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How to refresh data on horizontal header of QTableWidget?

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  • tovaxT Offline
    tovaxT Offline
    tovax
    wrote on last edited by
    #1

    Hi, all!

    I want to display cyclic data on horizontal header of QTableWidget, the cycle is 10ms.
    So I create a timer with 10ms interval, and set text in its timeout() slot:

    for (int32_t i = 0; i < 16; i++) {
        tableWidget->horizontalHeaderItem(i)->setText(QString::number(myData[i]));
    }
    

    But this causes the UI to be unsmooth.

    Then, I tried:

    for (int32_t i = 0; i < 16; i++) {
        tableWidget->item(0, i)->setText(QString::number(myData[i]));
    }
    

    It can refresh data smoothly.

    How to refresh data on horizontal header of QTableWidget, please?

    Best Regards!

    1 Reply Last reply
    0
    • tovaxT tovax

      @Christian-Ehrlicher
      Frequence has been modified to10Hz, and no difference from 100Hz.
      Best Regards!

      mrjjM Offline
      mrjjM Offline
      mrjj
      Lifetime Qt Champion
      wrote on last edited by
      #9

      @tovax
      Hi
      For each setHeaderData, you emit a headerDataChanged
      so i would guess on lots of view repaints are issued. (for each axisIndex)
      Since you always want to refresh whole header, i was wondering if you could test with
      delaying the headerDataChanged signal until after the loop.

      for (int32_t axisIndex = Axis::Index::Min; axisIndex <= Axis::Index::Max; axisIndex++) {
              tableModel->setHeaderData(axisIndex, Qt::Horizontal, posCmd.at(axisIndex), Qt::DisplayRole);
          }
       
      tableModel->HeaderChange(Axis::Index::Min, Axis::Index::Max ); // this issues the signal with 
                        headerDataChanged(orientation,Min,Max );
      
      
      tovaxT 1 Reply Last reply
      0
      • Christian EhrlicherC Offline
        Christian EhrlicherC Offline
        Christian Ehrlicher
        Lifetime Qt Champion
        wrote on last edited by
        #2

        10ms - 100Hz - how should someone ever read this?

        Your way is correct, if you need speed use a custom model derived from QAbstractTableModel and QTableView.

        Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
        Visit the Qt Academy at https://academy.qt.io/catalog

        tovaxT 2 Replies Last reply
        2
        • Christian EhrlicherC Christian Ehrlicher

          10ms - 100Hz - how should someone ever read this?

          Your way is correct, if you need speed use a custom model derived from QAbstractTableModel and QTableView.

          tovaxT Offline
          tovaxT Offline
          tovax
          wrote on last edited by
          #3

          @Christian-Ehrlicher
          Hi, thank you very much for your reply.
          "how should someone ever read this?", I think so, too.
          But my customer want to see the data refresh quickly...
          I have tried 100ms, unsmooth too.
          I will try to use QTableView, thanks again!

          1 Reply Last reply
          0
          • SGaistS Offline
            SGaistS Offline
            SGaist
            Lifetime Qt Champion
            wrote on last edited by
            #4

            Hi,

            They should also take into account the current refresh rates which are at 60fps on high end hardware.

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            Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

            tovaxT 1 Reply Last reply
            1
            • SGaistS SGaist

              Hi,

              They should also take into account the current refresh rates which are at 60fps on high end hardware.

              tovaxT Offline
              tovaxT Offline
              tovax
              wrote on last edited by
              #5

              @SGaist
              Hi,
              Thank you for your reply, it's very useful information, I have reduced the timer frequency to 10Hz.

              1 Reply Last reply
              0
              • Christian EhrlicherC Christian Ehrlicher

                10ms - 100Hz - how should someone ever read this?

