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Set Delay Timer

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  • M 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 ?

    VRoninV Offline
    VRoninV Offline
    VRonin
    wrote on last edited by
    #14

    @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

    "La mort n'est rien, mais vivre vaincu et sans gloire, c'est mourir tous les jours"
    ~Napoleon Bonaparte

    On a crusade to banish setIndexWidget() from the holy land of Qt

    M 1 Reply Last reply
    0
    • M Offline
      M Offline
      mpergand
      wrote on last edited by mpergand
      #15

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

      Why ?
      Explain any good reason to avoid it.

      J.HilkJ 1 Reply Last reply
      0
      • M mpergand

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

        Why ?
        Explain any good reason to avoid it.

        J.HilkJ Offline
        J.HilkJ Offline
        J.Hilk
        Moderators
        wrote on last edited by J.Hilk
        #16

        @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


        Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


        Q: What's that?
        A: It's blue light.
        Q: What does it do?
        A: It turns blue.

        1 Reply Last reply
        0
        • VRoninV 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

          M Offline
          M Offline
          mpergand
          wrote on last edited by
          #17

          @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.

          VRoninV 1 Reply Last reply
          0
          • M 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.

            VRoninV Offline
            VRoninV Offline
            VRonin
            wrote on last edited by
            #18

            @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)

            "La mort n'est rien, mais vivre vaincu et sans gloire, c'est mourir tous les jours"
            ~Napoleon Bonaparte

            On a crusade to banish setIndexWidget() from the holy land of Qt

            M 1 Reply Last reply
            3
            • VRoninV 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)

              M Offline
              M Offline
              mpergand
              wrote on last edited by
              #19

              @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.

              1 Reply Last reply
              0
              • VRoninV Offline
                VRoninV Offline
                VRonin
                wrote on last edited by VRonin
                #20

                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

                "La mort n'est rien, mais vivre vaincu et sans gloire, c'est mourir tous les jours"
                ~Napoleon Bonaparte

                On a crusade to banish setIndexWidget() from the holy land of Qt

                1 Reply Last reply
                0
                • Y Offline
                  Y Offline
                  Yrandom
                  wrote on last edited by Yrandom
                  #21

                  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

                  mrjjM 1 Reply Last reply
                  0
                  • Y 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

                    mrjjM Offline
                    mrjjM Offline
                    mrjj
                    Lifetime Qt Champion
                    wrote on last edited by mrjj
                    #22

                    @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

                    Y 1 Reply Last reply
                    2
                    • mrjjM 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

                      Y Offline
                      Y Offline
                      Yrandom
                      wrote on last edited by
                      #23

                      @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
                      }
                      
                      
                      
                      
                      mrjjM 1 Reply Last reply
                      0
                      • Y 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
                        }
                        
                        
                        
                        
                        mrjjM Offline
                        mrjjM Offline
                        mrjj
                        Lifetime Qt Champion
                        wrote on last edited by
                        #24

                        @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

                        Y 1 Reply Last reply
                        1
                        • mrjjM 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

                          Y Offline
                          Y Offline
                          Yrandom
                          wrote on last edited by
                          #25

                          @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
                          //
                          
                          
                          1 Reply Last reply
                          0
                          • M Offline
                            M Offline
                            mchinand
                            wrote on last edited by
                            #26

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

                            1 Reply Last reply
                            2

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