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How to center a column with a checkbox in QTableView?

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  • Christian EhrlicherC Offline
    Christian EhrlicherC Offline
    Christian Ehrlicher
    Lifetime Qt Champion
    wrote on last edited by
    #5

    And how to you set the value from the model? Using setIndexWidget is definitely no way to go.
    @gurpal2000 : fell free to provide a patch to Qt so it gets integrated... you can add me as reviewer.

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

    1 Reply Last reply
    3
    • G gurpal2000

      This is such a common use case that there are literally no trustworthy examples for beginners for this case.

      It'd make QT more of a pleasure to get into if there were examples for these common patterns. I agree with the OP that this is just a large amount of code for such a simple thing.

      Maybe even the components should just support this out of the box with minimal code. Why hasn't this been done though?

      VRoninV Offline
      VRoninV Offline
      VRonin
      wrote on last edited by VRonin
      #6
      This post is deleted!
      1 Reply Last reply
      1
      • VRoninV Offline
        VRoninV Offline
        VRonin
        wrote on last edited by
        #7
        This post is deleted!
        1 Reply Last reply
        1
        • VRoninV Offline
          VRoninV Offline
          VRonin
          wrote on last edited by
          #8

          Try something like this:

          #include <QApplication>
          #include <QTableWidget>
          #include <QStandardItemModel>
          #include <QProxyStyle>
          #include <QStyleOptionViewItem>
          enum {
            CheckAlignmentRole = Qt::UserRole + Qt::CheckStateRole + Qt::TextAlignmentRole
          };
          class CenteredBoxProxy : public QProxyStyle{
          public:
              QRect subElementRect(QStyle::SubElement element, const QStyleOption *option, const QWidget *widget) const override{
                  const QRect baseRes = QProxyStyle::subElementRect(element, option, widget);
                  if(element==SE_ItemViewItemCheckIndicator){
                      const QStyleOptionViewItem* const itemOpt = qstyleoption_cast<const QStyleOptionViewItem*>(option) ;
                      Q_ASSERT(itemOpt);
                      const QVariant alignData = itemOpt->index.data(CheckAlignmentRole);
                      if(alignData.isNull())
                         return baseRes;
                      const QRect itemRect = option->rect;
                      Q_ASSERT(itemRect.width()>baseRes.width() && itemRect.height()>baseRes.height());
                      const int alignFlag = alignData.toInt();
                      int x=0,y=0;
                      if(alignFlag & Qt::AlignLeft){
                          x=baseRes.x();
                      }
                      else if(alignFlag & Qt::AlignRight){
                          x=itemRect.x() + itemRect.width() - (baseRes.x()-itemRect.x())-baseRes.width();
                      }
                      else if(alignFlag & Qt::AlignHCenter){
                          x=itemRect.x() + (itemRect.width()/2)-(baseRes.width()/2);
                      }
                      return QRect(QPoint(x,baseRes.y()), baseRes.size());
                  }
                  return baseRes;
              }
          };
          
          int main(int argc, char **argv)
          {
              QApplication app(argc,argv);
              app.setStyle(new CenteredBoxProxy);
              QTableView wid;
              QStandardItemModel* model = new QStandardItemModel(&wid);
              model->insertColumns(0,3);
              model->insertRows(0,10);
              for(int i=0;i<10;++i){
                  model->setData(model->index(i,0), i%2==0 ? Qt::Unchecked : Qt::Checked, Qt::CheckStateRole);
                  model->setData(model->index(i,0), Qt::AlignCenter, CheckAlignmentRole);
                  model->setData(model->index(i,1), i%2==0 ? Qt::Unchecked : Qt::Checked, Qt::CheckStateRole);
                  model->setData(model->index(i,2), i);
                  Q_ASSERT(model->item(i,0));
                  model->item(i,0)->setFlags(model->item(i,0)->flags() | Qt::ItemIsUserCheckable);
              }
              wid.setModel(model);
          
              wid.show();
              return app.exec();
          }
          
          R 1 Reply Last reply
          5
          • VRoninV VRonin

            Try something like this:

