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Button inherit stylesheet for no reason

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qpushbuttmouseeventstylesheet
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  • L legitnameyo
    23 Apr 2019, 16:54

    Yes it seems as if you're right. How do I solve this? I haven't had this issue before when I declared both the_button and last_button as QPushButton instead of my custom QPushButton class

    M Offline
    M Offline
    mrjj
    Lifetime Qt Champion
    wrote on 23 Apr 2019, 19:03 last edited by mrjj
    #5

    @legitnameyo

    • . How do I solve this

    By doing it the Qt way.
    I assume you have a grid of buttons and only one to be selected at a given time so if you select another
    it should be drawn as normal and new as pressed. At least that's how i read your code.

    You can do that very easily with a QButtonGroup and the Checkable property on each button.
    Then Qt does the housekeeping for you.
    You can style the look when "selected" with QPushButton:checked
    That way you dont need last_button and you can apply the stylesheet to the parent and it will just work
    with setting / resetting the style.

    alt text

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    result
    alt text

    1 Reply Last reply
    6
    • J JonB
      23 Apr 2019, 17:14

      @legitnameyo
      I'm not an expert C++-er, but I don't get how your code works.

      private:
              QClickAgnostic * last_button = qobject_cast<QClickAgnostic *> ( sender() );
      

      What is sender() at the point this is initialized?

      void MainWindow::on_btn_left_click() {
          last_button->setStyleSheet(QString("QPushButton {color: #444444; background: #e6e6e6; border: 2px solid #cccccc; border-width: 0px 0px 2px 0px;} QPushButton:hover {border: 2px black solid; color: #333333;background-color: #F7F7F7;} QPushButton:pressed {background: #e6e6e6;}"));
      

      What is the value of last_button the very first time this function gets called?

      J Offline
      J Offline
      J.Hilk
      Moderators
      wrote on 23 Apr 2019, 19:13 last edited by
      #6

      @JonB

      What is sender() at the point this is initialized?

      as it's a qobject_cast and doesn't crash on start up, most likely a nullptr?

      What is the value of last_button the very first time this function gets called?

      as it's not checked against 0, it should fail. Maybe luck?

      using sender() is bad design anyway. One shouldn't use it if possible.

      @mrjj posted a nice qt alternative I would suggest the OP to use that ;)


      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
      4
      • L Offline
        L Offline
        legitnameyo
        wrote on 25 Apr 2019, 12:21 last edited by
        #7

        How do I implement this code way? I do my UI in code since that's what I prefer. This is what I've got so far and it isn't working...

        QButtonGroup *g_btns = new QButtonGroup(this);
        /* all buttons are created and I add the buttons in about this way*/
        btn1->setCheckable(true);
        //etc..
        g_btns->addButton(btn1);
        g_btns->addButton(btn2);
        g_btns->addButton(btn3);
        // etc ...
        
              connect(g_btns, SIGNAL(buttonClicked(int)), this, SLOT(onGroupButtonClicked(int)));
        
        void MainWindow::onGroupButtonClicked(int btn_id) {
        qDebug() << "clicked!";
        }
        

        And this gives me nothing. The onGroupButtonClicked does not activate.

        J J 2 Replies Last reply 25 Apr 2019, 12:25
        0
        • L legitnameyo
          25 Apr 2019, 12:21

          How do I implement this code way? I do my UI in code since that's what I prefer. This is what I've got so far and it isn't working...

          QButtonGroup *g_btns = new QButtonGroup(this);
          /* all buttons are created and I add the buttons in about this way*/
          btn1->setCheckable(true);
          //etc..
          g_btns->addButton(btn1);
          g_btns->addButton(btn2);
          g_btns->addButton(btn3);
          // etc ...
          
                connect(g_btns, SIGNAL(buttonClicked(int)), this, SLOT(onGroupButtonClicked(int)));
          
          void MainWindow::onGroupButtonClicked(int btn_id) {
          qDebug() << "clicked!";
          }
          

          And this gives me nothing. The onGroupButtonClicked does not activate.

          J Offline
          J Offline
          J.Hilk
          Moderators
          wrote on 25 Apr 2019, 12:25 last edited by
          #8

          @legitnameyo I never used QButtonGroup, but a quick look into the documentation tells me, you never gave your added buttons an ID

          void QButtonGroup::addButton(QAbstractButton *button, int id = -1)

          I'm guessing here and say, that buttons with the ID of -1 do not emit the buttonClicked(int) signal


          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.

          M 1 Reply Last reply 25 Apr 2019, 12:47
          3
          • L legitnameyo
            25 Apr 2019, 12:21

            How do I implement this code way? I do my UI in code since that's what I prefer. This is what I've got so far and it isn't working...

            QButtonGroup *g_btns = new QButtonGroup(this);
            /* all buttons are created and I add the buttons in about this way*/
            btn1->setCheckable(true);
            //etc..
            g_btns->addButton(btn1);
            g_btns->addButton(btn2);
            g_btns->addButton(btn3);
            // etc ...
            
                  connect(g_btns, SIGNAL(buttonClicked(int)), this, SLOT(onGroupButtonClicked(int)));
            
            void MainWindow::onGroupButtonClicked(int btn_id) {
            qDebug() << "clicked!";
            }
            

            And this gives me nothing. The onGroupButtonClicked does not activate.

