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Dynamic Handling of Hundreds of UI elements

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  • kshegunovK kshegunov

    @mrsurge
    Hello,
    For one you could make Qt do the casting for you:

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

    And then in your event filter you could connect the dialog's accepted signal to the line edit:

    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;
    }
    
    void MainWindow::saveDataToLineEdit(QWidget * widget)
    {
        QLineEdit * lineEdit = qobject_cast<QLineEdit *>(widget);
        Dialog * dialog = qobject_cast<Dialog *>(sender()->parent());
        // ... Transfer data between the dialog and the line edit here ...
    }
    

    Is this what you were asking for?

    Kind regards.

    EDIT:
    I've moved the mapper to the stack, as it's not necessary to create it with new (since you're using a modal dialog).

    M Offline
    M Offline
    mrsurge
    wrote on last edited by mrsurge
    #5

    @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 1 Reply Last reply
    0
    • 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
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