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Edit variables from other widget of QStackedWidget

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  • J jsulm
    9 Dec 2019, 12:06

    @hobbyProgrammer said in Edit variables from other widget of QStackedWidget:

    But won't that instantly trigger the showResult?

    No, why should it? connect() does not call anything. It just connects the signal to the slot. You have to emit the signal in order the slot being called. This is how signal/slot works.

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    hobbyProgrammer
    wrote on 9 Dec 2019, 12:13 last edited by
    #5

    @jsulm Thank you! It works.

    1 Reply Last reply
    0
    • J jsulm
      9 Dec 2019, 12:06

      @hobbyProgrammer said in Edit variables from other widget of QStackedWidget:

      But won't that instantly trigger the showResult?

      No, why should it? connect() does not call anything. It just connects the signal to the slot. You have to emit the signal in order the slot being called. This is how signal/slot works.

      H Offline
      H Offline
      hobbyProgrammer
      wrote on 9 Dec 2019, 13:53 last edited by
      #6

      @jsulm on my advanced construction it doesn't seem to work.
      I have a mainWindow and a QWidget. The widget contains a promoted QGraphicsView. I'd like to retreive information from the QGraphicsView to the mainWindow.
      I already tried by emitting a signal in QGraphicsView and connect it in the QWidget to a slot that sets a public integer to that value and send a signal for MainWindow. Then I go to the mainWindow and connect the signal from QWidget to a slot that handles the rest.

      It doesn't go to the signal in the QWidget.

      this is the code in the QWidget:

      #include "overview.h"
      #include "ui_overview.h"
      
      Overview::Overview(QWidget *parent) :
          QWidget(parent),
          ui(new Ui::Overview)
      {
          ui->setupUi(this);
          overviewView *ovView = qobject_cast<overviewView*>(ui->graphicsView);
          connect(ovView, &overviewView::valAdded, this, &Overview::giveSignalToMainWindow);
      }
      
      Overview::~Overview()
      {
          delete ui;
      }
      
      void Overview::giveSignalToMainWindow()
      {
          qDebug() << "overview";
          emit editFinished();
          val = ui->graphicsView->value;
          qDebug() << "Overview ui->graphicsView->value: "<< ui->graphicsView->value;
      }
      
      J 1 Reply Last reply 9 Dec 2019, 14:17
      0
      • H hobbyProgrammer
        9 Dec 2019, 13:53

        @jsulm on my advanced construction it doesn't seem to work.
        I have a mainWindow and a QWidget. The widget contains a promoted QGraphicsView. I'd like to retreive information from the QGraphicsView to the mainWindow.
        I already tried by emitting a signal in QGraphicsView and connect it in the QWidget to a slot that sets a public integer to that value and send a signal for MainWindow. Then I go to the mainWindow and connect the signal from QWidget to a slot that handles the rest.

        It doesn't go to the signal in the QWidget.

        this is the code in the QWidget:

        #include "overview.h"
        #include "ui_overview.h"
        
        Overview::Overview(QWidget *parent) :
            QWidget(parent),
            ui(new Ui::Overview)
        {
            ui->setupUi(this);
            overviewView *ovView = qobject_cast<overviewView*>(ui->graphicsView);
            connect(ovView, &overviewView::valAdded, this, &Overview::giveSignalToMainWindow);
        }
        
        Overview::~Overview()
        {
            delete ui;
        }
        
        void Overview::giveSignalToMainWindow()
        {
            qDebug() << "overview";
            emit editFinished();
            val = ui->graphicsView->value;
            qDebug() << "Overview ui->graphicsView->value: "<< ui->graphicsView->value;
        }
        
        J Offline
        J Offline
        jsulm
        Lifetime Qt Champion
        wrote on 9 Dec 2019, 14:17 last edited by
        #7

        @hobbyProgrammer I'm not sure I understand: do you mean slot connected to editFinished() is not called?

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

        H 1 Reply Last reply 9 Dec 2019, 14:20
        0
        • J jsulm
          9 Dec 2019, 14:17

          @hobbyProgrammer I'm not sure I understand: do you mean slot connected to editFinished() is not called?

          H Offline
          H Offline
          hobbyProgrammer
          wrote on 9 Dec 2019, 14:20 last edited by
          #8

          @jsulm No I mean that Overview::giveSignalToMainWindow is not even called.