            #include <QApplication>
            #include <QTableWidget>
            #include <QStandardItemModel>
            #include <QProxyStyle>
            #include <QStyleOptionViewItem>
            enum {
              CheckAlignmentRole = Qt::UserRole + Qt::CheckStateRole + Qt::TextAlignmentRole
            };
            class CenteredBoxProxy : public QProxyStyle{
            public:
                QRect subElementRect(QStyle::SubElement element, const QStyleOption *option, const QWidget *widget) const override{
                    const QRect baseRes = QProxyStyle::subElementRect(element, option, widget);
                    if(element==SE_ItemViewItemCheckIndicator){
                        const QStyleOptionViewItem* const itemOpt = qstyleoption_cast<const QStyleOptionViewItem*>(option) ;
                        Q_ASSERT(itemOpt);
                        const QVariant alignData = itemOpt->index.data(CheckAlignmentRole);
                        if(alignData.isNull())
                           return baseRes;
                        const QRect itemRect = option->rect;
                        Q_ASSERT(itemRect.width()>baseRes.width() && itemRect.height()>baseRes.height());
                        const int alignFlag = alignData.toInt();
                        int x=0,y=0;
                        if(alignFlag & Qt::AlignLeft){
                            x=baseRes.x();
                        }
                        else if(alignFlag & Qt::AlignRight){
                            x=itemRect.x() + itemRect.width() - (baseRes.x()-itemRect.x())-baseRes.width();
                        }
                        else if(alignFlag & Qt::AlignHCenter){
                            x=itemRect.x() + (itemRect.width()/2)-(baseRes.width()/2);
                        }
                        return QRect(QPoint(x,baseRes.y()), baseRes.size());
                    }
                    return baseRes;
                }
            };
            
            int main(int argc, char **argv)
            {
                QApplication app(argc,argv);
                app.setStyle(new CenteredBoxProxy);
                QTableView wid;
                QStandardItemModel* model = new QStandardItemModel(&wid);
                model->insertColumns(0,3);
                model->insertRows(0,10);
                for(int i=0;i<10;++i){
                    model->setData(model->index(i,0), i%2==0 ? Qt::Unchecked : Qt::Checked, Qt::CheckStateRole);
                    model->setData(model->index(i,0), Qt::AlignCenter, CheckAlignmentRole);
                    model->setData(model->index(i,1), i%2==0 ? Qt::Unchecked : Qt::Checked, Qt::CheckStateRole);
                    model->setData(model->index(i,2), i);
                    Q_ASSERT(model->item(i,0));
                    model->item(i,0)->setFlags(model->item(i,0)->flags() | Qt::ItemIsUserCheckable);
                }
                wid.setModel(model);
            
                wid.show();
                return app.exec();
            }
            
            R Offline
            R Offline
            Robert Hairgrove
            wrote on last edited by
            #9

            @VRonin ... THANK YOU! This works very well.

            1 Reply Last reply
            0
            • R Offline
              R Offline
              Robert Hairgrove
              wrote on last edited by
              #10

              I saw this in qstyle.h in the "enum SubElement":

                  SE_ViewItemCheckIndicator, // ### Qt 6: remove
                  SE_ItemViewItemCheckIndicator = SE_ViewItemCheckIndicator,
              

              ...
              I assume that SE_ItemViewItemCheckIndicator is safe to continue to use?

              1 Reply Last reply
              1
              • SGaistS Offline
                SGaistS Offline
                SGaist
                Lifetime Qt Champion
                wrote on last edited by
                #11

                Hi,

                Yes it is.

                Interested in AI ? www.idiap.ch
                Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                1 Reply Last reply
                1
                • R Offline
                  R Offline
                  Robert Hairgrove
                  wrote on last edited by
                  #12

                  I have adapted the code a little bit to take care of the focus rectangle which is also centered now. Of course, I will include a link to this forum topic in my code, which will be open source (thanks again, @VRonin :)