                Your way is correct, if you need speed use a custom model derived from QAbstractTableModel and QTableView.

                tovaxT Offline
                tovaxT Offline
                tovax
                wrote on last edited by
                #6

                @Christian-Ehrlicher
                I rewrite my code to use QAbstractTableModel and QTableView, but the UI still not smooth.
                The key code is "setHeaderData" in onPosCmd function, when I block it, the UI run smoothly.
                Here is the relevant code:

                QVariant MotionSheetTableModel::headerData(int32_t section, Qt::Orientation orientation, int32_t role) const
                {
                    if (role == Qt::DisplayRole) {
                        if (orientation == Qt::Horizontal) {
                            return horizontalHeaderList[section] + "\n" + posCmdList[section];
                        } else if (orientation == Qt::Vertical) {
                            return verticalHeaderList[section];
                        } else {
                            return QVariant();
                        }
                    }
                    return QVariant();
                }
                
                bool MotionSheetTableModel::setHeaderData(int32_t section, Qt::Orientation orientation, const QVariant &value, int32_t role)
                {
                    if (role == Qt::DisplayRole) {
                        posCmdList[section] = QString::number(value.value<double>(), 'f', 2);
                        emit headerDataChanged(orientation, section, section);
                    }
                    return true;
                }
                
                /* onPosCmd: triggered by timer(10Hz) */
                void MotionSheetWidget::onPosCmd(QVector<double> vector)
                {
                    posCmd = vector;
                
                    for (int32_t axisIndex = Axis::Index::Min; axisIndex <= Axis::Index::Max; axisIndex++) {
                        tableModel->setHeaderData(axisIndex, Qt::Horizontal, posCmd.at(axisIndex), Qt::DisplayRole);
                    }
                }
                

                Could you give me some suggestion, please?

                Best Regards!

                1 Reply Last reply
                0
                • Christian EhrlicherC Offline
                  Christian EhrlicherC Offline
                  Christian Ehrlicher
                  Lifetime Qt Champion
                  wrote on last edited by
                  #7

                  @tovax said in How to refresh data on horizontal header of QTableWidget?:

                  Could you give me some suggestion, please?

                  As above - don't try to update gui stuff at 100Hz.

                  Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
                  Visit the Qt Academy at https://academy.qt.io/catalog

                  tovaxT 1 Reply Last reply
                  0
                  • Christian EhrlicherC Christian Ehrlicher

                    @tovax said in How to refresh data on horizontal header of QTableWidget?:

                    Could you give me some suggestion, please?

                    As above - don't try to update gui stuff at 100Hz.

                    tovaxT Offline
                    tovaxT Offline
                    tovax
                    wrote on last edited by
                    #8

                    @Christian-Ehrlicher
                    Frequence has been modified to10Hz, and no difference from 100Hz.
                    Best Regards!

                    mrjjM 1 Reply Last reply
                    0
                    • tovaxT tovax

                      @Christian-Ehrlicher
                      Frequence has been modified to10Hz, and no difference from 100Hz.
                      Best Regards!

                      mrjjM Offline
                      mrjjM Offline
                      mrjj
                      Lifetime Qt Champion
                      wrote on last edited by
                      #9

                      @tovax
                      Hi
                      For each setHeaderData, you emit a headerDataChanged
                      so i would guess on lots of view repaints are issued. (for each axisIndex)
                      Since you always want to refresh whole header, i was wondering if you could test with
                      delaying the headerDataChanged signal until after the loop.

                      for (int32_t axisIndex = Axis::Index::Min; axisIndex <= Axis::Index::Max; axisIndex++) {
                              tableModel->setHeaderData(axisIndex, Qt::Horizontal, posCmd.at(axisIndex), Qt::DisplayRole);
                          }
                       
                      tableModel->HeaderChange(Axis::Index::Min, Axis::Index::Max ); // this issues the signal with 
                                        headerDataChanged(orientation,Min,Max );
                      
                      
                      tovaxT 1 Reply Last reply
                      0
                      • mrjjM mrjj

                        @tovax
                        Hi
                        For each setHeaderData, you emit a headerDataChanged
                        so i would guess on lots of view repaints are issued. (for each axisIndex)
                        Since you always want to refresh whole header, i was wondering if you could test with
                        delaying the headerDataChanged signal until after the loop.