          1 Reply Last reply
          0
          • H Offline
            H Offline
            hobbyProgrammer
            wrote on 9 Dec 2019, 14:26 last edited by
            #9
            void overviewView::loadFromCSV()
            {
                QString fileName = "C://users//user1//downloads//data.csv";
                QFile csvFile(fileName);
                QStringList dataList;
                if(csvFile.open(QIODevice::ReadOnly))
                {
                    QString data;
                    data = csvFile.readAll();
                    dataList = data.split('\n');
                    csvFile.close();
                }
            
                for(int i = 0; i < dataList.size(); i++)
                {
                    QString data2 = dataList.at(i);
                    QStringList dataList = data2.split(",");
                    for(int j = 0; j < dataList.size(); j++)
                    {
                        val = dataList.at(j);
                    }
                }
            
                emit valAdded();
                qDebug() << "overviewview: " << val;
            }
            
            J 1 Reply Last reply 9 Dec 2019, 14:29
            0
            • H hobbyProgrammer
              9 Dec 2019, 14:26
              void overviewView::loadFromCSV()
              {
                  QString fileName = "C://users//user1//downloads//data.csv";
                  QFile csvFile(fileName);
                  QStringList dataList;
                  if(csvFile.open(QIODevice::ReadOnly))
                  {
                      QString data;
                      data = csvFile.readAll();
                      dataList = data.split('\n');
                      csvFile.close();
                  }
              
                  for(int i = 0; i < dataList.size(); i++)
                  {
                      QString data2 = dataList.at(i);
                      QStringList dataList = data2.split(",");
                      for(int j = 0; j < dataList.size(); j++)
                      {
                          val = dataList.at(j);
                      }
                  }
              
                  emit valAdded();
                  qDebug() << "overviewview: " << val;
              }
              
              J Offline
              J Offline
              jsulm
              Lifetime Qt Champion
              wrote on 9 Dec 2019, 14:29 last edited by
              #10

              @hobbyProgrammer You made sure overviewView::valAdded was called?
              Do you really have only one overviewView instance (I'm asking because this is a mistake people often do :-))?

              Is ovView not nullptr here:

              overviewView *ovView = qobject_cast<overviewView*>(ui->graphicsView);
              

              ?

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

              H 1 Reply Last reply 9 Dec 2019, 14:39
              0
              • J jsulm
                9 Dec 2019, 14:29

                @hobbyProgrammer You made sure overviewView::valAdded was called?
                Do you really have only one overviewView instance (I'm asking because this is a mistake people often do :-))?

                Is ovView not nullptr here:

                overviewView *ovView = qobject_cast<overviewView*>(ui->graphicsView);
                

                ?

                H Offline
                H Offline
                hobbyProgrammer
                wrote on 9 Dec 2019, 14:39 last edited by
                #11

                @jsulm I added qDebug() << ovView
                and it gave me this:

                overviewView(0x1fef8160, name="graphicsView")
                

                so it doesn't seem to be a nullptr.
                Also I have only 1 ovView.

                J 1 Reply Last reply 10 Dec 2019, 06:42
                0
                • H hobbyProgrammer
                  9 Dec 2019, 14:39

                  @jsulm I added qDebug() << ovView
                  and it gave me this:

                  overviewView(0x1fef8160, name="graphicsView")
                  

                  so it doesn't seem to be a nullptr.
                  Also I have only 1 ovView.

                  J Offline
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                  jsulm
                  Lifetime Qt Champion
                  wrote on 10 Dec 2019, 06:42 last edited by
                  #12

                  @hobbyProgrammer Check what connect() returns.

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

                  H 1 Reply Last reply 10 Dec 2019, 07:57
                  0
                  • J jsulm
                    10 Dec 2019, 06:42

                    @hobbyProgrammer Check what connect() returns.

                    H Offline
                    H Offline
                    hobbyProgrammer
                    wrote on 10 Dec 2019, 07:57 last edited by
                    #13

                    @jsulm it returns true

                    J 1 Reply Last reply 10 Dec 2019, 15:22
                    0
                    • H hobbyProgrammer
                      10 Dec 2019, 07:57

                      @jsulm it returns true

                      J Offline
                      J Offline
                      jsulm
                      Lifetime Qt Champion
                      wrote on 10 Dec 2019, 15:22 last edited by
                      #14

                      @hobbyProgrammer Do you actually have event loop running when you emit the signal?

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

                      1 Reply Last reply
                      0

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                      10 Dec 2019, 15:22

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