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Dynamic Handling of Hundreds of UI elements

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  • M mrsurge

    @kshegunov

    QList<QLineEdit *> list = ui->doubleSpinBox->children<QLineEdit *>();
    foreach (QLineEdit * item, list)
        item->installEventFilter(this);
    

    returns

    **error: 'QLineEdit' does not refer to a value
    QList<QLineEdit > list = ui->doubleSpinBox->children<QLineEdit >();

    in my compiler. Remember I may be doing something really stupid, I'm new at qt

    kshegunovK Offline
    kshegunovK Offline
    kshegunov
    Moderators
    wrote on last edited by
    #6

    @mrsurge
    No, the problem is with my code, it happens sometimes when I don't double-check my examples. The proper function to use would be QObject::findChildren. I usually use it similarly to this:

    QList<QLineEdit *> list = ui->doubleSpinBox->findChildren<QLineEdit *>(QString(), Qt::FindDirectChildrenOnly);
    

    This should compile fine.

    Kind regards.

    Read and abide by the Qt Code of Conduct

    M 1 Reply Last reply
    0
    • kshegunovK kshegunov

      @mrsurge
      No, the problem is with my code, it happens sometimes when I don't double-check my examples. The proper function to use would be QObject::findChildren. I usually use it similarly to this:

      QList<QLineEdit *> list = ui->doubleSpinBox->findChildren<QLineEdit *>(QString(), Qt::FindDirectChildrenOnly);
      

      This should compile fine.

      Kind regards.

      M Offline
      M Offline
      mrsurge
      wrote on last edited by mrsurge
      #7

      @kshegunov
      your right that did compile just fine, but it only works for doubleSpinBox not doubleSpinBox_2 - doubleSpinBox_312

      kshegunovK 1 Reply Last reply
      0
      • M mrsurge

        @kshegunov
        your right that did compile just fine, but it only works for doubleSpinBox not doubleSpinBox_2 - doubleSpinBox_312

        kshegunovK Offline
        kshegunovK Offline
        kshegunov
        Moderators
        wrote on last edited by kshegunov
        #8

        @mrsurge

        Just apply the same principle:

        MainWindow::MainWindow(QWidget *parent)
            : QMainWindow(parent), ui(new Ui::MainWindow)
        {
            ui->setupUi(this);
        
            QList<QSpinBox *> sbList = findChildren<QSpinBox *>(QString(), Qt::FindDirectChildrenOnly);
            foreach (QSpinBox * spinBox, sbList)  {
                    spinBox->installEventFilter(this);  //< Do you need this??
        
                    QList<QLineEdit *> leList = spinBox->findChildren<QLineEdit *>(QString(), Qt::FindDirectChildrenOnly);
                    foreach (QLineEdit * lineEdit, leList)
                        lineEdit->installEventFilter(this);
            }
        }
        

        Read and abide by the Qt Code of Conduct

        M 1 Reply Last reply
        1
        • kshegunovK kshegunov

          @mrsurge

          Just apply the same principle:

          MainWindow::MainWindow(QWidget *parent)
              : QMainWindow(parent), ui(new Ui::MainWindow)
          {
              ui->setupUi(this);
          
              QList<QSpinBox *> sbList = findChildren<QSpinBox *>(QString(), Qt::FindDirectChildrenOnly);
              foreach (QSpinBox * spinBox, sbList)  {
                      spinBox->installEventFilter(this);  //< Do you need this??
          
                      QList<QLineEdit *> leList = spinBox->findChildren<QLineEdit *>(QString(), Qt::FindDirectChildrenOnly);
                      foreach (QLineEdit * lineEdit, leList)
                          lineEdit->installEventFilter(this);
              }
          }
          
          M Offline
          M Offline
          mrsurge
          wrote on last edited by mrsurge
          #9

          @kshegunov
          This worked :

          QList<QDoubleSpinBox *> sbList = ui->centralWidget->findChildren<QDoubleSpinBox *>(QString());
          foreach (QDoubleSpinBox * spinBox, sbList)  {
                      //spinBox->installEventFilter(this);  //< Do you need this??//<-no I don't
          