            J Offline
            J Offline
            jsulm
            Lifetime Qt Champion
            wrote on 25 Apr 2019, 12:26 last edited by
            #9

            @legitnameyo It should work. Do you get any warnings at runtime (related to connect)?
            Is g_btns in connect() really the one you're creating at the beginning of the code snippet you provided?

            https://forum.qt.io/topic/113070/qt-code-of-conduct

            1 Reply Last reply
            3
            • J J.Hilk
              25 Apr 2019, 12:25

              @legitnameyo I never used QButtonGroup, but a quick look into the documentation tells me, you never gave your added buttons an ID

              void QButtonGroup::addButton(QAbstractButton *button, int id = -1)

              I'm guessing here and say, that buttons with the ID of -1 do not emit the buttonClicked(int) signal

              M Offline
              M Offline
              mrjj
              Lifetime Qt Champion
              wrote on 25 Apr 2019, 12:47 last edited by
              #10

              @J.Hilk
              Was a good guess,
              but it seems, it will use negative values for auto numbering and does, in fact, emit them.

                QButtonGroup *buttonGroup = new QButtonGroup(this);
              
                  buttonGroup->addButton( ui->pushButton_2);
                  buttonGroup->addButton( ui->pushButton_3);
                  buttonGroup->addButton( ui->pushButton_4);
                  buttonGroup->addButton( ui->pushButton_5);
              
              
                  connect(buttonGroup, static_cast<void(QButtonGroup::*)(int)>(&QButtonGroup::buttonClicked),
                  [ = ](int id) {
                      qDebug() << id;
                  });
              
              

              outputs.
              -2
              -2
              -3
              -5
              -4

              J 1 Reply Last reply 25 Apr 2019, 12:56
              1
              • M mrjj
                25 Apr 2019, 12:47

                @J.Hilk
                Was a good guess,
                but it seems, it will use negative values for auto numbering and does, in fact, emit them.

                  QButtonGroup *buttonGroup = new QButtonGroup(this);
                
                    buttonGroup->addButton( ui->pushButton_2);
                    buttonGroup->addButton( ui->pushButton_3);
                    buttonGroup->addButton( ui->pushButton_4);
                    buttonGroup->addButton( ui->pushButton_5);
                
                
                    connect(buttonGroup, static_cast<void(QButtonGroup::*)(int)>(&QButtonGroup::buttonClicked),
                    [ = ](int id) {
                        qDebug() << id;
                    });
                
                

                outputs.
                -2
                -2
                -3
                -5
                -4

                J Offline
                J Offline
                J.Hilk
                Moderators
                wrote on 25 Apr 2019, 12:56 last edited by
                #11

                @mrjj
                I find this behavior actually not very intuitive.

                That the id increases when non is specified, maybe...
                But a higher negative number !?


                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.

                M 1 Reply Last reply 25 Apr 2019, 13:01
                0
                • J J.Hilk
                  25 Apr 2019, 12:56

                  @mrjj
                  I find this behavior actually not very intuitive.

                  That the id increases when non is specified, maybe...
                  But a higher negative number !?

                  M Offline
                  M Offline
                  mrjj
                  Lifetime Qt Champion
                  wrote on 25 Apr 2019, 13:01 last edited by
                  #12

                  @J.Hilk
                  Yep. I had to test it as sounded odd it would auto number with negative values.
                  But it seems design wants to allow to have some auto numbered and some manually
                  even i don't see why.

                  J 1 Reply Last reply 25 Apr 2019, 13:13
                  1
                  • M mrjj
                    25 Apr 2019, 13:01

                    @J.Hilk
                    Yep. I had to test it as sounded odd it would auto number with negative values.
                    But it seems design wants to allow to have some auto numbered and some manually
                    even i don't see why.

                    J Offline
                    J Offline
                    JonB
                    wrote on 25 Apr 2019, 13:13 last edited by
                    #13

                    @mrjj
                    Negative-decrementing auto-numbers are usually used for "anonymous" items while allowing positive numbers for explicit use. Then the numbers won't clash.

                    1 Reply Last reply
                    3
                    • L Offline
                      L Offline
                      legitnameyo
                      wrote on 25 Apr 2019, 16:18 last edited by legitnameyo
                      #14

                      There is NO error such as this one below

                      QMetaObject::connectSlotsByName: No matching signal for onGroupButtonClicked(int)
                      

                      And yes g_btns is defined only ONCE. Everything is in the order I got it in my code. However one thing that might change things up is that I use a custom class for my buttons called QClickAgnostic, which inherits from QPushButton as such above

                      and the buttons are created like this

                              QClickAgnostic *btn = new QClickAgnostic(ui->frame_of_btns);
                      
                      K 1 Reply Last reply 25 Apr 2019, 17:14
                      0
                      • L legitnameyo
                        25 Apr 2019, 16:18

                        There is NO error such as this one below

                        QMetaObject::connectSlotsByName: No matching signal for onGroupButtonClicked(int)
                        

                        And yes g_btns is defined only ONCE. Everything is in the order I got it in my code. However one thing that might change things up is that I use a custom class for my buttons called QClickAgnostic, which inherits from QPushButton as such above

                        and the buttons are created like this

                                QClickAgnostic *btn = new QClickAgnostic(ui->frame_of_btns);
                        
                        K Offline
                        K Offline
                        KillerSmath
                        wrote on 25 Apr 2019, 17:14 last edited by
                        #15

                        @legitnameyo
                        You need to notify the ButtonGroup about the click event.