                  #ifndef CENTEREDBOXPROXY_HPP
                  #define CENTEREDBOXPROXY_HPP
                  
                  #include <QProxyStyle>
                  #include <QStyleOptionViewItem>
                  
                  enum {
                    CheckAlignmentRole = Qt::UserRole
                                       + Qt::CheckStateRole
                                       + Qt::TextAlignmentRole
                  };
                  
                  class CenteredBoxProxy : public QProxyStyle {
                  public:
                    QRect subElementRect(QStyle::SubElement element,
                                         const QStyleOption *option,
                                         const QWidget *widget) const override {
                      const QRect baseRes = QProxyStyle::subElementRect(element, option, widget);
                      const QRect itemRect = option->rect;
                      QRect retval = baseRes;
                      QSize sz = baseRes.size();
                  
                      const QStyleOptionViewItem* const
                          itemOpt = qstyleoption_cast<const QStyleOptionViewItem*>(option);
                  
                      if (itemOpt) {
                        const QVariant alignData = itemOpt->index.data(CheckAlignmentRole);
                        if(!alignData.isNull()) {
                          const uint alignFlag = alignData.toUInt();
                          if (alignFlag & Qt::AlignHCenter) {
                            if (element == SE_ItemViewItemCheckIndicator) {
                              int x = itemRect.x() + (itemRect.width()/2) - (baseRes.width()/2);
                              retval = QRect( QPoint(x, baseRes.y()), sz);
                            } else if (element == SE_ItemViewItemFocusRect) {
                              sz.setWidth(baseRes.width()+baseRes.x());
                              retval = QRect( QPoint(0, baseRes.y()), sz);
                            }
                          }
                        }
                      }
                      return retval;
                    }
                  };
                  
                  #endif
                  
                  
                  VRoninV 1 Reply Last reply
                  2
                  • SGaistS Offline
                    SGaistS Offline
                    SGaist
                    Lifetime Qt Champion
                    wrote on last edited by
                    #13

                    Thanks for the update !

                    Interested in AI ? www.idiap.ch
                    Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                    1 Reply Last reply
                    0
                    • R Robert Hairgrove

                      I have adapted the code a little bit to take care of the focus rectangle which is also centered now. Of course, I will include a link to this forum topic in my code, which will be open source (thanks again, @VRonin :)

                      #ifndef CENTEREDBOXPROXY_HPP
                      #define CENTEREDBOXPROXY_HPP
                      
                      #include <QProxyStyle>
                      #include <QStyleOptionViewItem>
                      
                      enum {
                        CheckAlignmentRole = Qt::UserRole
                                           + Qt::CheckStateRole
                                           + Qt::TextAlignmentRole
                      };
                      
                      class CenteredBoxProxy : public QProxyStyle {
                      public:
                        QRect subElementRect(QStyle::SubElement element,
                                             const QStyleOption *option,
                                             const QWidget *widget) const override {
                          const QRect baseRes = QProxyStyle::subElementRect(element, option, widget);
                          const QRect itemRect = option->rect;
                          QRect retval = baseRes;
                          QSize sz = baseRes.size();
                      
                          const QStyleOptionViewItem* const
                              itemOpt = qstyleoption_cast<const QStyleOptionViewItem*>(option);
                      
                          if (itemOpt) {
                            const QVariant alignData = itemOpt->index.data(CheckAlignmentRole);
                            if(!alignData.isNull()) {
                              const uint alignFlag = alignData.toUInt();
                              if (alignFlag & Qt::AlignHCenter) {
                                if (element == SE_ItemViewItemCheckIndicator) {
                                  int x = itemRect.x() + (itemRect.width()/2) - (baseRes.width()/2);
                                  retval = QRect( QPoint(x, baseRes.y()), sz);
                                } else if (element == SE_ItemViewItemFocusRect) {
                                  sz.setWidth(baseRes.width()+baseRes.x());
                                  retval = QRect( QPoint(0, baseRes.y()), sz);
                                }
                              }
                            }
                          }
                          return retval;
                        }
                      };
                      
                      #endif
                      
                      
                      VRoninV Offline
                      VRoninV Offline
                      VRonin
                      wrote on last edited by
                      #14

                      @Robert-Hairgrove said in How to center a column with a checkbox in QTableView?:

                      retval = QRect( QPoint(0, baseRes.y()), sz);