             QList<QLineEdit *> leList = spinBox->findChildren<QLineEdit *>(QString(), Qt::FindDirectChildrenOnly);
             foreach (QLineEdit * lineEdit, leList)
                          lineEdit->installEventFilter(this);
          }
          

          many thanks for steering me in the right direction.

          now on to saving the item to the specific line item

          kshegunovK 1 Reply Last reply
          0
          • M mrsurge

            @kshegunov
            This worked :

            QList<QDoubleSpinBox *> sbList = ui->centralWidget->findChildren<QDoubleSpinBox *>(QString());
            foreach (QDoubleSpinBox * spinBox, sbList)  {
                        //spinBox->installEventFilter(this);  //< Do you need this??//<-no I don't
            
               QList<QLineEdit *> leList = spinBox->findChildren<QLineEdit *>(QString(), Qt::FindDirectChildrenOnly);
               foreach (QLineEdit * lineEdit, leList)
                            lineEdit->installEventFilter(this);
            }
            

            many thanks for steering me in the right direction.

            now on to saving the item to the specific line item

            kshegunovK Offline
            kshegunovK Offline
            kshegunov
            Moderators
            wrote on last edited by
            #10

            @mrsurge
            Yes, of course, I forgot we're in a main window. Anyway, I'm glad it worked. One note, though, if possible use the QObject::findChildren with Qt::FindDirectChildrenOnly so Qt will not go about recursively looking for all. If your spin boxes are in layouts, but not inside other widgets, this should also work:

            QList<QDoubleSpinBox *> sbList = ui->centralWidget->findChildren<QDoubleSpinBox *>(QString(), Qt::FindDirectChildrenOnly);
            

            Kind regards.

            Read and abide by the Qt Code of Conduct

            M 1 Reply Last reply
            0
            • kshegunovK kshegunov

              @mrsurge
              Yes, of course, I forgot we're in a main window. Anyway, I'm glad it worked. One note, though, if possible use the QObject::findChildren with Qt::FindDirectChildrenOnly so Qt will not go about recursively looking for all. If your spin boxes are in layouts, but not inside other widgets, this should also work:

              QList<QDoubleSpinBox *> sbList = ui->centralWidget->findChildren<QDoubleSpinBox *>(QString(), Qt::FindDirectChildrenOnly);
              

              Kind regards.

              M Offline
              M Offline
              mrsurge
              wrote on last edited by
              #11

              @kshegunov

              ok now how do I return a value from the dialog box to the doubleSpinBox that was clicked?

              kshegunovK 1 Reply Last reply
              0
              • M mrsurge

                @kshegunov

                ok now how do I return a value from the dialog box to the doubleSpinBox that was clicked?

                kshegunovK Offline
                kshegunovK Offline
                kshegunov
                Moderators
                wrote on last edited by
                #12

                @mrsurge
                I've provided some guidelines here.
                If this is working,

                QList<QLineEdit *> leList = spinBox->findChildren<QLineEdit *>(QString(), Qt::FindDirectChildrenOnly);
                

                then the line edit has a QSpinBox for a parent. You have the line edit that'd been clicked here:

                void MainWindow::saveDataToLineEdit(QWidget * widget)
                {
                    QLineEdit * lineEdit = qobject_cast<QLineEdit *>(widget);
                    // ... Then the line edit parent is ...
                    QSpinBox * spinBox = qobject_cast<QSpinBox *>(lineEdit->parent());
                    // ... and so on ...
                }
                

                Read and abide by the Qt Code of Conduct

                M 1 Reply Last reply
                0
                • kshegunovK kshegunov

                  @mrsurge
                  I've provided some guidelines here.
                  If this is working,

                  QList<QLineEdit *> leList = spinBox->findChildren<QLineEdit *>(QString(), Qt::FindDirectChildrenOnly);
                  

                  then the line edit has a QSpinBox for a parent. You have the line edit that'd been clicked here:

                  void MainWindow::saveDataToLineEdit(QWidget * widget)
                  {
                      QLineEdit * lineEdit = qobject_cast<QLineEdit *>(widget);
                      // ... Then the line edit parent is ...
                      QSpinBox * spinBox = qobject_cast<QSpinBox *>(lineEdit->parent());
                      // ... and so on ...
                  }
                  
                  M Offline
                  M Offline
                  mrsurge
                  wrote on last edited by mrsurge
                  #13