                        I took a look at the source code of the abstractbutton and noticed the button directly notifies the group that it was clicked. But you broke this step when you reimplemented the MouseReleaseEvent function.

                        See a snippet of this step.

                        void QAbstractButton::mouseReleaseEvent(QMouseEvent *e)
                        {
                        ...
                            if (hitButton(e->pos())) {
                                d->repeatTimer.stop();
                                d->click(); // call click function 
                                e->accept();
                            } else {
                                setDown(false);
                                e->ignore();
                            }
                        }
                        void QAbstractButtonPrivate::click()
                        {
                            ...
                            if (guard)
                                emitReleased();
                            if (guard)
                                emitClicked(); // call emitClicked
                        }
                        
                        void QAbstractButtonPrivate::emitClicked()
                        {
                          ...
                        #if QT_CONFIG(buttongroup)
                            if (guard && group) {
                                emit group->buttonClicked(group->id(q)); // emit the signal
                                if (guard && group)
                                    emit group->buttonClicked(q); // emit the signal
                            }
                        #endif
                        }
                        

                        So, you can solve this problem calling the click() function inside MouseReleaseEvent.

                        void QClickAgnostic::mouseReleaseEvent(QMouseEvent *e) {
                            if(e->button() == Qt::LeftButton) {
                                click(); // called
                                emit leftClicked();
                            } else if(e->button() == Qt::RightButton) {
                                click(); // called
                                emit rightClicked();
                            }
                        }
                        

                        @Computer Science Student - Brazil
                        Web Developer and Researcher
                        “Sometimes it’s the people no one imagines anything of who do the things that no one can imagine.” - Alan Turing

                        M 1 Reply Last reply 25 Apr 2019, 17:22
                        5
                        • K KillerSmath
                          25 Apr 2019, 17:14

                          @legitnameyo
                          You need to notify the ButtonGroup about the click event.

                          I took a look at the source code of the abstractbutton and noticed the button directly notifies the group that it was clicked. But you broke this step when you reimplemented the MouseReleaseEvent function.

                          See a snippet of this step.

                          void QAbstractButton::mouseReleaseEvent(QMouseEvent *e)
                          {
                          ...
                              if (hitButton(e->pos())) {
                                  d->repeatTimer.stop();
                                  d->click(); // call click function 
                                  e->accept();
                              } else {
                                  setDown(false);
                                  e->ignore();
                              }
                          }
                          void QAbstractButtonPrivate::click()
                          {
                              ...
                              if (guard)
                                  emitReleased();
                              if (guard)
                                  emitClicked(); // call emitClicked
                          }
                          
                          void QAbstractButtonPrivate::emitClicked()
                          {
                            ...
                          #if QT_CONFIG(buttongroup)
                              if (guard && group) {
                                  emit group->buttonClicked(group->id(q)); // emit the signal
                                  if (guard && group)
                                      emit group->buttonClicked(q); // emit the signal
                              }
                          #endif
                          }
                          

                          So, you can solve this problem calling the click() function inside MouseReleaseEvent.

                          void QClickAgnostic::mouseReleaseEvent(QMouseEvent *e) {
                              if(e->button() == Qt::LeftButton) {
                                  click(); // called
                                  emit leftClicked();
                              } else if(e->button() == Qt::RightButton) {
                                  click(); // called
                                  emit rightClicked();
                              }
                          }
                          
                          M Offline
                          M Offline
                          mrjj
                          Lifetime Qt Champion
                          wrote on 25 Apr 2019, 17:22 last edited by
                          #16

                          @KillerSmath
                          Good digging !

                          1 Reply Last reply
                          1
                          • L Offline
                            L Offline
                            legitnameyo
                            wrote on 25 Apr 2019, 17:45 last edited by
                            #17

                            @KillerSmath fix did the work, combined with @mrjj QGroupButton! I added this code to style the pressed button

                            void MainWindow::onGroupButtonClicked(int btn_id) {
                                g_btns->button(btn_id)->setStyleSheet(QString("QPushButton {color: #444444; background: #cccccc; border: 2px solid #cccccc; border-width: 0px 0px 2px 0px;} QPushButton:hover {border: 2px black solid; color: #333333; background-color: #F7F7F7;} QPushButton:pressed {background: #cccccc;}"));
                            }
                            
                            

                            Thanks a lot guys!

                            1 Reply Last reply
                            1

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                            25 Apr 2019, 16:18

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