                        for (int32_t axisIndex = Axis::Index::Min; axisIndex <= Axis::Index::Max; axisIndex++) {
                                tableModel->setHeaderData(axisIndex, Qt::Horizontal, posCmd.at(axisIndex), Qt::DisplayRole);
                            }
                         
                        tableModel->HeaderChange(Axis::Index::Min, Axis::Index::Max ); // this issues the signal with 
                                          headerDataChanged(orientation,Min,Max );
                        
                        
                        tovaxT Offline
                        tovaxT Offline
                        tovax
                        wrote on last edited by
                        #10

                        @mrjj
                        Hi,
                        According to your suggestion, I blocked "headerDataChanged" signal, and add this public function to Model Class:

                        void MotionSheetTableModel::HeaderChange(int32_t first, int32_t last)
                        {
                            emit headerDataChanged(Qt::Horizontal, first, last);
                        }
                        

                        But no significant improvement in test results.
                        Is my understanding right, please?

                        Best Regards!

                        mrjjM 1 Reply Last reply
                        0
                        • tovaxT tovax

                          @mrjj
                          Hi,
                          According to your suggestion, I blocked "headerDataChanged" signal, and add this public function to Model Class:

                          void MotionSheetTableModel::HeaderChange(int32_t first, int32_t last)
                          {
                              emit headerDataChanged(Qt::Horizontal, first, last);
                          }
                          

                          But no significant improvement in test results.
                          Is my understanding right, please?

                          Best Regards!

                          mrjjM Offline
                          mrjjM Offline
                          mrjj
                          Lifetime Qt Champion
                          wrote on last edited by mrjj
                          #11

                          @tovax
                          If by blocked you mean
                          // emit headerDataChanged(orientation, section, section);
                          and call your new function (HeaderChange) after the loop then we are on same page.

                          Ok so that didnt speed it up. :(
                          Im not sure how altering the list
                          posCmdList[section] = QString::number(value.value<double>(), 'f', 2);
                          would be slow.

                          I think i would insert some timing functions
                          (https://doc.qt.io/qt-5/qelapsedtimer.html is handy for that)
                          and see where the time is spend.
                          Now we know its not from pure updates so we need to find the spot where the time is used.

                          Also 10 times pr second does not sound that massive but I would try other values to see
                          where the sweet spot it.

                          tovaxT 1 Reply Last reply
                          0
                          • mrjjM mrjj

                            @tovax
                            If by blocked you mean
                            // emit headerDataChanged(orientation, section, section);
                            and call your new function (HeaderChange) after the loop then we are on same page.

                            Ok so that didnt speed it up. :(
                            Im not sure how altering the list
                            posCmdList[section] = QString::number(value.value<double>(), 'f', 2);
                            would be slow.

                            I think i would insert some timing functions
                            (https://doc.qt.io/qt-5/qelapsedtimer.html is handy for that)
                            and see where the time is spend.
                            Now we know its not from pure updates so we need to find the spot where the time is used.

                            Also 10 times pr second does not sound that massive but I would try other values to see
                            where the sweet spot it.

                            tovaxT Offline
                            tovaxT Offline
                            tovax
                            wrote on last edited by
                            #12

                            @mrjj
                            I add this debug code:

                            bool MotionSheetTableModel::setHeaderData(int32_t section, Qt::Orientation orientation, const QVariant &value, int32_t role)
                            {
                                Q_UNUSED(orientation);
                                if (role == Qt::DisplayRole) {
                                    QElapsedTimer timer;
                                    timer.start();
                                    posCmdList[section] = QString::number(value.value<double>(), 'f', 2);
                                    qDebug() << "MotionSheetTableModel::setHeaderData" << timer.nsecsElapsed();
                                    // emit headerDataChanged(orientation, section, section);
                                }
                            
                                return true;
                            }
                            

                            Result as follow:

                            MotionSheetTableModel::setHeaderData 28158
                            MotionSheetTableModel::setHeaderData 27646
                            MotionSheetTableModel::setHeaderData 28158
                            MotionSheetTableModel::setHeaderData 27646
                            MotionSheetTableModel::setHeaderData 28158
                            MotionSheetTableModel::setHeaderData 28670
                            MotionSheetTableModel::setHeaderData 53244
                            MotionSheetTableModel::setHeaderData 31741
                            MotionSheetTableModel::setHeaderData 28158
                            MotionSheetTableModel::setHeaderData 28158
                            MotionSheetTableModel::setHeaderData 28670
                            MotionSheetTableModel::setHeaderData 28158
                            MotionSheetTableModel::setHeaderData 28158
                            MotionSheetTableModel::setHeaderData 27646
                            MotionSheetTableModel::setHeaderData 28158
                            MotionSheetTableModel::setHeaderData 28158
                            MotionSheetTableModel::setHeaderData 28670
                            MotionSheetTableModel::setHeaderData 27646
                            MotionSheetTableModel::setHeaderData 28670
                            MotionSheetTableModel::setHeaderData 28670
                            

                            Nanoseconds, It looks fast enough.

                            Best Regards!

                            1 Reply Last reply
                            0
                            • mrjjM Offline
                              mrjjM Offline
                              mrjj
                              Lifetime Qt Champion
                              wrote on last edited by
                              #13

                              Hi
                              Yes it does indeed look ok fast.
                              I would then disable the new function to check if app still feels
                              laggy and its related to View redrawing.
                              ( not send the headerDataChanged signal)

                              i know you wont see the updates then but its a ok test to see if you are stressing
                              the event loop anyways.

                              If app still laggy with View not repainting it means the event loop is stressed.

                              tovaxT 3 Replies Last reply
                              0
                              • mrjjM mrjj

                                Hi
                                Yes it does indeed look ok fast.
                                I would then disable the new function to check if app still feels
                                laggy and its related to View redrawing.
                                ( not send the headerDataChanged signal)

                                i know you wont see the updates then but its a ok test to see if you are stressing
                                the event loop anyways.

                                If app still laggy with View not repainting it means the event loop is stressed.

                                tovaxT Offline
                                tovaxT Offline
                                tovax
                                wrote on last edited by
                                #14

                                @mrjj
                                Hi,
                                When not send the headerDataChanged signal, the app run smoothly.
                                By the way, if the data display in the table cell, the app run smoothly too.

                                1 Reply Last reply
                                0
                                • mrjjM mrjj

                                  Hi
                                  Yes it does indeed look ok fast.
                                  I would then disable the new function to check if app still feels
                                  laggy and its related to View redrawing.
                                  ( not send the headerDataChanged signal)

                                  i know you wont see the updates then but its a ok test to see if you are stressing
                                  the event loop anyways.

                                  If app still laggy with View not repainting it means the event loop is stressed.

                                  tovaxT Offline
                                  tovaxT Offline
                                  tovax
                                  wrote on last edited by
                                  #15

                                  @mrjj
                                  Here is the system time in relevent function:

                                  onPosCmd - start "22:06:33:908"
                                  setHeaderData 0 "22:06:33:908"
                                  setHeaderData 1 "22:06:33:908"
                                  setHeaderData 2 "22:06:33:909"
                                  setHeaderData 3 "22:06:33:909"
                                  setHeaderData 4 "22:06:33:909"
                                  setHeaderData 5 "22:06:33:910"
                                  setHeaderData 6 "22:06:33:910"
                                  setHeaderData 7 "22:06:33:910"
                                  setHeaderData 8 "22:06:33:911"
                                  setHeaderData 9 "22:06:33:911"
                                  setHeaderData 10 "22:06:33:911"
                                  setHeaderData 11 "22:06:33:911"
                                  setHeaderData 12 "22:06:33:912"
                                  setHeaderData 13 "22:06:33:912"
                                  setHeaderData 14 "22:06:33:912"
                                  setHeaderData 15 "22:06:33:913"
                                  onPosCmd - end "22:06:33:913"
                                  headerData 0 "22:06:33:953"
                                  headerData 1 "22:06:33:954"
                                  headerData 8 "22:06:33:956"
                                  headerData 9 "22:06:33:957"
                                  headerData 10 "22:06:33:958"
                                  headerData 11 "22:06:33:959"
                                  headerData 12 "22:06:33:960"
                                  headerData 13 "22:06:33:961"
                                  headerData 14 "22:06:33:962"
                                  headerData 15 "22:06:33:963"
                                  headerData 0 "22:06:33:976"
                                  headerData 1 "22:06:33:978"
                                  headerData 8 "22:06:33:980"
                                  headerData 9 "22:06:33:982"
                                  headerData 10 "22:06:33:984"
                                  headerData 11 "22:06:33:985"
                                  headerData 12 "22:06:33:987"
                                  headerData 13 "22:06:33:989"
                                  headerData 14 "22:06:33:990"
                                  headerData 15 "22:06:33:992"
                                  