                      This seams dodgy. Could you try making the second column the one with the centred checkbox and see if it still works as expected

                      R 1 Reply Last reply
                      0
                      • VRoninV VRonin

                        @Robert-Hairgrove said in How to center a column with a checkbox in QTableView?:

                        retval = QRect( QPoint(0, baseRes.y()), sz);

                        This seams dodgy. Could you try making the second column the one with the centred checkbox and see if it still works as expected

                        R Offline
                        R Offline
                        Robert Hairgrove
                        wrote on last edited by Robert Hairgrove
                        #15

                        @VRonin ... Looks OK to me. But thanks for the suggestion, because I should have tried this myself before posting the update (and I hadn't).

                        The normal behavior for item views seems to be this:

                        1. When the widget has focus, the view item's focus indicator fills out the background of the entire item rectangle and is darker in color (e.g. when navigating the view with the arrow keys);
                        2. When the widget goes out of focus (e.g. clicking outside of the entire widget), there is another focus indicator which is shown, lighter in color, but only over the text normally accompanying the checkbox -- not over the checkbox itself.

                        When the checkbox has no text (i.e. when it is centered), this seems a little odd. This update "fixes" the non-focussed focus rectangle. :)

                        1 Reply Last reply
                        0
                        • VRoninV Offline
                          VRoninV Offline
                          VRonin
                          wrote on last edited by
                          #16

                          Sorry I should have been more specific, my only concern is on having 0 as first argument to QPoint there as I think it's in coordinates of the scrollarea not of the item itself so my concern is that if the checkbox is in any column except the first column, retval would still point somewhere in the first column

                          1 Reply Last reply
                          0
                          • A.A.SEZENA A.A.SEZEN

                            You can try a different use...
                            Add QWidget instead of QCheckBox in your QTableView.
                            for example:

                             QWidget * checkWidget = new QWidget(this);
                             QCheckBox * check = new QCheckBox(this);
                             QHBoxLayout * checkLayout = new QHBoxLayout(checkWidget);
                              checkLayout->addWidget(check);
                              checkLayout->setAlignment(Qt::AlignCenter);
                              checkLayout->setContentsMargins(0,0,0,0);
                            

                            // add checkWidget to QTableView

                            A Offline
                            A Offline
                            Alexey Serebryakov
                            wrote on last edited by
                            #17

                            @A-A-SEZEN It does not work.

                            A.A.SEZENA 1 Reply Last reply
                            0
                            • A Alexey Serebryakov

                              @A-A-SEZEN It does not work.

                              A.A.SEZENA Offline
                              A.A.SEZENA Offline
                              A.A.SEZEN
                              wrote on last edited by
                              #18

                              @Alexey-Serebryakov .. I am actively using those codes. With only one difference. QTableWidget instead of QTableView.

                                                  else if(yapi->slAlan[i] == "ISLEM") {
                                                      auto * checkWidget = new QWidget(this);
                                                      auto * check = new QCheckBox(this);
                                                      auto * checkLayout = new QHBoxLayout(checkWidget);
                                                      checkLayout->addWidget(check);
                                                      checkLayout->setAlignment(Qt::AlignCenter);
                                                      checkLayout->setContentsMargins(0,0,0,0);
                                                      check->setMaximumWidth(yapi->slColumnWidth[i].toInt());
                                                      check->setChecked(q.value(yapi->slAlan[i]).toString() == "2");
                                                      check->setCheckable(!bPasif);
                                                      if(!renk.isEmpty()) {
                                                          checkWidget->setStyleSheet(tr("background-color: %1").arg(renk));
                                                      }
                                                      tablo->setCellWidget(iSatir, i, checkWidget);
                                                      checkWidget->setContextMenuPolicy(Qt::CustomContextMenu);
                                                      connect(checkWidget, &QMenu::customContextMenuRequested, this, &kucukbas::doganPopupMenu);
                                                      connect(check, &QCheckBox::stateChanged, this, [=]() {
                                                          doganKaydet("ISLEM",
                                                                      check->isChecked() ? "2" : "0",
                                                                      idDogan());
                                                      });
                                                  }
                              
                              
                              1 Reply Last reply
                              0

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