                  @kshegunov said:

                  bool MainWindow::eventFilter(QObject * obj, QEvent * event)
                  {
                  if(event->type() == QEvent::MouseButtonPress)
                  {
                  Dialog mdialog;

                      QSignalMapper mapper(&mdialog);
                      mapper.setMapping(qobject_cast<QWidget *>(obj));
                      QObject::connect(&mdialog, SIGNAL(accepted()), &mapper, SLOT(map()));
                      QObject::connect(&mapper, SIGNAL(mapped(QWidget *)), this, SLOT(saveDataToLineEdit(QWidget *)));
                  
                      mdialog.exec();
                  }
                  return false;
                  

                  }

                  my compiler says

                  mapper.setMapping(qobject_cast<QWidget *>(obj));
                  

                  requires a second argument

                  mapper.setMapping(qobject_cast<QWidget *>(obj),0);
                  

                  works but i have no idea what thats doing

                  kshegunovK 1 Reply Last reply
                  0
                  • M mrsurge

                    @kshegunov said:

                    bool MainWindow::eventFilter(QObject * obj, QEvent * event)
                    {
                    if(event->type() == QEvent::MouseButtonPress)
                    {
                    Dialog mdialog;

                        QSignalMapper mapper(&mdialog);
                        mapper.setMapping(qobject_cast<QWidget *>(obj));
                        QObject::connect(&mdialog, SIGNAL(accepted()), &mapper, SLOT(map()));
                        QObject::connect(&mapper, SIGNAL(mapped(QWidget *)), this, SLOT(saveDataToLineEdit(QWidget *)));
                    
                        mdialog.exec();
                    }
                    return false;
                    

                    }

                    my compiler says

                    mapper.setMapping(qobject_cast<QWidget *>(obj));
                    

                    requires a second argument

                    mapper.setMapping(qobject_cast<QWidget *>(obj),0);
                    

                    works but i have no idea what thats doing

                    kshegunovK Offline
                    kshegunovK Offline
                    kshegunov
                    Moderators
                    wrote on last edited by
                    #14

                    @mrsurge
                    Yes, I forgot the sender. That should be:

                    mapper.setMapping(&mdialog, qobject_cast<QWidget *>(obj));
                    

                    QSignalMapper is a simple utility class to provide mapping of signals without parameters to signals/slots with a single parameter. This is done, because QDialog::accepted has no notion of the QLineEdit that triggers the event filter, so what the line does is simply to remap the signal to a slot that accepts the QLineEdit object as a parameter.

                    Kind regards.

                    Read and abide by the Qt Code of Conduct

                    M 1 Reply Last reply
                    0
                    • kshegunovK kshegunov

                      @mrsurge
                      Yes, I forgot the sender. That should be:

                      mapper.setMapping(&mdialog, qobject_cast<QWidget *>(obj));
                      

                      QSignalMapper is a simple utility class to provide mapping of signals without parameters to signals/slots with a single parameter. This is done, because QDialog::accepted has no notion of the QLineEdit that triggers the event filter, so what the line does is simply to remap the signal to a slot that accepts the QLineEdit object as a parameter.

                      Kind regards.

                      M Offline
                      M Offline
                      mrsurge
                      wrote on last edited by
                      #15

                      @kshegunov

                      Ok I have a separate form, cpp, and .h for my dialog, does all this still apply? do i need to add anything to my dialog.cpp or .h?

                      kshegunovK 1 Reply Last reply
                      0
                      • M mrsurge

                        @kshegunov

                        Ok I have a separate form, cpp, and .h for my dialog, does all this still apply? do i need to add anything to my dialog.cpp or .h?

                        kshegunovK Offline
                        kshegunovK Offline
                        kshegunov
                        Moderators
                        wrote on last edited by
                        #16

                        @mrsurge
                        Hello,

                        Ok I have a separate form, cpp, and .h for my dialog, does all this still apply? do i need to add anything to my dialog.cpp or .h?

                        It shouldn't matter how you initialize the dialog, provided you call QDialog::accept() at the appropriate place, i.e. when a save/ok button is clicked.

                        Kind regards.

                        Read and abide by the Qt Code of Conduct

                        1 Reply Last reply
                        0

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