                                  It doesn't seem to waste much time on signaling.

                                  1 Reply Last reply
                                  0
                                  • Christian EhrlicherC Offline
                                    Christian EhrlicherC Offline
                                    Christian Ehrlicher
                                    Lifetime Qt Champion
                                    wrote on last edited by Christian Ehrlicher
                                    #16

                                    What resize mode do you use? And can you provide a small test example so we can run it e.g. with callgrind to see where the time is spend.

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                                    tovaxT 1 Reply Last reply
                                    0
                                    • mrjjM mrjj

                                      Hi
                                      Yes it does indeed look ok fast.
                                      I would then disable the new function to check if app still feels
                                      laggy and its related to View redrawing.
                                      ( not send the headerDataChanged signal)

                                      i know you wont see the updates then but its a ok test to see if you are stressing
                                      the event loop anyways.

                                      If app still laggy with View not repainting it means the event loop is stressed.

                                      tovaxT Offline
                                      tovaxT Offline
                                      tovax
                                      wrote on last edited by
                                      #17

                                      @mrjj
                                      From "setHeaderData" to "headerData" waste 40ms. Will this have an impact, please?

                                      1 Reply Last reply
                                      0
                                      • Christian EhrlicherC Christian Ehrlicher

                                        What resize mode do you use? And can you provide a small test example so we can run it e.g. with callgrind to see where the time is spend.

                                        tovaxT Offline
                                        tovaxT Offline
                                        tovax
                                        wrote on last edited by
                                        #18

                                        @Christian-Ehrlicher
                                        Hi,
                                        The resize mode is QHeaderView::Stretch, this is the config of tableView:

                                            tableView = new QTableView(this);
                                            tableView->setModel(tableModel);
                                        
                                            tableView->setFrameShape(QFrame::NoFrame);
                                        
                                            tableView->horizontalHeader()->setVisible(true); 
                                            tableView->horizontalHeader()->setSectionResizeMode(QHeaderView::Stretch);
                                        
                                            tableView->verticalHeader()->setVisible(true); 
                                            tableView->verticalHeader()->setSectionResizeMode(QHeaderView::Stretch);
                                        
                                            tableView->setSelectionBehavior(QAbstractItemView::SelectItems);
                                            tableView->setSelectionMode(QAbstractItemView::ExtendedSelection);
                                            tableView->setAlternatingRowColors(true);
                                        
                                        1 Reply Last reply
                                        0
                                        • Christian EhrlicherC Offline
                                          Christian EhrlicherC Offline
                                          Christian Ehrlicher
                                          Lifetime Qt Champion
                                          wrote on last edited by
                                          #19

                                          @tovax said in How to refresh data on horizontal header of QTableWidget?:

                                          The resize mode is QHeaderView::Stretch

                                          Ok, this is at least not a problem for the update. So please provide a small testcase.

                                          Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
                                          Visit the Qt Academy at https://academy.qt.io/catalog

                                          tovaxT 2 Replies Last reply
                                          0
                                          • Christian EhrlicherC Christian Ehrlicher

                                            @tovax said in How to refresh data on horizontal header of QTableWidget?:

                                            The resize mode is QHeaderView::Stretch

                                            Ok, this is at least not a problem for the update. So please provide a small testcase.

                                            tovaxT Offline
                                            tovaxT Offline
                                            tovax
                                            wrote on last edited by
                                            #20
                                            This post is deleted!
                                            1 Reply Last reply
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