj

:D my bad
i did that but i pas the function by reference

void MainWindow::openConfi(){
//
 //try to add something like confi = new Konfiguration(&app,this) like in the main() is not working either.
// pass by reference mistake :D
    confi->show();
// Debugger stoppt at show()
}

//
// IT work now. :D
//

mchinand

I wonder if this could be achieved using Property Animation instead of using timers and stylesheet manipulation.